Faculty Profiles - SUZUKI Nobuhiro

Papers - SUZUKI Nobuhiro

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Cymbidium chlorotic mosaic virus, a new sobemovirus isolated from a spring orchid (Cymbidium goeringii) in Japan Reviewed

Hideki Kondo, Shogo Takemoto, Kazuyuki Maruyama, Sotaro Chiba, Ida Bagus Andika, Nobuhiro Suzuki

ARCHIVES OF VIROLOGY 160 ( 8 ) 2099 - 2104 2015.8

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

Cymbidium chlorotic mosaic virus (CyCMV), isolated from a spring orchid (Cymbidium goeringii), was characterized molecularly. CyCMV isometric virions comprise a single, positive-strand RNA genome of 4,083 nucleotides and 30-kDa coat protein. The virus genome contains five overlapping open reading frames with a genomic organization similar to that of sobemoviruses. BLAST searches and phylogenetic analysis revealed that CyCMV is most closely related to papaya lethal yellowing virus, a proposed dicot-infecting sobemovirus (58.8 % nucleotide sequence identity), but has a relatively distant relationship to monocot-infecting sobemoviruses, with only modest sequence identities. This suggests that CyCMV is a new monocot-infecting member of the floating genus Sobemovirus.

DOI： 10.1007/s00705-015-2460-9

Large-scale multiplex polymerase chain reaction assay for diagnosis of viral reactivations after allogeneic hematopoietic stem cell transplantation Reviewed

Natsuko Inazawa, Tsukasa Hori, Naoki Hatakeyama, Masaki Yamamoto, Yuko Yoto, Masanori Nojima, Nobuhiro Suzuki, Norio Shimizu, Hiroyuki Tsutsumi

JOURNAL OF MEDICAL VIROLOGY 87 ( 8 ) 1427 - 1435 2015.8

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

Viral reactivations following hematopoietic stem cell transplantation are thought to result from the breakdown of both cell-mediated and humoral immunity. As a result, many viruses could be reactivated individually or simultaneously. Using a multiplex polymerase chain reaction (PCR), we prospectively examined many kinds of viral DNAs at a time in 105 patients who underwent allogeneic hematopoietic stem cell transplantation. In total, 591 whole blood samples were collected weekly from pre- to 42 days post-transplantation and the following 13 viruses were tested; herpes simplex virus 1 (HSV-1), HSV-2, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpes virus 6 (HHV-6), HHV-7, HHV-8, adenovirus, BK virus (BKV), JC virus (JCV), parvovirus B19, and hepatitis B virus (HBV). Several viral DNAs were detected in 12 patients before hematopoietic stem cell transplantation. The detection rate gradually increased after transplantation and peaked at 21 days. The most frequently detected virus was HHV-6 (n=63; 60.0%), followed by EBV (n=11; 10.5%), CMV (n=11; 10.5%), and HHV-7 (n=9; 8.6%). Adenovirus and HBV were each detected in one patient (1.0%). Detection of HHV-6 DNA was significantly more common among patients undergoing cord blood transplantation or with steroid treatment. EBV DNA tended to be more common in patients treated with anti-thymocyte globulin. Multiplex PCR was useful for detecting many viral reactivations after hematopoietic stem cell transplantation, simultaneously. Cord blood transplantation, steroid treatment, or anti-thymocyte globulin use was confirmed to be risk factors after transplantation. J. Med. Virol. 87:1427-1435, 2015. (c) 2015 Wiley Periodicals, Inc.

DOI： 10.1002/jmv.24161

50-plus years of fungal viruses Reviewed

Said A. Ghabrial, Jose R. Caston, Daohong Jiang, Max L. Nibert, Nobuhiro Suzuki

VIROLOGY 479 356 - 368 2015.5

Language：English Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Mycoviruses are widespread in all major taxa of fungi. They are transmitted intracellularly during cell division, sporogenesis, and/or cell-to-cell fusion (hyphal anastomosis), and thus their life cycles generally lack an extracellular phase. Their natural host ranges are limited to individuals within the same or closely related vegetative compatibility groups, although recent advances have established expanded experimental host ranges for some mycoviruses. Most known mycoviruses have dsRNA genomes packaged in isometric particles, but an increasing number of positive- or negative-strand ssRNA and ssDNA viruses have been isolated and characterized. Although many mycoviruses do not have marked effects on their hosts, those that reduce the virulence of their phytopathogenic fungal hosts are of considerable interest for development of novel biocontrol strategies. Mycoviruses that infect endophytic fungi and those that encode killer toxins are also of special interest. Structural analyses of mycoviruses have promoted better understanding of vieus assembly, function, and evolution. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2015.02.034

Editorial: Viruses threatening stable production of cereal crops Reviewed

Nobuhiro Suzuki, Takahide Sasaya, Il-Ryong Choi

FRONTIERS IN MICROBIOLOGY 6 470 2015.5

The chestnut blight fungus for studies on virus/host and virus/virus interactions: From a natural to a model host Reviewed

Ana Eusebio-Cope, Liying Sun, Toru Tanaka, Sotaro Chiba, Shin Kasahara, Nobuhiro Suzuki

VIROLOGY 477 164 - 175 2015.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

The chestnut blight fungus, Cryphonectria parasitica, is an important plant pathogenic ascomycete. The fungus hosts a wide range of viruses and now has been established as a model filamentous fungus for studying virus/host and virus/virus interactions. This is based on the development of methods for artificial virus introduction and elimination, host genome manipulability, available host genome sequence with annotations, host mutant strains, and molecular tools. Molecular tools include subcellular distribution markers, gene expression reporters, and vectors with regulatable promoters that have been long available for unicellular organisms, cultured cells, individuals of animals and plants, and certain filamentous fungi. A comparison with other filamentous fungi such as Neurospora crassa has been made to establish clear advantages and disadvantages of C parasitica as a virus host. In addition, a few recent studies on RNA silencing vs. viruses in this fungus are introduced. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2014.09.024

Differential contributions of plant Dicer-like proteins to antiviral defences against potato virus X in leaves and roots Reviewed

Ida Bagus Andika, Kazuyuki Maruyama, Liying Sun, Hideki Kondo, Tetsuo Tamada, Nobuhiro Suzuki

PLANT JOURNAL 81 ( 5 ) 781 - 793 2015.3

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

Members of the plant Dicer-like (DCL) protein family are the critical components of the RNA-silencing pathway that mediates innate antiviral defence. The distinct antiviral role of each individual DCL protein has been established with mostly based on observations of aerial parts of plants. Thus, although the roots are closely associated with the life cycle of many plant viruses, little is known about the antiviral activities of DCL proteins in roots. We observed that antiviral silencing strongly inhibits potato virus X (PVX) replication in roots of some susceptible Solanaceae species. Silencing of the DCL4 homolog in Nicotiana benthamiana partially elevated PVX replication levels in roots. In Arabidopsis thaliana, which was originally considered a non-host plant of PVX, high levels of PVX accumulation in inoculated leaves were achieved by inactivation of DCL4, while in the upper leaves and roots, it required the additional inactivation of DCL2. In transgenic A.thaliana carrying the PVX amplicon with a green fluorescent protein (GFP) gene insertion in the chromosome (AMP243 line), absence of DCL4 enabled high levels of PVX-GFP accumulation in various aerial organs but not in the roots, suggesting that DCL4 is critical for intracellular antiviral silencing in shoots but not in roots, where it can be functionally compensated by other DCL proteins. Together, the high level of functional redundancies among DCL proteins may contribute to the potent antiviral activities against PVX replication in roots.
Significance StatementThis study demonstrates the differential contributions of DCL proteins between leaves and roots.

DOI： 10.1111/tpj.12770

Detection and analysis of non-retroviral RNA virus-like elements in plant, fungal, and insect genomes. Reviewed International journal

Hideki Kondo, Sotaro Chiba, Nobuhiro Suzuki

Methods in molecular biology (Clifton, N.J.) 1236 73 - 88 2015

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

Endogenous non-retroviral RNA like sequences (NRVSs) have been discovered in the genome of a wide range of eukaryotes. These are considered as fossil RNA viral elements integrated into host genomes by as-yet-known mechanisms, and in many cases, those fossils are estimated to be millions-of-years-old. It is likely that the number of NRVS records will increase rapidly due to the growing availability of whole-genome sequences for many kinds of eukaryotes. Discovery of the novel NRVSs and understanding of their phylogenetic relationship with modern viral relatives provide important information on deep evolutionary history of RNA virus-host interactions. In this chapter, therefore, the common strategies for the identification and characterization of endogenous NRVSs from plants, insects, and fungi are described.

DOI： 10.1007/978-1-4939-1743-3_7

Taxonomic reorganization of family Partitiviridae and other recent progress in partitivirus research Reviewed

Max L. Nibert, Said A. Ghabrial, Edgar Maiss, Till Lesker, Eeva J. Vainio, Daohong Jiang, Nobuhiro Suzuki

VIRUS RESEARCH 188 128 - 141 2014.8

Language：English Publisher：ELSEVIER SCIENCE BV

Phylogenetic analyses have prompted a taxonomic reorganization of family Partitiviridae (encapsidated, bisegmented dsRNA viruses that infect plants, fungi, or protozoa), the focus of this review. After a brief introduction to partitiviruses, the taxonomic changes are discussed, including replacement of former genera Partitivirus, Alphacryptovirus, and Betacryptovirus, with new genera Alphapartitivirus, Betapartitivirus, Gammapartitivirus, and Deltapartitivirus, as well as redistribution of species among these new genera. To round out the review, other recent progress of note in partitivirus research is summarized, including discoveries of novel partitivirus sequences by metagenomic approaches and mining of sequence databases, determinations of fungal partitivirus particle structures, demonstrations of fungal partitivirus transmission to new fungal host species, evidence for other aspects of partitivirus host interactions and host effects, and identification of other fungal or plant viruses with some similarities to partitiviruses. Some outstanding questions are also discussed. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.virusres.2014.04.007

A novel single-stranded RNA virus isolated from a phytopathogenic filamentous fungus, Rosellinia necatrix, with similarity to hypo-like viruses Reviewed

Rui Zhang, Shengxue Liu, Sotaro Chiba, Hideki Kondo, Satoko Kanematsu, Nobuhiro Suzuki

FRONTIERS IN MICROBIOLOGY 5 360 2014.7

Language：English Publishing type：Research paper (scientific journal) Publisher：FRONTIERS RESEARCH FOUNDATION

Here we report a biological and molecular characterization of a novel positive-sense RNA virus isolated from a field isolate (NW10) of a filamentous phytopathogenic fungus, the white root rot fungus that is designated as Rosellinia necatrix fusarivirus 1 (RnFV1). A recently developed technology using zinc ions allowed us to transfer RnFV1 to two mycelially incompatible Rosellinia necatrix strains. A biological comparison of the virus-free and -recipient isogenic fungal strains suggested that RnFV1 infects latently and thus has no potential as a virocontrol agent. The virus has an undivided positive-sense RNA genome of 6286 nucleotides excluding a poly (A) tail. The genome possesses two non-overlapping open reading frames (ORFs): a large ORF1 that encodes polypeptides with RNA replication functions and a smaller ORF2 that encodes polypeptides of unknown function. A lack of coat protein genes was suggested by the failure of virus particles from infected mycelia. No evidence was obtained by Northern analysis or classical 5'-RACE for the presence of subgenomic RNA for the downstream ORE Sequence similarities were found in amino-acid sequence between RnFV1 putative proteins and counterparts of a previously reported mycovirus, Fusarium graminearum virus 1 (FgV1). Interestingly, several related sequences were detected by BLAST searches of independent transcriptome assembly databases one of which probably represents an entire virus genome. Phylogenetic analysis based on the conserved RNA-dependent RNA polymerase showed that RnFV1, FgV1, and these similar sequences are grouped in a cluster distinct from distantly related hypoviruses. It is proposed that a new taxonomic family termed Fusariviridae be created to include RnFV1 and FgV1.

DOI： 10.3389/fmicb.2014.00360

Biological properties and expression strategy of rosellinia necatrix megabirnavirus 1 analysed in an experimental host, Cryphonectria parasitica Reviewed

Lakha Salaipeth, Sotaro Chiba, Ana Eusebio-Cope, Satoko Kanematsu, Nobuhiro Suzuki

JOURNAL OF GENERAL VIROLOGY 95 ( Pt 3 ) 740 - 750 2014.3

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

Rosellinia necatrix megabirnavirus 1 (RnMBV1) with a bipartite dsRNA genome (dsRNA1 and dsRNA2) confers hypovirulence to its natural host, the white root rot fungus, and is thus regarded as a potential virocontrol (biocontrol) agent. Each segment has two large ORFs: ORF1 and partially overlapping ORF2 on dsRNA1 encode the major capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), whilst ORF3 and ORF4 on dsRNA2 encode polypeptides with unknown functions. Here, we report the biological and molecular characterization of this virus in the chestnut blight fungus, Cryphonectria parasitica, a filamentous fungus that has been used as a model for mycovirus research. Transfection with purified RnMBV1 particles into an RNA-silencing-defective strain (Delta dcl-2) of C. parasitica and subsequent anastomosis with the WT strain (EP155) resulted in stable persistent infection in both host strains. However, accumulation levels in the two strains were different, being similar to 20-fold higher in Delta dcl-2 than in EP155. Intriguingly, whilst RnMBV1 reduced both virulence and growth rate in Delta dcl-2, it attenuated virulence without affecting significantly other traits in EP155. Western blot analysis using antiserum against recombinant proteins encoded by either ORF1 or ORF2 demonstrated the presence of a 250 kDa protein in purified virion preparations, suggesting that RdRp is expressed as a CP fusion product via a - 1 frameshift. Antiserum against the ORF3-encoded protein allowed the detection of 150, 30 and 23 kDa polypeptides specifically in RnMBV1-infected mycelia. Some properties of an RnMBV1 mutant with genome rearrangements, which occurred after transfection of Delta dcl-2 and EP155, were also presented. This study provides an additional example of C. parasitica serving as a versatile, heterologous fungus for exploring virus host interactions and virus gene expression strategies.

DOI： 10.1099/vir.0.058164-0

Transcriptional mapping of the messenger and leader RNAs of orchid fleck virus, a bisegmented negative-strand RNA virus Reviewed

Hideki Kondo, Kazuyuki Maruyama, Sotaro Chiba, Ida Bagus Andika, Nobuhiro Suzuki

VIROLOGY 452 166 - 174 2014.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

The transcriptional strategy of orchid fleck virus (OFV), which has a two-segmented negative-strand RNA genome and resembles plant nucleorhabdoviruses, remains unexplored. In this study, the transcripts of six genes encoded by OFV RNA1 and RNA2 in the poly(A)-enriched RNA fraction from infected plants were molecularly characterized. All of the OFV mRNAs were initiated at a start sequence 3'-UU-5' with one to three non-viral adenine nucleotides which were added at the 5' end of each mRNA, whereas their 3' termini ended with a 5'-AUUUAAA(U/G)AAAA(A)n-3' sequence. We also identified the presence of polyadenylated short transcripts derived from the 3'-terminal leader regions of both genomic and antigenomic strands, providing the first example of plus- and minus-strand leader RNAs in a segmented minus-strand RNA virus. The similarity in the transcriptional strategy between this bipartite OFV and monopartite rhabdoviruses, especially nucleorhabdoviruses (family Rhabdoviridae) is additional support for their close relationship. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2014.01.007

Genome rearrangement of a mycovirus Rosellinia necatrix megabirnavirus 1 affecting its ability to attenuate virulence of the host fungus Reviewed

Satoko Kanematsu, Takeo Shimizu, Lakha Salaipeth, Hajime Yaegashi, Atsuko Sasaki, Tsutae Ito, Nobuhiro Suzuki

VIROLOGY 450 308 - 315 2014.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Rosellinia necatrix megabirnavirus 1 (RnMBV1) is a bi-segmented double-stranded RNA mycovirus that reduces the virulence of the fungal plant pathogen R. necatrix. We isolated strains of RnMBV1 with genome rearrangements (RnMBV1-RS1) that retained dsRNA1, encoding capsid protein (ORF1) and RNA-dependent RNA polymerase (ORF2), and had a newly emerged segment named dsRNAS1, but with loss of dsRNA2, which contains two ORFs of unknown function. Analyses of two variants of dsRNAS1 revealed that they both originated from dsRNA1 by deletion of ORFI and partial tandem duplication of ORF2, retaining a much shorter 5' untranslated region (UTR). R. necatrix transfected with RnMBV-RS1 virions showed maintenance of virulence on host plants compared with infection with RnMBV1. This suggests that dsRNAS1 is able to be transcribed and packaged, as well as suggesting that dsRNA2, while dispensable for virus replication, is required to reduce the virulence of R. necatrix. (C) 2013 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.virol.2013.12.002

Complete genome sequence of Habenaria mosaic virus, a new potyvirus infecting a terrestrial orchid (Habenaria radiata) in Japan Reviewed

Hideki Kondo, Takanori Maeda, I. Wayan Gara, Sotaro Chiba, Kazuyuki Maruyama, Tetsuo Tamada, Nobuhiro Suzuki

ARCHIVES OF VIROLOGY 159 ( 1 ) 163 - 166 2014.1

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

The complete genomic sequence of Habenaria mosaic virus (HaMV), which infects terrestrial orchids (Habenaria radiata), has been determined. The genome is composed of 9,499 nucleotides excluding the 3'-terminal poly(A) tail, encoding a large polyprotein of 3,054 amino acids with the genomic features typical of a potyvirus. Putative proteolytic cleavage sites were identified by sequence comparison to those of known potyviruses. The HaMV polyprotein showed 58 % amino acid sequence identity to that encoded by the most closely related potyvirus, tobacco vein banding mosaic virus. Phylogenetic analysis of the polyprotein amino acid sequence and its coding sequences confirmed that HaMV formed a cluster with the chilli veinal mottle virus group, most of which infect solanaceous plants. These results suggest that HaMV is a distinct member of the genus Potyvirus.

DOI： 10.1007/s00705-013-1784-6

[Cryphonectria parasitica as a host of fungal viruses: a tool useful to unravel the mycovirus world]. Reviewed

Suzuki N

Uirusu 64 ( 1 ) 11 - 24 2014

[Diverse double-stranded RNA viruses infecting fungi]. Reviewed

Chiba S, Suzuki N

Uirusu 64 ( 2 ) 225 - 238 2014

Language：Japanese Publisher：The Japanese Society for Virology

Most of reported fungal viruses (mycoviruses) have double-stranded RNA (dsRNA) genomes. This may reflect the simple, easy method for mycovirus hunting that entails detection of dsRNAs as a sign of viral infections. There are an increasing number of screens of various fungi, particularly phytopathogenic fungi for viruses pathogenic to host fungi or able to confer hypovirulence to them. This bases on an attractive research field of biological control of fungal plant diseases using viruses (virocontrol), mainly targeting important phytopathogenic fungi. While isolated viruses usually induce asymptomatic symptoms, they show a considerably high level of diversity. As of 2014, fungal dsRNA viruses are classified into six families: Reoviridae, Totiviridae, Chrysoviridae, Partitiviridae, Megabirnaviridae and Quadriviridae. These exclude unassigned mycoviruses which will definitely be placed into distinct families and/or genera. In this review article, dsRNA viruses isolated from the kingdom Fungi including as-yet-unclassified taxa are overviewed. Some recent achievements in the related field are briefly introduced as well.

DOI： 10.2222/jsv.64.225

Other Link： https://jlc.jst.go.jp/DN/JLC/20008436588?from=CiNii

Nyamiviridae: Proposal for a new family in the order Mononegavirales Reviewed

Jens H. Kuhn, Sadia Bekal, Yingyun Cai, Anna N. Clawson, Leslie L. Domier, Marieke Herrel, Peter B. Jahrling, Hideki Kondo, Kris N. Lambert, Kathie A. Mihindukulasuriya, Norbert Nowotny, Sheli R. Radoshitzky, Urs Schneider, Peter Staeheli, Nobuhiro Suzuki, Robert B. Tesh, David Wang, Lin-Fa Wang, Ralf G. Dietzgen

ARCHIVES OF VIROLOGY 158 ( 10 ) 2209 - 2226 2013.10

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

Nyamanini virus (NYMV) and Midway virus (MIDWV) are unclassified tick-borne agents that infect land birds and seabirds, respectively. The recent molecular characterization of both viruses confirmed their already known close serological relationship and revealed them to be nonsegmented, single- and negative-stranded RNA viruses that are clearly related to, but quite distinct from, members of the order Mononegavirales (bornaviruses, filoviruses, paramyxoviruses, and rhabdoviruses). A third agent, soybean cyst nematode virus 1 (SbCNV-1, previously named soybean cyst nematode nyavirus), was recently found to be an additional member of this new virus group. Here, we review the current knowledge about all three viruses and propose classifying them as members of a new mononegaviral family, Nyamiviridae.

DOI： 10.1007/s00705-013-1674-y

Orchid fleck virus structural proteins N and P form intranuclear viroplasm like structures in the absence of viral infection Reviewed

Hideki Kondo, Sotaro Chiba, Ida Bagus Andika, Kazuyuki Maruyama, Tetsuo Tamada, Nobuhiro Suzuki

Journal of Virology 87 ( 13 ) 7423 - 7434 2013.7

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

Orchid fleck virus (OFV) has a unique two-segmented negative-sense RNA genome that resembles that of plant nucleorhabdoviruses. In infected plant cells, OFV and nucleorhabdoviruses induce an intranuclear electron-lucent viroplasm that is believed to be the site for virus replication. In this study, we investigated the molecular mechanism by which OFV viroplasms are produced in vivo. Among OFV-encoded proteins, the nucleocapsid protein (N) and the putative phosphoprotein (P) were present in nuclear fractions of OFV-infected Nicotiana benthamiana plants. Transient coexpression of N and P, in the absence of virus infection, was shown to be sufficient for formation of an intranuclear viroplasm-like structure in plant cells. When expressed independently as a fluorescent protein fusion product in uninfected plant cells, N protein accumulated throughout the cell, while P protein accumulated in the nucleus. However, the N protein, when coexpressed with P, was recruited to a subnuclear region to induce a large viroplasm-like focus. Deletion and substitution mutagenesis demonstrated that the P protein contains a nuclear localization signal (NLS). Artificial nuclear targeting of the N-protein mutant was insufficient for formation of viroplasm-like structures in the absence of P. A bimolecular fluorescence complementation assay confirmed interactions between the N and P proteins within subnuclear viroplasm-like foci and interactions of two of the N. benthamiana importin-α homologues with the P protein but not with the N protein. Taken together, our results suggest that viroplasm formation by OFV requires nuclear accumulation of both the N and P proteins, which is mediated by P-NLS, unlike nucleorhabdovirus viroplasm utilizing the NLS on protein N. © 2013, American Society for Microbiology.

DOI： 10.1128/JVI.00270-13

A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing Reviewed

Sotaro Chiba, Yu-Hsin Lin, Hideki Kondo, Satoko Kanematsu, Nobuhiro Suzuki

JOURNAL OF VIROLOGY 87 ( 12 ) 6727 - 6738 2013.6

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

A novel victorivirus, termed Rosellinia necatrix victorivirus 1 (RnVV1), was isolated from a plant pathogenic ascomycete, white root rot fungus Rosellinia necatrix, coinfected with a partitivirus. The virus was molecularly and biologically characterized using the natural and experimental hosts (chestnut blight fungus, Cryphonectria parasitica). RnVV1 was shown to have typical molecular victorivirus attributes, including a monopartite double-stranded RNA genome with two open reading frames (ORFs) encoding capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), a UAAUG pentamer presumed to facilitate the coupled termination/reinitiation for translation of the two ORFs, a spherical particle structure similar to 40 nm in diameter, and moderate levels of CP and RdRp sequence identity (34 to 58%) to those of members of the genus Victorivirus within the family Totiviridae. A reproducible transfection system with purified RnVV1 virions was developed for the two distinct fungal hosts. Transfection assay with purified RnVV1 virions combined with virus elimination by hyphal tipping showed that the effects of RnVV1 on the phenotype of the natural host were negligible. Interestingly, comparison of the RNA silencing-competent (standard strain EP155) and -defective (Delta dcl-2) strains of C. parasitica infected with RnVV1 showed that RNA silencing acted against the virus to repress its replication, which was restored by coinfection with hypovirus or transgenic expression of an RNA silencing suppressor, hypovirus p29. Phenotypic changes were observed in the Delta dcl-2 strain but not in EP155. This is the first reported study on the host range expansion of a Totiviridae member that is targeted by RNA silencing.

DOI： 10.1128/JVI.00557-13

A second quadrivirus strain from the phytopathogenic filamentous fungus Rosellinia necatrix Reviewed

Yu-Hsin Lin, Sakae Hisano, Hajime Yaegashi, Satoko Kanematsu, Nobuhiro Suzuki

ARCHIVES OF VIROLOGY 158 ( 5 ) 1093 - 1098 2013.5

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

We report the biological and molecular characterisation of a second quadrivirus strain termed Rosellinia necatrix quadrivirus 1 strain W1118 (RnQV1-W1118) from the ascomycete white root rot fungus. Commonalities with the first quadrivirus (RnQV1-W1075) include its quadripartite genome structure, spherical particle morphology, sequence heterogeneity in the extreme terminal end, 72-82% sequence identity between the corresponding proteins, and its ability to cause a latent infection. Distinguishing features include different conserved terminal sequences and the degree of susceptibility of two major capsid proteins to proteolytic degradation, which is thought to occur during virion purification. Identification of this second quadrivirus strain strengthens our earlier proposal that "Rosellinia necatrix quadrivirus 1" should be considered the type species of a novel family, "Quadriviridae".

DOI： 10.1007/s00705-012-1580-8

Assessment of change in biofilm architecture by nutrient concentration using a multichannel microdevice flow system Reviewed

Zoe Sanchez, Akio Tani, Nobuhiro Suzuki, Reiko Kariyama, Hiromi Kumon, Kazuhide Kimbara

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 115 ( 3 ) 326 - 331 2013.3

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

A new multichannel microdevice flow system with stainless steel flow chamber was used for architecture visualization, development monitoring and structural quantification of GFP-labeled Pseudomonas aeruginosa PAO1 live biofilms. Direct in situ investigations using confocal laser scanning microscopy (CLSM) at 72 h revealed structural pattern differences as a result of nutrient concentration gradients. When grown in LB medium, round, dispersed cellular aggregates were formed whereas in 1/3-diluted LB medium, biofilms were mostly flat and compact. However, COMSTAT analyses showed no considerable differences in biomass and thickness between the two LB concentrations. Characterization of time-dependent development of biofilms grown in 1/3-diluted LB medium showed full maturation of colonies by 120 h reaching maximum biomass at 17.1 mu m(3)/mu m(2) and average thickness at 44.4 mu m. Consequent thinning and formation of openings through interior in colonies occurred by 168 h. These results suggest that the new system tested allowed a fast and thick biofilm development on the surface of the stainless steel flow chamber. These findings may provide better estimates of biofilm activity and systematic evaluation of the effects of different parameters on biofilm morphology and development in industrial and biomedical systems. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.

DOI： 10.1016/j.jbiosc.2012.09.018

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