Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s00203-024-03956-y

researchmap

Other Link： https://link.springer.com/article/10.1007/s00203-024-03956-y/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Mary Ann Liebert Inc  

DOI： 10.1089/fpd.2023.0064

researchmap

Other Link： https://www.liebertpub.com/doi/pdf/10.1089/fpd.2023.0064

Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

Background

The primary aim of this study was to investigate the occurrence, characteristics, and antimicrobial resistance patterns of various Shigella serogroups isolated from patients with acute diarrhea of the Infectious Diseases Hospital in Kolkata from 2011–2019.

Principal findings

During the study period, Shigella isolates were tested for their serogroups, antibiotic resistance pattern and virulence gene profiles. A total of 5.8% of Shigella spp. were isolated, among which S. flexneri (76.1%) was the highest, followed by S. sonnei (18.7%), S. boydii (3.4%), and S. dysenteriae (1.8%). Antimicrobial resistance against nalidixic acid was higher in almost all the Shigella isolates, while the resistance to β-lactamases, fluoroquinolones, tetracycline, and chloramphenicol diverged. The occurrence of multidrug resistance was found to be linked with various genes encoding drug-resistance, multiple mutations in the topoisomerase genes, and mobile genetic elements. All the isolates were positive for the invasion plasmid antigen H gene (ipaH). Dendrogram analysis of the plasmid and pulsed-field electrophoresis (PFGE) profiles revealed 70–80% clonal similarity among each Shigella serotype.

Conclusion

This comprehensive long-term surveillance report highlights the clonal diversity of clinical Shigella strains circulating in Kolkata, India, and shows alarming resistance trends towards recommended antibiotics. The elucidation of this study’s outcome is helpful not only in identifying emerging antimicrobial resistance patterns of Shigella spp. but also in developing treatment guidelines appropriate for this region.

DOI： 10.1371/journal.pntd.0011964

researchmap

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

DOI： 10.3389/fmicb.2024.1370093

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Development of safe, highly effective and affordable enteric fever vaccines is a global health priority. Live, oral typhoid vaccines induce strong mucosal immunity and long-term protection, but safety remains a concern. In contrast, efficacy wears off rapidly for injectable, polysaccharide-based vaccines, which elicit poor mucosal response. We previously reported Salmonella Typhi outer membrane protein, T2544 as a potential candidate for bivalent (S. Typhi and S. Paratyphi A) vaccine development. Here, we show that intranasal immunization with a subunit vaccine (chimera of T2544 and cholera toxin B subunit) induced strong systemic and intestinal mucosal immunity and protection from S. Typhi challenge in a mouse model. CTB-T2544 augmented gut-homing receptor expression on lymphocytes that produced Th1 and Th17 cytokines, secretory IgA in stool that inhibited bacterial motility and epithelial attachment, antibody recall response and affinity maturation with increased number of follicular helper T cells and CD4+ central and effector memory cells.

DOI： 10.1038/s41541-024-00812-4

researchmap

Other Link： https://www.nature.com/articles/s41541-024-00812-4

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: South Asia remains home to foodborne diseases caused by Vibrio species. We aimed to compile and update information on the epidemiology of vibriosis in South Asia. METHODS: For this systematic review and meta-analysis, we searched PubMed, Web of Science, EMBASE, and Google Scholar for studies related to vibriosis in South Asia published up to May 2023. A random-effects meta-analysis was used to estimate the pooled isolation rate of non-cholera-causing Vibrio species. RESULTS: In total 38 studies were included. Seven of these were case reports and 22 were included in the meta-analysis. Reported vibriosis cases were caused by non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis, and V. vulnificus. The overall pooled isolation rate was 4.0% (95% CI: 3.0-5.0%) in patients with diarrhea. Heterogeneity was high (I2= 98.0%). The isolation rate of non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis were 9.0 (95% CI: 7.0-10.0%), 1.0 (95% CI: 1.0-2.0%), and 2.0 (95% CI: 1.0-3.0%), respectively. Regarding V. parahaemolyticus, O3:K6 was the most frequently isolated serotype. Cases peaked during summer. Several studies reported antibiotic-resistant strains and those harboring extended-spectrum beta-lactamases genes. CONCLUSIONS: This study demonstrates a high burden of infections caused by non-cholera-causing Vibrio species in South Asia.

DOI： 10.1016/j.ijid.2024.01.022

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Background

Worldwide, noroviruses are the leading cause of acute gastroenteritis (AGE) in people of all age groups. In India, norovirus rates between 1.4 to 44.4% have been reported. Only a very few complete norovirus genome sequences from India have been reported.

Objective

To perform full genome sequencing of noroviruses circulating in India during 2017–2021, identify circulating genotypes, assess evolution including detection of recombination events.

Methodology

Forty-five archived norovirus-positive samples collected between October 2017 to July 2021 from patients with AGE from two hospitals in Kolkata, India were processed for full genome sequencing. Phylogenetic analysis, recombination breakpoint analysis and comprehensive mutation analysis were also performed.

Results

Full genome analysis of norovirus sequences revealed that strains belonging to genogroup (G)I were genotyped as GI.3[P13]. Among the different norovirus capsid-polymerase combinations, GII.3[P16], GII.4 Sydney[P16], GII.4 Sydney[P31], GII.13[P16], GII.16[P16] and GII.17 were identified. Phylogenetic analysis confirmed phylogenetic relatedness with previously reported norovirus strains and all viruses were analyzed by Simplot. GII[P16] viruses with multiple residue mutations within the non-structural region were detected among circulating GII.4 and GII.3 strains. Comprehensive mutation analysis and selection pressure analysis of GII[P16] viruses showed positive as well as negative selection sites. A GII.17 strain (NICED-BCH-11889) had an untypeable polymerase type, closely related to GII[P38].

Conclusion

This study highlights the circulation of diverse norovirus strains in eastern India. These findings are important for understanding norovirus epidemiology in India and may have implications for future vaccine development.

DOI： 10.1186/s13099-023-00594-5

researchmap

Other Link： https://link.springer.com/article/10.1186/s13099-023-00594-5/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Human Salmonella infections pose significant public health challenges globally, primarily due to low diagnostic yield of systemic infections, emerging and expanding antibiotic resistance of both the typhoidal and non-typhoidal Salmonella strains and the development of asymptomatic carrier state that functions as a reservoir of infection in the community. The limited long-term efficacy of the currently licensed typhoid vaccines, especially in smaller children and non-availability of vaccines against other Salmonella serovars necessitate active research towards developing a multivalent vaccine with wider coverage of protection against pathogenic Salmonella serovars. We had earlier reported immunogenicity and protective efficacy of a subunit vaccine containing a recombinant outer membrane protein (T2544) of Salmonella Typhi in a mouse model. This was achieved through the robust induction of serum IgG, mucosal secretory IgA and Salmonella-specific cytotoxic T cells as well as memory B and T cell response. Here, we report the development of a glycoconjugate vaccine, containing high molecular weight complexes of Salmonella Typhimurium O-specific polysaccharide (OSP) and recombinant T2544 that conferred simultaneous protection against S. Typhi, S. Paratyphi, S. Typhimurium and cross-protection against S. enteritidis in mice. Our findings corroborate with the published studies that suggested the potential of Salmonella OSP as a vaccine antigen. The role of serum antibodies in vaccine-mediated protection is suggested by rapid seroconversion with high titers of serum IgG and IgA, persistently elevated titers after primary immunization along with a strong antibody recall response with higher avidity serum IgG against both OSP and T2544 and significantly raised SBA titers of both primary and secondary antibodies against different Salmonella serovars. Elevated intestinal secretory IgA and bacterial motility inhibition by the secretory antibodies supported their role as well in vaccine-induced protection. Finally, robust induction of T effector memory response indicates long term efficacy of the candidate vaccine. The above findings coupled with protection of vaccinated animals against multiple clinical isolates confirm the suitability of OSP-rT2544 as a broad-spectrum candidate subunit vaccine against human infection due to typhoidal and non-typhoidal Salmonella serovars.

DOI： 10.3389/fimmu.2023.1304170

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：The Society for Antibacterial and Antifungal Agents, Japan  

DOI： 10.4265/jmc.29.2_55

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Ebola virus disease (Ebola) is highly pathogenic, transmissible, and often deadly, with debilitating consequences. Superspreading within a cluster is also possible. In this study, we aim to document Ebola basic reproduction number (R0): the average number of new cases associated with an Ebola case in a completely susceptible population. METHODS: We undertook a systematic review and meta-analysis. We searched PubMed, EMBASE, and Web of Science for studies published between 1976 and February 27, 2023. We also manually searched the reference lists of the reviewed studies to identify additional studies. We included studies that reported R0 during Ebola outbreaks in Africa. We excluded studies that reported only the effective reproduction number (Rt). Abstracting data from included studies was performed using a pilot-tested standard form. Two investigators reviewed the studies, extracted the data, and assessed quality. The pooled R0 was determined by a random-effects meta-analysis. R0 was stratified by country. We also estimated the theoretically required immunization coverage to reach herd-immunity using the formula of (1-1/R0) × 100 %. RESULTS: The search yielded 2042 studies. We included 53 studies from six African countries in the systematic review providing 97 Ebola mean R0 estimates. 27 (with 46 data points) studies were included in the meta-analysis. The overall pooled mean Ebola R0 was 1.95 (95 % CI 1.74-2.15), with high heterogeneity (I2 = 99.99 %; τ2 = 0.38; and p < 0.001) and evidence of small-study effects (Egger's statistics: Z = 4.67; p < 0.001). Mean Ebola R0 values ranged from 1.2 to 10.0 in Nigeria, 1.1 to 7 in Guinea, 1.14 to 8.33 in Sierra Leone, 1.13 to 5 in Liberia, 1.2 to 5.2 in DR Congo, 1.34 to 2.7 in Uganda, and from 1.40 to 2.55 for all West African countries combined. Pooled mean Ebola R0 was 9.38 (95 % CI 4.16-14.59) in Nigeria, 3.31 (95 % CI 2.30-4.32) in DR Congo, 2.0 (95 % CI 1.25-2.76) in Uganda, 1.83 (95 % CI 1.61-2.05) in Liberia, 1.73 (95 % CI 1.47-2.0) in Sierra Leonne, and 1.44 (95 % CI 1.29-1.60) in Guinea. In theory, 50 % of the population needs to be vaccinated to achieve herd immunity, assuming that Ebola vaccine would be 100 % effective. CONCLUSIONS: Ebola R0 varies widely across countries. Ebola has a much wider R0 range than is often claimed (1.3-2.0). It is possible for an Ebola index case to infect more than two susceptible individuals.

DOI： 10.1016/j.tmaid.2023.102685

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

ABSTRACT

We isolated a Vibrio fluvialis strain (IDH5335) from a stool sample collected from a patient with diarrhea. In this announcement, we report the complete genomic sequence of this organism, which was obtained by combining Illumina and Oxford Nanopore sequencing data.

DOI： 10.1128/mra.00707-23

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.imlet.2023.09.009

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

Strain KK2020170T, a Gram-stain negative, yellow colony-forming bacterium, was isolated from surface seawater sampled in Kojima Bay, Okayama, Japan. Phylogenetic analysis based on the 16S rRNA gene revealed that strain KK2020170T belongs to the genus Flavobacterium, with Flavobacterium haoranii LQY-7T (98.1% similarity) being its closest relative, followed by Flavobacterium sediminis MEBiC07310T (96.9%) and Flavobacterium urocaniciphilum YIT 12746T (96.0%). Whole-genome shotgun sequencing showed that strain KK2020170T, when paralleled with F. haoranii LQY-7 T, had 81.3% average nucleotide identity, and 24.6% in silico DNA-DNA hybridization values, respectively. The DNA G + C content of strain KK2020170T was 31.1 mol%. The most abundant fatty acids (> 10%) of strain KK2020170T were iso-C15: 0, iso-C17: 0 3-OH and iso-C15: 1 G. The dominant respiratory quinone of the strain was menaquinone MK-6. Based on the phylogenetic and phenotypic analysis results, we propose that strain KK2020170T represents a novel species, for which the name Flavobacterium okayamense sp. nov. has been proposed. The type strain is KK2020170T (= ATCC TSD-280 T = NBRC 115344 T).

DOI： 10.1007/s00203-023-03682-x

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Mary Ann Liebert Inc  

DOI： 10.1089/jmf.2022.k.0112

researchmap

Other Link： https://www.liebertpub.com/doi/pdf/10.1089/jmf.2022.K.0112

Publishing type：Research paper (scientific journal)   Publisher：Korean Society for Parasitology  

Schistosomiasis causes significant morbidity and mortality worldwide. This study aimed to assess the effect of schistosomula lung antigen preparation (SLAP) and soluble egg antigen (SEA) on a murine schistosomiasis mansoni model. Ninety laboratory-bred male Swiss albino mice were divided into 6 groups. Two doses of the vaccine were given at 2-week intervals. All mice were subcutaneously infected with 80±10 Schistosoma mansoni cercariae 2 weeks after the last vaccination dose. They were sacrificed 7 weeks post-infection. Parasitological and histopathological studies were conducted to assess the effect of inoculated antigens (single or combined). The results showed that the combination of SLAP and SEA (combination group) led to a significant reduction in worm burden (65.56%), and liver and intestine egg count (59% and 60.59%, respectively). The oogram pattern revealed a reduction in immature and mature eggs (15±0.4 and 10±0.8, respectively) and an increased number of dead eggs in the combination group (P&lt;0.001). In terms of histopathological changes, the combination group showed notably small compact fibrocellular egg granuloma and moderate fibrosis in the liver. A high percentage of destroyed ova was observed in the intestine of the combination group. This study demonstrates for the first time the prophylactic effect of combined SLAP and SEA vaccine. The vaccine induced a significant reduction in the parasitological and pathological impacts of schistosomiasis mansoni in hepatic and intestinal tissues, making it a promising vaccine candidate for controlling schistosomiasis.

DOI： 10.3347/phd.22154

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Korean Society for Parasitology  

Despite the recent progress in public health measures, malaria remains a troublesome disease that needs to be eradicated. It is essential to develop new antimalarial medications that are reliable and secure. This report evaluated the pharmacokinetics and antimalarial activity of 1,2,6,7-tetraoxaspiro[7.11]nonadecane (N-89) using the rodent malaria parasite Plasmodium berghei in vivo. After a single oral dose (75 mg /kg) of N-89, its pharmacokinetic parameters were measured, and t&lt;sub&gt;1/2&lt;/sub&gt; was 0.97 h, T&lt;sub&gt;max&lt;/sub&gt; was 0.75 h, and bioavailability was 7.01%. A plasma concentration of 8.1 ng/ml of N-89 was maintained for 8 h but could not be detected at 10 h. The dose inhibiting 50% of parasite growth (ED&lt;sub&gt;50&lt;/sub&gt;) and ED&lt;sub&gt;90&lt;/sub&gt; values of oral N-89 obtained following a 4-day suppressive test were 20 and 40 mg/kg, respectively. Based on the plasma concentration of N-89, we evaluated the antimalarial activity and cure effects of oral N-89 at a dose of 75 mg/kg 3 times daily for 3 consecutive days in mice harboring more than 0.5% parasitemia. In all the N-89- treated groups, the parasites were eliminated on day 5 post-treatment, and all mice recovered without a parasite recurrence for 30 days. Additionally, administering oral N-89 at a low dose of 50 mg/kg was sufficient to cure mice from day 6 without parasite recurrence. This work was the first to investigate the pharmacokinetic characteristics and antimalarial activity of N-89 as an oral drug. In the future, the following steps should be focused on developing N-89 for malaria treatments; its administration schedule and metabolic pathways should be investigated.

DOI： 10.3347/phd.23044

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.envres.2023.115374

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.parint.2022.102720

researchmap

Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

We have previously reported 1,2,6,7-tetraoxaspiro [7.11]nonadecane (N-89) as a promising antimalarial compound. In this study, we evaluated the effect of transdermal therapy (tdt) of N-89 in combination (tdct) with other antimalarials as an application for children. We prepared ointment formulas containing N-89 plus another antimalarial drug, specifically, mefloquine, pyrimethamine, or chloroquine. In a 4-day suppressive test, the ED50 values for N-89 alone or combined with either mefloquine, pyrimethamine, or chloroquine were 18, 3, 0.1, and 3 mg/kg, respectively. Interaction assays revealed that N-89 combination therapy showed a synergistic effect with mefloquine and pyrimethamine, but chloroquine provoked an antagonistic effect. Antimalarial activity and cure effect were compared for single-drug application and combination therapy. Low doses of tdct N-89 (35 mg/kg) combined with mefloquine (4 mg/kg) or pyrimethamine (1 mg/kg) gave an antimalarial effect but not a cure effect. In contrast, with high doses of N-89 (60 mg/kg) combined with mefloquine (8 mg/kg) or pyrimethamine (1 mg/kg), parasites disappeared on day 4 of treatment, and mice were completely cured without any parasite recurrence. Our results indicated that transdermal N-89 with mefloquine and pyrimethamine provides a promising antimalarial form for application to children.

DOI： 10.3390/pathogens12030398

researchmap

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.tmaid.2023.102554

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.2147/ijn.s401876

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Korean Society for Parasitology  

The discovery of new antimalarial drugs can be developed using asynchronized &lt;i&gt;Plasmodium berghei&lt;/i&gt; malaria parasites in vivo in mice. Studies on a particular stage are also required to assess the effectiveness and mode of action of drugs. In this report, we used endoperoxide 6-(1,2,6,7-tetraoxaspiro [7.11] nonadec-4-yl) hexan-1-ol (N-251) as a model antimalarial compound on &lt;i&gt;P. chabaudi&lt;/i&gt; parasites. We examined the antimalarial effect of N-251 against ring-stage- and trophozoite-stage-rich &lt;i&gt;P. chabaudi&lt;/i&gt; parasites and asynchronized &lt;i&gt;P. berghei&lt;/i&gt; parasites using the 4-day suppressive test. The ED&lt;sub&gt;50&lt;/sub&gt; values were 27, 22, and 22 mg/kg, respectively, and the antimalarial activity of N-251 was verified in both rodent malaria parasites. To assess the stage-specific effect of N-251 in vivo, we evaluated the change of parasitemia and distribution of parasite stages using ring-stage- and trophozoite-stage-rich &lt;i&gt;P. chabaudi&lt;/i&gt; parasites with one-day drug administration for one life cycle. We discovered that the parasitemias decreased after 13 and 9 hours post-treatment in the ring-stage- and trophozoite-stage-rich groups, respectively. Additionally, in the ring-stage-rich N-251 treated group, the ring-stage parasites hindered trophozoite parasite development. For the trophozoite-stage-rich N-251 treated group, the distribution of the trophozoite stage was maintained without a change in parasitemia until 9 hours. Because of these findings, it can be concluded that N-251 suppressed the trophozoite stage but not the ring stage. We report for the first time that N-251 specifically suppresses the trophozoite stage using &lt;i&gt;P. chabaudi&lt;/i&gt; in mice. The results show that &lt;i&gt;P. chabaudi&lt;/i&gt; is a reliable model for the characterization of stage-specific antimalarial effects.

DOI： 10.3347/phd.22119

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Future Medicine Ltd  

Aim: To characterize extensively drug-resistant Pseudomonas aeruginosa from a patient with diarrhea. Materials &amp; methods: Antimicrobial susceptibility was tested by the disk diffusion method. The P. aeruginosa genome was sequenced to identify virulence, antibiotic resistance and prophages encoding genes. Results: P. aeruginosa had a wide spectrum of resistance to antibiotics. Genomic analysis of P. aeruginosa revealed 76 genes associated with antimicrobial resistance, xenobiotic degradation and the type three secretion system. Conclusion: This is the first report on diarrhea associated with P. aeruginosa. Since no other organism was identified, the authors assume that the patient had dysbiosis due to antibiotic exposure, leading to antibiotic-associated diarrhea. The in vivo toxicity expressed by the pathogen may be associated with T3SS.

DOI： 10.2217/fmb-2022-0140

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

Aims

A rapid rise in resistance to conventional antibiotics for Shigella spp. has created a problem in treating shigellosis. Hence, there is an urgent need for new and non-conventional anti-bacterial agents. The aim of this study is to show how Asiatic acid, a plant-derived compound, inhibits the intracellular growth of Shigella flexneri.

Methods and results

Shigella flexneri sensitive and resistant strains were used for checking antimicrobial activity of Asiatic acid by gentamicin protection assay. Asiatic acid inhibited the intracellular growth of all strains. Gene expression analysis showed antimicrobial peptide (AMP) up-regulation by Asiatic acid in intestinal cells. Further western blot analysis showed that ERK, p38, and JNK are activated by Asiatic acid. ELISA was performed to check IL-8, IL-6, and cathelicidin secretion. The antibacterial effect of Asiatic acid was further verified in an in vivo mouse model.

Conclusions

The reason behind the antibacterial activities of Asiatic acid is probably over-expression of antimicrobial peptide genes. Besides, direct antimicrobial activities, antimicrobial peptides also carry immunomodulatory activities. Here, Asiatic acid increased IL-6 and IL-8 secretion to induce inflammation. Overall, Asiatic acid up-regulates antimicrobial peptide gene expression and inhibits intracellular S. flexneri growth. Moreover, Asiatic acid reduced bacterial growth and recovered intestinal tissue damages in in vivo mice model.

DOI： 10.1093/jambio/lxac076

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s11274-022-03436-9

researchmap

Other Link： https://link.springer.com/article/10.1007/s11274-022-03436-9/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/jam.15794

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jam.15794

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Antimicrobial resistance (AMR) in bacteria is an important global health problem affecting humans, animals, and the environment. AMR is considered as one of the major components in the “global one health”. Misuse/overuse of antibiotics in any one of the segments can impact the integrity of the others. In the presence of antibiotic selective pressure, bacteria tend to develop several defense mechanisms, which include structural changes of the bacterial outer membrane, enzymatic processes, gene upregulation, mutations, adaptive resistance, and biofilm formation. Several components of mobile genetic elements (MGEs) play an important role in the dissemination of AMR. Each one of these components has a specific function that lasts long, irrespective of any antibiotic pressure. Integrative and conjugative elements (ICEs), insertion sequence elements (ISs), and transposons carry the antimicrobial resistance genes (ARGs) on different genetic backbones. Successful transfer of ARGs depends on the class of plasmids, regulons, ISs proximity, and type of recombination systems. Additionally, phage-bacterial networks play a major role in the transmission of ARGs, especially in bacteria from the environment and foods of animal origin. Several other functional attributes of bacteria also get successfully modified to acquire ARGs. These include efflux pumps, toxin-antitoxin systems, regulatory small RNAs, guanosine pentaphosphate signaling, quorum sensing, two-component system, and clustered regularly interspaced short palindromic repeats (CRISPR) systems. The metabolic and virulence state of bacteria is also associated with a range of genetic and phenotypic resistance mechanisms. In spite of the availability of a considerable information on AMR, the network associations between selection pressures and several of the components mentioned above are poorly understood. Understanding how a pathogen resists and regulates the ARGs in response to antimicrobials can help in controlling the development of resistance. Here, we provide an overview of the importance of genetic network and regulation of AMR in bacterial pathogens.

DOI： 10.3389/fcimb.2022.952491

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

We examined the stools of 23 patients in Kolkata, who were diagnosed as cholera patients because Vibrio cholerae O1 was detected from their stools by culturing methods, and further explored by metagenomic sequencing analysis. Subsequently, the presence of the gene encoding A subunit of cholera toxin (ctxA) and the cholera toxin (CT) level in these stool samples were examined. ctxA was examined by both metagenomic sequencing analysis and polymerase chain reaction. In these examinations, two samples did not show positive in any of these tests. The metagenomic analysis showed that the genes for Streptococcus pneumoniae and Salmonella enterica were present in the stools of these two patients, respectively. Therefore, these two patients were not considered to have diarrhea due to V. cholerae infection. From these results, we predicted that some Kolkata residents harbor a small number of V. cholerae in their intestines as a form of subclinical infection with V. cholerae. Next, we analyzed the stool samples of 22 diarrhea patients from which V. cholerae was not isolated. The results showed that 3 of the patients seemed to have subclinical infection of V. cholerae based on the amount of the genes. These results indicated that subclinical infections with V. cholerae O1 occur in Kolkata.

DOI： 10.1038/s41598-022-24167-9

PubMed

researchmap

Other Link： https://www.nature.com/articles/s41598-022-24167-9

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

Background

Shigella remains one of the most common causes of diarrhoea in South Asia. Current estimates of the prevalence of Shigella are critical for guiding control measures. We estimated the prevalence of Shigella species and serogroups in South Asia.

Methods

We performed a systematic review using PubMed, EMBASE, Google Scholar and Web of Science for peer-reviewed studies published between 2000 and 19 June 2022. We also manually searched the reference lists of the reviewed studies to identify additional studies. We included studies that detected the presence of Shigella in stool by culture or polymerase chain reaction (PCR). Studies associated with outbreaks were excluded. Two investigators independently reviewed the studies, extracted the data and performed quality assessment. A random-effects meta-analysis was performed to determine the pooled prevalence of Shigella.

Results

Our search yielded 5707 studies, of which 91 studies from five South Asian countries were included in the systematic review, 79 in the meta-analysis of Shigella prevalence and 63 in the meta-analysis of Shigella serogroups prevalence. The pooled prevalence of Shigella was 7% [95% confidence interval (CI): 6–7%], with heterogeneity (I2 = 98.7; P &amp;lt; 0.01). The prevalence of Shigella was higher in children aged &amp;lt;5 years (10%; 95% CI: 8–11%), in rural areas (12%; 95% CI: 10–14%) and in studies using PCR (15%; 95% CI: 11–19%).

Shigella flexneri (58%) was the most abundant serogroup, followed by Shigella sonnei (19%), Shigella boydii (10%) and Shigella dysenteriae (9%). Shigella flexneri 2a was the most frequently isolated serotype (36%), followed by serotype 3a (12%), serotype 6 (12%) and serotype 1b (6%). The prevalence of non-typeable Shigella was 10.0%.

Conclusions

Although the prevalence of Shigella in South Asia remains generally high, it varies by age group and geographical area, with data lacking in some countries. Effective Shigella vaccines would be advantageous for both endemic communities and travellers.

DOI： 10.1093/jtm/taac132

PubMed

researchmap

Other Link： https://academic.oup.com/jtm/article-pdf/30/1/taac132/49254194/taac132.pdf

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Background

India is an attractive destination for travelers. Unfortunately, numerous reports exist on traveler’s diarrhea (TD) and fecal colonization with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) among international travelers visiting India. Here, we systematically reviewed studies published on the acquisition of ESBL-EC and TD attack rates among international visitors to India.

Methods

Design: Systematic review and meta-analysis.

A systematic search was performed using Google Scholar, PubMed, EMBASE, Web of Science, and gray literature from 2000 to December 2021, for studies containing data for ESBL-EC acquisition or TD experience related to a trip to India. Random effects models were used to compute the prevalence of ESBL-EC acquisition and TD attack.

Results

The literature search yielded a total of 5023 records. Of these, 31 met our inclusion criteria for systematic review and only 17 could be meta-analyzed (9 for TD, and 8 for ESBL-EC). The overall pooled attack rate of TD was 39% (95% confidence interval, CI: 25–53%). In studies where travelers' memory was used to diagnose TD, the pooled attack rate of TD was slightly higher (42%, 95% CI: 21–64%) compared to those where TD was objectively documented (33%, 95% CI: 17–49%). There were significant risks to be colonized with ESBL-EC among the travelers who experienced TD. The pooled rate of ESBL-EC colonization was 72% (CI: 67–78%). Most ESBL-EC produced CTX-M-15 enzyme. Furthermore, most of the travelers who acquired ESBL-EC were from highly industrialized countries recruited from travel clinics: Canada (n = 80), Germany (n = 69), Netherlands (n = 20), Sweden (n = 18), Japan (n = 10), Finland (n = 8), USA (n = 7), Spain (n = 5), and Denmark (n = 3).

Conclusions

TD pooled attack rate and ESBL-EC acquisition among international travelers visiting India were high in this study. However, we cannot make generalizations based upon this TD pooled attack rate for the current situation, due to a lack of current data. Our study highlights that travelers should be advised on TD to ensure that they do not disregard the risk of contracting TD and be better prepared as a result. It also illustrates the importance of international travel in acquiring antibiotic-resistant Escherichia coli.

DOI： 10.1186/s40794-022-00179-1

PubMed

researchmap

Other Link： https://link.springer.com/article/10.1186/s40794-022-00179-1/fulltext.html

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s42770-022-00788-0

researchmap

Other Link： https://link.springer.com/article/10.1007/s42770-022-00788-0/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Rotavirus (RV) is the leading cause of acute gastroenteritis and watery diarrhea in children under 5 years accounting for high morbidity and mortality in countries with poor socioeconomic status. Although vaccination against RV has been implemented in more than 100 countries, the efficacy of vaccine has been challenged in low-income settings. The lack of any FDA-approved drug against RV is an additional concern regarding the treatment associated with rotavirus-induced infantile death. With the purpose for the discovery of anti-RV therapeutics, we assessed anti-rotaviral potential of quercetin, a well-characterized antioxidant flavonoid. In vitro study revealed that quercetin treatment resulted in diminished production of RV-SA11 (simian strain) viral particles in a concentration-dependent manner as estimated by the plaque assay. Consistent with this result, Western blot analysis also revealed reduced synthesis of viral protein in quercetin-treated RV-SA11-infected MA104 cells compared to vehicle (DMSO) treated controls. Not surprisingly, infection of other RV strains A5-13 (bovine strain) and Wa (Human strain) was also found to be abridged in the presence of quercetin compared to DMSO. The IC₅₀ of quercetin against three RV strains ranges between 2.79 and 4.36 Mm, and S.I. index is greater than 45. Concurrent to the in vitro results, in vivo study in mice model also demonstrated reduced expression of viral proteins and viral titer in the small intestine of quercetin-treated infected mice compared to vehicle-treated infected mice. Furthermore, the result suggested anti-rotaviral activity of quercetin to be interferon-independent. Mechanistic study revealed that the antiviral action of quercetin is co-related with the inhibition of RV-induced early activation of NF-κB pathway. Overall, this study delineates the strong anti-RV potential of quercetin and also proposes it as future therapeutics against rotaviral diarrhea.

DOI： 10.3389/fmicb.2022.951716

PubMed

researchmap

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Canadian Science Publishing  

The degradation of polymeric chitin by chitinase liberates soluble N-acetyl glucosamine oligosaccharides (GlcNAc_n≥2), a source of nutrition that can also induce a state of natural genetic competence in Vibrio parahaemolyticus. This analysis revealed that among seven predicted chitinases, the synergistic action of VPA0055 (ChiA2), VP0619 (ChiB), and VPA0832 (Cdx) were essential for the robust growth and high transformation frequency on chitin. The endochitinase, ChiA2, and periplasmic chitinase, Cdx were indispensable for chitin degradation. ChiB was not essential for growth on chitin but did have an effect on the rate of chitin degradation. Interestingly, the loss of Cdx drastically reduced growth on insoluble chitin, but growth on soluble GlcNAc_5/6 remained same. The utilization of GlcNAc_5/6 was only inhibited when there was mutation of Cdx with the other periplasmic chitinases VP0755 and VP2486. This suggests that Cdx might also be involved in extracellular degradation of chitin, in addition to its role as a periplasmic chitinase. Moreover, the periplasmic chitin oligosaccharide-binding protein (CBP) was found to be essential for the efficient utilization of chitin. The CBP was specifically needed for the processing of GlcNAc_4-6 during growth on chitin. Overall, this study provides detailed analysis of the machinery behind chitin degradation in V. parahaemolyticus.

DOI： 10.1139/cjm-2021-0328

researchmap

Other Link： https://cdnsciencepub.com/doi/pdf/10.1139/cjm-2021-0328

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/jam.15594

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jam.15594

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WHO Press  

OBJECTIVE: To evaluate the clinical accuracy of rapid diagnostic tests for the detection of Ebola virus. METHODS: We searched MEDLINE®, Embase® and Web of Science for articles published between 1976 and October 2021 reporting on clinical studies assessing the performance of Ebola virus rapid diagnostic tests compared with reverse transcription polymerase chain reaction (RT-PCR). We assessed study quality using the QUADAS-2 criteria. To estimate the pooled sensitivity and specificity of these rapid diagnostic tests, we used a bivariate random-effects meta-analysis. FINDINGS: Our search identified 113 unique studies, of which nine met the inclusion criteria. The studies were conducted in the Democratic Republic of the Congo, Guinea, Liberia and Sierra Leone and they evaluated 12 rapid diagnostic tests. We included eight studies in the meta-analysis. The pooled sensitivity and specificity of the rapid tests were 86% (95% confidence interval, CI: 80-91) and 95% (95% CI: 91-97), respectively. However, pooled sensitivity decreased to 83% (95% CI: 77-88) after removing outliers. Pooled sensitivity increased to 90% (95% CI: 82-94) when analysis was restricted to studies using the RT-PCR from altona Diagnostics as gold standard. Pooled sensitivity increased to 99% (95% CI: 67-100) when the analysis was restricted to studies using whole or capillary blood specimens. CONCLUSION: The included rapid diagnostic tests did not detect all the Ebola virus disease cases. While the sensitivity and specificity of these tests are moderate, they are still valuable tools, especially useful for triage and detecting Ebola virus in remote areas.

DOI： 10.2471/blt.21.287496

PubMed

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/jsde.12587

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jsde.12587

Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.2147/idr.s364526

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Background: Approximately 2.9 million people worldwide suffer from cholera each year, many of whom are destitute. However, understanding of immunity against cholera is still limited. Several studies have reported the duration of antibodies following cholera; however, systematic reviews including a quantitative synthesis are lacking. Objective: To meta-analyze cohort studies that have evaluated vibriocidal, cholera toxin B subunit (CTB), and lipopolysaccharide (LPS) antibody levels following a clinical cholera case. Methods: Design: Systematic review and meta-analysis. We searched PubMed and Web of science for studies assessing antibodies against Vibrio cholerae in cohorts of patients with clinical cholera. Two authors independently extracted data and assessed the quality of included studies. Random effects models were used to pool antibody titers in adults and older children (aged ≥ 6 years). In sensitivity analysis, studies reporting data on young children (2–5 years) were included. Results: Nine studies met our inclusion criteria for systematic review and seven for meta-analysis. The pooled mean of vibriocidal antibody titers in adults and older children (aged ≥ 6 years) was 123 on day 2 post-symptom onset, which sharply increased on day 7 (pooled mean = 6956) and gradually waned to 2247 on day 30, 578 on day 90, and 177 on day 360. Anti-CTB IgA antibodies also peaked on day 7 (pooled mean = 49), followed by a rapid decrease on day 30 (pooled mean = 21), and further declined on day 90 (pooled mean = 10), after which it plateaued from day 180 (pooled mean = 8) to 360 (pooled mean = 6). Similarly, anti-CTB IgG antibodies peaked in early convalescence between days 7 (pooled mean = 65) and 30 (pooled mean = 69), then gradually waned on days 90 (pooled mean = 42) and 180 (pooled mean = 30) and returned to baseline on day 360 (pooled mean = 24). Anti-LPS IgA antibodies peaked on day 7 (pooled mean = 124), gradually declined on day 30 (pooled mean = 44), which persisted until day 360 (pooled mean = 10). Anti LPS IgG antibodies peaked on day 7 (pooled mean = 94). Thereafter, they decreased on day 30 (pooled mean = 85), and dropped further on days 90 (pooled mean = 51) and 180 (pooled mean = 47), and returned to baseline on day 360 (pooled mean = 32). Sensitivity analysis including data from young children (aged 2–5 years) showed very similar findings as in the primary analysis. Conclusions: This study confirms that serological antibody (vibriocidal, CTB, and LPS) titers return to baseline levels within 1 year following clinical cholera, i.e., before the protective immunity against subsequent cholera wanes. However, this decay should not be interpreted as waning immunity because immunity conferred by cholera against subsequent disease lasts 3–10 years. Our study provides evidence for surveillance strategies and future research on vaccines and also demonstrates the need for further studies to improve our understanding of immunity against cholera.

DOI： 10.3390/ijerph19127141

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/jam.15548

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jam.15548

Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

A complex virulence-regulatory cascade controls expression of the cholera toxin genes (ctxAB) in Vibrio cholerae, which eventually leads to the production and secretion of choleragen (CT), responsible for rice watery diarrhoea in infected individuals. The cholera toxin promoter (PctxAB) contains a series of heptad repeats (5′-TTTTGAT-3′), which has previously been shown to play a crucial role in transcriptional regulation of ctxAB by recruiting the transcriptional activators ToxT, ToxR and the nucleoid-associated protein H-NS along the ctx promoter. The number of these repeats differs not only between the two biotypes of V. cholerae O1 strains, but also among the strains belonging to the same biotype. In this study, we examined if regulation of PctxAB is influenced in any way by the number of these repeats. Based on our observations, we posit that ctx activation indeed depends on the number of TTTTGAT heptad repeats within PctxAB, and occupation of the distal repeats by H-NS could prevent transcriptional activation of the ctx genes in V. cholerae O1 pandemic isolates. Our results suggest that ToxT-dependent transcriptional activation may not require entire displacement of H-NS and supports a recently described revised model of ToxT and H-NS mediated PctxAB transcriptional regulation.

DOI： 10.1093/femsle/fnac041

researchmap

Other Link： https://academic.oup.com/femsle/article-pdf/369/1/fnac041/43678568/fnac041.pdf

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Fecal contamination of water sources and open defecation have been linked to cholera outbreaks in India. However, a systematic review on the drivers responsible for these outbreaks has yet to be published. Here, we systematically review the published literature on cholera outbreaks in India between 2011 and 2020. We searched studies in English in three databases (MEDLINE, EMBASE, and Web of Science) and the Integrated Disease Surveillance Program that tracks cholera outbreaks throughout India. Two authors independently extracted data and assessed the quality of the included studies. Quantitative data on the modes of transmission reviewed in this study were assessed for any change over time between 2011–2015 and 2016–2020. Our search retrieved 10823 records initially, out of which 81 full-text studies were assessed for eligibility. Among these 81 studies, 20 were eligible for inclusion in this review. There were 565 reported outbreaks between 2011 and 2020 that led to 45,759 cases and 263 deaths. Outbreaks occurred throughout the year; however, they exploded with monsoons (June through September). In Tamil Nadu, a typical peak of cholera outbreaks was observed from December to January. Seventy-two percent (33,089/45,759) of outbreak-related cases were reported in five states, namely Maharashtra, West Bengal, Punjab, Karnataka, and Madhya Pradesh. Analysis of these outbreaks highlighted the main drivers of cholera including contaminated drinking water and food, inadequate sanitation and hygiene (including open defecation), and direct contact between households. The comparison between 2011–2015 and 2016–2020 showed a decreasing trend in the outbreaks that arose due to damaged water pipelines. Many Indians still struggle with open defecation, sanitation, and clean water access. These issues should be addressed critically. In addition, it is essential to interrupt cholera short-cycle transmission (mediated by households, stored drinking water and foodstuffs) during an outbreak. As cholera is associated with deprivation, socio-economic development is the only long-term solution.

DOI： 10.3390/ijerph19095738

PubMed

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

We sought to summarize knowledge, misconceptions, beliefs, and practices about Ebola that might impede the control of Ebola outbreaks in Africa. We searched Medline, EMBASE, CINAHL, and Google Scholar (through May 2019) for publications reporting on knowledge, attitudes, and practices (KAP) related to Ebola in Africa. In total, 14 of 433 articles were included. Knowledge was evaluated in all 14 articles, and they all highlighted that there are misconceptions and risk behaviors during an Ebola outbreak. Some communities believed that Ebola spreads through the air, mosquito bites, malice from foreign doctors, witchcraft, and houseflies. Because patients believe that Ebola was caused by witchcraft, they sought help from traditional healers. Some people believed that Ebola could be prevented by bathing with salt or hot water. Burial practices where people touch Ebola-infected corpses were common, especially among Muslims. Discriminatory attitudes towards Ebola survivors or their families were also prevalent. Some Ebola survivors were not accepted back in their communities; the possibility of being ostracized from their neighborhoods was high and Ebola survivors had to lead a difficult social life. Most communities affected by Ebola need more comprehensive knowledge on Ebola. Efforts are needed to address misconceptions and risk behaviors surrounding Ebola for future outbreak preparedness in Africa.

DOI： 10.3390/ijerph19084714

PubMed

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

BACKGROUND: Cholera is an acute diarrheal disease caused by Vibrio cholerae O1 or O139. Cholera rapid diagnostic tests (RDTs) are widely used to screen for cholera cases. However, their accuracy has not been systematically reviewed. OBJECTIVES: To evaluate the diagnostic accuracy of cholera RDTs. METHODS: Systematic review and meta-analysis. DATA SOURCES: Medline, EMBASE and Web of science through to November 2020; references of included studies and a technical guidance on cholera RDTs. This review is registered with PROSPERO (CRD42021233124). STUDY ELIGIBILITY CRITERIA: Cross-sectional studies comparing the performance of cholera RDTs either to stool culture or PCR. PARTICIPANTS: Individuals with clinically suspected cholera. DATA EXTRACTION: Two authors independently extracted data and assessed the quality using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) criteria. RESULTS: Eighteen studies were included in the systematic review of which 17 were used for meta-analysis. Crystal VC was the most frequently used RDT (13 studies), followed by Cholkit and Institut Pasteur cholera dipstick (three studies each), SD Bioline (two studies), Artron (one study) and Smart (one study). Using direct testing (n = 12 627 specimens), the bivariate random-effects model yielded a pooled sensitivity and specificity of 91% (95% CI 87%-94%) and 80% (95% CI 74%-84%), respectively. However, through alkaline peptone water (APW) enrichment (n = 3403 specimens), the pooled sensitivity and specificity were 89% (95% CI 79%-95%) and 98% (95% CI 95%-99%), respectively. CONCLUSION: Cholera RDTs, especially when enriched with APW, have moderate sensitivity and specificity. Although less useful for clinical management, the current generation of RDTs have clear utility for surveillance efforts if used in a principled manner. Enrichment of stool specimens in APW before using cholera RDTs reduces the possibility of obtaining false-positive results, despite the few cholera cases that go undetected. It is noteworthy that APW-enriched cholera RDTs are not necessarily rapid tests, and are not listed in the Global Task Force on Cholera Control/WHO target product profile.

DOI： 10.1016/j.cmi.2021.08.027

PubMed

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：The Society for Antibacterial and Antifungal Agents, Japan  

DOI： 10.4265/bio.27.57

researchmap

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Vibrio cholerae can survive cold stress by entering into a viable but non-culturable (VBNC) state, and resuscitation can be induced either by temperature upshift only or the addition of an anti-dormancy stimulant such as resuscitation-promoting factors (Rpfs) at suitable temperature. In this study, the role of proteinase K was analyzed as an Rpf in V. cholerae. A VBNC state was induced in V. cholerae AN59 in artificial seawater (ASW) media at 4 °C, and recovery could be achieved in filtered VBNC microcosm, called spent ASW media, merely by a temperature upshift to 37 °C. The resuscitation ability of spent ASW was further enhanced by the addition of proteinase K. The mode of action of proteinase K was investigated by comparing its effect on the growth of the VBNC and culturable state of V. cholerae in ASW and spent ASW media. The presence of proteinase K allowed culturable cells to grow faster in ASW by reducing the generation time. However, this effect of proteinase K was more pronounced in stressed VBNC cells. Moreover, proteinase K-supplemented spent ASW could also accelerate the transition of VBNC into recovered cells followed by rapid growth. Additionally, we found that dead bacterial cells were the substrate on which proteinase K acts to support high growth in spent ASW. So, the conclusion is that the proteinase K could efficiently promote the recovery and growth of dormant VBNC cells at higher temperatures by decreasing the duration of the initial lag phase required for transitioning from the VBNC to recovery state and increasing the growth rate of these recovered cells.

DOI： 10.3390/microorganisms9122618

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

The rapid diagnosis of cholera contributes to adequate outbreak management. This meta-analysis assesses the diagnostic accuracy of cholera rapid tests (RDTs) to detect Vibrio cholerae O1. METHODS: Systematic review and meta-analysis. We searched four databases (Medline, EMBASE, Google Scholar, and Web of Science up to 8 September 2021) for studies that evaluated cholera RDTs for the detection of V. cholerae O1 compared with either stool culture or polymerase chain reaction (PCR). We assessed the studies' quality using the QUADAS-2 criteria. In addition, in this update, GRADE approach was used to rate the overall certainty of the evidence. We performed a bivariate random-effects meta-analysis to calculate the pooled sensitivity and specificity of cholera RDTs. RESULTS: Overall, 20 studies were included in this meta-analysis. Studies were from Africa (n = 11), Asia (n = 7), and America (Haiti; n = 2). They evaluated eight RDTs (Crystal VC-O1, Crystal VC, Cholkit, Institut Pasteur cholera dipstick, SD Bioline, Artron, Cholera Smart O1, and Smart II Cholera O1). Using direct specimen testing, sensitivity and specificity of RDTs were 90% (95% CI, 86 to 93) and 86% (95% CI, 81 to 90), respectively. Cholera Sensitivity was higher in studies conducted in Africa [92% (95% CI, 89 to 94)] compared with Asia [82% (95% CI, 77 to 87)]. However, specificity [83% (95% CI, 71 to 91)] was lower in Africa compared with Asia [90% (95% CI, 84 to 94)]. GRADE quality of evidence was estimated as moderate. CONCLUSIONS: Against culture or PCR, current cholera RDTs have moderate sensitivity and specificity for detecting Vibrio cholerae O1.

DOI： 10.3390/diagnostics11112095

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s00705-021-05197-6

researchmap

Other Link： https://link.springer.com/article/10.1007/s00705-021-05197-6/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Cholera toxin (CT)-producing Vibrio cholerae O1 and O139 cause acute diarrheal disease and are proven etiological agents of cholera epidemics and pandemics. On the other hand, V. cholerae non-O1/non-O139 are designated as non-agglutinable (NAG) vibrios and are not associated with epidemic cholera. The majority of NAG vibrios do not possess the gene for CT (ctx). In this study, we isolated three NAG strains (strains No. 1, 2, and 3) with ctx from pond water in Kolkata, India, and examined their pathogenic properties. The enterotoxicity of the three NAG strains in vivo was examined using the rabbit ileal intestinal loop test. Strain No. 1 induced the accumulation of fluid in the loop, and the volume of fluid was reduced by simultaneous administration of anti-CT antiserum into the loop. The volume of fluid in the loop caused by strains No. 2 and 3 was small and undetectable, respectively. Then, we cultured these three strains in liquid medium in vitro at two temperatures, 25°C and 37°C, and examined the amount of CT accumulated in the culture supernatant. CT was accumulated in the culture supernatant of strain No.1 when the strain was cultured at 25°C, but that was low when cultured at 37°C. The CT amount accumulated in the culture supernatants of the No. 2 and No. 3 strains was extremely low at both temperature under culture conditions examined. In order to clarify the virulence properties of these strains, genome sequences of the three strains were analyzed. The analysis showed that there was no noticeable difference among three isolates both in the genes for virulence factors and regulatory genes of ctx. However, vibrio seventh pandemic island-II (VSP-II) was retained in strain No. 1, but not in strains No. 2 or 3. Furthermore, it was revealed that the genotype of the B subunit of CT in strain No. 1 was type 1 and those of strains No. 2 and 3 were type 8. Histopathological examination showed the disappearance of villi in intestinal tissue exposed to strain No. 1. In addition, fluid accumulated in the loop due to the action of strain No. 1 had hemolytic activity. This indicated that strain No. 1 may possesses virulence factors to induce severe syndrome when the strain infects humans, and that some strains of NAG vibrio inhabiting pond water in Kolkata have already acquired virulence, which can cause illness in humans. There is a possibility that these virulent NAG vibrios, which have acquired genes encoding factors involved in virulence of V. cholerae O1, may emerge in various parts of the world and cause epidemics in the future.

DOI： 10.3389/fmicb.2021.726273

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s11274-021-03113-3

researchmap

Other Link： https://link.springer.com/article/10.1007/s11274-021-03113-3/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Cholera is an acute diarrheal disease caused by pathogenic strains of V. cholerae generated by lysogenization of the filamentous cholera toxin phage CTXΦ. The analysis revealed that recent isolates possessed altered CTXΦ prophage array of prototype El Tor strain and were defective in replicating the CTXΦ genome.

DOI： 10.1128/msphere.00337-21

researchmap

Publishing type：Research paper (scientific journal)   Publisher：The Society for Free Radical Research Japan  

DOI： 10.3164/jcbn.20-201

researchmap

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：The Society for Antibacterial and Antifungal Agents, Japan  

DOI： 10.4265/bio.26.113

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

DOI： 10.3389/fcimb.2020.572096

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/1348-0421.12829

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1348-0421.12829

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Vibrios can degrade chitin surfaces to soluble N-acetyl glucosamine oligosaccharides (GlcNAcn) that can be utilized as a carbon source and also induce a state of natural genetic competence. In this study, we characterized chitin-dependent growth and natural competence in Vibrio parahaemolyticus and its regulation. We found that growth on chitin was regulated through chitin sensors ChiS (sensor histidine kinase) and TfoS (transmembrane transcriptional regulator) by predominantly controlling the expression of chitinase VPA0055 (ChiA2) in a TfoX-dependent manner. The reduced growth of ΔchiA2, ΔchiS and ΔtfoS mutants highlighted the critical role played by ChiA2 in chitin breakdown. This growth defect of ΔchiA2 mutant could be recovered when chitin oligosaccharides GlcNAc2 or GlcNAc6 were supplied instead of chitin. The ΔtfoS mutant was also able to grow on GlcNAc2 but the ΔchiS mutant could not, which indicates that GlcNAc2 catabolic operon is dependent on ChiS and independent of TfoS. However, the ΔtfoS mutant was unable to utilize GlcNAc6 because the periplasmic enzymes required for the breakdown of GlcNAc6 were found to be downregulated at the mRNA level. We also showed that natural competence can be induced only by GlcNAc6, not GlcNAc2, because the expression of competence genes was significantly higher in the presence of GlcNAc6 compared to GlcNAc2. Moreover, this might be an indication that GlcNAc2 and GlcNAc6 were detected by different receptors. Therefore, we speculate that GlcNAc2-dependent activation of ChiS and GlcNAc6-dependent activation of TfoS might be crucial for the induction of natural competence in V. parahaemolyticus through the upregulation of the master competence regulator TfoX.

DOI： 10.3390/microorganisms8091303

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

It has been well known that Vibrio cholerae inhabit in environmental water. As many patients infected with cholera toxin-producing V. cholerae O1 (toxigenic V. cholerae O1) emerge in Kolkata, India, it has been thought that toxigenic V. cholerae O1 is easily detected in environmental water in Kolkata. However, we could not isolate toxigenic V. cholerae O1 from environmental water in Kolkata, though NAG Vibrio (generic name of V. cholerae non-O1/non-O139) is constantly detected. To clear the reason for the non-isolation of toxigenic V. cholerae O1, we examined the viability of V. cholera O1 and NAG Vibrios in the artificial low ionic strength aquatic solution. We found that the viability of toxigenic V. cholerae O1 in the solution is low, but that of NAG Vibrios is high. Subsequently, we examined the viability of NAG Vibrios possessing cholera toxin gene (ctx) in the same condition and found that the viability of these NAG Vibrios is low. These results indicate that the existence of ctx in V. cholerae affects the viability of V. cholerae in the aquatic solution used in this experiment. We thought that there was closely relation between the low viability of toxigenic V. cholerae O1 in the artificial low ionic strength aquatic solution and the low frequency of isolation of the strain from environmental water.

DOI： 10.1248/bpb.b20-00350

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Non-O1/non-O139 nontoxigenic Vibrio cholerae associated with cholera-like diarrhea has been reported in Kolkata, India. However, the property involved in the pathogenicity of these strains has remained unclear. The character of 25 non-O1/non-O139 nontoxigenic V. cholerae isolated during 8 years from 2007 to 2014 in Kolkata was examined. Determination of the serogroup showed that the serogroups O6, O10, O35, O36, O39, and O70 were represented by two strains in each serogroup, and the remaining isolates belonged to different serogroups. To clarify the character of antibiotic resistance of these isolates, an antibiotic resistance test and the gene analysis were performed. According to antimicrobial drug susceptibility testing, 13 strains were classified as drug resistant. Among them, 10 strains were quinolone resistant and 6 of the 13 strains were resistant to more than three antibiotics. To define the genetic background of the antibiotic character of these strains, whole-genome sequences of these strains were determined. From the analysis of these sequences, it becomes clear that all quinolone resistance isolates have mutations in quinolone resistance-determining regions. Further research on the genome sequence showed that four strains possess Class 1 integrons in their genomes, and that three of the four integrons are found to be located in their genomic islands. These genomic islands are novel types. This indicates that various integrons containing drug resistance genes are spreading among V. cholerae non-O1/non-O139 strains through the action of newly generated genomic islands.

DOI： 10.1111/1348-0421.12790

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.gene.2019.144016

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1186/s41182-019-0167-4

researchmap

Other Link： http://link.springer.com/article/10.1186/s41182-019-0167-4/fulltext.html

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1099/mic.0.000798

researchmap

Authorship：Last author  

researchmap

Authorship：Lead author  

researchmap

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.pep.2018.04.004

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Linear alkylbenzene sulfonate (LAS) and polyoxyethylene lauryl ether (POLE) are major surfactants contained in the laundry detergents. In the present study, the antibacterial activities of the surfactants to aquatic microorganisms were compared. When freshwater samples from a small river in Okayama city were treated with each of the surfactants, only LAS showed the significant antibacterial activity. Several strains, which survived after the treatment with 2.0% LAS, were isolated and identified by sequencing of 16S rDNA. All strains were classified into the family Enterobacteriaceae. However, this family was not a major member of the aquatic microflora, suggesting that the bacteria in Enterobacteriaceae have a common property of LAS-resistance in the river water.

DOI： 10.4265/bio.22.229

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Cholera is an acute diarrheal disease and a major public health problem in many developing countries in Asia, Africa, and Latin America. Since the Bay of Bengal is considered the epi-center for the seventh cholera pandemic, it is important to understand the genetic dynamism of Vibrio cholerae from Kolkata, as a representative of the Bengal region. We analyzed whole genome sequence data of V. cholerae O1 isolated from cholera patients in Kolkata, India, from 2007 to 2014 and identified the heterogeneous genomic region in these strains. In addition, we carried out a phylogenetic analysis based on the whole genome single nucleotide polymorphisms to determine the genetic lineage of strains in Kolkata. This analysis revealed the heterogeneity of the Vibrio seventh pandemic island (VSP)-II in Kolkata strains. The ctxB genotype was also heterogeneous and was highly related to VSP-II types. In addition, phylogenetic analysis revealed the shifts in predominant strains in Kolkata. Two distinct lineages, 1 and 2, were found between 2007 and 2010. However, the proportion changed markedly in 2010 and lineage 2 strains were predominant thereafter. Lineage 2 can be divided into four sublineages, I, II, III and IV. The results of this study indicate that lineages 1 and 2-I were concurrently prevalent between 2007 and 2009, and lineage 2-III observed in 2010, followed by the predominance of lineage 2-IV in 2011 and continued until 2014. Our findings demonstrate that the epidemic of cholera in Kolkata was caused by several distinct strains that have been constantly changing within the genetic lineages of V. cholerae O1 in recent years.

DOI： 10.1371/journal.pntd.0005386

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Vibrio vulnificus is a gram-negative halophilic estuarine bacterium. It is an opportunistic human pathogen causing rapidly progressive fatal septicemia and necrotizing wound infection. This species also causes hemorrhagic septicemia called vibriosis in cultured eels. A range of virulence factors have been proposed to play a role in pathogenesis of the bacterium during human and/or eel infection. Among these factors, the metalloprotease (V. vulnificus protease: VVP) and the cytolytic toxin (V. vulnificus hemolysin: VVH) are significantly important. VVP elicits the characteristic edematous and hemorrhagic skin damage. On the other hand, VVH exhibits powerful hemolytic and cytolytic activities and it also contributes to the bacterial invasion from the intestine to the blood stream. In addition, a few V. vulnificus strains isolated from diseased eels were recently found to produce a serine protease termed as V. vulnificus serine protease (VvsA) instead of VVP. Similar to VVP, VvsA may also possess various toxic activities such as collagenolytic, cytotoxic and edema-forming activity. In this review, we clarify the regulation of V. vulnificus VVP, VVH and VvsA in terms of expression at mRNA and protein level. The explanation is given on the basis of quorum sensing system, which is dependent on the bacterial cell density. In addition, we also outline the role of environmental factors and global regulators, such as histone-like nucleoid structuring protein, cyclic AMP receptor protein, RpoS, HlyU, Fur, ToxRS, AphB and LeuO, in this regulation. Altogether, we compiled the cumulative impact of these regulatory systems on the pathogenicity of V. vulnificus.

DOI： 10.1111/1348-0421.12465

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese  

CiNii Article

CiNii Books

researchmap

Other Link： http://search.jamas.or.jp/link/ui/2017275887

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Vibrio mimicus is an estuarine bacterium, while it can cause severe diarrhea, wound infection, and otitis media in humans. This pathogen secretes a relatively important toxin named V. mimicus metalloprotease (VMP). In this study, we clarified regulation of the VMP production according to the quorum-sensing master regulatory protein named LuxR. First, the full length of luxR gene, encoding LuxR, was detected in V. mimicus strain E-37, an environmental isolate. Next, the putative consensus binding sequence of LuxR protein could be detected in the upstream (promoter) region of VMP encoding gene, vmp. Finally, the effect of disruption of luxR gene on the expression of vmp and production of VMP was evaluated. Namely, the expression of vmp was significantly diminished by luxR disruption and the production of VMP was severely altered. Taken together, here we report that VMP production is under the positive regulation of the quorum-sensing master regulatory protein, LuxR.

DOI： 10.1002/jobm.201600002

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

In an attempt to discover inhibitory compounds against pore-forming toxins, some of the major toxins produced by bacteria, we herein examined the effects of four kinds of indolo[3,2-b]quinoline derivatives on hemolysis induced by the aerolysin-like hemolysin (ALH) of Aeromonas sobria and also by the alpha-hemolysin of Staphylococcus aureus. The results showed that hemolysis induced by ALH was significantly reduced by every derivative, while that induced by alpha-hemolysis was significantly reduced by three out of the four derivatives. However, the degrees of reduction induced by these derivatives were not uniform. Each derivative exhibited its own activity to inhibit the respective hemolysin. Compounds 1 and 2, which possessed the amino group bonding the naphthalene moiety at the C-11 position of indolo[3,2-b]quinoline, had strong inhibitory effects on the activity of ALH. Compound 4 which consisted of benzofuran and quinoline had strong inhibitory effects on the activity of alpha-hemolysin. These results indicated that the amino group bonding the naphthalene moiety of compounds 1 and 2 assisted in their ability to inhibit ALH activity, while the oxygen atom at the 10 position of compound 4 strengthened its interaction with alpha-hemolysin. These compounds also suppressed the hemolytic activity of the supernatant of A. sobria or A. hydrophila, suggesting that these compounds were effective at the site of infection of these bacteria.

DOI： 10.1248/bpb.b15-00708

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Temperature is one of the important parameters regulating the expression of virulence factors in bacteria. The global regulator, a histone-like nucleoid structuring protein (H-NS), is known to play a crucial role in this regulation. In the present study, we first clarified the role of H-NS in the temperature-dependent regulation of virulence factor production in Vibrio vulnificus, including that of the cytolytic toxin (V vulnificus hemolysin: VVH) and the proteolytic enzyme (V. vulnificus protease: VVP). The expression of hns itself was subjected to temperature regulation, where hns was expressed more at 26 degrees C than at 37 degrees C. VVH production and the expression of its gene vvhA were increased by disruption of the hns gene. H-NS appeared to affect the vvhA expression by the well-documented transcriptional silencing mechanism. On the other hand, hns disruption resulted in the reduction of VVP production and the expression of its gene vvpE. H-NS was suggested to positively regulate vvpE expression through the increase in the level of the rpoS mRNA. Moreover, H-NS was found to contribute to the survival of V vulnificus in stressful environments. When compared to the wild type strain, the hns mutant exhibited reduced survival rates when subjected to acidic pH, hyperosmotic and oxidative stress.

DOI： 10.4265/bio.20.263

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Vibrio vulnificus is a halophilic estuarine bacterium, but this species causes fatal septicemia in humans. V. vulnificus may encounter many kinds of stresses either in the natural environment or in the human body. One of the striking stresses is the exposure to the reactive oxygen species including nitric oxide (NO). The present study revealed that NO could participate in the regulation of the V. vulnificus community behavior. When the bacterium was cultivated in the presence of sub-lethal doses of an NO donor, the expression of the genes encoding NO-detoxifying enzymes was significantly increased. The NO donor was also found to cause significant increase in production of a metalloprotease, a putative virulence factor, by the bacterium.

DOI： 10.4265/bio.20.199

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

A real-time loop-mediated isothermal amplification (RealAmp) assay for the detection of Listeria was developed. The RealAmp assay, using primers specific for the hemolysin-encoding hlyA gene, was verified using Listeria monocytogenes strains (n=58) from different regions of the world. Both the sensitivity and specificity of the RealAmp assay were high. The RealAmp assay could detect 10(3)CFUml(-1) within 30min. A comparative evaluation of the RealAmp assay, the API Listeria assay, and the real-time PCR assay revealed that the RealAmp assay is simpler, faster, and has a higher specificity than the other two assays.
Significance and Impact of the StudyConventional culture and molecular detection methods are always time consuming and require a specific laboratory infrastructure, thereby restricting their use for the rapid detection and diagnosis of pathogens. A real-time loop-mediated isothermal amplification (RealAmp) assay performed by ESEtube scanner to rapidly detect Listeria monocytogenes isolated from food was developed. The results showed that the RealAmp assay using the tube scanner was more efficient and precise than the conventional API Listeria assay and the real-time PCR assay.

DOI： 10.1111/lam.12429

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Many bacterial species are known to become viable but nonculturable (VBNC) under conditions that are unsuitable for growth. In this study, the requirements for resuscitation of VBNC-state Vibrio cholerae cells were found to change over time. Although VBNC cells could initially be converted to culturable by treatment with catalase or HT-29 cell extract, they subsequently entered a state that was not convertible to culturable by these factors. However, fluorescence microscopy revealed the presence of live cells in this state, from which VBNC cells were resuscitated by co-cultivation with HT-29 human colon adenocarcinoma cells. Ultimately, all cells entered a state from which they could not be resuscitated, even by co-cultivation with HT-29. These characteristic changes in VBNC-state cells were a common feature of strains in both V. cholerae O1 and O139 serogroups. Thus, the VBNC state of V. cholerae is not a single property but continues to change over time.

DOI： 10.1111/1348-0421.12246

Web of Science

researchmap

Authorship：Last author  

researchmap

Publishing type：Research paper (scientific journal)   Publisher：The Society for Antibacterial and Antifungal Agents, Japan  

DOI： 10.4265/bio.20.77

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Of human pathogenic Vibrio species, V mimicus causes gastroenteritis whereas V vulnificus causes fatal septicemia after consumption of contaminated seafood. These two pathogens produce hemolytic toxins termed V mimicus hemolysin (VMH) and V vulnificus hemolysin (VVH), respectively. These toxins elicit the cytolysis of various eukaryotic cells, as well as erythrocytes. The human intestine secretes cationic antimicrobial peptides (AMPs) to prevent infectious diseases. Paneth cells in the small intestine secrete a-defensin 5 (HD-5) and epithelial cells in the large intestine produce LL-37. In the present study, we examined the bactericidal activities of AMPs against V mimicus and V vulnificus. Although HD-5 showed no bactericidal activity, LL-37 revealed significant activity against both Vibrio species, suggesting that neither V mimicus nor V vulnificus can multiply in the large intestine. We also tested whether AMPs had the ability to inactivate the hemolytic toxins. Only HD-5 was found to inactivate VMH, but not VVH, in a dose-dependent manner through the direct binding to VMH. Therefore, it is considered that V mimicus cannot penetrate the small intestinal epithelium because the cytolytic action of VMH is inactivated by HD-5.

DOI： 10.4265/bio.19.199

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Vibrio mimicus, a human pathogen that causes gastroenteritis, produces an enterotoxic hemolysin as a virulence factor. The hemolysin is secreted extracellularly as an inactive protoxin and converted to a mature toxin through removal of the N-terminal propeptide, which comprises 151 amino acid residues. In this study, a novel protease having the trypsin-like substrate specificity was purified from the bacterial culture supernatant. The N-terminal amino acid sequence of the purified protein was identical with putative trypsin VMD27150 of V. mimicus strain VM573. The purified protease was found to cause maturation of the protoxin by cleavage of the Arg(151)Ser(152) bond. Deletion of the protease gene resulted in increased amounts of the protoxin in the culture supernatant. In addition, expression of the hemolysin and protease genes was detected during the logarithmic growth phase. These findings indicate that the protease purified may mediate maturation of the hemolysin.

DOI： 10.1111/1348-0421.12177

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) leads to serious health problems as a chronic respiratory infectious disease. Here we established a real-time fluorescence loop-mediated isothermal amplification assay (RealAmp) using a portable ESE Quant tube scanner as a convenient rapid detection method for MTB. The method efficacy from sputum samples was further investigated, and the reaction time was only 20 min with the detection limit low to 10(2) CPU/ml concentration of MTB. We assessed a total of 1067 samples by the RealAmp assay, comparing the results with smear microscopy and conventional culture methods. To examine whether the failure to detect TB by culturing is due to low sensitivity or true absence, we examined the culture negative samples by commercial real time PCR MTB detection kit, and the results were compared with RealAmp. The data showed that RealAmp assay had a higher positive rate than that of sputum smear and culture methods. RealAmp had a sensitivity of 96.70% and a specificity of 91.55% when compared with culture. In addition, its sensitivity and specificity were 95.29% and 86.88% respectively compared with examination of smear samples using light microscopy. The sensitivity of RealAmp in comparison to real time PCR was 98.25% and specificity was 99.11% in validation of culture negative samples. The present study revealed the newly established RealAmp assay as a convenient, efficient, sensitive and specific method that could be an alternative for rapid detection of MTB and a tool to validate culture and smear negative samples. Furthermore, the portability of the ESE Quant tube scanner also contributed to the promising application for grassroots and field detection of MTB. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mimet.2014.06.011

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Previously, we reported that viable but nonculturable (VBNC) Vibrio cholerae was converted into a culturable state by coculture with several eukaryotic cell lines including HT-29 cells. In this study, we found that a factor converting VBNC V. cholerae into a culturable state (FCVC) existed in cell extracts of eukaryotic cells. FCVC was nondialyzable, proteinase K-sensitive, and stable to heating at &lt;60 degrees C for 5 min. We prepared thiosulfate citrate bile salts sucrose (TCBS) plates with FCVC (F-TCBS plates). After confirming that VBNC V. cholerae O1 and O139 formed typical yellow colonies on F-TCBS plates, we tried to isolate cholera toxin gene-positive VBNC V. cholerae from environmental water samples collected in urban slum areas of Kolkata, India and succeeded in isolating V. cholerae O1 El Tor variant strains harboring a gene for the cholera toxin. The possible importance of VBNC V. cholerae O1 as a source of cholera outbreaks is discussed.

DOI： 10.1002/mbo3.164

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Vibrio vulnificus is a halophilic estuarine bacterium while it causes fatal septicemia or necrotizing wound infections in humans. This pathogen secretes the metalloprotease (V. vulnificus protease: VVP) and the cytolysin (V. vulnificus hemolysin: VVH) as protein toxins; however, their production was coordinated in response to the bacterial cell density. This regulation is termed quorum sensing (QS) and is mediated by the small diffusible molecule called autoinducer 2 (AI-2). In the present study, we investigated effects of disruption of luxO encoding a central response regulator of the QS circuit, as well as effects of temperature and growth phase, on the toxin production by V. vulnificus. Disruption of luxO was found to increase VVP production and expression of its gene vvpE. The expression of smcR, crp and rpoS, of which products positively regulate vvpE expression, and luxS encoding the AI-2 synthetase were also significantly increased. On the other hand, the luxO disruption resulted in reduction of VVH production and expression of its gene vvhA. Expression of other two genes affecting the QS circuit, luxT and rpoN, were also significantly decreased. The regulation systems of VVP production were found to exert their action during the stationary phase of the bacterial growth and to be operated strongly at 26 A degrees C. By contrast, those of VVH production apparently started at the log phase and were operated more effectively at 37 A degrees C.

DOI： 10.1007/s11274-013-1501-3

Web of Science

researchmap

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vibrio vulnificus is a ubiquitous estuarine microorganism but causes fatal systemic infections in cultured eels or shrimps, as well as in immunocompromised humans. An extracellular metalloprotease has been reported to be a potential virulence factor of the bacterium; however, a few strains isolated from a diseased eel or shrimp were recently found to produce a serine protease termed VvsA. In the present study, we first clarified the regulatory characteristics of the VvsA production in V. vulnificus strain NCIMB 2137, a metalloprotease-gene negative strain isolated from a diseased eel. V. vulnificus coordinates expression of virulence genes in response to the bacterial cell density, which is termed quorum sensing (QS) and is mediated by the small diffusible molecule called autoinducer 2 (AI-2). When cultivated at 26 degrees C, the vvsA expression was closely related with expression of the luxS gene encoding the synthase of the AI-2 precursor LuxS. Both VvsA and AI-2 were sufficiently secreted at early stationary phase of the bacterial growth. In contrast, when cultivated at 37 degrees C, far less amounts of the AI-2 and VvsA were produced even at the stationary phase. Disruption of the luxS gene was found to decrease significantly the vvsA expression and VvsA production. Disruption of luxO encoding the central response regulator of the QS circuit caused an increase in the vvsA expression and VvsA production at the logarithmic growth phase. These findings indicate that VvsA production is positively regulated by the V. vulnificus LuxS-dependent QS system, which operated more effectively at 26 degrees C than at 37 degrees C. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.aquaculture.2013.09.041

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

An ecological study of pathogenic vibrios in aquatic environments of Okayama was carried out. The number of Vibrio parahaemolyticus detected in the sea area was comparatively smaler than that found in the survey of about two decades ago. Various reasons for the decrease in the case of food poisoning by V. parahaemolyticus have been suggested but the lower number of the vibrio in aquatic environments may be one explanation. Although the number of V. vulnificus was also not as large, most of the isolates possessed the pathogenic genes, vvp and vvh, suggesting the potential for fatal pathogenicity to patients having underlying diseases. As for V. cholerae, some non-O1/non-O139 serovar isolates were detected in a fresh water area, and many of them had hlyA, the gene for hemolysin which acts as a pathogenic factor in sporadic cases of diarrhea. Thus, the total number of pathogenic vibrios detected was not of concern. However, the marine products of these areas are shipped in wide area and are for general consumption. Therefore, it is necessary to continue to survey pathogenic vibrios in aquatic environments in order to ensure food hygiene.

DOI： 10.4265/bio.18.53

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

DOI： 10.3389/fmicb.2013.00339

Web of Science

researchmap

Authorship：Lead author  

DOI： 10.1016/B978-0-12-382219-2.00119-8

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Okayama Medical Association  

DOI： 10.4044/joma.125.35

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Viable but nonculturable (VBNC) Vibrio cholerae non-O1/non-O139, V. parahaemolyticus, enterohemorrhagic Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli, Shigella flexneri, and Salmonella enterica were converted to the culturable state by co-culture with selected eukaryotic cells, e.g., HT-29, Caco-2, T84, HeLa, Intestine 407, and CHO cells.

DOI： 10.1111/j.1348-0421.2012.00440.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Although it is well-known that variations of the microbial community in a specific location of human body may be associated with some diseases, the developing change of the oral microbiota related to oral diseases before and after wearing the removable partial dentures (RPD) is not completely understood. In this study, three kinds of samples (saliva, supra- and subgingival plaque, and oral mucosal surfaces) were collected from the 10-patients group at three different times: before, 1-month and 6-months after the treatment. Ten healthy adults were also selected as the control group. Denaturing gradient gel electrophoresis was applied to identify the bacterial profiles and to analyze the dynamics of the oral microbial population in the pre- and post-therapy. The ANOVA of Repeated Measurement Data indicated that, in the saliva and mucosal surfaces, wearing RPDs caused significant change of numbers of amplicons. As many as 607 amplicons were chosen to cut out and re-amplify by PCR. After cloning and sequencing, a total of 16 bacterial genera were identified. The health-associated genera such as Streptococcus, Neisseria, Rothia, Corynebacterium, Leptotrichia, Gemella, Veillonella, Selenomona and Actinomyces tended to decrease, whereas the disease-associated species including Streptococcus mutans tended to increase. In general, wearing RPDs influenced the diversity of the bacterial species in the oral microbial ecosystem. It is noteworthy that the oral environment will be changed from the healthy status towards the disease status after the treatment.

DOI： 10.1007/s11274-012-1030-5

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Vibrio vulnificus is a ubiquitous estuarine microorganism but causes fatal systemic infections in immunocompromised humans, cultured eels or shrimps. An extracellular metalloprotease VVP/VvpE has been reported to be a potential virulence factor of the bacterium; however, a few strains isolated from a diseased eel or shrimp were recently found to produce a serine protease termed VvsA, but not VVP/VvpE. In the present study, we found that these strains had lost the 80 kb genomic region including the gene encoding VVP/VvpE. We also purified VvsA from the culture supernatant through ammonium sulfate fractionation, gel filtration and ion-exchange column chromatography, and the enzyme was demonstrated to be a chymotrypsin-like protease, as well as those from some vibrios. The gene vvsA was shown to constitute an operon with a downstream gene vvsB, and several Vibrio species were found to have orthologues of vvsAB. These findings indicate that the genes vvp/vvpE and vvsAB might be mobile genetic elements.

DOI： 10.1007/s11274-011-0969-y

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

A sensitive rRNA-targeted reverse transcription-quantitative polymerase chain reaction (RT-qPCR) method was developed for detection of Vibrio cholerae/mimicus, V. parahaemolyticus/alginolyticus and Campylobacter jejuni/coli by using specific primers. Counts of the enteric pathogens spiked in human stools were quantified at the lower detection limit of 103 cells/g stool by RT-qPCR, in marked contrast with conventional quantitative polymerase chain reaction (qPCR) at the detection limit of 105 to 106 cells/g stool. The bacterial counts determined by RT-qPCR were almost equivalent to those determined by the culture method and fluorescence in situ hybridization (FISH) during the course of in vitro culture. Bacterial rRNA in the stools was stable for at least 4 weeks when the stools were kept as the suspensions in RNA-stabilizing agent, RNAlater (R), even at 37oC. These data suggested that the rapid and high sensitive rRNA-targeted RT-qPCR was applicable for the accurate quantification of viable enteric pathogens, such as V. cholerae/mimicus, V. parahaemolyticus/alginolyticus and C. jejuni/coli.

DOI： 10.1111/j.1348-0421.2011.00405.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A total of 81 Salmonella isolates from retail meats and seafood in Hebei province, China, were assayed for the presence of and horizontal transfer of class 1 integrons. By the PCR screening for the integrons, class 1 integron was detected from strains in serotypes of Derby, Indiana, London and Choleraesuis, which were isolated from pork, chicken or seafood: however, two isolates contained the empty integron that lacked the resistance cassette, a potential hotspot for development of the multidrug resistance. In contrast, two other isolates had the antibiotic resistance gene cassettes within the class 1 integron, which were dfrA1-aadA1 and aadB-cmlA, respectively. The conjugation experiments demonstrated the plasmid-mediated transfer of the class 1 integrons. Furthermore, each of the integrons was transmitted to Streptococcus mutans via natural gene transformation. These findings suggest the possible transfer of class 1 integrons from foodborne pathogens to human residential bacteria via horizontal gene transfer. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijfoodmicro.2011.07.006

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Vibrio vulnificus is an etiological agent causing serious systemic infections in the immu-nocompromised humans or cultured eels. This species commonly produces a hemolytic toxin consisting of the cytolysin domain and the lectin-like domain. For hemolysis, the lectin-like domain specifically binds to cholesterol in the erythrocyte membrane, and to form a hollow oligomer, the toxin is subsequently assembled on the membrane. The cytolysin domain is essential for the process to form the oligomer. Three-dimensional structure model revealed that two domains connected linearly and the C-terminus was located near to the joint of the domains. Insertion of amino acid residues between two domains was found to cause inactivation of the toxin. In the C-terminus, deletion, substitution or addition of an amino acid residue also elicited reduction of the activity. However, the cholesterol-binding ability was not affected by the mutations. These results suggest that mutation of the C- or N-terminus of the lectin-like domain may result in blockage of the toxin assembly. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.toxicon.2011.03.013

Web of Science

researchmap

Authorship：Last author   Language：English   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Bacteria of the genus Vibrio are normal habitants of the aquatic environment but the some species are believed to be human pathogens. Pathogenic vibrios produce various pathogenic factors, and the proteases are also recognized to play pathogenic roles in the infection: the direct: roles by digesting many kinds of host proteins or indirect roles by processing other pathogenic protein factors. Especially VVP from Vibrio vulnificus is thought to be a major pathogenic factor of the vibrio. Although HA/P, the V. cholerae hemagglutinin/protease, is not a direct toxic factor of cholera vibrio, its significance is an undeniable fact. Production of HA/P is regulated together with major pathogenic factors such as CT (cholera toxin) or TCP (toxin co-regulated pilus) by a quorum-sensing system. HA/P is necessary for full expression of pathogenicity of the vibrio by supporting growth and translocation in the digestive tract. Processing of protein toxins such as CT or El Tor hemolysin is also an important pathogenic role.

DOI： 10.4265/bio.16.1

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

Cationic and amphiphilic antimicrobial peptides (AMPs) such as alpha-defensins and cathelicidins are factors related to innate immunity. In the present study, we examined the protective effects of two AMPs, human neutrophil peptide-3 and alpha-defensin-5, against the opportunistic pathogen Enterococcus faecalis (E. faecalis). The alpha-defensins had dose-dependent bactericidal activity, whereas they showed no synergistic effect on the antimicrobial actions of antibiotics. Although AMPs often neutralize bacterial bioactive products, neither alpha-defensin reduced the proteolytic activity of GelE, a toxic protease from E. faecalis. On the other hand, the alpha-defensins were found to be fairly stable even in the presence of excess amounts of GelE. These results indicate that alpha-defensins may be defensive factors against E. faecalis in humans.

DOI： 10.1248/jhs.56.618

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A total of 387 retail meat, seafood and milk powder samples were collected from nine cities in northern China in 2005 and screened for the presence of Salmonella. Salmonella strains isolated were subjected to serotyping and antimicrobial susceptibility testing. Salmonella was isolated from 81 (20.9%, 81/387) samples and classified into 23 serotypes. The isolates were frequently resistant to sulfamethoxazole (86.4%), sulfamethoxazole/trimethoprim (48.1%), nalidixic acid (30.9%). tetracycline (19.8%), carboxybenzylpenicillin (17.3%), amoxicillin (17.3%) and ampicillin (16.0%). The multiple resistance (resistance to &gt;= 3 antibiotics) was found in 29.6% (n = 24) isolates. Additionally, 4 isolates from chicken displayed the ACSSuTNx profile, resistant to ampicillin, chloramphenicol, streptomycin, sulfonamide, tetracycline and nalidixic acid, in particular, strain HBS084 showing the resistance to as many as 20 antibiotics. Salmonella from chicken showed the higher frequency of antimicrobial resistance. Our findings indicate that in northern China food products of animal origin can be a source of exposure for consumers to multiresistant Salmonella strains. (c) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijfoodmicro.2010.07.034

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Vibrio vulnificus, a ubiquitous microorganism in aquatic environments, causes serious septicemia to the immunocompromised host. In addition to protoheme, this species can utilize Fe-TCPP [ferric tetrakis (4-carboxyphenyl) porphine] as an iron source. In the present study, heme c bound covalently to the protein in cytochrome c, as well as the Fe-TCPP complex formed with a nanopeptide with a high affinity, was found to be useful iron sources for V. vulnificus. This bacterium was also revealed to use Zn-TCPP as a single zinc source. However, other metalloporphyrins such as Mn-TCPP and Pt-TCPP delayed the bacterial growth in the broth containing Fe-TCPP, suggesting interference in the iron assimilation. These results indicate that V. vulnificus may acquire metal ions from both free and peptide-bound metalloporphyrins.

DOI： 10.4265/bio.15.1

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

The persistence of DNA after the cell death causes a major issue in aspects of medical or biological studies. The signal from viable bacterial cells cannot be distinguished from the dead cells in the conventional DNA-based detection methods. In the present study, the loop-mediated isothermal amplification (LAMP) method combined with the ethidium monoazide (EMA) treatment was applied for specific detection of viable, but not dead, Salmonella cells. For this method (EMA-LAMP), we designed a series of primers, which recognize six distinct sequences of the target invA gene conserved in Salmonella. The invA gene of the viable cells was remarkably amplified within 1 hr when as small amounts as 100 fg of DNA was subjected to EMA-LAMP. Because EMA selectively penetrated into the dead cells and bound covalently to DNA, the gene of the dead cells could not be amplified. This study offers a novel DNA-based method to distinguish the viable bacterial cells from the dead cells. ©2009 The Pharmaceutical Society of Japan.

DOI： 10.1248/jhs.55.820

Scopus

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

Vibrio mimicus is a causative agent of human gastroenteritis and food poisoning, and this species produces an enterotoxic hemolysin (V. mimicus hemolysin) as a virulence determinant. Vibrio mimicus hemolysin is secreted as an 80 kDa precursor, which is later converted to the 66 kDa mature toxin through removal of an N-terminal propeptide via cleavage of the Arg151-Ser152 bond. In this article, we investigate the role of the endogenous metalloprotease (V. mimicus protease) in the maturation of V. mimicus hemolysin. In vitro experiments using purified proteins showed that, although it activated the precursor at the early stage via cleavage of the Asn157-Val158 bond, V. mimicus protease finally converted the activated and physiologically maturated toxin to a 51 kDa protein through removal of the C-terminal polypeptide. This 51 kDa derivative was unable to lyse erythrocytes because of its inability to bind to the erythrocyte membrane. Vibrio mimicus protease-negative strains were found to produce high levels of V. mimicus hemolysin at the logarithmic phase of bacterial growth and maintained high hemolytic activity even at the stationary phase. These findings indicate that, although it is not directly related to toxin maturation in vivo, V. mimicus protease can modulate the activity of V. mimicus hemolysin and/or its precursor through limited proteolysis.

DOI： 10.1111/j.1742-4658.2008.06827.x

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

Vibrio mimicus (V mimicus) is a causative agent of human gastroenteritis and food poisoning. Although several toxic or virulence factors have been isolated from the bacterium, an enterotoxic hemolysin is a sole toxin produced by all clinical isolates. In the present study, we found that the antibody against the hemolysin significantly inhibited the fluid-accumulating action of the living cells inoculated into a rabbit ileal loop, and that the hemolysin gene (vmhA) was probably expressed by the bacterium in the ileal loop. Additionally, in spit of the comparable motility and similar proteome profiles, a vmhA mutant revealed the reduced fluid-accumulating activity. Theses findings suggest that the hemolysin contributes to full virulence of V. mimicus.

DOI： 10.1248/jhs.54.686

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

Vibrio vulnificus is a causative agent of septicemia or wound infection in human and eel; however. the genetic variation between human and eel isolates has been reported. In the present study, the difference in the vvp gene encoding a tissue-damaging metalloprotease Was (type B vvp) was 95.2% identical with that of strain L-180 from human blood investigated. The acne of strain E86 from a diseased eel (type A vvp). PCR using oligonucleotide primers designed to differentiate two types of the acne showed that eel avirulent strains (9 isolates) commonly carry type A ut;p. whereas eel virulent strains (18 isolates) revealed significant genetic variation. The vvp genes From strains including strain E86 were placed on type B while those from 3 strains, were on type A. other strains were found to he negative but analysis Showed that they secreted a serine protease (VVA0302) instead of the negative, but PAGE and amino acid sequencing metalloprotease. This protease is all orthologue of a toxic protease from Vibrio parahaemolyticus a human pathogen causing wound infection as well Lis gastroenteritis. These findings suggest that, in addition to metalloprotease. the extracellular serine protease may contribute to pathogenicity of V. vulnificus. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.micpath.2008.01.001

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Vibrio parahaemolyticus, a causative agent of wound infections as well as food poisoning, harbors two collagenase genes: vppC and prtV. When cultivated at 26 degrees C in gelatin broth supplemented with 3.0% NaCl, significant collagenolytic activity was detected in the culture supernatant at the early stationary phase. Native polyacrylamide gel electrophoresis analysis revealed a 90-kDa protein, and N-terminal amino acid sequencing showed that this protein was VppC, generated through truncation of 72 N-terminal amino acid residues. Additionally, significant expression of only vppC was observed by reverse transcriptase PCR. By contrast, a vppC-negative mutant constructed through single crossover homologous recombination secreted a 50-kDa-collagenolytic enzyme; however, this enzyme was a serine protease that was reported previously. These results suggest that VppC is a primary extracellular collagenase produced by V. parahaemolyticus.

DOI： 10.1111/j.1574-6968.2008.01159.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC ANTIBACTERIAL & ANTIFUNGAL AGENTS, JAPAN  

Vibrio cholerae isolates from environmental and clinical origins in the Bengal region in which epidemics of cholera break out periodically were analyzed with particular emphasis on the molecular epidemiological features. The presence of the virulence genes (ctxA, tcpA and toxR) in the isolates was analyzed by the PCR (polymerase chain reaction) method. PFGE (pulsed-field gel electrophoresis) was performed to determine the clonal relationships between the clinical and environmental strains. Antiblograms and O serovars of the isolates were also examined. O1 and O139 strains from both clinical and environmental sources were all positive for the three virulence genes while non-O1/non-O139 strains from both sources were all negative for ctxA and tcpA but positive for toxR. PFGE patterns of recent isolates of O1 and O139 were similar in each serovar regardless of origin, suggesting a clonal relationship between the clinical and environmental strains, although comparison with past isolates or isolates from different geographical area showed some differences.

DOI： 10.4265/bio.13.1

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

Vibrio vulnificus. all opportunistic human pathogen causing fetal septicemia, produces a 50-kDa pore-forming toxin as a virulence factor. This toxin consists of 451 amino acid residues: however. there are two types of this toxin on the basis of the difference of some,amino acid residues, type 1 (Leu(281), Ser(415), Asn(435)/Asp(435), Asn(438)) and type 2 (Ile(281), Asn(415), Asn(435), Thr(438)). In the present study, two characteristic properties of type 2 toxin that was elaborated by V. vulnificus cells or synthesized by the in vitro system were compared to those of type 1 toxin. Type 2 toxin was found to be more resistant to spontaneous inactivation at 37 degrees C and to specific inactivation by cholesterol. On the other hand a variant of type 2 toxin (Asp(435), Asn(438)) showed the same properties as type 1 toxin. The replacement of the 438th Asn to Thr (N438T), but not the 435th Asp to Asn (D435N). resulted in reversion of the variant type 2 toxin to typical type 2 toxin. These findings indicate that a single amino acid residue. Thr(438), may be critical for higher stability of type 2 toxin. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.micpath.2007.07.002

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

Five strains of multidrug-resistant Pseudomonas aeruginosa (P aeruginosa) were isolated from inpatients at a local hospital in China. The most frequent resistance was to cefoperazone, ciprofloxacin, ceftriaxone, cefotaxime, gentamicin, piperacillin, trimethoprim sulfamethoxazole, and tobramycin. These strains were found to contain the class 1 integron, in which the 2360-bp gene cassettes were flanked by 5&apos;- and 3&apos;-conserved segments. Sequence analysis revealed that the gene cassettes contained aacA4 and cmlA1 genes; however, the latter gene had a nonsense mutation resulting in the production of a truncated protein. To the best of our knowledge, this is the first report of a nonsense mutation in the cmlA1 gene. Moreover, the R aeruginosa strains showed identical profiles in pulsed-field gel electrophoresis, suggesting that they were derived from the same clone. These results emphasize the importance of controlling the spread of multidrug-resistant pathogens in hospitals.

DOI： 10.1248/jhs.53.750

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

Vibrio mimicus (V mimicus), a causative agent of gastroenteritis and food poisoning, secretes a 63-kDa enterotoxic hemolysin as the most potent virulence factor. The vmhA gene encoding an 83-kDa precursor of the hemolysin was expressed from the early to late log phase of the bacterial growth, and the 79-kDa inactive protoxin was detected from the culture supernatant in the same growth phase. The N-terminal amino acid sequence of the protoxin was determined to be NH2-Asn-Ile-Ser-Asp-Pro-Val indicating cleavage of the Ala(25)-Asn(26) bond by a signal peptidase. In contrast, the hemolytic activity and the mature hemolysin in the culture supernatant were detected only at the late log phase. The maturation of the hemolysin, therefore, is suggested to be achieved by two-step processing, cleavage of the signal peptide followed by the growth phase-dependent removal of the 16-kDa propeptide.

DOI： 10.1248/jhs.53.430

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

In the present study, we examined the antibiotic sensitivity of 19 bacterial strains [5 coagulase-negative Staphylococcus, 2 methicillin-resistant Staphylococcus aureus (S. aureus), 2 Enterococcus faecium (E. faecium), 5 Escherichia coli (E. coli), 3 Cedecea sp., 1 Klebsiella pneumoniae (K. pneumoniae), and 1 Burkholderia cepacia (B. cepacia)], which were isolated from renal transplantation patients using the Kirby-Bauer method. We also investigated the production of beta-lactamase and extended-spectrum beta-lactamase (ESBL), and the presence of the integrase gene (inI1) and resistance gene cassette. Among the 19 strains tested, all displayed severe multiresistance, and 12 strains produced beta-lactamase, in which 6 strains were ESBL positive. Eleven strains were revealed to possess the class 1 integron; however, neither class 2 nor 3 was detected. Additionally, 3 drug resistance genes, aadA2, dfrA17, and aadA5, were found in some strains. The results indicate that the horizontal transfer of the beta-lactamase gene and/or the class 1 integron may contribute significantly to the spread of multiresistant bacteria among renal transplantation patients.

DOI： 10.1248/jhs.53.185

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

Haemolysin (VMH) is a virulent factor produced by Vibrio mimicus, a human pathogen that causes diarrhoea. As intestinal epithelial cells are the primary targets of haemolysin, we investigated its effects on ion transport in human colonic epithelial Caco-2 cells. VMH increased the cellular short circuit current (Isc), used to estimated ion fluxes, and I-125 efflux of the cells. The VMH-induced increases in Isc and I-125 efflux were suppressed by depleting Ca2+ from the medium or by pretreating the cells with BAPTA-AM or by Rp-adenosin 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS). The Cl- channel inhibitors 4,4'-disothiocyanatostibene-2,2'-disulfonic acid (DIDS), glybenclamide, and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) suppressed the VMH-induced increases in Isc and I-125 efflux. Moreover, VMH increased the intracellular concentrations of Ca2+ and cAMP. Thus, VMH stimulates Caco-2 cells to secrete Cl- by activating both Ca2+-dependent and cAMP-dependent Cl- secretion mechanisms. VMH forms ion-permeable pores in the lipid bilayer that are non-selectively permeable to small ions. However, the ion permeability of these pores was not inhibited by glybenclamide and DIDS, and VMH did not change the cell membrane potential. These observations indicate that the pores formed on the cell membrane by VMH are unlikely to be involved in VMH-induced Cl- secretion. Notably, VMH stimulated fluid accumulation in the iliac loop test that was fully suppressed by a combination of DIDS and glybenclamide. Thus, Ca2+-dependent and cAMP-dependent Cl- secretion may be important therapeutic targets with regard to the diarrhoea that is induced by Vibrio mimicus.

DOI： 10.1111/j.1462-5822.2006.00809.x

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

Vibrio vulnificus is ubiquitous in aquatic environments; however, it occasionally causes serious and often fatal infections in humans. These include invasive septicemia contracted through consumption of raw seafood, as well as wound infections acquired through contact with brackish or marine waters. In most cases of septicemia, the patients have underlying disease(s), such as liver dysfunction or alcoholic cirrhosis, and the secondary skin lesions including cellulitis, edema and hemorrhagic bulla appear on the limbs. Although V. Vul produces various virulent factors including polysaccharide capsule, type IV pili, hemolysin and proteolytic enzymes, the 45-kDa metalloprotease may be a causative factor of the skin lesions, because the purified protease enhances vascular permeability through generation of chemical mediators and also induces serious hemorrhagic damage through digestion of the vascular basement membrane. As well as other bacteria, V. Vul can regulate the protease production through the quorum-sensing system depending on bacterial cell density. However, this system operates efficiently at 25 degrees C, but not at 37 degrees C. Therefore, V. vulnificus may produce sufficient amounts of the protease only in the interstitial tissue of the limbs, in which temperature is lower than the internal temperature of the human body.

DOI： 10.1111/j.1346-8138.2006.00139.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

A dichloromethane (DCM)-degrading bacterium, Ralstonia metallidurans PD11 NBRC 101272, was immobilized in a polyvinyl alcohol (PVA) gel to use in a bioreactor for DCM treatment. After 4-month incubation of PVA gel beads with R. metallidurans PD11 and DCM in a mineral salt medium, the cells were tightly packed in the mesh of the gel. Forty beads of the gel in 10 ml of a batch system model showed effective activity degrading 500 and 1,000 mg l(-1) DCM within 2 and 3 h, respectively. Although reduction of pH due to accumulation of chloride ion liberated from DCM decreased the activity, it was recovered by adjustment to neutral pH. The activity of the immobilized cells was not affected by addition of nutrients which were preferentially utilized by R. metallidurans PD11, unlike the activity of the free-living cells. A continuous flow system with a column was more effective for rapid degradation of DCM. Thus, the PVA gel-immobilized cell of R. metallidurans PD11 is thought to be a prospective candidate to develop the bioreactor.

DOI： 10.1007/s00253-005-0194-4

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS INC  

Vibrio vulnificus, a ubiquitous estuarine bacterium, is divided into two groups based on the virulence potential. Group 1 is a causative agent of human fatal septicemia, which is characterized by edematous and hemorrhagic secondary skin lesions on the limbs. This human pathogen secretes a toxic metalloprotease as an important virulence determinant. The protease can evoke the skin damage through enhancement of the vascular permeability and destruction of the capillaries. Group 2 is an etiological agent of epizooticus in the cultured eels. Significant levels of metalloprotease as well as autoinducer, a well-known signal molecule of cell-density dependent regulatory system for production of virulence determinants, were found to be secreted by both the groups at early stationary phase but not middle logarithmic phase when the bacteria were cultivated at 25 degrees C. Expression of the protease gene also was found to be increased several times at the stationary phase. Therefore, the autoinducer molecules that had accumulated might have accelerated the expression of the protease gene. In contrast, when cultivated at 37 degrees C, far less amounts of the protease and autoinducer were produced even at the stationary phase. Most patients suffering from V. vulnificus septicemia have underlying diseases causing elevation of the serum iron level. When incubated in human serum supplemented with ferric chloride at 37 degrees C, only Group 1 V. vulnificus showed steady bacterial multiplication and protease production but secretion of significant level of autoinducer could not be detected. Hence, the protease production by Group 1 V. vulnificus in human serum containing ferric ion is also dependent on the bacterial growth; however, protease production in this condition does not require the accumulation of the autoinducer.

DOI： 10.1080/15569540500320862

Web of Science

researchmap

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society for Bacteriology  

DOI： 10.3412/jsb.61.261

CiNii Article

CiNii Books

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Presence of the quorum-sensing regulation system in Vibrio mimicus was investigated. The culture supernatants of V mimicus strains were found to possess AI-2 autoinducer like activity, and the strains were found to harbor the genes which are homologous to luxS, luxO, and luxR of V harveyi. These genes of V harveyi have been shown to be important components of V harveyi-like quorum-sensing system. The luxO gene homologue known to encode LuxO, the central component of the regulation system, was disrupted, and effects on protease and hemolysin activity were studied. Disruption of luxO gene resulted in the increased protease activity, but the hemolysin activity did not vary considerably.

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Vibrio mimicus (Vm) haemagglutinins (HAs), such as an extracellular HA/protease (Vm-HA/protease) and a major outer membrane protein-HA (Vm-OMPHA), have been recognized as the putative adherence factors for the bacterium. However, the mechanism by which HAs coordinate the adherence function of the bacterium remains as yet unknown. We report herein the positive interaction between Vm-HA/protease and Vm-OMPHA resulting in significant enhancement of the haemagglutinating ability. In this interaction, no cleaved polypeptide was detected; however, limited proteolysis of Vm-OMPHA was confirmed by SDS-PAGE. The proteolytic activation of the native cell-associated Vm-ONIPHA by limited proteolysis was also demonstrated in several V mimicus strains. Proteolytic activation of OMPRA was also achieved with various proteases from bacterial and eukaryotic sources. These findings may indicate a novel coordination of V mimicus HAs in the adherence of the bacterium.

Web of Science

researchmap

Language：English   Publishing type：Part of collection (book)   Publisher：Elsevier Inc.  

Bacteria of the genus Vibrio are normal habitants of the aquatic environment. These species can be classified into two groups according to the types of diseases they cause: One group causes gastrointestinal infections and the other extraintestinal infections. Although the most important pathogenic factor of Vibrio cholerae O1/O139 is cholera enterotoxin (CT), a hemolysin (El Tor hemolysin) produced by biovar eltor is also reported to cause diarrhea. A thermostable direct hemolysin (TDH) produced by Vibrio parahaemolyticus is also believed to be a major pathogenic component of the species. This chapter offers a review of recent information on hemolysins of pathogenic vibrios with special reference to the two representatives. Hemolysins produced by pathogenic vibrio are classified into three groups, namely the VCC group, TDH group, and others. This review focused on four hemolysins: VCC, Vp-TDH, W H and VMH, which have been extensively studied. All four are poreforming toxins, but their precise mechanism of action remains to be investigated. VCC, Vp-TDH, and VMH have activity that causes diarrhea, the major symptom of infection of these vibrios, although VCC is no more than a supplemental factor of CT and VMH is only one of the many enterotoxic factors. © 2006 Elsevier Inc. All rights reserved.

DOI： 10.1016/B978-012088445-2/50049-4

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC GENERAL MICROBIOLOGY  

Enteroinvasive Escherichia coli (EIEC) O164 strain RIMD05091045 was isolated from a travelling patient suffering from diarrhoea at the Osaka airport quarantine facility in Japan. The strain showed multidrug resistance against streptomycin, spectinomycin, co-trimoxazole (trimethoprim/sulfamethoxazole) and ampicillin, and reduced susceptibility to ciprofloxacin. Molecular characterization of the multidrug-resistance phenotype revealed the presence of a class 1 integron containing three genes, a dihydrofolate reductase type XII gene, dfrXII, which confers resistance to trimethoprim, an aminoglycoside adenyltransferase gene, aadA2, which confers resistance to streptomycin and spectinomycin, and an ORF of unknown function. Southern blot hybridization and conjugation experiments showed that the class 1 integron was located on a transferable plasm id that was less than 90 kb in size. The resistance of EIEC 0164 to ampicillin was found to be due to the presence of TEM-1 beta-lactamase. On the other hand, a single mutation that has not previously been described, P1 58-to-S, was detected downstream of the quinolone-resistance-determining region of parC of topoisomerase IV and may be responsible for the reduced susceptibility to ciprofloxacin in this strain.

DOI： 10.1099/jmm.0.45908-0

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

Biofilm formation is an important phenotype associated with chronic Pseudomonas aeruginosa infections. In the present study, a total of 48 P. aeruginosa strains isolated from clinical specimens were examined for their biofilm-forming ability using a microtiter plate method. The different biofilm-forming abilities were demonstrated among the strains; however, most strains formed a larger biofilm than strain PAO1, a reference strain. The genetic typing was also carried out by enterobacterial repetitive intergenic consensus-based polymerase chain reaction. Although they were divided into five groups (A to E), most of the strains showing the higher biofilm-forming ability were found to be in groups D and E, suggesting a significant relationship between the biofilm-forming ability and the genetic group.

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Vibrio vulnificus can be divided into two groups on the basis of pathogenesis. Group 1 is pathogenic only to humans, whereas group 2 is pathogenic to eels and occasionally to humans. Although both groups produce a 50-kDa cytotoxin-hemolysin (V vulnificus hemolysin; VVH), the toxins are different. In the present study, the nucleotide sequence of the toxin gene (vvhA) of strain CDC B3547 (a group 2 strain) was determined, and the deduced amino acid sequence was compared to that of strain L-180 (a group I strain). The nucleotide sequence of vvhA of strain CDC B3547 was about 96 % identical with that of strain L-180, which results in a difference of 3 amino acid residues in the C-terminal lectin domain of VVH. Nevertheless, two primer sets for polymerase chain reaction could be designed to differentiate the toxin gene of each strain. When 27 V vulnificus clinical isolates were tested, group 1 strains (9 strains) were shown to react only to the primers designed for vvhA of strain L-180; whereas, the gene of group 2 strains (18 strains) could be amplified with the primers for vvhA of strain CDC B3547. These findings may lead to development of a novel genetic grouping system related to the virulence potential or to the host range.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

The hemolysin of Vibrio mimicus (VMH) is a pore-forming toxin with both enterotoxiic and hemolytic activity. The hemolysis by VMH is induced by creation of pores in the membrane of erythrocyte; however, the mechanism for the enterotoxic action of VMH has remained unclear. In order to clarify the mechanism, we incubated T84 cells (a human colon carcinoma cell line) with VMH and found that the levels of ATP and cyclic AMP of culture medium increased after exposure of the cells to VMH. Subsequently. we found that the fluid accumulating activity of VMH in a mouse internal loop assay was reduced by administration of glibenclamide, an inhibitor of cyclic AMP-dependent chloride channels, into the intestinal loop. These results suggest that the stimulation of cells to produce nucleotides by VMH is linked to the enterotoxic activity of the toxin.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

Arthrobacter sp. strain PY1, a bacterium having the ability to degrade 1.3-dichlotopropanol (1.3-DCP), was isolated from a soil sample of a chemical plant. Strain PY1 degraded 1000 mg/l (7.75 mM) of 1.3-DCP completely within 7 days, and the ability was elevated by acclimatization up to 4000 mg/l/week. Addition of nutrients such as peptone, glucose or glycerol showed no or slight effect on the degrading activity. These results suggest that strain PY1 is a useful organism in a biological control system for 1,3-DCP pollution. The ability to degrade 1.3-DCP was induced by addition of 1.3-DCP to the culture of strain PY1. A 1.3-DCP-degrading enzyme (Deh-PY1) was purified from the cytoplasmic fraction of strain PY1 by fractionation with ammonium sulfate, hydrophobic chromatography and anion exchange chromatography. Purified Deh-PY1 is a tetramer of a homogeneous subunit having a molecular weight of 20 kDa. Analysis of the N-terminal amino acid sequence of Deh-PY1 showed that the 31 residues were quite similar to those of known 1.3-DCP-dehalogenases of other organisms. Arthrobarter sp. strain AD2 and Corynebacterium sp. strain N-1074, although some differences in composition or enzymatic characteristics were observed. The Km value and Vmax of Deh-PY1 were 2.67 mM and 7.81 mumol/min/mg, respectively. and the optimum reaction temperature and pH were 40-50degreesC and 9.5-10.5.

DOI： 10.1248/jhs.50.605

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Vibrio vulnificus is an opportunistic human pathogen causing septicemia, and the infection is characterized by formation of the edematous. skin lesions on limbs. This pathogenic species secretes a thermolysin-like metalloprotease as a virulence determinant. The metalloprotease was confirmed to activate human factor XII-plasma kallikrein-kinin cascade that results in liberation of bradykinin, a chemical mediator enhancing the vascular permeability, from high-molecular weight kininogen. Namely, the metalloprotease showed to generate active fragments by cleavage of Arg-Ile, Arg-Val or Gly-Leu peptide bond in human zymogens (plasma prekallikrein and factor XII). In spite of induction of the sufficient vascular permeability-enhancing and edema-forming reaction in the guinea pig model, a serine protease from V. parahaemolyticus, a human pathogen causing primarily watery diarrhea, showed far less ability to activate and to cleave the human zymogens. These results in part may explain why only V. vulnificus often causes serious edematous skin damages in humans. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.toxicon.2004.08.013

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vibrio vulnificus is a causative agent of serious food-borne diseases in humans related to consumption of raw seafoods. This human pathogen secretes a metalloprotease (VVP) that evokes enhancement of the vascular permeability and disruption of the capillaries. Production of microbial proteases is generally induced at early stationary phase of its growth. This cell density dependent regulation of VVP production in V vulnificus known to be the quorum-sensing. When V. vulnificus was cultivated in Luria-Bertani (LB) medium, accumulation of the autoinducer, the signal molecule operating the quorum-sensing system, was detected. Moreover, expression of the vvp gene encoding VVP was found to be closely related with expression of the luxS gene that encode the synthase of the autoinducer precursor (luxS). These findings may indicate VVP production is controlled by the quorum-sensing system in LB medium. Futhermore, this system functioned more effectively at 26 degreesC than at 37 degreesC. When incubated at 37 degreesC in human serum supplemented with ferric chloride, production of VVP and expression of vvp increased in proportion to the concentration of ferric ion; whereas, expression of luxS was not increased. This suggests that VVP production in human serum containing ferric ion may be regulated mainly by the system other than the quorum-sensing system. (C) 2604 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.femsle.2004.09.023

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

Vibrio vulnificus biotype 1, a causative agent of fatal septicemia or wound infection in humans, is known to produce a toxic metalloprotease as an important virulence determinant. V. vulnificus biotype 2 (serovar E), a primary eel pathogen, was found to elaborate an extracellular metalloprotease that was indistinguishable from that of biotype 1. The potential of V. vulnificus biotype 1 for production of the metalloprotease was compared with biotype 2 and other human non-pathogenic Vibrio species (Vibrio anguillarum and Vibrio proteolyticus). When cultivated at 25degreesC in tryptone-yeast extract broth supplemented with 0.9% NaCl, all bacteria multiplied sufficiently and secreted significant amounts of the metalloprotease. However, at 37degreesC with 0.9% NaCl, V. anguillarum neither grew nor produced the metalloprotease. In human serum, only V. vulnificus biotype 1 revealed a steady multiplication accompanied with production of the extracellular metalloprotease. This prominent ability of biotype 1 in growth and protease production may contribute to cause serious systemic diseases in humans. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.micpath.2003.10.001

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

Vibrio vulnificus biotype 2, a primary eel pathogen, is also an opportunistic pathogen for humans. The strains in this biotype secrete a cytolysin into the culture medium. The cytolysin from the strain CDC B3547 (ATCC 33817), which was originally isolated from a human leg wound, can disrupt various kinds of eukaryotic cells including erythrocytes and mast cells, and artificial vesicles, liposomes. The cytolysin is a 50 kDa single-chain protein and is categorized into the pore-forming toxins. After binding tightly to the cell-membrane cholesterol in a temperature-independent manner, the toxin molecules assemble each other in a temperature-dependent manner, forming a small transmembrane pore. When incubated with a metalloprotease from the same species, the cytolysin is converted to the nicked toxin composed of some peptide chains, joined with disulfide bond(s). This nicked toxin is more hydrophilic while maintaining comparable cytolytic activity.

DOI： 10.1081/TXR-120030650

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Distribution of virulence-associated genes in Vibrio mimicus was studied including the toxin genes ctxA, tdh, st and vmh and the genes necessary for regulation of toxin production, toxR, toxS, toxT, tcpA and tcpP. Approximately half of clinical V mimicus isolates possessed one or more genes encoding V cholerae enterotoxic factors such as ctxA, tdh and st. All of the clinical and environmental isolates possessed vmh encoding V mimicus hemolysin (VMH). The ctxA encoding cholera toxin was detected in only 2 strains, 5% of the clinical isolates. Furthermore, there were very few strains possessing tcpP and toxT needed for the expression of ctxA. These results may suggest that VMH is a more important pathogenic factor than well recognized toxins such as cholera toxin (CT) in V mimicus infection.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Twenty-three strains of Salmonella spp. isolated from healthy humans in Guangdong, China, were examined for their susceptibility to ten common antibiotics and the presence of antibiotic resistance integrons. All the strains were resistant to at least one antibiotic, and 4 strains were positive for the intI1 gene. Polymerase chain reaction using in-F and in-B primers showed the existence of amplicons; of 1,009 bp in two, 1,664 bp in one, and 1,009 bp and 1,664 bp in one of the intI1-positive isolates, respectively. Sequence analysis revealed that the 1,009-bp amplicon harbored gene cassette aadA2, conferring resistance to spectinomycin, and the 1,664-bp amplicon harbored genes aadA5 and dfr17, conferring resistance to spectinomycin, streptomycin and trimethoprim. Meanwhile the experiments of plasmid conjugation and Southern hybridization with intI1 as the DNA probe indicated that all the integrons found in these strains were chromosomal. Because the strains carrying class 1 integrons were isolated from healthy humans, it suggests the need for all-round surveillance of the antibiotic resistance of pathogens.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society for Antibacterial and Antifungal Agents Japan  

The widely used organic solvent dichloromethane (DCM) has various toxic effects including carcinogenesis. We isolated a DCM-degrading bacterium Ralstonia metallidurans PD11 from drainage water which grew with DCM as a sole carbon source. PD11 was a methylotrophic bacterium with the ability to grow with C1 compounds such as methanol or methylamine. Although the existence of methylotrophic bacteria having DCM-degrading ability has been reported, there has been no report on Ralstonia sp. to date. The DCM-degrading activity of PD11 was increased by acclimatization, finally reaching a level to degrade 2,500 mg DCM/l within a week. The cell-free extract of PD11 showed DCM-degrading activity by liberating chloride which was stimulated by addition of glutathione, suggesting that the DCM dehalogenationg enzyme could be classified into the glutathione S-transferase super family.

DOI： 10.4265/bio.9.89

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC MICROBIOLOGY & BIOTECHNOLOGY  

Numerous secreted and cell-associated virulence factors have been proposed to account for the fulminating and destructive nature of Vibrio vulnificus infections. Among the putative virulence factors are an elastase, elastolytic protease, and a cytolytic hemolysin. Effects of the elastase on the hemolysin were assessed by evaluating changes of hemolytic activities either in the presence or absence of the protease. Although hemolytic activity in the culture supernatant was lowered by the purified elastase added in vitro, the cellular level of hemolytic activity was unaffected by the mutation of vvpE encoding the elastase. Growth kinetic studies revealed that hemolysin reached its maximum level in the exponential phase of growth, and the elastase appeared at the onset of the stationary phase. These results have provided insight into the regulation of virulence factors: temporally coordinate regulation of virulence factors is essential for the overall success of the pathogen during pathogenesis.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

In response to low iron availability, Vibrio parahaemolyticus synthesizes and secretes a polyhydroxycarboxylate-type siderophore vibrioferrin which is composed of 1 mol each of 2-ketoglutaric acid, L-alanine, ethanolamine, and citric acid. We have previously reported the cloning and characterization of the pvuA gene, which encodes the 78-kDa outer membrane receptor protein for ferric vibrioferrin. In this study, nine genes involved in the biosynthesis and transport of vibrioferrin have been identified in the genomic regions surrounding the pvuA gene. The genes were sequenced, and gene disruptants were constructed by insertion mutation for phenotype analysis. Five of the genes, named pvsABCDE, constitute an operon that is expressed under iron-limiting conditions. Homology searches of their predicted protein products suggested that the four genes pvsABDE are implicated in the biosynthesis of the siderophore. Another gene in the same operon,pvsC, encodes a putative exporter that is homologous to members of the major facilitator superfamily of multidrug efflux pumps. The remaining four genes, named pvuBCDE, encode proteins strongly homologous to Escherichia coli FecBCDE, respectively, which are components of the ATP-binding cassette transporter system for ferric dicitrate. Reverse transcriptase PCR analysis revealed that these transport genes are transcribed as a single mRNA with the upstream genes, psuA and pvuA. Phenotypic comparison between the wild-type strain and its targeted gene disruptants supported the biological functions for the respective operons that were expected on the basis of the homology search.

DOI： 10.1128/JB.185.23.6938-6949.2003

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING LTD  

Vibrio parahaemolyticus is a potentially pathogenic bacterium, occurring naturally in estuarine and marine environments throughout the world. The incidence of this organism in an aquatic environment depends upon many ecofactors. Sea water and organic material were collected during the warm weather season from a coast of the Seto Inland Sea, Japan, and analysed to determine V. parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 99% of samples were positive for V. parahaemolyticus with densities of 3 to&gt; 1400 cells per 100 ml of water or 10 g of organic samples by the most-probable-number (MPN)-PCR technique, but only 76.6% were positive by the conventional MPN culture technique, with densities ranging from 3 to&gt; 1400 cells per 100 ml of water or 10 g of organics. Furthermore, the tdh and trh genes were positive in 41.5% and 8.5% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN culture procedure. The difference in detection between the MPN culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors.

DOI： 10.1046/j.1462-2920.2003.00458.x

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A zinc metalloprotease secreted by Vibrio vulnificus, an opportunistic human pathogen causing septicemia and wound infection, stimulates exocytotic histamine release from rat mast cells. This protease consists of two functional domains: the N-terminal domain that catalyzes proteolytic reaction and the C-terminal domain that promotes the association with a protein substrate or cell membrane. Like the intact protease, the N-terminal domain alone also induced histamine release from rat peritoneal mast cells in a dose- and time-dependent manner. However, the reaction induced was apparently weak and went on more slowly. The nickel-substituted protease or its N-terminal domain, each of which has the reduced proteolytic activity due to decreased affinity to a substrate, showed much less histamine-releasing activity. When injected into the rat dorsal skin, the N-terminal domain also evoked enhancement of the hypodermic vascular permeability, while the activity was comparable to that of the protease. Taken together, the protease may stimulate histamine release through the action of the catalytic center of the N-terminal domain on the target substance(s) on the mast cell membrane. The C-terminal domain may support the in vitro action of the N-terminal domain by coordination of the association of the protease with the membrane, but it may not modulate the in vivo action. (C) 2003 Elsevier Science Inc. All rights reserved.

DOI： 10.1016/S0024-3205(03)00094-8

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

In this study, we compared the apoptotic activities of clinical and environmental isolates of Vibrio vulnificus toward macrophages in vitro and in vivo. The clinical isolates induced apoptosis in macrophage-like cells in vitro and in macrophages in vivo. This suggests that macrophage apoptosis may be important for the clinical virulence of V. vulnificus.

DOI： 10.1128/IAI.71.1.533-535.2003

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

An exocellular metalloprotease produced by Vibrio fluvialis, an enteropathogenic vibrio, was purified and characterized. The metalloprotease (V. fluvialis protease [VFP]) was found to have very similar characteristics to V. vulnificus protease, including a molecular mass of 45 kDa, sensitivity to chelating agents or competitive inhibitors for thermolysin-like metalloproteases, and the substrate specificity. The structural gene for VFP was also cloned, and its nucleotide sequence was determined. The deduced amino acid sequence confirmed that VFP was a member of the thermolysin family. VFP, like V. vulnificus protease, showed the haemagglutinating, permeability-enhancing and haemorrhagic activities in addition to the proteolytic activity toward oligopeptide, casein or elastin. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1006/mpat.2002.0520

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Although Vibrio vulnificus is known to be able to utilize ferrioxamine B as an iron source, its outer membrane receptor remains to be determined. In this study, we found that V. vulnificus expressed a new outer membrane protein of 78 kDa when grown in the presence of desferrioxamine B under iron-limiting conditions. The desferrioxamine B-dependent iron uptake was only observed in bacterial cells expressing this protein. Furthermore, non-denaturing polyacrylamide gel electrophoresis followed by autoradiography of the outer membrane preparation containing the 78-kDa protein preincubated with [Fe-55]ferrioxamine B provided a single radioactive band in which the 78-kDa outer membrane protein was present as the major component. These lines of evidence suggest that the inducible 78-kDa protein may serve as the cell-surface receptor for ferrioxamine B. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.

DOI： 10.1016/S0378-1097(02)00741-3

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

We previously reported that Vibrio parahaemolyticus expresses two outer membrane proteins of 78 and 83 kDa concomitant with production of siderophore vibrioferrin in response to iron starvation stress and that these proteins are the ferric vibrioferrin receptor and heme receptor, respectively (S. Yamamoto, T. Akiyama, N. Okujo, S. Matsuura, and S. Shinoda, Microbiol. Immunol. 39:759-766, 1995; S. Yamamoto, V. Hara, K. Tomochika, and S. Shinoda, FEMS Microbiol. Lett. 128:195-200, 1995). In this study, the Fur titration assay (FURTA) system was applied to isolate DNA fragments containing a potential Fur box from a genomic DNA library of V. parahaemolyticus WP1. Sequencing a 3.2-kb DNA insert in one FURTA-positive clone revealed that an amino acid sequence deduced from a partial gene, which was preceded by a full-length gene (psuA) encoding a receptor for a siderophore of unknown origin, was consistent with the N-terminal amino acid sequence of the 78-kDa ferric vibrioferrin receptor. Then, the full-length gene (pvuA) encoding the ferric vibrioferrin receptor was cloned and characterized. The deduced protein encoded by pvuA displayed the highest similarity (31% identity; 48% similarity) to RumA, a ferric rhizoferrin receptor of Morganella morganii. Primer extension and Northern blot analyses indicated that psuA and pvuA constitute an operon which is transcribed from a Fur-repressed promoter upstream of psuA. The product of the pvuA gene and its function were confirmed by generating a pvuA-disrupted mutant, coupled with genetic complementation studies. A mutant with disruption in the upstream psuA gene also displayed a phenotype impaired in the utilization of ferric vibrioferrin.

DOI： 10.1128/jb.184.4.936-946.2002

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vibrio vulnificus strain L-180, a clinical isolate, can obtain iron from a synthetic heme, iron-tetra(4-sulfonatophenyl)porphyrin (Fe-TPPS), as well as from a natural heme, protoheme. This assimilation of iron bound to TPPS was demonstrated to be a common property of V. vulnificus by testing a total of 27 strains isolated from both clinical and environmental sources. Strain L-180 could also utilize Fe-TCPP, but not Fe-TMPyP, as a sole iron source. TPPS or its complex with a metal ion reduced bacterial multiplication in the broth containing a minimum dose of Fe-TPPS. When inoculated into human serum supplemented with Fe-TCPP, L-180 could grow only in the presence of a protease from the same bacterium. In both TPPS and TCPP, each side chain of a porphyrin ring has a negative charge. Therefore, this negative charge may be important for interaction with an outer membrane receptor involving in a heme-assimilating system of V. vulnificus. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0378-1097(02)00448-2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Seawater and organic material (live and/or dead matter deposited on any substratum submersed in seawater) were collected during the cool weather season from a coast of the Seto-Inland Sea, Japan, and analyzed to determine Vibrio parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by the polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 95% of the samples were positive for V. parahaemolyticus (with densities of 3 to &gt; 1400 cells per 100 ml water or 10 g organic samples) by the most-probable-number (MPN)-PCR technique with species-specific toxR primers, but only 40% were positive by the conventional MPN-culture technique (with densities ranging from 3 to 240 cells per 100 ml water or 10 g organics). Furthermore, the tdh and trh genes were positive in 55% and 20% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN-culture procedure. The difference in detection between the MPN-culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0378-1097(02)00449-4

Web of Science

researchmap

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

A 50 kDa protease designated as VPPI was purified from the culture supernatant of a clinical strain of Vibrio parahaemolyticus by ammonium sulfate fractionation, Sephacryl S-200 HR gel filtration and Fractogel EMD TMAE 650 ion-exchange chromatography. VPPI was inhibited by EDTA, EGTA and serine protease inhibitors, suggesting that it is a calcium-dependent serine protease. N-terminal amino acid sequence of VPPI was quite similar to that of V. metschnikovii protease and antibody against VPPI inhibited the activity of V metschnikovii protease, suggesting the similarity of the two proteases. It was demonstrated that VPPI or its related protease widely distribute in not only V parahaemolyticus but also V alginolyticus.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society for Antibacterial and Antifungal Agents Japan  

Vibrio parahaemolyticus is an important etiological agent of gastroenteritis associated with seafood consumption in Japan and many parts of the world. Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), encoded by the tdh and trh genes respectively, are the most recognized pathogenic factors of this bacterium. During this study a high percentage of V. parahaemolyticus isolated from an area was found to be positive for the tdh and/or trh genes by PCR, although almost all of the isolates lacked the ability to produce active hemolysin. Such tdh and/or trh positive strains were isolated from a specific coastal area, but not isolated from four other areas of the Seto-Inland Sea. This particular area, Kojima Bay, receives freshwater from several adjacent rivers, and such influx of water may have special effects on the growth V. parahaemolyticus, as evidenced by the high density of this bacterium in water samples (2300 to 4600 per 100 mi). V. parahaemolyticus of various sero-groups were isolated from each area
however, Kojima Bay samples were dominated by O1, O3, and O4 sero-groups.

DOI： 10.4265/bio.7.37

Scopus

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Vibrio vulnificus, an opportunistic human pathogen, produces a 45-kDa zinc metalloprotease (V. vulnificus protease; VVP) as an important virulence determinant. VVP injected intradermally into the dorsal skin causes the hemorrhagic damage through specific degradation of type IV collage in the vascular basement membrane. The N-terminal 35-kDa polypeptide (VVP-N), the catalytic domain, also evoked the hemorrhagic skin reaction within minutes. However, the hemorrhagic activity of VVP-N was one-third of that of VVP. Besides, the proteolytic activity of VVP-N toward the reconstituted basement membrane or type IV collagen was found to be about 50 % of VVP. VVP-N, like VVP, was quickly inactivated by an equimolar amount Of alpha (2)-macroglobulin, a broad-spectrum plasma protease inhibitor, These findings indicate that the C-terminal 10-kDa polypeptide, the substrate-binding domain mediating the effective binding to protein substrates, functions to augment the hemorrhagic reaction of VVP. (C) 2001 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0041-0101(01)00171-4

Web of Science

researchmap

Language：Japanese   Publisher：岡山大学環境計測共同利用施設  

CiNii Article

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

A total of 42 clinical strains of Vibrio mimicus were examined for the presence of virulence associated genes toxR, toxS, toxT, tcpP, ctx and tcpA by PCR assay. Almost all strains were shown to have the toxR gene, while the toxS gene was found in 27 strains. On the other hand, five strains possessed both toxT and tcpP genes, but others had neither. Only two strains were positive for amplification of the ctx gene, whereas no PCR product with tcpA primers was detected. The results indicate the incomplete copies of virulence cascade in V mimicus strains. The pathogenesis and epidemic potential of this species is also discussed.

DOI： 10.1111/j.1348-0421.2001.tb01292.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society for Antibacterial and Antifungal Agents Japan  

Differentiating viable cells from nonviable cells is of considerable importance in the monitoring of food-borne pathogens. A reverse transcription-polymerase chain reaction (RT-PCR) assay was developed to detect mRNA from the phospholipase gene (phl) of Vibrio mimicus. Viable V. mimicus cells were killed by heat or ethanol treatment and kept for various periods at room temperature. Total RNA from V. mimicus was extracted, treated with DNase and subjected to RT-PCR with primers for the phl gene. The phl mRNA was detected in the viable cells, but it gradually disappeared when the killed cells were left at room temperature and became undetectable after 8 h of storage. Furthermore, RT-PCR generated a 493 bp fragment from the total RNA extracted from as few as about 103 organisms, confirming the sensitivity of the assay. The amplification of the phl mRNA was specific for V. mimicus, as no amplification was found when fifteen other Vibrio species and seven related organisms were tested. The results indicated a good relationship between the detection of the phl mRNA and viability of V. mimicus cells because the phl transcript is rapidly degraded upon cell death. This work shows the usefulness of RT-PCR as a sensitive method for the specific detection of viable V. mimicus.

DOI： 10.4265/bio.6.81

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

We investigated the recovery of dormant and injured cells along with the normally culturable cells of Vibrio species with special emphasis on V. parahaemolyticus using both selective and non-selective media at moderate (20 C) and standard (37 C) culture temperatures from a bay water environment. Culture temperatures (20 or 37 C) did not affect the recovery of V. parahaemolyticus but did for other vibrios, We observed similar seasonality of V. parahaemolyticus as in most other environmental studies. V. parahaemolyticus and other Vibrio species were recovered in higher numbers by a replica plating method compared to most probable number (MPN) and direct TCBS (thiosulfate citrate bile-salt sucrose) agar counts. Even with the replica plating method, however, vibrios number goes down to a minimum level and K parahaemolyticus was undetectable during the cool temperature period of the year, although total bacterial cells and CPU on nutrient agar (with 2% NaCl) did not vary so much during the study period.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Sequencing of Fur titration assay-positive clones obtained from genomic DNA libraries of Vibrio parahaemolyticus, V. mimicus and V. vulnificus revealed open reading frames encoding proteins of 202, 205 and 202 amino acid residues, respectively. Each open reading frame was preceded by a predicted Fur box which overlaps a likely promoter with similarity to the -10 and -35 consensus sequence of Escherichia coli, The deduced amino acid sequences shared considerable homology with bacterial Mn-containing superoxide dismutases (MnSODs). Consistent with this, these Vibrio strains produced proteins with SOD activity resistant to inhibition by H2O2 and KCN only when grown under iron-limiting conditions. Primer extension analysis of the total RNA from these vibrios revealed iron-repressible expression of the genes. Furthermore, when grown under iron-limiting conditions, E. coli carrying a plasmid with each cloned gene overexpressed protein with the same electrophoretic mobility and insensitivity of SOD activity to H2O2 and KCN. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by N-terminal amino acid sequencing revealed that proteins (MnSODs) having N-terminal amino acid sequences consistent with those deduced from the corresponding genes were present in cell lysates of the vibrios grown under these iron-limited conditions, These results demonstrate that the genes cloned in this study are sodA homologs encoding MnSODs, whose expression is regulated by the iron status of the growth medium. PCR using a primer set based on the V. parahaemolyticus sodA sequence revealed the presence of homologous genes in certain other Vibrio species.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

The biodegrading ability of drainage water from research laboratories to dichloromethane (DCM) and chloroform (CF) was surveyed. When DCM was used as a sole carbon source in a synthetic mineral salt medium, some water samples showed ability to degrade DCM, and DCM-degrading bacteria were isolated from them, whereas no samples showed CF degradation activity. Two isolates, strain P3310, a Flavimonas sp., and strain G31, a Chryseobacterium sp., were used for further investigations. Both strains were able to use DCM as a carbon source for growth and also grow in complex media containing other carbon sources, suggesting they were facultative methylotroph. Both strains needed 6 days at 30 degrees C to completely degrade 200 mg/l of DCM with the first isolated cells, but this was shortened to 2 days with the first subculture, suggesting they were acclimatized. Although the DCM-degrading activity of strain G31 was inhibited by addition of other carbon sources such as peptone or glucose, that of strain P3310 was not affected. Thus, strain P3310 may be a useful candidate for bioremediation to eliminate DCM from drainage.

DOI： 10.1248/jhs.46.187

Web of Science

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

L-2,4-Diaminobutyrate decarboxylase (DABA DC) catalyzes the formation of 1,3-diaminopropane (DAP) from DABA. In the present study, the ddc gene encoding DABA DC from Enterobacter aerogenes ATCC 13038 was cloned and characterized, Determination of the nucleotide sequence revealed an open reading frame of 1470 bp encoding a 53659-Da protein of 490 amino acids, whose deduced NH2-terminal sequence was identical to that of purified DABA DC from E. aerogenes. The deduced amino acid sequence was highly similar to those of Acinetobacter baumannii and Haemophilus influenzae DABA DCs encoded by the ddc genes. The lysine-307 of the E. aerogenes DABA DC was identified as the pyridoxal 5'-phosphate binding residue by site-directed mutagenesis, Furthermore, PCR analysis revealed the distribution of E. aerogenes ddc homologs in some other species of Enterobacteiacene. Such a relatively wide occurrence of the ddc homologs implies biological significance of DABA DC and its product DAP.

DOI： 10.1248/bpb.23.649

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC  

An inhibitor to the muscarinic acetylcholine receptor (mAChR) was purified from the venom of Crotalus atrox (western diamondback rattlesnake). The inhibitor was found to be a 30-kDa homodimer protein with phospholipase A, activity. In order to determine the subtype selectivity of the purified inhibitor, the inhibitory effect on the binding of two orthosteric antagonists, [H-3]quinuclidinyl benzilate ([H-3]QNB) and [[H-3]N-methylscopolamine methyl chloride ([H-3]NMS), to five subtypes of cloned human mAChR was tested. The purified inhibitor reduced the binding of [H-3]QNB and/or [H-3]NMS to all subtypes of the mAChR while showing the highest inhibitory effect on the M-5 subtype. The K-d values of the receptors for the antagonists were increased in the presence of the inhibitor; however, the B-max values were not changed. The effects of the purified inhibitor on the dissociation of [H-3]NMS from the receptors were also investigated. Dissociation of the antagonist was remarkably slowed down by addition of the inhibitor. These findings may suggest an allosteric action of the purified inhibitor. In addition, the present study indicates that the presence of mAChR inhibitors is quite common in snake venoms. (C) 2000 Academic Press.

DOI： 10.1006/abbi.2000.1784

Web of Science

researchmap

Authorship：Lead author   Language：English   Publisher：EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

Zinc metalloproteases produced by human pathogenic microorganisms show a wide variety of pathological actions. In local infections, the proteases cause necrotic or hemorrhagic tissue damage through digestion of structural components of the ground substance, and also form edematous lesions through generation of inflammatory mediators, while in systemic infections, the proteases act as a synergist-ic virulence factor through disordered proteolysis of many plasma proteins. Clostridial neurotoxins, Bacteroides fragilis enterotoxin and Bacillus anthracis lethal factor are also zinc metalloproteases. (C) 2000 Editions scientifiques et medicales Elsevier SAS.

DOI： 10.1016/S1286-4579(00)00280-X

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHARMACEUTICAL SOC JAPAN  

A total of 120 strains of Vibrio mimicus, 51 clinical and 69 environmental were examined for the presence of three types of hemolysin genes (vmh, tdh and hlx) by PCR. Ninety-six percent (115) of the strains contained at least one of these hemolysin genes. Only 5 strains from the environment were missing all three hemolysin genes, The tdh was only found in 20 of the 51 clinical isolates of V, mimicus, This mag indicate that the tdh gene is a virulence determinant of V. mimicus. More than 90% of the strains isolated from both the environment and patients possessed the vmh gene. Two clinical isolates possessed the hlx gene alone and had no other enterotoxic factors.

DOI： 10.1248/jhs.46.63

Web of Science

researchmap

Authorship：Lead author   Language：Japanese   Publisher：Pharmaceutical Society of Japan  

Vibrio vulnificus is an opportunistic human pathogen causing wound infection and septicemia, characterized by hemorrhagic and edematous damage to the skin of limbs. When injected into the dorsal skin, an extracellular metalloprotease from this vibrio (V. vulnificus protease: VVP) enhanced the vascular permeability through activation of the Hageman factor-plasma kallikrein-kinin cascade and/or stimulation of exocytotic histamine release. Additionally, VVP caused the hemorrhagic skin lesion through disorganization of the vascular basement membrane layer due to specific degradation of type IV collagen, which is known to form the backbone structure of the basement membrane. However, injected VVP was quickly inactivated by a plasma glycoprotein, α-macroglobulin, at a molar ratio of 1 : 1. This glycoprotein was leaked from the capillaries by the actions of VVP, which resulted in in situ inactivation by physical entrapment. When VVP (45000 Da) was incubated at 37°C, a 35000 Da fragment was generated by the autocatalytic removal of a 10000Da C-terminal polypeptide. This N-terminal fragment showed significant proteolytic activity, however, because of a markedly decreased affinity to the protein substrates, its permeability-enhancing and hemorrhagic activity was reduced to less than 50%. These findings indicate that the C-terminal polypeptide is not essential for but promotes skin reactions caused by VVP.

DOI： 10.1248/yakushi1947.120.11_1149

Scopus

PubMed

researchmap

Authorship：Last author   Language：English  

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society for Antibacterial and Antifungal Agents Japan  

Eight strains of cytochrome P450 (P450)-producing bacteria were isolated from M9 medium containing a P450-inducer as the sole carbon source from the environment. Strains EP1 to EP6 utilizing 2-ethoxyphenol as the sole carbon source were isolated from the soil of a weed-filled field, the water of a paddy field, laboratory effluent, domestic effluent and river water. Strain MP1 utilizing 2-methoxyphenol and strain CP1 utilizing camphor were isolated from oil-polluted soil and the soil of a weed-filled field, respectively. This suggests the distribution of P450-producing bacteria in the environment. Metyrapone (2-methyl-1,2-di-3-pyridyl-1-propanone) inhibited the growth of P450-producing bacteria on the media containing a P450-inducer as the sole carbon source, strongly suggesting that the P450 is involved in the catabolism of the inducer.

DOI： 10.4265/bio.5.111

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

A total of 51 Vibrio minicus clinical strains from different geographic locations were examined by arbitrarily primed polymerase chain reaction (AP-PCR), The primer VMH-3 divided them into 28 groups, although 18 groups consisted of a single strain at present. All groups had a common 1.0-kb amplification fragment. Most of the groups consisted of strains from same region, although two exceptional groups showed a few amplification fragments including strains from different regions. AP-PCR groups were not consistently associated with serogroups, AP-PCR is thought to be a valuable and easy method for the epidemiological study of V. minicus.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society for Antibacterial and Antifungal Agents Japan  

Degradation of dichloromethane (DCM) by two environmental isolates, Flevimones sp. strain P3310 and Chryseobacterum sp. strain G31, were studied. The ability of the strains was raised to degrade 3,000 mg/l of DCM by acclimatization, although the original isolates could degrade less than 500 mg/l. The first step in the degradation process was dechlorination, and the liberated chloride ions caused the reduction of pH and the bacterial growth
the addition of phosphate salts, however, restored the growth and the degrading ability of the culture by increasing the buffer capacity. The DCM-degrading activity was also detected in the cell-free extract and the culture-supernatant. These results suggest that the isolates or their products are possible candidates for bioremediation to eliminate DCM pollution.

DOI： 10.4265/bio.5.117

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

In many bacteria, the ferric uptake regulatory protein (Fur) has a central role in the negative regulation of genes affected by iron limitation. In this study, Vibrio parahaemolyticus strains carrying mutations in the fur gene encoding Fur were isolated by the manganese selection method to assess the function of Fur in connection with alternations in the coordinate expression of the siderophore vibrioferrin (VF) and iron-repressible outer membrane proteins (IROMPs), Ten out of 25 manganese-resistant mutants constitutively produced VF and expressed at least two IROMPs irrespective of the iron concentration in the medium. PCR-direct DNA sequencing of the fur genes in these mutants identified four different point mutations causing amino acid changes. Moreover, a fur overexpressing plasmid was constructed to prepare antiserum against V; parahaemolyticus Fur. Western blotting with this antiserum revealed that the intracellular abundance of the wild-type Fur was not significantly affected by the iron concentrations in the growth medium, and that the Fur proteins of the mutant strains occurred at substantially smaller amounts and/or migrated more rapidly in sodium dodecyl sulfate-polyacrylamide gel electrophoresis than the wild-type Fur. These data afford an additional insight into the structure-function relationship of Fur and imply its involvement in the iron acquisition systems of V. parahaemolyticus, although it is yet unknown whether its action on the target genes is direct or indirect.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATL RESEARCH COUNCIL CANADA  

A soluble cytochrome P450 (P450(EP1A)) induced by 2-ethoxyphenol was purified to apparent homogeneity from Corynebacterium sp. strain EP I. The P450(EP1A) showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular weight of about 45 kDa. The GO-reduced difference spectra of P450(EP1A) had a Soret maximum at 447.6 nm. The substrate difference spectra with 2-ethoxyphenol showed an absorption maximum at 394.0 nm. The purified P450(EP1A) degraded 2-ethoxyphenol in an assay system composed of spinach ferredoxin-NADP(+) oxidoreductase and NADPH. The reaction activity decreased to 1.4% of its original activity by addition of CO. The existence of catechol in the reaction mixture was confirmed after the metabolic reaction, indicating that P450EP1A catalyzes O-dealkylation of 2-ethoxyphenol. In addition to 2-ethoxyphenol, the P450(EP1A) metabolized 2-methoxyphenol, 1,1,1-trichloroethane, carbon tetrachloride. benzene, and toluene.

DOI： 10.1139/cjm-45-10-833

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC  

Snake venoms can contain a variety of well-studied neurotoxins, especially nicotinic acetylcholine receptor inhibitor, normally called postsynaptic neurotoxin. Karlsson first reported muscarinic acetylcholine receptor (mAChR) inhibitor from snake venom. In a previous study in our laboratory, we found a mAChR inhibitor from Naja naja sputatrix venom that bound to rat brain synaptosomes. Brain synaptosomes contain all subtypes of mAChRs, and thus the exact selectivity of the inhibitor could not be determined. mAChR inhibitor from N. naja sputatrix venom was purified and the binding to all human mAChR subtypes (M1, M2, M3, M4, and M5) was investigated and is reported in this communication. The inhibitor bound to all subtypes of the human mAChR, but showed considerably high selectivity for the R15 subtype. It was also found that the reduction of disulfide bonds in the inhibitor eliminated the binding to the mAChR. This suggests that a specific tertiary conformation maintained by disulfide bonds is essential for binding to the mAChR. An oligo peptide, QIHDNCYNE, comparable to a part of the inhibitor molecule, was synthesized and studied for its binding to the mAChR. The synthetic peptide did not show any binding activity, suggesting this portion of the inhibitor molecule is not involved in mAChR binding. The selective binding of the M5 mAChR subtype to antagonists has not yet been reported. Therefore, the purified inhibitor reported in this communication may be a useful tool to clarify the mechanism of muscarinic cholinergic transmission. (C) 1999 Academic Press.

DOI： 10.1006/abbi.1999.1321

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vibrio vulnificus, an opportunistic human pathogen, can obtain iron from a variety of heme proteins. This process involves the digestion of heme proteins by an exoprotease to liberate protoheme (iron-protoporphyrin IX). In the present study, we tested whether this pathogen also uses a synthetic heme compound, Fe-alpha,beta,gamma,delta-tetraphenylporphine tetrasulfonic acid (Fe-TPPS), as an iron source. When inoculated into a medium containing Fe-TPPS, V. vulnificus L-180 multiplication was seen to be dependent on the concentration of the synthetic heme compound; a mutant lacking the ability to utilize protoheme did not multiply. Cells of the strain grown under the iron-restricted condition showed time-dependent uptake of Fe-TPPS. The ability to use either protoheme or Fe-TPPS was significantly reduced by the addition of an excess amount of free TPPS or Cu-TPPS. The data suggest that, V. vulnificus may assimilate Fe-TPPS, at least partially, through the same system as that for protoheme. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0378-1097(99)00016-6

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：JAPANESE SOCIETY FOR BACTERIOLOGY  

DOI： 10.3412/jsb.54.763

CiNii Article

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00085759749?from=CiNii

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CENTER ACADEMIC PUBL JAPAN  

Vibrio vulnificus protease (VVP), a 45-kDa zinc metalloprotease, consists of two functional domains: an N-terminal 35-kDa polypeptide having endoproteinase activity, and a C-terminal 10-kDa polypeptide that mediates the binding of VVP to the erythrocyte membrane. Therefore, VVP, but not its N-terminal endoproteinase domain alone, has agglutinating activity to rabbit erythrocytes. When a single zinc atom in the catalytic center was substituted by treatment with CuCl2 or NiCl2, proteolytic and hemagglutinating activities were reduced by Ni substitution but not by Cu substitution, Cu-treated 35-kDa polypeptide showed sufficient affinity of the catalytic center and weak binding ability to the erythrocyte membrane, but the Ni-treated polypeptide did not. These results suggest that the binding of endoproteinase domain to membrane is also necessary for hemagglutination.

Web of Science

researchmap

Language：English   Publisher：CENTER ACADEMIC PUBL JAPAN  

Vibrio parahaemolyticus strains isolated from different sources were assayed for their ability to produce a siderophore, vibrioferrin, under iron-limited growth conditions. The mean value +/- standard error of mean (mu M vibrioferrin in spent culture supernatant/optical density at 660 nm) was 832.3 +/- 66.9 for clinical isolates (n=44), which was significantly higher (P&lt;0.01) than those for food isolates (461.0 +/- 66.5; n=37) and coastal isolates (378.8 +/- 37.2; n=26). This suggests that greater productivity of vibrioferrin by clinical isolates may be associated with a selective advantage for survival and proliferation under conditions of iron-limitation such as in the intestine.

Web of Science

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

Vibrio parahaemolyticus strains isolated from different sources were assayed for their ability to produce a siderophore, vibrioferrin, under iron-limited growth conditions. The mean value } standard error of mean (μM vibrioferrin in spent culture supernatant/optical density at 660nm) was 832.3 } 66.9 for clinical isolates (n 44), which was significantly higher (P 0.01) than those for food isolates (461.0 } 66.5; n 37) and coastal isolates (378.8 } 37.2; n 26). This suggests that greater productivity of vibrioferrin by clinical isolates may be associated with a selective advantage for survival and proliferation under conditions of iron-limitation such as in the intestine.

CiNii Article

researchmap

Language：English  

CiNii Article

CiNii Books

researchmap

Other Link： http://search.jamas.or.jp/link/ui/1999112700

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Vibrio vulnificus is an opportunistic human pathogen causing wound infections and septicemia, characterized by hemorrhagic and edematous damage to the skin. This human pathogen secretes a metalioprotease (V. vulnificus protease [VVP]) as an important virulence determinant. When several bacterial metalioproteases including VVP were injected intradermally into dorsal skin, VVP showed the greatest hemorrhagic activity. The level of the in vivo hemorrhagic activity of the bacterial metalloproteases was significantly correlated with that of the in vitro proteolytic activity for the reconstituted basement membrane gel. Of two major basement membrane components (laminin and type IV collagen), only type IV collagen was easily digested by VVP. Additionally, the immunoglobulin G antibody against type IV collagen, but not against laminin, showed sufficient protection against the hemorrhagic reaction caused by VVP. Capillary vessels are known to be stabilized by binding of the basal surface of vascular endothelial cells to the basement membrane. Therefore, specific degradation of type IV collagen may cause destruction of the basement membrane, breakdown of capillary vessels, and leakage of blood components including erythrocytes.

DOI： 10.1128/iai.66.10.4851-4855.1998

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

Vibrio mimicus is the closest organism to Vibrio cholerae, V. mimicus E-33, which is a highly adhesive and enteropathogenic strain, is known to produce three types of hemagglutinins (HAs), i.e., a 31-kDa exocellular metalloprotease (Vm-HA/protease), lipopolysaccharide (Vm-LPSHA), and a 39-kDa major outer membrane protein (Vm-OMPHA). Hemagglutination induced by Vm-LPSHA and Vm-OMPHA was inhibited by glyco proteins, including mucin, fetuin, and asialofetuin, but not by monosaccharides, disaccharides, or N-acetylated saccharides. The inhibitory potential of each glycoprotein for Vm-OMPHA was greatly augmented by treatment with a glycolytic enzyme such as beta-D-galactosidase or beta-D-glucosidase, while pronase treatment achieved complete abolition of the inhibitory potential, The inhibitory ability of the glycoproteins for Vm-LPSHA was also abolished by pronase treatment; however, glycolytic enzyme treatment showed no effect, Hence, the polypeptide portion of glycoproteins may directly associate with Vm-OMPHA and Vm-LPSHA, but the sugar moiety mag act as a barrier to interaction with Vm-OMPHA. The glycoproteins as well as Fab antibodies against Vm-OMPHA and Vm-LPSHA eliminated the ability of E-33 cells to agglutinate rabbit erythrocytes and dto attach to rabbit intestinal mucosa, Additionally, expression of the hemagglutinating ability by the bacterial cells was accompanied by efficient bacterial adherence to the intestinal mucosa, Finally, the hemagglutinating activity of Vm-OMPHA was markedly increased by incubation with Vm-HA/protease, These results indicate that all three HAs may have significant roles in the glycoprotein mediated intestinal adherence of V. mimicus E-33.

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

It has been generally thought that the polysaccharide moiety of lipopolysaccharide (LPS) maintains only serological specificity, while the lipid A portion determines various biological functions. However, we found that hemagglutination was a common function of the polysaccharide moiety of LPSs from important human enteropathogenic bacteria. Of the LPSs examined, Vibrio cholerae O139 LPS showed the highest hemagglutinating activity, Glycoproteins, such as mucin and fetuin, showed efficient inhibition of the hemagglutinating ability, Since cell-mediated hemagglutination is known to he correlated with bacterial adherence, hemagglutination induced by the polysaccharide moiety is interpreted to indicate that cell-surface LPS is a potential adhesin.

Web of Science

researchmap

DOI： 10.1007/BF02770805

CiNii Article

researchmap

Authorship：Lead author  

DOI： 10.1006/mpat.1997.0149

PubMed

CiNii Article

researchmap

Authorship：Last author   Language：Japanese   Publisher：The Pharmaceutical Society of Japan  

The first recognized outbreaks of hemorrhagic colitis occurred in 1982 in the United State and its etiologic agent was identified to be Escherichia coli O157 : H7,a serotype not previously associated with diseases in humans. In Japan, isolates of the serotype O157 : H7 from contaminated drinking water were first implicated in an outbreak occurred in 1990 in a kindergarten of the Saitama Prefecture, and at least other 12 such outbreaks have been recorded in 1993-1995. In the year 1996,unprecedentedly large outbreaks and many sporadic cases of disease caused by E. coli O157 : H7 occurred in various parts of Japan, affecting more than 9000 people in total (11 deaths). In most cases, however, the ultimate source of the infection could not be traced. Although many different serotypes of E. coli, which are collectively referred to as enterohemorrhagic E. coli (EHEC), were found to cause bloody diarrhea, the serotype O157 : H7 has been recognized worldwide as the pathogen associated most frequently with serious complications known as hemolytic colitis and hemolytic uremic syndrome. E. coli O157 : H7 is characteristic of a low infectious dose, on the order of a few hundred organisms, which contributes to the spread of the infection in outbreak situations. Cattle are considered to be the major reservoir of EHEC including O157 : H7. EHEC strains produce at least two immunologically distinct cytotoxins that closely resemble the Shiga toxin produced by the Shigella dysenteriae type 1 strains. These toxins (called Shiga-like toxins or Vero toxins) appear to be responsible for causing many pathological effects associated with EHEC infections. However, how the toxins move from the intestinal tract lumen to the sites where they damage the kidney remains to be evaluated. Moreover, there are some doubts about the value of antibiotic therapy in such infections because of the observation that some antibiotics can increase the toxin expression in vitro and because of the concern that EHEC which are lysing due to their actions in the gastrointestinal tract lumen may actually release more toxin than do intact bacterial cells. Unique biochemical characteristics of E. coli O157 : H7-it ferments sorbitol very slowly and usually does not make β-glucuronidase- are used to differentiate this strain from other enteric E. coli strains. Alternative methods based on the detection of the toxins themselves by enzyme immunoassay are employed in parallel. This review describes the current understanding of the infectious disease caused by E. coli O157 : H7,with an emphasis on the main diagnostic tests and epidemiology for this serotype and the role of the toxins in pathogenesis.

DOI： 10.1248/jhs1956.43.1

CiNii Article

CiNii Books

researchmap

Other Link： http://search.jamas.or.jp/link/ui/1997166835

Authorship：Lead author,　Corresponding author  

DOI： 10.3109/15569549709016455

CiNii Article

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

An environmental isolate of V. mimicus, strain E-33, has been reported to produce and secrete a hemolysin of 63kDa. The hemolysin is enterotoxic in test animals. The nucleotide sequence of the structural gene of the hemolysin was determined. We found a 2, 232bp open reading frame, which codes a peptide of 744 amino acids, with a calculated molecular weight of 83, 903 Da. The sequence for the structural gene was closely related to the V. cholerae el for hlyA gene, coding an exocellular hemolysin. The amino terminal amino-acid sequence of the 63kDa hemolysin, purified from V. mimicus, was determined by the Edman degradation method and found to be NH₂=-S-V-S-A-N-N-V-T-N-N-N-E-T. This sequence is identical from S-152 to T-164 predicted from the nucleotide sequence. So, it seems that the mature hemolysin in V. mimicus is processed upon deleting the first 151 amino acids, and the molecular mass is 65, 972 Da. Analyzing the deduced amino-acid sequence, we also found a potential signal sequence of 24 amino acids at the amino terminal. Our results suggest that, like V. cholerae hemolysin, two-step processing also exists in V. mimicus hemolysin.

CiNii Article

researchmap

Authorship：Lead author  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

In vitro growth experiments were conducted to evaluate the ability of vulnibactin, a siderophore produced by Vibrio vulnificus, to sequester transferrin- or lactoferrin-bound iron for growth. Comparative studies with the strain producing vulnibactin and its exocellular protease-deficient mutant revealed the involvement of the protease in addition to vulnibactin in effective utilization of iron ion (Fe³⁺) bound to transferrin and lactoferrin. It appears that the protease causes cleavage of these proteins, thereby making bound iron more accessible to vulnibactin.

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Two hemagglutinins (HAs) mediating the agglutinability to rabbit erythrocytes were isolated from 32-h culture supernatant of enterotoxigenic strain E-33 of Vibrio mimicus by ultrafiltration followed by gel filtration and anion-exchange column chromatography. The HAs were designated R-HA and C- HA on the basis of specific hemagglutinating activity towards rabbit erythrocytes only (R-HA) and towards chicken and rabbit erythrocytes (C-HA). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent staining with Coomassie brilliant blue revealed no detectable protein band and a single band of M(r) 39,000 in the case of R-HA and C-HA, respectively. However, silver staining of the gel containing R-HA revealed the appearance of low-molecular-weight material. These two HAs differed from each other and from previously reported HA/protease in receptor specificity, molecular composition, and biochemical and immunochemical properties. No simple sugar other than glycoproteins, including mucin, inhibited hemagglutinating activities of both C-HA and R-HA. Rabbit antibody against R-HA or C-HA could agglutinate E-33 whole cells, implying a possible cell surface origin of the two HAs. The isolated E-33 lipopolysaccharide (LPS) or its polysaccharide moiety conferred biochemical and immunochemical properties identical to those of R-HA, confirming that the R-HA represents polysaccharide of LPS. The LPS preparations from heterologous strains of Vibrio mimicus and Vibrio cholerae non-O1 confirmed that the hemagglutinating ability is a common function of LPS. On the other hand, the antibody against C-HA specifically recognized a major outer membrane protein (OMP) with an M(r) of around 39,000 in both homologous and heterologous strains of V. mimicus, suggesting an OMP origin of C-HA. Furthermore, the antibody recognized a major OMP with an M(r) of around 37,000 in V. cholerae. Although the immunogenicity of LPS and OMP is well documented for important intestinal pathogens, the hemagglutinating properties of such attractive cell surface components are hitherto unrecognized and will definitely contribute towards understanding their role in bacterial adherence.

DOI： 10.1128/iai.64.10.4035-4041.1996

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

A study of the major pathogenic characteristics of Vibrio mimicus was carried out with 77 strains isolated from aquatic environments in Okayama, Japan. Of the strains tested, 96% demonstrated in vitro adherence to the rabbit intestinal mucosa, of which 36, 20, and 43% belonged to the strongly, moderately, and weakly adhesive groups, respectively. Of the 27 strains which appeared to be enterotoxigenic in the experiments using rabbit ileal loops, 74% belonged to the strongly adhesive group. All strains of V. mimicus at early log phase showed cell-mediated hemagglutination, and 70% of strongly hemagglutinative strains belonged to the strongly adhesive group, implying a possible correlation between cell-mediated hemagglutination and bacterial adherence. However, no significant correlation could be detected in the production of putative exocellular pathogenic factors and bacterial adherence or enterotoxigenicity.

DOI： 10.1128/aem.62.10.3871-3874.1996

Scopus

PubMed

researchmap

Authorship：Lead author   Language：English  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

Exocellular proteases produced by Vibrio fluvialis, V. furnissii, V. metschnikovii and V. campbellii were characterized and compared to those of V. mimicus protease (VMP) and V. vulnfcus protease (VVP). These proteases possessed both elastolytic and hemagglutinating abilities and were identified, except that of V. metschnikovii, as metalloprotease. Conversely, V. metschnikovii protease failed to exhibit some of the salient features for metalloproteases suggesting the existence of protease(s) other than metalloprotease. However, antibodies against VVP cross-reacted to these proteases and to VMP indicating antigenic relatedness amongst vibrio proteases. This study, thus, demonstrated the prevalent distributions of antigenically related proteases both in pathogenic and non-pathogenic vibrios, bringing their status as a virulence determinant into question.

CiNii Article

CiNii Books

researchmap

Other Link： http://search.jamas.or.jp/link/ui/1996104022

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Kluwer Academic Publishers  

A new siderophore named vulnibactin has been isolated from low iron cultures of Vibrio vulnificus, a human pathogen. The structure was established as N-[3-(2,3-dihydroxybenzamido)propyl]-1,3-bis[2-(2-hydroxyphenyl)-trans-5-methyl-2-oxazoline-4-carboxamido]propane by a combination of acid hydrolysis, nuclear magnetic resonance spectroscopy and positive fast atom bombardment mass spectrometry. Vulnibactin is characterized as containing one residue of 2,3-dihydroxybenzoic acid as well as two residues of salicylic acid, both of which are involved in the formation of oxazoline rings with l-threonine bound to a norspermidine backbone. In addition, two other compounds with siderophore activity were purified and their structures were also determined. These two compounds provided further support for the structure of vulnibactin. © 1994 Rapid Communications of Oxford Ltd.

DOI： 10.1007/BF00140480

Scopus

PubMed

researchmap

Authorship：Lead author  

CiNii Article

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

The protease elaborated by Vibrio mimicus is known to possess hemagglutinating ability to chicken erythrocytes, the well-known HA/protease. A non-protease hemagglutinin (HA) with strong agglutinating ability towards rabbit erythrocytes was obtained from 32hr culture supernatant of a pathogenic environmental strain of V. mimicus. This HA (V. mimicus HA: VMHA) appeared stable at relatively higher temperature and agglutinated the erythrocytes from rabbit, guinea pig and mouse but not the erythrocytes from chicken, bovine, horse and sheep. Simple sugars, metal ions and chelating agents failed to inhibit the activity of VMHA. The activity of VMHA was found to be sensitive to digestion by proteolytic enzymes including HA/protease. These results provide evidence for the existence of novel HA other than HA/protease in V. mimicus.

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Cystathionine β‐synthase (β‐CTSase), which catalyses cystathionine synthesis from serine and homocysteine, was purified to homogeneity from Saccharomyces cerevisiae. The molecular mass of the enzyme was estimated to be 235 kDa by gel filtration and 55 kDa by sodium dodecyl sulphate–polyacrylamide gel electrophoresis, indicating that it is a homotetramer. The N‐terminal amino acid sequence of the enzyme perfectly coincided with that deduced from the nucleotide sequence of CYS4, except for the absence of initiation methionine. The purified β‐CTSase catalysed cysteine synthesis from serine (or O‐acetylserine) and H2S. From this finding, we discuss the multifunctional nature and evolutionary divergence of S‐metabolizing enzymes. Copyright © 1994 John Wiley &amp
Sons Ltd.

DOI： 10.1002/yea.320100306

Scopus

PubMed

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

Some properties and mechanism of action of a hemolysin (VMH) produced by an enteropathogenic Vibrio mimicus strain was examined. VMH was heat-labile and inhibited by addition of divalent cations, including Ca²⁺, Mg²⁺ and Mn²⁺. The hemolysis by VMH was inhibited by incubating with gangliosides, suggesting that the ganglioside was the binding site on the erythrocyte membrane for VMH. Existence of a galactose moiety on reducing end of the ganglioside molecule and a sialic acid on the galactose moiety was suggested to be important for the binding of VMH molecule. Colloid osmotic manner of the hemolysis by VMH was demonstrated.

CiNii Article

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

A Vibrio vulnificus hemolysin (VVH) was purified by two steps of hydrophobic column chromatography on Phenyl-Sepharose HP. The first chromatography was carried out at pH 6.0. In this pH condition, VVH efficiently bound to the column, but the hemolysin fraction eluted was accompanied with colored substance(s). To eliminate this colored substance, the second chromatography was carried out at pH 9.8 in the presence of 1% 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS), a zwitterionic detergent. Homogeneity of the hemolysin thus obtained was shown by polyacrylamide gel electrophoresis. The specific activity increased 33, 600 times and the yield was 35%. The method is simple and useful to supply enough VVH for study of the role of the hemolysin in the infection by V. vulnificus or on the mechanism of action of the hemolysin.

CiNii Article

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa Healthcare  

Vibrio vulnificus is an opportunistic human pathogen causing septicemia or wound-infections characterized by the formation of edema, necrotic ulcer and cellulitis on the skin. This bacterium produces various exocellular toxic factors, among which, 45 kDa protease and 56 (or 50) kDa cytolysin have been studied extensively. The protease is a zinc metalloprotease and degrades a number of biologically important proteins including elastin, fibrinogen, plasma protease inhibitors and complement components. It also enhances vascular permeability through activation of the Hag-factor-plasma kallikrein-kinin cascade and/or exmytotic histamine release from mast cells, and forms a hemorrhagic lesion which finally provokes severe dermonecrosis. Thus, the protease is the mast probable candidate for edema formation and bacterial invasion during the infection. Iron is an essential element for the growth of microorganisms. V. vulnificus is known to be able to utilize heme proteins such as hemoglobin as its sole iron source. Since V. vulnificus protease has the ability to digest heme proteins and to liberate heme residue fran globin protein, this enzyme may contribute to efficient heme uptake by the bacterium. However, V. vulnificus protease inoculated into a mmal is quickly inactivated by a 700 kDa plasma glycoprotein, alpha-macroglobulin, at molar ratio of 1 : 1. This plasma protein leaks fram the vascular system as a result of the permeability-enhancing and hemorrhagic actions of the protease, resulting in in situ inactivation of the protease by physical entrapment. It is therefore presumed that the depression of alpha-macroglobulin activity enhances the infectivity of V. vulnificus. V. vulnificus cytolysin can disrupt various eukaryotic cells, such as erythrocyte, mast cell and CHO (Chinese hamster ovary) cell, and an artificial vesicle, lipsome. Studies on its cytolytic action on the erythrocyte have shown that the cytotoxin initially binds to cell-surface cholesterol in a temperature independent mer. Then, some toxin molecules bound to the membrane aggregate and form a small (diameter of 53 nm) transmembrane-pore in a temperature dependent manner. Finally, the cell membrane is burst owing to the influx of extracellular substances including water via the pore resulting in the increase in the intracellular osmotic pressure. Some divalent cations (e.g. Ca2+ Mg2+ and Mn2+) block the final hemolytic stage by an unknown mechanism. This toxin also causes tissue damage and enhances permeability, perhaps due to histamine leakage from disrupted mast cells. Therefore, the cytolysin, like the protease, is also a putative factor for the development of skin lesions. Needless to say, the cytolysin seems to provide intracellularly stored-iron including hemoglobin to the bacterium. The gene encoding V, vulnificus cytolysin was cloned and sequenced, and this CNA fragment has been used as a probe for identification of the vibrio. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

DOI： 10.3109/15569549309014409

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The occurrence of a human pathogen, Vibrio cholerae, in aquatic environments and the distribution of toxigenic strains were studied for 2 years. The pathogen was isolated from freshwater, brackish and marine environments. V. cholerae non-01 was frequently recovered but the 01 serogroup was not detected. Of the 57 environmental strains tested, eight (12%) were found to be potentially toxigenic. A number of atypical V. cholerae 01 strains were found which showed higher virulence potentials than the serogroup non-01 strains. A significant correlation of the incidence of the pathogen was noted with water temperature in freshwater environments. In marine environments, a reciprocal correlation of the V. cholerae count and salinity was observed. The present study describes the ecology of V. cholerae in aquatic environments of a temperate region and notes that the occurrence of potentially virulent strains could be of public health significance.

Scopus

PubMed

researchmap

Authorship：Lead author   Language：English   Publisher：The Japanese Biochemical Society  

The metalloprotease produced by Vibrio vulnificus (VVP) is known to be quickly inactivated by plasma proteins which belong to the class of α-macroglobulins in vitro at a molar ratio of 1:1. But the in vivo potential of the inactivators has not been studied. Macroalbumin (MA), a member of a -macroglobulins in guinea pig plasma, was found to inactivate VVP by means of physical entrapment in vitro. In vivo actions of VVP, permeability-enhancing and hemorrhagic actions, were greatly augmented by simultaneous injection of the antibody against MA, which had no effect on in vitro proteolytic action toward azocasein. The interstitial-tissue space in the normal guinea pig skin contains a negligible amount of MA. However, sufficient MA was present in the extravascular fluid collected after the intradermal injection of VVP. Besides, in the extravascular fluid, VVP formed a complex with MA and no inactivator other than MA was found. These results indicate that plasma MA leaked from the vascular system owing to the permeability-enhancing and hemorrhagic actions of VVP, resulting in inactivation of VVP in situ.

CiNii Article

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

Vibrio mimicus, a causative agent of gastroenteritis, has also been reported to attribute to extraintestinal infections. Recently we have purified a metalloprotease produced by the pathogen: however, the role of the protease in V. mimicus infection has not been documented. The V. mimicus protease (VMP) was found to enhance vascular permeability and form edema when injected into the dorsal skin of guinea pig and rat. The permeability enhancement by VMP was observed in a dose-dependent manner in both guinea pig and rat skin. In guinea pig, an inhibitor of the angiotensin-converting enzyme was found to augment the permeability enhancement reaction. The permeability enhancement was significantly blocked by soybean trypsin inhibitor (SBTI), an inhibitor of plasma kallikrein reaction. In vitro conversion of plasma prekallikrein to kallikrein by VMP was also noted. In rat skin, the permeability enhancement reaction was not blocked by antihistamine or SBTI. However, the reaction was partially blocked when a mixture of antihistamine and SBTI was administered with VMP. It is apparent from the study that in guinea pig skin, VMP enhances vascular permeability through activation of plasma kallikrein-kinin system which generates bradykinin, whereas in addition to the activation of plasma kallikrein-kinin cascade in the case of rat, stimulation of histamine release from mast cells and other unknown mechanism seem to be also a cause of the permeability enhancement reaction. These results suggest that VMP may play a role in extraintestinal infections with edema caused by the pathogen.

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Recently, we have purified and characterised a metalloprotease produced by Vibrio mimicus. The role of V. mimicus protease (VMP) in fluid accumulation (FA) in rabbit ileal loops (RIL) was investigated. Although live cells or crude VMP prepared from cell-free culture supernatant showed activity in RIL, the purified VMP failed to induce FA in the RIL. When VMP in crude preparation was inactivated by preparing the fraction in the presence of EGTA (Ethyleneglycol-bis [beta-aminoethylether]-N, N, N1, N1,-tetraacetic acid), a chelating agent for Ca2+ (EGTA-crude), or treatment with phosphoramidon (a metalloprotease inhibitor), the preparation became negative in RIL assay. Again, the EGTA-crude induced FA in RIL when retreated with 2mM CaCl2 after elimination of EGTA. The results show evidences of attribution of VMP in RIL activity. These observations, therefore, suggest that the protease produced by V. mimicus may play a potential role in enterotoxigenicity.

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Abstract An environmental survey was done to study the ecology and distribution of Vibrio parahaemolyticus in 5 selected stations in Okayama Prefecture, which included fresh, brackish, and marine aquatic environments. Water and plankton samples were collected monthly for quantitative and qualitative analyses during the period October, 1987 to October, 1989 for V. parahaemolyticus. The pathogen was not detected from fresh water environments. A seasonality of the organism was observed in brackish and marine environments where average salinity ranged between 0.39 and 1.28%.Plankton samples yielded higher densities of V. parahaemolyticus compared with water samples. By applying several enrichment techniques, the pathogen was detected quite frequently during the winter months in the environments with temperatures ranging between 10 and 14°C. The identification following conventional tests, by the API 20E system and by serological methods reveal that the API 20E system is satisfactory to identify V. parahaemolyticus and further confirms that the serological method could be a simpler and more rapid procedure for V. parahaemolyticus identification. Copyright © 1990, Wiley Blackwell. All rights reserved

DOI： 10.1111/j.1574-6968.1990.tb04046.x

Scopus

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)  

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

A protease produced by Vibrio mimicus was purified to apparent homogeneity by ammonium sulfate fractionation and successive column chromatography on Sephacryl S-100 and Mono Q Monobeads. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) of the final preparation of the enzyme revealed the homogeneity of the purified enzyme. Conventional PAGE showed that the purified protease migrated as a single band with protease activity. The molecular weight of the protease was estimated to be about 31,000 on the basis of its mobility on sodium dodecyl sulfate-PAGE. The purified protease had both proteolytic and hemagglutination (HA) activities. The proteolytic and HA activities were inhibited by metalloprotease inhibitors and heat treatment. V. mimicus protease therefore appeared as a heat-labile, bifunctional molecule capable of mediating proteolysis and HA. The immunodiffusion analysis showed that the proteases produced by Vibrio cholerae and V. mimicus are immunologically cross-reactive.

Scopus

PubMed

researchmap

Authorship：Lead author   Language：English   Publisher：The Japanese Biochemical Society  

Vibrio vulnificus, an etiologic agent of wound infections and septicemia in humans, elaborates a metalloprotease which is known to be an important virulence factor of the Vibrio. The proteolytic activity of V. vulnificus metalloprotease (VVP) toward casein and elastin was inhibited by α₂-macroglobulin (α₂ M) at the molar ratio of 1:1, although partial activity was maintained. Permeability-enhancing and hemorrhagic activities were also inhibited, but the peptidase activity toward Z-Gly-Phe-NH₂ was not reduced, even by an excess amount of α₂ M. VVP formed a complex with α₂ M through cleavage of the bait regions of all four α₂ M subunits and elicitation of conformational change of the α₂M molecule, which resulted in entrapment of VVP in the α₂ M molecule. The peptidase activity of α₂ M-VVP complex was inhibited by low-molecular-weight inhibitors such as phosphoramidon, but IgG antibody against VVP failed to neutralize its peptidase activity. Of human plasma proteins, α₂ M was the only inhibitor for VVP. These findings indicate that VVP produced during V. vulnificus infection is inactivated by plasma α₂ M that leaks from the vascular system.

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

An environmental study was done to examine the prevalence of Vibrio mimicus in some aquatic environments of Dhaka, Bangladesh, and of Okayama, Japan. Water samples from Dhaka environments and water and plankton samples from Okayama environments were quantitatively as well as qualitatively analyzed throughout the seasons for V. mimicus. The organism was isolated from Bangladesh environments throughout the year, whereas it was not isolated in Okayama when the water temperature fell below 10 degrees C. Samples with as many as 9.0 x 10(2) CFU of V. mimicus per 100 ml of water in Dhaka and 1.5 x 10(4) CFU of V. mimicus per 100 ml of water in Okayama were detected during the study period. V. mimicus was not found in any environment with an average salinity of 10% or more. Brackish environments with an average salinity of 4% were observed to be the optimal natural condition for the pathogen. Using the API 20E system with the conventional test methods, we observed variations in biochemical properties within the V. mimicus species. This study reveals the inefficacy of the API 20E system to identify a significant percentage of V. mimicus. Therefore, in addition to the API 20E system, a salt tolerance test and a string test are recommended for identification of this species. Susceptibility testing of strains isolated from Okayama environments showed higher resistance to ampicillin and susceptibility to trimethoprim-sulfamethoxazole when compared with environmental isolates of V. mimicus from Bangladesh.

DOI： 10.1128/aem.55.8.2073-2078.1989

Scopus

PubMed

researchmap

Authorship：Lead author   Language：English   Publisher：Center For Academic Publications Japan  

The protease produced by Vibrio vulnifrcus enhances vascular permeability through histamine release from mast cells and activation of the plasma kallikrein-kinin system which generates bradykinin when injected into the dorsal skin. V. vulnificus living cells also enhanced vascular permeability within a few hours after the injection into the dorsal skin. The permeability-enhancing activity of living cells was greatly reduced by addition of soybean trypsin inhibitor, a specific inhibitor for plasma kallikrein-kinin system, or anti-protease IgG. Two protease-deficient mutants induced by nitrosoguanidine treatment had only one-tenth permeability-enhancing activity of a wild-type strain. These results indicate that V. vulnificus elaborates the protease in vivo and that the protease elaborated enhances vascular permeability through release of chemical mediators such as histamine and bradykinin and forms edema.

CiNii Article

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

A protease was purified from a strain of Vibrio vulnificus isolated from the blood of a septicemic human. The vibrio was cultured in bacto peptone-yeast extract medium, and the protease was purified by a purification procedure including ultrafiltration of the culture supernatant with an Amicon YM 5 membrane, diethylaminoethyl-Sephacel column chromatography, Sephacryl S-200 column chromatography and fast protein liquid chromatography on Mono Q column. The protease preparation revealed homogeneity on polyacrylamide gel electrophoresis and about 30, 000-fold purification was achieved, with a yield of about 30%. The isoelectric point of the purified V. vulnificus protease was about 5.80 and its molecular weight was ca. 45, 000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The optimum pH of the protease activity was 8.0. The V. vulnificus protease was inhibited by a metalloprotease inhibitor and zinc ion and/or ferrous ion were essential for its enzyme activity. No cysteine residue was detected in the V. vulnificus protease. The protease had caseinolytic, elastolytic and collagenolytic activities.

CiNii Article

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Vibrio vulnificus protease, which had been purified from the culture supernatant of a strain isolated from a septicemic human patient, enhanced hypodermic vascular permeability and formed hemorrhagic spot caused by tissue destruction in a dose-dependent manner within a range of 0.3-10.0 μg when injected intradermally (i.d.) into rat dorsal skin. Enhancement of permeability was observed within 2 min, and the permeability-enhancing reaction terminated at 10 min after the injection. This reaction was blocked by simultaneous injection of an antihistamine, diphenhydramine, suggesting that the permeability-enhancing reaction of V. vulnificus protease was due to histamine release in vivo. Hemorrhage caused by V. vulnificus protease was also rapidly observed, but this reaction was not inhibited by the antihistamine. © 1987.

DOI： 10.1111/j.1574-6968.1987.tb01989.x

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Vibrio vulnificus protease (VVP) stimulated histamine release from isolated mast cells in a dose- and temperature-dependent manner within a range of 0.2-4.0 μg/0.5 ml. Histamine release was accompanied by degranulation, and no leakage of lactate dehydrogenase from cells was observed, indicating that the histamine release was not due to cytolysis but to exocytosis. This release, completed within 30 s at 37°C, suggested that the mechanism of action of VVP on mast cells is different from that of other proteases, such as trypsin or α-chymotrypsin, which release histamine from the cells slowly. © 1986.

DOI： 10.1111/j.1574-6968.1986.tb01425.x

Scopus

researchmap

Language：Japanese   Publisher：The Pharmaceutical Society of Japan  

Distribution of diarrhenogenic species of genus Vibrio in estuarine area of Ohta River, Hiroshima, and Asahi River, Okayama, was investigated. Diarrhenogenic vibrios, such as Vibrio parahaemolyticus, V. fluvialis or NAG vibrio, inhabit in estuarine region. Because the former two vibrios are slightly halophilic, they cannot survive in fresh water. However, the number of V. parahaemolyticus detected in brackish water area of the river was much more than that of sea region. In brackish water area, the salinity was lower than optimal concentration for the vibrio because sea water was mixed with fresh water, but nutrient salts content, such as phosphate and nitrogen compounds, was higher than that of sea region. These nutrient salts seemed to stimulate a growth of the vibrios in estuarine region. The number of V. fluvialis was variable and in some sampling points, its number was comparable to the number of V. parahaemolyticus. NAG vibrio was also widely distributed in the estuarine region investigated, but the number was fewer than that of V. parahaemolyticus or V. fluvialis

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：Center For Academic Publications Japan  

Some properties of he nolysin produced by Vibrio vulnificus were investigated. The hemolysin was heat labile, and the hemolytic activity was inhibited by adding cholesterol or divalent cations. Cholesterol inhibited the temperature-independent hemolysin-binding step, suggesting that cholesterol made up the binding site. of the cell membrane, whereas the divalent cations inhibited the temperature-dependent membrane-degradation step. However, the V. vulnificus hemolysin was stable to oxygen and sulfhydryl reagents and was not inactivated by antiserum against streptolysin O, suggesting that the V. vulnificus hemolysin differs from oxygen-labile hemolysins which bind to cholesterol. The V. vulnificus hemolysin seems to be one of the exceptional cholesterol-binding hemolysins.

CiNii Article

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：(株)近代出版  

J-GLOBAL

researchmap

Language：Japanese   Publisher：(公社)日本薬学会  

J-GLOBAL

researchmap

Language：Japanese   Publisher：日本細菌学会  

J-GLOBAL

researchmap

Language：Japanese  

J-GLOBAL

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：The Pharmaceutical Society of Japan  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：The Pharmaceutical Society of Japan  

CiNii Article

CiNii Books

researchmap

Event date： 2019.9.5 - 2019.9.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan  

researchmap

Event date： 2019.9.5 - 2019.9.6

Language：English   Presentation type：Poster presentation  

Venue：Sapporo, Japan  

researchmap

Event date： 2019.9.5 - 2019.9.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan  

researchmap

Event date： 2019.9.5 - 2019.9.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan  

researchmap

Event date： 2019.3.20 - 2019.3.23

Language：Japanese   Presentation type：Poster presentation  

Venue：千葉  

researchmap

Event date： 2019.2.28 - 2019.3.1

Language：English   Presentation type：Poster presentation  

Venue：Hanoi, Vietnam  

researchmap

Event date： 2019.2.28 - 2019.3.1

Language：English   Presentation type：Poster presentation  

Venue：Hanoi, Vietnam  

researchmap

Event date： 2019.2.28 - 2019.3.1

Language：English   Presentation type：Poster presentation  

Venue：Hanoi, Vietnam  

researchmap

Event date： 2018.10.25

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：猪苗代  

researchmap

Event date： 2018.10.6 - 2018.10.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山  

researchmap

Event date： 2018.9.4 - 2018.9.7

Language：English   Presentation type：Poster presentation  

researchmap

Event date： 2018.3.27 - 2018.3.29

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡  

researchmap

Event date： 2018.3.27 - 2018.3.29

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡  

researchmap