Microbiology Society Acta Medica Okayama 0022-1317 106 12 2025 Thorough characterization of a new curvulavirid from a Japanese strain of Cryphonectria nitschkei 002177 EN Sabitree Shahi ​Institute of Plant Science and Resources, Okayama University Sakae Hisano ​Institute of Plant Science and Resources, Okayama University Wasiatus Sa'diyah ​Institute of Plant Science and Resources, Okayama University Yoshihiro Takaki ​Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Hideki Kondo ​Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki ​Institute of Plant Science and Resources, Okayama University A new curvulavirid was isolated from a Japanese strain of the filamentous ascomycete Cryphonectria nitschkei and thoroughly characterized. The virus termed Cryphonectria nitschkei curvulavirus 1 (CnCvV1) has a bi-segmented dsRNA genome. CnCvV1 dsRNA1 encodes an RNA-dependent RNA polymerase (592 amino acids), while dsRNA2 possesses two ORFs, one that encodes a protein associated with the genomic dsRNA and the other that encodes a hypothetical protein of unknown function. CnCvV1 could be experimentally introduced into another virus-free strain of C. nitschkei and two strains of different fungal species within the genus Cryphonectria (Cryphonectria parasitica and Cryphonectria carpinicola). Based on phenotypic comparison, the virus caused asymptomatic infection in the three newly established fungal strains. However, there was a reduced colony growth rate and increased CnCvV1 accumulation in an RNA silencing-deficient mutant (Δdcl2), relative to the wt strain EP155 of a model virus host fungus (C. parasitica). These findings suggest that CnCvV1 is targeted by RNA silencing in C. parasitica. This study provides a foundation for further exploration of curvulavirids that have been biologically understudied. No potential conflict of interest relevant to this article was reported.

Microbiology Society Acta Medica Okayama 0022-1317 106 7 2025 Summary of taxonomy changes ratified by the International Committee on Taxonomy of Viruses (ICTV) from the Animal dsRNA and ssRNA(−) Viruses Subcommittee, 2025 002112 EN Holly R. Hughes Centers for Disease Control and Prevention Matthew J. Ballinger Biological Sciences, Mississippi State University Yiming Bao National Genomics Data Center, China National Center for Bioinformation; Beijing Institute of Genomics, Chinese Academy of Sciences; University of Chinese Academy of Sciences Nicolas Bejerman Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Instituto Nacional de Tecnología Agropecuaria (INTA) Kim R. Blasdell CSIRO Health and Biosecurity Thomas Briese Center for Infection and Immunity, and Department of Epidemiology, Mailman School of Public Health, Columbia University Julia Brignone Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui. INEVH -ANLIS Jean Paul Carrera Instituto Conmemorativo Gorgas de Estudios de la Salud Lander De Coninck Division of Clinical and Epidemiological Virology, KU Leuven William Marciel de Souza Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky Humberto Debat Instituto Nacional de Tecnología Agropecuaria (INTA) Ralf G. Dietzgen QAAFI, The University of Queensland Ralf Dürrwald Robert Koch Institut Mert Erdin Department of Virology, University of Helsinki Anthony R. Fooks Animal and Plant Health Agency (APHA) Kristian M. Forbes Department of Biological Sciences, University of Arkansas Juliana Freitas-Astúa Embrapa Cassava and Fruits Jorge B. Garcia Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui. INEVH -ANLIS Jemma L. Geoghegan Department of Microbiology and Immunology, University of Otago Rebecca M. Grimwood Department of Microbiology and Immunology, University of Otago Masayuki Horie Osaka International Research Center for Infectious Diseases, Osaka Metropolitan University Timothy H. Hyndman School of Veterinary Medicine, Murdoch University Reimar Johne German Federal Institute for Risk Assessment John D. Klena Viral Special Pathogens Branch, The Centers for Disease Control and Prevention Hideki Kondo Institute of Plant Science and Resources, Okayama University Eugene V. Koonin Computational Biology Branch, Division of Intramural Research National Library of Medicine, National Institutes of Health Alexei Y. Kostygov University of Ostrava Mart Krupovic Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit Jens H. Kuhn Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health Michael Letko Paul G. Allen School for Global Health, Washington State University Jun-Min Li Institute of Plant Virology, Ningbo University Yiyun Liu National Genomics Data Center, China National Center for Bioinformation; Beijing Institute of Genomics, Chinese Academy of Sciences; University of Chinese Academy of Sciences Maria Laura Martin Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui. INEVH -ANLIS Nathaniel Mull Department of Natural Sciences, Shawnee State University Yael Nazar Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui. INEVH -ANLIS Norbert Nowotny College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai Health Márcio Roberto Teixeira Nunes Universidade Federal do Pará Arnfinn Lodden Økland Pharmaq Analytiq Dennis Rubbenstroth Institute of Diagnostic Virology, Friedrich-Loeffler-Institut Brandy J. Russell Centers for Disease Control and Prevention Eric Schott Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science Stephanie Seifert Paul G. Allen School for Global Health, Washington State University Carina Sen Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui. INEVH -ANLIS Elizabeth Shedroff Viral Special Pathogens Branch, The Centers for Disease Control and Prevention Tarja Sironen Department of Virology, University of Helsinki Teemu Smura Department of Virology, University of Helsinki Camila Prestes Dos Santos Tavares Integrated Group of Aquaculture and Environmental Studies, Federal University of Paraná Robert B. Tesh Department of Pathology, The University of Texas Medical Branch Natasha L. Tilston Department of Microbiology and Immunology, Indiana University School of Medicine Noël Tordo Institut Pasteur Nikos Vasilakis Department of Pathology, The University of Texas Medical Branch Peter J. Walker University of Queensland Fei Wang Wuhan Institute of Virology, Chinese Academy of Sciences Anna E. Whitfield North Carolina State University Shannon L.M. Whitmer Viral Special Pathogens Branch, The Centers for Disease Control and Prevention Yuri I. Wolf Computational Biology Branch, Division of Intramural Research National Library of Medicine, National Institutes of Health Han Xia Wuhan Institute of Virology, Chinese Academy of Sciences Gong-Yin Ye Institute of Insect Sciences, Zhejiang University Zhuangxin Ye Institute of Plant Virology, Ningbo University Vyacheslav Yurchenko University of Ostrava Mingli Zhao Department of Pathobiology and Population Sciences, Royal Veterinary College RNA viruses are ubiquitous in the environment and are important pathogens of humans, animals and plants. In 2024, the International Committee on Taxonomy of Viruses Animal dsRNA and ssRNA(−) Viruses Subcommittee submitted 18 taxonomic proposals for consideration. These proposals expanded the known virosphere by classifying 9 new genera and 88 species for newly detected virus genomes. Of note, newly established species expand the large family of Rhabdoviridae to 580 species. A new species in the family Arenaviridae includes a virus detected in Antarctic fish with a unique split nucleoprotein ORF. Additionally, four new species were established for historically isolated viruses with previously unsequenced genomes. Furthermore, three species were abolished due to incomplete genome sequence information, and one family was moved from being unassigned in the phylum Negarnaviricota into a subphylum and order. Herein, we summarize the 18 ratified taxonomic proposals and the general features of the current taxonomy, thereby supporting public and animal health responses. No potential conflict of interest relevant to this article was reported.

Microbiology Society Acta Medica Okayama 0022-1317 106 7 2025 Summary of taxonomy changes ratified by the International Committee on Taxonomy of Viruses from the Plant Viruses Subcommittee, 2025 002114 EN Luisa Rubino Istituto per la Protezione Sostenibile delle Piante, CNR Peter Abrahamian USDA-ARS, BARC, National Germplasm Resources Laboratory Wenxia An Liaoning Key Laboratory of Urban Integrated Pest Management and Ecological Security, Shenyang University Miguel A. Aranda Centro de Edafología y Biología Aplicada del Segura-CSIC José T. Ascencio-Ibañez Department of Molecular and Structural Biochemistry, North Carolina State University Nicolas Bejerman Unidad de Fitopatología y Modelización Agrícola (UFYMA) INTA-CONICET Arnaud G. Blouin Plant Protection Department Thierry Candresse UMR 1332 Biologie du Fruit et Pathologie, University of Bordeaux, INRAE Tomas Canto Margarita Salas Center for Biological Research (CIB-CSIC) Spanish Council for Scientific Research (CSIC) Mengji Cao National Citrus Engineering and Technology Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University John P. Carr Department of Plant Sciences, University of Cambridge Won Kyong Cho Agriculture and Life Sciences Research Institute, Kangwon National University Fiona Constable Agriculture Victoria Research, Department of Energy, Environment and Climate Action and School of Applied Systems Biology, La Trobe University Indranil Dasgupta University of Delhi South Campu Humberto Debat Unidad de Fitopatología y Modelización Agrícola (UFYMA) INTA-CONICET Ralf G. Dietzgen Queensland Alliance for Agriculture and Food Innovation, The University of Queensland Michele Digiaro CIHEAM, Istituto Agronomico Mediterraneo of Bari Livia Donaire Centro de Edafología y Biología Aplicada del Segura-CSIC Toufic Elbeaino CIHEAM, Istituto Agronomico Mediterraneo of Bari Denis Fargette Virus South Data Fiona Filardo Queensland Department of Primary Industries Matthias G. Fischer Max Planck Institute for Marine Microbiology Nuria Fontdevila Plant Protection Department Adrian Fox Fera Science Ltd (Fera), York Biotech Campus Juliana Freitas-Astua Embrapa Cassava and Fruits, Brazilian Agricultural Research Corporation Marc Fuchs Plant Pathology, Cornell University Andrew D.W. Geering Queensland Alliance for Agriculture and Food Innovation, The University of Queensland Mahan Ghafari Department of Biology, University of Oxford Anders Hafrén Swedish University of Agriculture John Hammond USDA-ARS, USNA, Floral and Nursery Plants Research Unit Rosemarie Hammond USDA-ARS, BARC, Molecular Plant Pathology Laboratory Beata Hasiów-Jaroszewska Institute of Plant Protection-NRI Eugenie Hebrard PHIM Plant Health Institute, University of Montpellier, INRAE, CIRAD, IRD, Institute Agro Carmen Hernández Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de Valencia-CSIC Jean-Michel Hily Institut Français de la Vigne et du Vin Ahmed Hosseini Vali-e-Asr University of Rafsanjan, Department of Plant Protection Roger Hull Retired from John Innes Centre Alice K. Inoue-Nagata Embrapa Hortaliças Ramon Jordan USDA-ARS, USNA, Floral and Nursery Plants Research Unit Hideki Kondo Institute of Plant Science and Resources, Okayama University Jan F. Kreuze International Potato Center (CIP) Mart Krupovic Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit Kenji Kubota Institute for Plant Protection, NARO Jens H. Kuhn Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health Scott Leisner Department of Biological Sciences, University of Toledo Jean-Michel Lett CIRAD, UMR PVBMT Chengyu Li Liaoning Key Laboratory of Urban Integrated Pest Management and Ecological Security, Shenyang University Fan Li State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University Jun Min Li Institute of Plant Virology, Ningbo University Paola M. López-Lambertini Instituto de Patología Vegetal (IPAVE), INTA, Unidad de Fitopatología y Modelización Agrícola (UFYMA) INTA-CONICET Juan J. Lopez-Moya Centre for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB) Francois Maclot UMR 1332 Biologie du Fruit et Pathologie, University of Bordeaux, INRAE Kristiina Mäkinen Department of Agricultural Sciences, University of Helsinki Darren Martin Institute of Infectious Disease and Molecular Medicine, University of Cape Town Sebastien Massart Plant Pathology Laboratory, TERRA Gembloux Agro-Bio Tech, University of Liege W. Allen Miller Department of Plant Pathology, Entomology and Microbiology, Iowa State University Musa Mohammadi Department of Plant Protection, Gorgan University of Agricultural Sciences and Natural Resources Dimitre Mollov USDA-APHIS, Plant Protection and Quarantine Emmanuelle Muller CIRAD, AGAP Institut; AGAP Institut, University of Montpellier; CIRAD, INRAE Tatsuya Nagata Instituto de Ciências Biológicas, Universidade de Brasília Jesús Navas-Castillo Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora” (IHSM-UMA-CSIC), Consejo Superior de Investigaciones Científicas Yutaro Neriya Utsunomiya University Francisco M. Ochoa-Corona Oklahoma State University, Institute for Biosecurity & Microbial Forensics Kazusato Ohshima Saga University Vicente Pallás Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de Valencia-CSIC Hanu Pappu Department of Plant Pathology, Washington State University Karel Petrzik Institute of Plant Molecular Biology Mikhail Pooggin PHIM Plant Health Institute, University of Montpellier, INRAE, CIRAD, IRD Maria Isabella Prigigallo Istituto per la Protezione Sostenibile delle Piante, CNR Pedro L. Ramos-González Applied Molecular Biology Laboratory, Instituto Biológico de São Paulo Simone Ribeiro Embrapa Recursos Genéticos e Biotecnologia Katja R. Richert-Pöggeler Julius Kühn Institute, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics Philippe Roumagnac CIRAD, UMR PHIM Avijit Roy USDA-ARS, BARC, Molecular Plant Pathology Laboratory, Beltsville, MD, USA Sead Sabanadzovic Department of Agricultural Science and Plant Protection, Mississippi State University Dana Šafářová Department of Cell Biology and Genetics, Faculty of Science, Palacký University Olomouc Pasquale Saldarelli Istituto per la Protezione Sostenibile delle Piante, CNR Hélène Sanfaçon Summerland Research and Development Centre, Agriculture and Agri-Food Canada Cecilia Sarmiento Department of Chemistry and Biotechnology, Tallinn University of Technology Takahide Sasaya Strategic Planning Headquarters, NARO Kay Scheets Department of Plant Pathology, Ecology and Evolution, Oklahoma State University Willem E.W. Schravesande Molecular Plant Pathology, University of Amsterdam Susan Seal Natural Resources Institute, University of Greenwich Yoshifumi Shimomoto Kochi Agricultural Research Center Merike Sõmera Department of Chemistry and Biotechnology, Tallinn University of Technology Livia Stavolone Istituto per la Protezione Sostenibile delle Piante, CNR Lucy R. Stewart Currently unaffiliated Pierre-Yves Teycheney CIRAD, UMR PVBMT & UMR PVBMT, Université de la Réunion John E. Thomas Queensland Alliance for Agriculture and Food Innovation, The University of Queensland Jeremy R. Thompson Plant Health and Environment Laboratory Antonio Tiberini Council for Agricultural Research and Economics, Research Centre for Plant Protection and Certification Yasuhiro Tomitaka Institute for Plant Protection, NARO Ioannis Tzanetakis Department of Entomology and Plant Pathology, Division of Agriculture, University of Arkansas System Marie Umber INRAE, UR ASTRO Cica Urbino PHIM Plant Health Institute, University of Montpellier, INRAE, CIRAD, IRD, Institute Agro Harrold A. van den Burg Molecular Plant Pathology, University of Amsterdam René A.A. Van der Vlugt Wageningen University and Research Arvind Varsani The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University Adriaan Verhage Rijk Zwaan Breeding B.V. Dan Villamor Department of Entomology and Plant Pathology, Division of Agriculture, University of Arkansas System Susanne von Bargen Humboldt-Universität zu Berlin, Thaer-Institute of Agricultural and Horticultural Sciences Peter J. Walker The University of Queensland Thierry Wetzel Dienstleistungszentrum Ländlicher Raum Rheinpfalz Anna E. Whitfield North Carolina State University Stephen J. Wylie Food Futures Institute, Murdoch University Caixia Yang Liaoning Key Laboratory of Urban Integrated Pest Management and Ecological Security, Shenyang University F. Murilo Zerbini Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa Song Zhang National Citrus Engineering and Technology Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University In March 2025, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote, newly proposed taxa were added to those under the mandate of the Plant Viruses Subcommittee. In brief, 1 new order, 3 new families, 6 new genera, 2 new subgenera and 206 new species were created. Some taxa were reorganized. Genus Cytorhabdovirus in the family Rhabdoviridae was abolished and its taxa were redistributed into three new genera Alphacytorhabdovirus, Betacytorhabdovirus and Gammacytorhabdovirus. Genus Waikavirus in the family Secoviridae was reorganized into two subgenera (Actinidivirus and Ritunrivirus). One family and four previously unaffiliated genera were moved to the newly established order Tombendovirales. Twelve species not assigned to a genus were abolished. To comply with the ICTV mandate of a binomial format for virus species, eight species were renamed. Demarcation criteria in the absence of biological information were defined in the genus Ilarvirus (family Bromoviridae). This article presents the updated taxonomy put forth by the Plant Viruses Subcommittee and ratified by the ICTV. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0168-1702 351 2025 Evidence for the replication of a plant rhabdovirus in its arthropod mite vector 199522 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Miki Fujita Institute of Plant Science and Resources (IPSR), Okayama University Paul Telengech Institute of Plant Science and Resources (IPSR), Okayama University Kazuyuki Maruyam Institute of Plant Science and Resources (IPSR), Okayama University Kiwamu Hyodo Institute of Plant Science and Resources (IPSR), Okayama University Aline Daniele Tassi Tropical Research and Education Center, University of Florida Ronald Ochoa Systematic Entomology Laboratory, USDA Ida Bagus Andika College of Plant Protection, Northwest A&F University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Transmission of plant viruses that replicate in the insect vector is known as persistent-propagative manner. However, it remains unclear whether such virus-vector relationships also occur between plant viruses and other biological vectors such as arthropod mites. In this study, we investigated the possible replication of orchid fleck virus (OFV), a segmented plant rhabdovirus, within its mite vector (Brevipalpus californicus s.l.) using quantitative RT-qPCR, western blotting and next-generation sequencing. Time-course RT-qPCR and western blot analyses showed an increasing OFV accumulation pattern in mites after virus acquisition. Since OFV genome expression requires the transcription of polyadenylated mRNAs, polyadenylated RNA fractions extracted from the viruliferous mite samples and OFV-infected plant leaves were used for RNA-seq analysis. In the mite and plant datasets, a large number of sequence reads were aligned to genomic regions of OFV RNA1 and RNA2 corresponding to transcribed viral gene mRNAs. This includes the short polyadenylated transcripts originating from the leader and trailer regions at the ends of the viral genome, which are believed to play a crucial role in viral transcription/replication. In contrast, a low number of reads were mapped to the non-transcribed regions (gene junctions). These results strongly suggested that OFV gene expression occurs both in mites and plants. Additionally, deep sequencing revealed the accumulation of OFV-derived small RNAs in mites, although their size profiles differ from those found in plants. Taken together, our results indicated that OFV replicates within a mite vector and is targeted by the RNA-silencing mechanism. No potential conflict of interest relevant to this article was reported.

MDPI AG Acta Medica Okayama 1999-4915 16 7 2024 Metatranscriptomic Sequencing of Sheath Blight-Associated Isolates of Rhizoctonia solani Revealed Multi-Infection by Diverse Groups of RNA Viruses 1152 EN Michael Louie R. Urzo Microbiology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños Timothy D. Guinto Microbiology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños Ana Eusebio-Cope Fit-for-Future Genetic Resources Unit, Rice Breeding Innovations Department, International Rice Research Institute (IRRI), University of the Philippines Los Baños Bernard O. Budot Institute of Weed Science, Entomology, and Plant Pathology, College of Agriculture and Food Science, University of the Philippines Los Baños Mary Jeanie T. Yanoria Traits for Challenged Environments Unit, Rice Breeding Innovations Department, International Rice Research Institute (IRRI), University of the Philippines Los Baños Gilda B. Jonson Traits for Challenged Environments Unit, Rice Breeding Innovations Department, International Rice Research Institute (IRRI), University of the Philippines Los Baños Masao Arakawa Faculty of Agriculture, Meijo University Hideki Kondo Plant-Microbe Interactions Group, Institute of Plant Science and Resources (IPSR), Okayama University Nobuhiro Suzuki Plant-Microbe Interactions Group, Institute of Plant Science and Resources (IPSR), Okayama University Rice sheath blight, caused by the soil-borne fungus Rhizoctonia solani (teleomorph: Thanatephorus cucumeris, Basidiomycota), is one of the most devastating phytopathogenic fungal diseases and causes yield loss. Here, we report on a very high prevalence (100%) of potential virus-associated double-stranded RNA (dsRNA) elements for a collection of 39 fungal strains of R. solani from the rice sheath blight samples from at least four major rice-growing areas in the Philippines and a reference isolate from the International Rice Research Institute, showing different colony phenotypes. Their dsRNA profiles suggested the presence of multiple viral infections among these Philippine R. solani populations. Using next-generation sequencing, the viral sequences of the three representative R. solani strains (Ilo-Rs-6, Tar-Rs-3, and Tar-Rs-5) from different rice-growing areas revealed the presence of at least 36 viruses or virus-like agents, with the Tar-Rs-3 strain harboring the largest number of viruses (at least 20 in total). These mycoviruses or their candidates are believed to have single-stranded RNA or dsRNA genomes and they belong to or are associated with the orders Martellivirales, Hepelivirales, Durnavirales, Cryppavirales, Ourlivirales, and Ghabrivirales based on their coding-complete RNA-dependent RNA polymerase sequences. The complete genome sequences of two novel RNA viruses belonging to the proposed family Phlegiviridae and family Mitoviridae were determined. No potential conflict of interest relevant to this article was reported.

American Society for Microbiology Acta Medica Okayama 0022-538X 99 3 2025 A capsidless (+)RNA yadokarivirus hosted by a dsRNA virus is infectious as particles, cDNA, and dsRNA e02166-24 EN Muhammad Fadli Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Sakae Hisano Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Guy Novoa Department of Structure of Macromolecules, Centro Nacional Biotecnología (CNB-CSIC), Campus de Cantoblanco José R. Castón Department of Structure of Macromolecules, Centro Nacional Biotecnología (CNB-CSIC), Campus de Cantoblanco Hideki Kondo Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Capsidless yadokariviruses (members of the order Yadokarivirales) with (+)RNA genomes divert the capsid of their partner icosahedral double-stranded RNA (dsRNA) viruses in different families of the order Ghabrivirales into the replication site. A yadokarivirus, AfSV2, has been reported from a German strain of the ascomycete fungus Aspergillus foetidus coinfected by two dsRNA viruses, a victorivirus (AfSV1, family Pseudototiviridae) and an alternavirus (AfFV, family Alternaviridae). Here, we identified AfSV1 as the partner of AfSV2 in a Japanese A. foetidus strain after showing the infectiousness of AfSV2 in three forms: virus particles (heterocapsid), transforming full-length complementary DNA (cDNA), and purified replicated form (RF) dsRNA that is believed to be inactive as a translational template. Virion transfection of virus-free A. foetidus protoplasts resulted in the generation of two strains infected either by AfSV1 alone or by both AfSV1 and AfSV2. Transformants with AfSV2 full-length cDNA launched AfSV2 infection only in the presence of AfSV1, but not those with AfSV2 RNA-directed RNA polymerase mutant cDNA. The purified fractions containing AfSV2 RF dsRNA also launched infection when transfected into protoplasts infected by AfSV1. Treatment with dsRNA-specific RNase III, but not with proteinase K, S1 nuclease, or DNase I, abolished the infectivity of AfSV2 RF dsRNA. Furthermore, we confirmed the infectiousness of gel-purified AfSV2 RF dsRNA in the presence of AfSV1. Taken together, our results show the unique infectious entity of AfSV2 and the expansion of yadokarivirus partners in the family Pseudototiviridae and provide interesting evolutionary insights. No potential conflict of interest relevant to this article was reported.

American Society for Microbiology Acta Medica Okayama 2379-5042 9 8 2024 New lineages of RNA viruses from clinical isolates of Rhizopus microsporus revealed by fragmented and primer-ligated dsRNA sequencing (FLDS) analysis EN Wasiatus Sa'diyah Institute of Plant Science and Resources, Okayama University Yan-Jie Zhao Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology (Donated by IFO), University of Tsukuba Yuto Chiba Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology (Donated by IFO), University of Tsukuba Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Sayaka Ban Medical Mycology Research Center, Chiba University Takashi Yaguchi Medical Mycology Research Center, Chiba University Syun-Ichi Urayama Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology (Donated by IFO), University of Tsukuba Daisuke Hagiwara Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology (Donated by IFO), University of Tsukuba Rhizopus microsporus is a species in the order Mucorales that is known to cause mucormycosis, but it is poorly understood as a host of viruses. Here, we examined 25 clinical strains of R. microsporus for viral infection with a conventional double-stranded RNA (dsRNA) assay using agarose gel electrophoresis (AGE) and the recently established fragmented and primer-ligated dsRNA sequencing (FLDS) protocol. By AGE, five virus-infected strains were detected. Then, full-length genomic sequences of 12 novel RNA viruses were revealed by FLDS, which were related to the families Mitoviridae, Narnaviridae, and Endornaviridae, ill-defined groups of single-stranded RNA (ssRNA) viruses with similarity to the established families Virgaviridae and Phasmaviridae, and the proposed family "Ambiguiviridae." All the characterized viruses, except a potential phasmavirid with a negative-sense RNA genome, had positive-sense RNA genomes. One virus belonged to a previously established species within the family Mitoviridae, whereas the other 11 viruses represented new species or even new genera. These results show that the fungal pathogen R. microsporus harbors diverse RNA viruses and extend our understanding of the diversity of RNA viruses in the fungal order Mucorales, division Mucoromycota. Identifying RNA viruses from clinical isolates of R. microsporus may expand the repertoire of natural therapeutic agents for mucormycosis in the future. No potential conflict of interest relevant to this article was reported.

National Academy of Sciences Acta Medica Okayama 0027-8424 121 25 2024 Argonaute-independent, Dicer-dependent antiviral defense against RNA viruses e2322765121 EN Yukiyo Sato Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Antiviral RNA interference (RNAi) is conserved from yeasts to mammals. Dicer recognizes and cleaves virus-derived double-stranded RNA (dsRNA) and/or structured single-stranded RNA (ssRNA) into small-interfering RNAs, which guide effector Argonaute to homologous viral RNAs for digestion and inhibit virus replication. Thus, Argonaute is believed to be essential for antiviral RNAi. Here, we show Argonaute-independent, Dicer-dependent antiviral defense against dsRNA viruses using Cryphonectria parasitica (chestnut blight fungus), which is a model filamentous ascomycetous fungus and hosts a variety of viruses. The fungus has two dicer-like genes (dcl1 and dcl2) and four argonaute-like genes (agl1 to agl4). We prepared a suite of single to quadruple agl knockout mutants with or without dcl disruption. We tested these mutants for antiviral activities against diverse dsRNA viruses and ssRNA viruses. Although both DCL2 and AGL2 worked as antiviral players against some RNA viruses, DCL2 without argonaute was sufficient to block the replication of other RNA viruses. Overall, these results indicate the existence of a Dicer-alone defense and different degrees of susceptibility to it among RNA viruses. We discuss what determines the great difference in susceptibility to the Dicer-only defense. No potential conflict of interest relevant to this article was reported.

National Academy of Sciences Acta Medica Okayama 0027-8424 121 25 2024 Replication of single viruses across the kingdoms, Fungi, Plantae, and Animalia e2318150121 EN Paul Telengech Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Kiwamu Hyodo Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Hiroaki Ichikawa Institute of Agrobiological Sciences, National Agriculture and Food Research Organization Ryusei Kuwata Faculty of Veterinary Medicine, Okayama University of Science Hideki Kondo Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University It is extremely rare that a single virus crosses host barriers across multiple kingdoms. Based on phylogenetic and paleovirological analyses, it has previously been hypothesized that single members of the family Partitiviridae could cross multiple kingdoms. Partitiviridae accommodates members characterized by their simple bisegmented double-stranded RNA genome; asymptomatic infections of host organisms; the absence of an extracellular route for entry in nature; and collectively broad host range. Herein, we show the replicability of single fungal partitiviruses in three kingdoms of host organisms: Fungi, Plantae, and Animalia. Betapartitiviruses of the phytopathogenic fungusRosellinia necatrix could replicate in protoplasts of the carrot (Daucus carota), Nicotiana benthamiana and Nicotiana tabacum, in some cases reaching a level detectable by agarose gel electrophoresis. Moreover, betapartitiviruses showed more robust replication than the tested alphapartitiviruses. One of the fungal betapartitiviruses, RnPV18, could persistently and stably infect carrot plants regenerated from virion-transfected protoplasts. Both alpha- and betapartitiviruses, although with different host preference, could replicate in two insect cell lines derived from the fall armyworm Spodoptera frugiperda and the fruit fly Drosophila melanogaster. Our results indicate the replicability of single partitiviruses in members of three kingdoms and provide insights into virus adaptation, host jumping, and evolution. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0304-8608 167 12 2022 Identification of novel totiviruses from the ascomycetous fungus Geotrichum candidum 2833 2838 EN Haris Ahmed Khan Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Sabitree Shahi Institute of Plant Science and Resources (IPSR), Okayama University Muhammad Faraz Bhatti Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Mycoviruses are widely distributed across the kingdom Fungi, including ascomycetous yeast strains of the class Saccharomycetes. Geotrichum candidum is an important fungal pathogen belonging to Saccharomycetes and has a diverse host range. Here, we report the characterization of four new classical totiviruses from two distinct Geotrichum candidum strains from Pakistan. The four identified viruses were tentatively named “Geotrichum candidum totivirus 1, 2, 3a, and 3b” (GcTV1-3b). The complete dsRNA genomes of the identified totiviruses are 4621, 4592, 4576, and 4576 bp in length, respectively. All totivirus genomes have two open reading frames, encoding a capsid protein (CP) and an RNA-dependent RNA polymerase (RdRP), respectively. The downstream RdRP domain is assumed to be expressed as a CP-RdRP fusion product via -1 frameshifting mediated by a heptameric slippery site. Sequence comparisons and phylogenetic analysis showed that each of the discovered viruses belongs to a new species of the genus Totivirus in the family Totiviridae, with GcTV1 and GcTV3 (a and b strains) clustering in one subgroup and GcTV2 in another subgroup. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4409 11 22 2022 Natural Cross-Kingdom Spread of Apple Scar Skin Viroid from Apple Trees to Fungi 3686 EN Mengyuan Tian State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University Shuang Wei State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University Ruiling Bian State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University Jingxian Luo State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University Haris Ahmed Khan State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University Huanhuan Tai College of Agronomy, Northwest A&F University Hideki Kondo Institute of Plant Science and Resources, Okayama University Ahmed Hadidi U.S. Department of Agriculture, Agricultural Research Service Ida Bagus Andika College of Plant Health and Medicine, Qingdao Agricultural University Liying Sun Institute of Plant Science and Resources, Okayama University Viroids are the smallest known infectious agents that are thought to only infect plants. Here, we reveal that several species of plant pathogenic fungi that were isolated from apple trees infected with apple scar skin viroid (ASSVd) carried ASSVd naturally. This finding indicates the spread of viroids to fungi under natural conditions and further suggests the possible existence of mycoviroids in nature. A total of 117 fungal isolates were isolated from ASSVd-infected apple trees, with the majority (85.5%) being an ascomycete Alternaria alternata and the remaining isolates being other plant-pathogenic or -endophytic fungi. Out of the examined samples, viroids were detected in 81 isolates (69.2%) including A. alternata as well as other fungal species. The phenotypic comparison of ASSVd-free specimens developed by single-spore isolation and ASSVd-infected fungal isogenic lines showed that ASSVd affected the growth and pathogenicity of certain fungal species. ASSVd confers hypovirulence on ascomycete Epicoccum nigrum. The mycobiome analysis of apple tree-associated fungi showed that ASSVd infection did not generally affect the diversity and structure of fungal communities but specifically increased the abundance of Alternaria species. Taken together, these data reveal the occurrence of the natural spread of viroids to plants; additionally, as an integral component of the ecosystem, viroids may affect the abundance of certain fungal species in plants. Moreover, this study provides further evidence that viroid infection could induce symptoms in certain filamentous fungi. No potential conflict of interest relevant to this article was reported.

American Society for Microbiology Acta Medica Okayama 2150-7511 2022 Three-Layered Complex Interactions among Capsidless (+)ssRNA Yadokariviruses, dsRNA Viruses, and a Fungus EN Yukiyo Sato Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Sakae Hisano Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Carlos Jose Lopez-Herrera Instituto de Agricultura Sostenible C.S.I.C., Alameda del Obispo Hideki Kondo Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University We have previously discovered a virus neo-lifestyle exhibited by a capsidless positive-sense (+), single-stranded (ss) RNA virus YkV1 (family Yadokariviridae) and an unrelated double-stranded (ds) RNA virus YnV1 (proposed family "Yadonushiviridae") in a phytopathogenic ascomycete, Rosellinia necatrix. YkV1 has been proposed to replicate in the capsid provided by YnV1 as if it were a dsRNA virus and enhance YnV1 replication in return. Recently, viruses related to YkV1 (yadokariviruses) have been isolated from diverse ascomycetous fungi. However, it remains obscure whether such viruses generally show the YkV1-like lifestyle. Here, we identified partner viruses for three distinct yadokariviruses, YkV3, YkV4a, and YkV4b, isolated from R. necatrix that were coinfected with multiple dsRNA viruses phylogenetically distantly related to YnV1. We first established transformants of R. necatrix carrying single yadokarivirus cDNAs and fused them with infectants by single partner candidate dsRNA viruses. Consequently, YkV3 and YkV4s replicated only in the presence of RnMBV3 (family Megabirnaviridae) and RnMTV1 (proposed family "Megatotiviridae"), respectively. The partners were mutually interchangeable between the two YkV4 strains and three RnMTV1 strains but not between other combinations involving YkV1 or YkV3. In contrast to YkV1 enhancing YnV1 accumulation, YkV4s reduced RnMTV1 accumulation to different degrees according to strains. Interestingly, YkV4 rescued the host R. necatrix from impaired growth induced by RnMTV1. YkV3 exerted no apparent effect on its partner (RnMBV3) or host fungus. Overall, we revealed that while yadokariviruses generally require partner dsRNA viruses for replication, each yadokarivirus partners with a different dsRNA virus species in the three diverse families and shows a distinct symbiotic relation in a fungus. IMPORTANCE A capsidless (+)ssRNA virus YkV1 (family Yadokariviridae) highjacks the capsid of an unrelated dsRNA virus YnV1 (proposed family "Yadonushiviridae") in a phytopathogenic ascomycete, while YkV1 trans-enhances YnV1 replication. Herein, we identified the dsRNA virus partners of three yadokariviruses (YkV3, YkV4a, and YkV4b) with genome organization different from YkV1 as being different from YnV1 at the suborder level. Their partners were mutually interchangeable between the two YkV4 strains and three strains of the partner virus RnMTV1 (proposed family "Megatotiviridae") but not between other combinations involving YkV1 or YkV3. Unlike YkV1, YkV4s reduced RnMTV1 accumulation and rescued the host fungus from impaired growth induced by RnMTV1. YkV3 exerted no apparent effect on its partner (RnMBV3, family Megabirnaviridae) or host fungus. These revealed that while each yadokarivirus has a species-specific partnership with a dsRNA virus, yadokariviruses collectively partner extremely diverse dsRNA viruses and show three-layered complex mutualistic/antagonistic interactions in a fungus. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1999-4915 14 8 2022 A Transfectable Fusagravirus from a Japanese Strain of Cryphonectria carpinicola with Spherical Particles 1722 EN Subha Das Institute of Plant Science and Resources, Okayama University Sakae Hisano Institute of Plant Science and Resources, Okayama University Ana Eusebio-Cope Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University A novel dsRNA virus (Cryphonectria carpinicola fusagravirus 1, CcFGV1), isolated from a Japanese strain (JS13) of Cryphonectria carpinicola, was thoroughly characterized. The biological comparison of a set of isogenic CcFGV1-infected and -free (JS13VF) strains indicated asymptomatic infection by CcFGV1. The sequence analysis showed that the virus has a two open reading frame (ORF) genome of 9.6 kbp with the RNA-directed RNA polymerase domain encoded by ORF2. The N-terminal sequencing and peptide mass fingerprinting showed an N-terminally processed or degraded product (150 kDa) of the 5'-proximal ORF1-encoded protein (1462 amino acids) to make up the CcFGV1 spherical particles of similar to 40 nm in diameter. Interestingly, a portion of CcFGV1 dsRNA co-fractionated with a host protein of 70 kDa. The purified CcFGV1 particles were used to transfect protoplasts of JS13VF as well as the standard strain of an experimental model filamentous fungal host Cryphonectria parasitica. CcFGV1 was confirmed to be associated with asymptomatic infection of both fungi. RNA silencing was shown to target the virus in C. parasitica, resulting in reduced CcFGV1 accumulation by comparing the CcFGV1 content between RNA silencing-competent and -deficient strains. These results indicate the transfectability of spherical particles of a fusagravirus associated with asymptomatic infection. No potential conflict of interest relevant to this article was reported.

FRONTIERS MEDIA SA Acta Medica Okayama 2235-2988 12 2022 Mycovirus Hunting Revealed the Presence of Diverse Viruses in a Single Isolate of the Phytopathogenic Fungus Diplodia seriata From Pakistan 913619 EN Haris Ahmed Khan Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Paul Telengech Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Muhammad Faraz Bhatti Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Diplodia seriata in the family Botryosphaeriaceae is a cosmopolitan phytopathogenic fungus and is responsible for causing cankers, fruit rot and leaf spots on economically important plants. In this study, we characterized the virome of a single Pakistani strain (L3) of D. seriata. Several viral-like contig sequences were obtained via a previously conducted next-generation sequencing analysis. Multiple infection of the L3 strain by eight RNA mycoviruses was confirmed through RT-PCR using total RNA samples extracted from this strain; the entire genomes were determined via Sanger sequencing of RT-PCR and RACE clones. A BLAST search and phylogenetic analyses indicated that these eight mycoviruses belong to seven different viral families. Four identified mycoviruses belong to double-stranded RNA viral families, including Polymycoviridae, Chrysoviridae, Totiviridae and Partitiviridae, and the remaining four identified mycoviruses belong to single-stranded RNA viral families, i.e., Botourmiaviridae, and two previously proposed families "Ambiguiviridae" and "Splipalmiviridae". Of the eight, five mycoviruses appear to represent new virus species. A morphological comparison of L3 and partially cured strain L3ht1 suggested that one or more of the three viruses belonging to Polymycoviridae, "Splipalmiviridae" and "Ambiguiviridae" are involved in the irregular colony phenotype of L3. To our knowledge, this is the first report of diverse virome characterization from D. seriata. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0168-1702 307 2 2022 A new tetra-segmented splipalmivirus with divided RdRP domains from Cryphonectria naterciae, a fungus found on chestnut and cork oak trees in Europe 198606 EN Yukiyo Sato Institute of Plant Science and Resources, Okayama University Sabitree Shahi Institute of Plant Science and Resources, Okayama University Paul Telengech Institute of Plant Science and Resources, Okayama University Sakae Hisano Institute of Plant Science and Resources, Okayama University Carolina Cornejo Swiss Federal Research Institute WSL, Forest Health & Biotic Interactions Daniel Rigling Swiss Federal Research Institute WSL, Forest Health & Biotic Interactions Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Positive-sense (+), single-stranded (ss) RNA viruses with divided RNA-dependent RNA polymerase (RdRP) domains have been reported from diverse filamentous ascomycetes since 2020. These viruses are termed splipalmiviruses or polynarnaviruses and have been characterized largely at the sequence level, but ill-defined biologically. Cryphonectria naterciae, from which only one virus has been reported, is an ascomycetous fungus potentially plant-pathogenic to chestnut and oak trees. We molecularly characterized multiple viruses in a single Portuguese isolate (C0614) of C. naterciae, taking a metatranscriptomic and conventional double-stranded RNA approach. Among them are a novel splipalmivirus (Cryphonectria naterciae splipalmivirus 1, CnSpV1) and a novel fusagravirus (Cryphonectria naterciae fusagravirus 1, CnFGV1). This study focused on the former virus. CnSpV1 has a tetra-segmented, (+)ssRNA genome (RNA1 to RNA4). As observed for other splipalmiviruses reported in 2020 and 2021, the RdRP domain is separately encoded by RNA1 (motifs F, A and B) and RNA2 (motifs C and D). A hypothetical protein encoded by the 5′-proximal open reading frame of RNA3 shows similarity to a counterpart conserved in some splipalmiviruses. The other RNA3-encoded protein and RNA4-encoded protein show no similarity with known proteins in a blastp search. The tetra-segment nature was confirmed by the conserved terminal sequences of the four CnSpV1 segments (RNA1 to RNA4) and their 100% coexistence in over 100 single conidial isolates tested. The experimental introduction of CnSpV1 along with CnFGV1 into a virus free strain C0754 of C. naterciae vegetatively incompatible with C0614 resulted in no phenotypic alteration, suggesting asymptomatic infection. The protoplast fusion assay indicates a considerably narrow host range of CnSpV1, restricted to the species C. naterciae and C. carpinicola. This study contributes to better understanding of the molecular and biological properties of this unique group of viruses. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0304-8608 167 4 2022 A novel deltapartitivirus from red clover 1201 1204 EN Paul Telengech Institute of Plant Science and Resources, Okayama University Sabitree Shahi Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University The family Partitiviridae has five genera, among which is the genus Deltapartitivirus. We report here the complete genome sequence of a deltapartitivirus from red clover, termed “red clover cryptic virus 3” (RCCV3). RCCV3 has a bisegmented double-stranded (ds) RNA genome. dsRNA1 and dsRNA2 are 1580 and 1589 nucleotides (nt) in length and are predicted to encode an RNA-directed RNA polymerase (RdRP) and a capsid protein (CP), respectively. The RCCV3 RdRP shares the highest sequence identity with the RdRP of a previously reported deltapartitivirus, Medicago sativa deltapartitivirus 1 (MsDPV1) (76.5%), while the RCCV3 CP shows 50% sequence identity to the CP of MsDPV1. RdRP- and CP-based phylogenetic trees place RCCV3 into a clade of deltapartitiviruses. The sequence and phylogenetic analyses clearly indicate that RCCV3 represents a new species in the genus Deltapartitivirus. RCCV3 was detectable in all three tested cultivars of red clover. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0304-8608 167 2022 A novel victorivirus from the phytopathogenic fungus Neofusicoccum parvum 923 929 EN Haris Ahmed Khan Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Yukiyo Sato Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Atif Jamal Crop Diseases Research Institute, National Agricultural Research Centre Muhammad Faraz Bhatti Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Neofusicoccum parvum is an important plant-pathogenic ascomycetous fungus that causes trunk diseases in a variety of plants. A limited number of reports on mycoviruses from this fungus are available. Here, we report the characterization of a novel victorivirus, Neofusicoccum parvum victorivirus 3 (NpVV3). An agarose gel dsRNA profile of a Pakistani strain of N. parvum, NFN, showed a band of similar to 5 kbp that was not detectable in Japanese strains of N. parvum. Taking a high-throughput and Sanger sequencing approach, the complete genome sequence of NpVV3 was determined to be 5226 bp in length with two open reading frames (ORF1 and ORF2) that encode a capsid protein (CP) and an RNA-dependent RNA polymerase (RdRP). The RdRP appears to be translated by a stop/restart mechanism facilitated by the junction sequence AUGucUGA, as is found in some other victoriviruses. BLASTp searches showed that NpVV3 CP and RdRP share the highest amino acid sequence identity (80.5% and 72.4%, respectively) with the corresponding proteins of NpVV1 isolated from a French strain of N. parvum. However, NpVV3 was found to be different from NpVV1 in its terminal sequences and the stop/restart facilitator sequence. NpVV3 particles similar to 35 nm in diameter were partially purified and used to infect an antiviral-RNA-silencing-deficient strain (Delta cl2) of an experimental ascomycetous fungal host, Cryphonectria parasitica. NpVV3 showed symptomless infection in the new host strain. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1345-2630 88 2 2022 Plant viruses and viroids in Japan 105 127 EN Shin-ichi Fuji Faculty of Bioresource Sciences, Akita Prefectural University Tomofumi Mochizuki Graduate School of Life and Environmental Sciences, Osaka Prefecture University Mitsuru Okuda Office of the President, National Agriculture and Food Research Organization (NARO) Shinya Tsuda Department of Clinical Plant Science, Faculty of Bioscience and Applied Chemistry Satoshi Kagiwada Department of Clinical Plant Science, Faculty of Bioscience and Applied Chemistry, Hosei University Ken-Taro Sekine Faculty of Agriculture, University of the Ryukyus Masashi Ugaki Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo Keiko T. Natsuaki Tokyo University of Agriculture Masamichi Isogai Faculty of Agriculture, Iwate University Tetsuo Maoka Institute for Plant Protection, National Agriculture and Food Research Organization (NIPP, NARO) Minoru Takeshita Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazak Nobuyuki Yoshikawa Agri-Innovation Center, Iwate University Kazuyuki Mise Graduate School of Agriculture, Kyoto University Takahide Sasaya 3 Department of Research Promotion, Institute for Plant Protection, National Agriculture and Food Research Organization (NIPP, NARO) Hideki Kondo Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University Kenji Kubota Division of Core Technology for Pest Control Research, Institute for Plant Protection, National Agriculture and Food Research Organization (NIPP, NARO) Yasuyuki Yamaji Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo Toru Iwanami Faculty of Agriculture, Tokyo University of Agriculture Kazusato Ohshima Department of Biological Resource Science, Faculty of Agriculture, Saga University Kappei Kobayashi Faculty of Agriculture, Ehime University Tatsuji Hataya Research Faculty of Agriculture, Hokkaido University Teruo Sano Hirosaki University Nobuhiro Suzuki Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological innovation. Herein, the official changes of virus taxonomy, including the establishment of megataxonomy and amendments of the codes of virus classification and nomenclature, recently made by the International Committee on Taxonomy of Viruses were summarized. The continued efforts of the plant virology community of Japan to index all plant viruses and viroids occurring in Japan, which represent 407 viruses, including 303 virus species and 104 unclassified viruses, and 25 viroids, including 20 species and 5 unclassified viroids, as of October 2021, were also introduced. These viruses and viroids are collectively classified into 81 genera within 26 families of 3 kingdoms (Shotokuvirae, Orthornavirae, Pararnavirae) across 2 realms (Monodnaviria and Riboviria). This review also overviewed how Japan’s plant virus/viroid studies have contributed to advance virus/viroid taxonomy. No potential conflict of interest relevant to this article was reported.

Frontiers Media SA Acta Medica Okayama 1664-302X 12 2021 Identification of a Novel Quinvirus in the Family Betaflexiviridae That Infects Winter Wheat 715545 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Naoto Yoshida Agricultural Research Institute, HOKUREN Federation of Agricultural Cooperatives Miki Fujita Institute of Plant Science and Resources (IPSR), Okayama University Kazuyuki Maruyama Institute of Plant Science and Resources (IPSR), Okayama University Kiwamu Hyodo Institute of Plant Science and Resources (IPSR), Okayama University Hiroshi Hisano Institute of Plant Science and Resources (IPSR), Okayama University Tetsuo Tamada Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika College of Plant Health and Medicine, Qingdao Agricultural University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Yellow mosaic disease in winter wheat is usually attributed to the infection by bymoviruses or furoviruses; however, there is still limited information on whether other viral agents are also associated with this disease. To investigate the wheat viromes associated with yellow mosaic disease, we carried out de novo RNA sequencing (RNA-seq) analyses of symptomatic and asymptomatic wheat-leaf samples obtained from a field in Hokkaido, Japan, in 2018 and 2019. The analyses revealed the infection by a novel betaflexivirus, which tentatively named wheat virus Q (WVQ), together with wheat yellow mosaic virus (WYMV, a bymovirus) and northern cereal mosaic virus (a cytorhabdovirus). Basic local alignment search tool (BLAST) analyses showed that the WVQ strains (of which there are at least three) were related to the members of the genus Foveavirus in the subfamily Quinvirinae (family Betaflexiviridae). In the phylogenetic tree, they form a clade distant from that of the foveaviruses, suggesting that WVQ is a member of a novel genus in the Quinvirinae. Laboratory tests confirmed that WVQ, like WYMV, is potentially transmitted through the soil to wheat plants. WVQ was also found to infect rye plants grown in the same field. Moreover, WVQ-derived small interfering RNAs accumulated in the infected wheat plants, indicating that WVQ infection induces antiviral RNA silencing responses. Given its common coexistence with WYMV, the impact of WVQ infection on yellow mosaic disease in the field warrants detailed investigation. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0304-8608 166 2021 A second capsidless hadakavirus strain with 10 positive-sense single-stranded RNA genomic segments from Fusarium nygamai 2711 2722 EN Haris Ahmed Khan Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Yukiyo Sato Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Atif Jamal Crop Diseases Research Institute, National Agricultural Research Centre Muhammad Faraz Bhatti Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University A unique capsidless virus with a positive-sense, single-stranded RNA genome (hadakavirus 1, HadV1), a member of the extended picorna-like supergroup, was isolated previously from the phytopathogenic fungus Fusarium oxysporum. Here, we describe the molecular and biological characterisation of a second hadakavirus strain from Fusarium nygamai, which has not been investigated in detail previously as a virus host. This virus, hadakavirus 1 strain 1NL (HadV1-1NL), has features similar to the first hadakavirus, HadV1-7n, despite having a different number of segments (10 for HadV1-1NL vs. 11 for HadV1-7n). The 10 genomic RNA segments of HadV1-1NL range in size from 0.9 kb to 2.5 kb. All HadV1-1NL segments show 67% to 86% local nucleotide sequence identity to their HadV1-7n counterparts, whereas HadV1-1NL has no homolog of HadV1-7n RNA8, which encodes a zinc-finger motif. Another interesting feature is the possible coding incapability of HadV1-1NL RNA10. HadV1-1NL was predicted to be capsidless based on the RNase A susceptibility of its replicative form dsRNA. Phenotypic comparison of multiple virus-infected and virus-free single-spore isolates indicated asymptomatic infection by HadV1-1NL. Less-efficient vertical transmission via spores was observed as the infected fungal colonies from which the spores were derived became older, as was observed for HadV1-7n. This study shows a second example of a hadakavirus that appears to have unusual features. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2079-7737 10 2 2021 Identification of an RNA Silencing Suppressor Encoded by a Symptomless Fungal Hypovirus, Cryphonectria Hypovirus 4 100 EN Annisa Aulia Institute of Plant Science and Resources (IPSR), Okayama University Kiwamu Hyodo Institute of Plant Science and Resources (IPSR), Okayama University Sakae Hisano Institute of Plant Science and Resources (IPSR), Okayama University Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Bradley I. Hillman Plant Biology and Pathology, Rutgers University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Previously, we have reported the ability of a symptomless hypovirus Cryphonectria hypovirus 4 (CHV4) of the chestnut blight fungus to facilitate stable infection by a co-infecting mycoreovirus 2 (MyRV2)—likely through the inhibitory effect of CHV4 on RNA silencing (Aulia et al., Virology, 2019). In this study, the N-terminal portion of the CHV4 polyprotein, termed p24, is identified as an autocatalytic protease capable of suppressing host antiviral RNA silencing. Using a bacterial expression system, CHV4 p24 is shown to cleave autocatalytically at the di-glycine peptide (Gly214-Gly215) of the polyprotein through its protease activity. Transgenic expression of CHV4 p24 in Cryphonectria parasitica suppresses the induction of one of the key genes of the antiviral RNA silencing, dicer-like 2, and stabilizes the infection of RNA silencing-susceptible virus MyRV2. This study shows functional similarity between CHV4 p24 and its homolog p29, encoded by the symptomatic prototype hypovirus CHV1. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 0042-6822 554 2021 Cryphonectria nitschkei chrysovirus 1 with unique molecular features and a very narrow host range 55 62 EN Sabitree Shahi Institute of Plant Science and Resources, Okayama University Sotaro Chiba Graduate School of Bioagricultural Sciences, Nagoya University Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Cryphonectria nitschkei chrysovirus 1 (CnCV1), was described earlier from an ascomycetous fungus, Cryphonectria nitschkei strain OB5/11, collected in Japan; its partial sequence was reported a decade ago. Complete sequencing of the four genomic dsRNA segments revealed molecular features similar to but distinct from previously reported members of the family Chrysoviridae. Unique features include the presence of a mini-cistron preceding the major large open reading frame in each genomic segment. Common features include the presence of CAA repeats in the 5′-untranslated regions and conserved terminal sequences. CnCV1-OB5/11 could be laterally transferred to C. nitschkei and its relatives C. radicalis and C. naterciae via coculturing, virion transfection and protoplast fusion, but not to fungal species other than the three species mentioned above, even within the genus Cryphonectria, suggesting a very narrow host range. Phenotypic comparison of a few sets of CnCV1-infected and -free isogenic strains showed symptomless infection in new hosts. No potential conflict of interest relevant to this article was reported.

Nature Research Acta Medica Okayama 2041-1723 11 1 2020 Establishment of Neurospora crassa as a model organism for fungal virology 5627 EN Shinji Honda Faculty of Medical Sciences, University of Fukui Ana Eusebio-Cope Institute of Plant Science and Resources, Okayama University Shuhei Miyashita Graduate School of Agricultural Science, Tohoku University Ayumi Yokoyama Faculty of Medical Sciences, University of Fukui Annisa Aulia Institute of Plant Science and Resources, Okayama University Sabitree Shahi Institute of Plant Science and Resources, Okayama University Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University The filamentous fungus Neurospora crassa is used as a model organism for genetics, developmental biology and molecular biology. Remarkably, it is not known to host or to be susceptible to infection with any viruses. Here, we identify diverse RNA viruses in N. crassa and other Neurospora species, and show that N. crassa supports the replication of these viruses as well as some viruses from other fungi. Several encapsidated double-stranded RNA viruses and capsid-less positive-sense single-stranded RNA viruses can be experimentally introduced into N. crassa protoplasts or spheroplasts. This allowed us to examine viral replication and RNAi-mediated antiviral responses in this organism. We show that viral infection upregulates the transcription of RNAi components, and that Dicer proteins (DCL-1, DCL-2) and an Argonaute (QDE-2) participate in suppression of viral replication. Our study thus establishes N. crassa as a model system for the study of host-virus interactions. The fungus Neurospora crassa is a model organism for the study of various biological processes, but it is not known to be infected by any viruses. Here, Honda et al. identify RNA viruses that infect N. crassa and examine viral replication and RNAi-mediated antiviral responses, thus establishing this fungus as a model for the study of host-virus interactions. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-302X 11 2020 Molecular Characterization of a Novel Polymycovirus From Penicillium janthinellum With a Focus on Its Genome-Associated PASrp 592789 EN Yukiyo Sato Institute of Plant Science and Resources, Okayama University Atif Jamal Crop Diseases Research Institute, National Agricultural Research Centre Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University The genus Polymycovirus of the family Polymycoviridae accommodates fungal RNA viruses with different genomic segment numbers (four, five, or eight). It is suggested that four members form no true capsids and one forms filamentous virus particles enclosing double-stranded RNA (dsRNA). In both cases, viral dsRNA is associated with a viral protein termed "proline-alanine-serine-rich protein" (PASrp). These forms are assumed to be the infectious entity. However, the detailed molecular characteristics of PASrps remain unclear. Here, we identified a novel five-segmented polymycovirus, Penicillium janthinellum polymycovirus 1 (PjPmV1), and characterized its purified fraction form in detail. The PjPmV1 had five dsRNA segments associated with PASrp. Density gradient ultracentrifugation of the PASrp-associated PjPmV1 dsRNA revealed its uneven structure and a broad fractionation profile distinct from that of typical encapsidated viruses. Moreover, PjPmV1-PASrp interacted in vitro with various nucleic acids in a sequence-non-specific manner. These PjPmV1 features are discussed in view of the diversification of genomic segment numbers of the genus Polymycovirus. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 0168-8162 30 1-3 2003 Orchid Fleck Virus: Brevipalpus californicus Mite Transmission, Biological Properties and Genome Structure 215 223 EN Hideki Kondo Research Institute for Bioresources, Okayama University Takanori Maeda Research Institute for Bioresources, Okayama University Tetsuo Tamada Research Institute for Bioresources, Okayama University Orchid fleck virus (OFV) causes necrotic or chlorotic ring spots and fleck symptoms in many orchid species world-wide. The virus has non-enveloped, bacilliform particles of about 40 nm × 100–150 nm and is sap-transmissible to several plant species. OFV is transmitted by the mite Brevipalpus californicus (Banks) in a persistent manner and efficiently transmitted by both adults and nymphs, but not by larvae. Viruliferous mites retain their infectivity for 3 weeks on a virus-immune host. The genome of OFV consists of two molecules of 6431 (RNA1) and 6001 nucleotides (RNA2). The RNAs have conserved and complementary terminal sequences. RNA1 contains five open reading frames (ORF), and RNA2 encodes a single ORF. Although some of the encoded proteins of OFV have sequences similar to those of proteins of plant rhabdoviruses, OFV differs from viruses in the family Rhabdoviridae in having a bipartite genome. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 0304-8608 154 1 2008 Identification and characterization of structural proteins of orchid fleck virus 37 45 EN Hideki Kondo Research Institute for Bioresources, Okayama University Takanori Maeda College of Bioresource Sciences, Nihon University Tetsuo Tamada Research Institute for Bioresources, Okayama University Orchid fleck virus (OFV) has a bipartite negative-sense RNA genome with sequence similarities to plant rhabdoviruses. The non-enveloped bullet-shaped particles of OFV are similar to those of the internal ribonucleoprotein (RNP)-M protein structure of rhabdoviruses, but they are about half the size of typical plant rhabdoviruses. Purified preparations contained intact bullet-shaped and filamentous particles. The filamentous particles showed a tightly coiled coil structure or a coiled structure with a helical twist, which resembles the RNP complex of rhabdoviruses. OFV bullet-shaped particles were structurally stable in solutions containing 2% Triton X-100 and 0.8 M NaCl. Western blot analyses revealed that the bullet-shaped particles contained N, P and M proteins, while filamentous particles contained mainly N and P proteins. In addition, a small amount of the L protein was detected in both types of particles. Thus, the structural proteins of OFV have properties similar to those of rhabdoviruses, except that the particles are non-enveloped and are relatively resistant to detergent-treatment under high-salt conditions. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0032-0862 70 1 2020 Pathogenetic roles of beet necrotic yellow vein virus RNA5 in the exacerbation of symptoms and yield reduction, development of scab‐like symptoms, and Rz1‐resistance breaking in sugar beet 219 232 EN Tetsuo Tamada Institute of Plant Science and Resources (IPSR), Okayama University Hirokatsu Uchino Research Center, Nippon Beet Sugar Mfg. Co., Ltd. Toshimi Kusume Hokkaido Central Agricultural Experiment Station Minako Iketani‐Saito Hokkaido Central Agricultural Experiment Station Sotaro Chiba Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika Institute of Plant Science and Resources (IPSR), Okayama University Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Beet necrotic yellow vein virus (BNYVV) generally has a four‐segmented positive‐sense RNA genome (RNAs 1–4), but some European and most Asian strains have an additional segment, RNA5. This study examined the effect of RNA5 and RNA3 on different sugar beet cultivars using a Polymyxa‐mediated inoculation system under field and laboratory conditions. In field tests, the degree of sugar yield served as an index for assessing the virulence of BNYVV strains. Japanese A‐II type isolates without RNA5 caused mostly 15%–90% sugar yield reductions, depending on the susceptibility of sugar beet cultivars, whereas the isolates with RNA5 induced more than 90% yield losses in the seven susceptible cultivars, but small yield losses in one Rz1‐resistant and Rizor cultivars. However, a laboratory‐produced isolate containing RNA5 but lacking RNA3 caused higher yield losses in Rizor than in susceptible plants, and induced scab‐like symptoms on the root surface of both susceptible and resistant plants. In laboratory tests, A‐II type isolates without RNA5 had low viral RNA accumulation levels in roots of Rizor and Rz1‐resistant plants at early stages of infection, but in the presence of RNA5, viral RNA3 accumulation levels increased remarkably. This increased RNA3 accumulation was not observed in roots of the WB42 accession with the Rz2 gene. In contrast, the presence of RNA3 did not affect RNA5 accumulation levels. Collectively, this study demonstrated that RNA5 is involved in the development of scab‐like symptoms and the enhancement of RNA3 accumulation, and suggests these characteristics of RNA5 are associated with Rz1‐resistance breaking. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 0168-1702 244 2018 A neo-virus lifestyle exhibited by a (+)ssRNA virus hosted in an unrelated dsRNA virus: Taxonomic and evolutionary considerations 75 83 EN Sakae Hisano Institute of Plant Science and Resources (IPSR), Okayama University Rui Zhang Institute of Plant Science and Resources (IPSR), Okayama University Md. Iqbal Faruk Institute of Plant Science and Resources (IPSR), Okayama University Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Recent studies illustrate that fungi as virus hosts provides a unique platform for hunting viruses and exploring virus/virus and virus/host interactions. Such studies have revealed a number of as-yet-unreported viruses and virus/virus interactions. Among them is a unique intimate relationship between a (+)ssRNA virus, yado-kari virus (YkV1) and an unrelated dsRNA virus, yado-nushi virus (YnV1). YkV1 dsRNA, a replicated form of YkV1, and RNA-dependent RNA polymerase, are trans-encapsidated by the capsid protein of YnV1. While YnV1 can complete its replication cycle, YkV1 relies on YnV1 for its viability. We previously proposed a model in which YkV1 diverts YnV1 capsids as the replication sites. YkV1 is neither satellite virus nor satellite RNA, because YkV1 appears to encode functional RdRp and enhances YnV1 accumulation. This represents a unique mutualistic virus/virus interplay and similar relations in other virus/host fungus systems are detectable. We propose to establish the family Yadokariviridae that accommodates YkV1 and recently discovered viruses phylogenetically related to YkV1. This article overviews what is known and unknown about the YkV1/YnV1 interactions. Also discussed are the YnV1 Phytoreo_S7 and YkV1 2A-like domains that may have been captured via horizontal transfer during the course of evolution and are conserved across extant diverse RNA viruses. Lastly, evolutionary scenarios are envisioned for YkV1 and YnV1. No potential conflict of interest relevant to this article was reported.

Nature Research Acta Medica Okayama 2058-5276 1 1 2016 A capsidless ssRNA virus hosted by an unrelated dsRNA virus 15001 EN Rui Zhang Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Sakae Hisano Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Akio Tani Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Hideki Kondo Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Satoko Kanematsu NARO Institute of Fruit Tree Science Nobuhiro Suzuki Agrivirology Laboratory, Institute of Plant Science and Resources, Okayama University Viruses typically encode the capsid that encases their genome, while satellite viruses do not encode a replicase and depend on a helper virus for their replication1. Here, we report interplay between two RNA viruses, yado-nushi virus 1 (YnV1) and yado-kari virus 1 (YkV1), in a phytopathogenic fungus, Rosellinia necatrix2. YkV1 has a close phylogenetic affinity to positive-sense, single-stranded (+)ssRNA viruses such as animal caliciviruses3, while YnV1 has an undivided double-stranded (ds) RNA genome with a resemblance to fungal totiviruses4. Virion transfection and infectious full-length cDNA transformation has shown that YkV1 depends on YnV1 for viability, although it probably encodes functional RNA-dependent RNA polymerase (RdRp). Immunological and molecular analyses have revealed trans-encapsidation of not only YkV1 RNA but also RdRp by the capsid protein of the other virus (YnV1), and enhancement of YnV1 accumulation by YkV1. This study demonstrates interplay in which the capsidless (+)ssRNA virus (YkV1), hijacks the capsid protein of the dsRNA virus (YnV1), and replicates as if it were a dsRNA virus. No potential conflict of interest relevant to this article was reported.

American Society for Microbiology Acta Medica Okayama 2150-7511 11 3 2020 Hadaka Virus 1: a Capsidless Eleven-Segmented Positive-Sense Single-Stranded RNA Virus from a Phytopathogenic Fungus, Fusarium oxysporum e00450-20 EN Yukiyo Sato Institute of Plant Science and Resources, Okayama University Wajeeha Shamsi Institute of Plant Science and Resources, Okayama University Atif Jamal Crop Diseases Research Institute, National Agricultural Research Centre Muhammad Faraz Bhatti Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST) Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University The search for viruses infecting fungi, or mycoviruses, has extended our knowledge about the diversity of RNA viruses, as exemplified by the discovery of polymycoviruses, a phylogenetic group of multisegmented RNA viruses with unusual forms. The genomic RNAs of known polymycoviruses, which show a phylogenetic affinity for animal positive-sense single-stranded RNA [(+)RNA] viruses such as caliciviruses, are comprised of four conserved segments with an additional zero to four segments. The double-stranded form of polymycovirus genomic RNA is assumed to be associated with a virally encoded protein (proline-alanine-serine-rich protein [PASrp]) in either of two manners: a capsidless colloidal form or a filamentous encapsidated form. Detailed molecular characterizations of polymycoviruses, however, have been conducted for only a few strains. Here, a novel polymyco-related virus named Hadaka virus 1 (HadV1), from the phytopathogenic fungus Fusarium oxysporum, was characterized. The genomic RNA of HadV1 consisted of an 11-segmented positive-sense RNA with highly conserved terminal nucleotide sequences. HadV1 shared the three conserved segments with known polymycoviruses but lacked the PASrp-encoding segment. Unlike the known polymycoviruses and encapsidated viruses, HadV1 was not pelleted by conventional ultracentrifugation, possibly due to the lack of PASrp. This result implied that HadV1 exists only as a soluble form with naked RNA. Nevertheless, the 11 genomic segments of HadV1 have been stably maintained through host subculturing and conidiation. Taken together, the results of this study revealed a virus with a potential novel virus lifestyle, carrying many genomic segments without typical capsids or PASrp-associated forms. IMPORTANCE Fungi collectively host various RNA viruses. Examples include encapsidated double-stranded RNA (dsRNA) viruses with diverse numbers of genomic segments (from 1 to 12) and capsidless viruses with nonsegmented (+)RNA genomes. Recently, viruses with unusual intermediate features of an infectious entity between encapsidated dsRNA viruses and capsidless (+)RNA viruses were found. They are called polymycoviruses, which typically have four to eight dsRNA genomic segments associated with one of the virus-encoded proteins and are phylogenetically distantly related to animal (+)RNA caliciviruses. Here, we identified a novel virus phylogenetically related to polymycoviruses, from the phytopathogenic fungus Fusarium oxysporum. The virus, termed Hadaka virus 1 (HadV1), has 11 (+)RNA genomic segments, the largest number in known (+)RNA viruses. Nevertheless, HadV1 lacked a typical structural protein of polymycoviruses and was not pelleted by standard ultracentrifugation, implying an unusual capsidless nature of HadV1. This study reveals a potential novel lifestyle of multisegmented RNA viruses. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-302X 11 2020 Diverse Partitiviruses From the Phytopathogenic Fungus,Rosellinia necatrix 1064 EN Paul Telengech Institute of Plant Science and Resources, Okayama University Sakae Hisano Institute of Plant Science and Resources, Okayama University Cyrus Mugambi Institute of Plant Science and Resources, Okayama University Kiwamu Hyodo Institute of Plant Science and Resources, Okayama University Juan Manuel Arjona-Lopez Institute of Plant Science and Resources, Okayama University Carlos Jose Lopez-Herrera Institute for Sustainable Agriculture,Spanish Research Council Satoko Kanematsu Institute of Fruit Tree Science, National Agriculture and Food Research Organization (NARO) Hideki Kondo Institute of Plant Science and Resources, Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources, Okayama University Partitiviruses (dsRNA viruses, familyPartitiviridae) are ubiquitously detected in plants and fungi. Although previous surveys suggested their omnipresence in the white root rot fungus,Rosellinia necatrix, only a few of them have been molecularly and biologically characterized thus far. We report the characterization of a total of 20 partitiviruses from 16R. necatrixstrains belonging to 15 new species, for which "Rosellinia necatrix partitivirus 11-Rosellinia necatrix partitivirus 25" were proposed, and 5 previously reported species. The newly identified partitiviruses have been taxonomically placed in two genera,Alphapartitivirus, andBetapartitivirus. Some partitiviruses were transfected into reference strains of the natural host,R. necatrix, and an experimental host,Cryphonectria parasitica, using purified virions. A comparative analysis of resultant transfectants revealed interesting differences and similarities between the RNA accumulation and symptom induction patterns ofR. necatrixandC. parasitica. Other interesting findings include the identification of a probable reassortment event and a quintuple partitivirus infection of a single fungal strain. These combined results provide a foundation for further studies aimed at elucidating mechanisms that underly the differences observed. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-302X 11 2020 Virome Analysis of Aphid Populations That Infest the Barley Field: The Discovery of Two Novel Groups of Nege/Kita-Like Viruses and Other Novel RNA Viruses 509 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Miki Fujita Institute of Plant Science and Resources (IPSR), Okayama University Hiroshi Hisano Institute of Plant Science and Resources (IPSR), Okayama University Kiwamu Hyodo Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika College of Plant Health and Medicine, Qingdao Agricultural University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Aphids (order Hemiptera) are important insect pests of crops and are also vectors of many plant viruses. However, little is known about aphid-infecting viruses, particularly their diversity and relationship to plant viruses. To investigate the aphid viromes, we performed deep sequencing analyses of the aphid transcriptomes from infested barley plants in a field in Japan. We discovered virus-like sequences related to nege/kita-, flavi-, tombus-, phenui-, mononega-, narna-, chryso-, partiti-, and luteoviruses. Using RT-PCR and sequence analyses, we determined almost complete sequences of seven nege/kitavirus-like virus genomes; one of which was a variant of the Wuhan house centipede virus (WHCV-1). The other six seem to belong to four novel viruses distantly related to Wuhan insect virus 9 (WhIV-9) or Hubei nege-like virus 4 (HVLV-4). We designated the four viruses as barley aphid RNA virus 1 to 4 (BARV-1 to -4). Moreover, some nege/kitavirus-like sequences were found by searches on the transcriptome shotgun assembly (TSA) libraries of arthropods and plants. Phylogenetic analyses showed that BARV-1 forms a clade with WHCV-1 and HVLV-4, whereas BARV-2 to -4 clustered with WhIV-9 and an aphid virus, Aphis glycines virus 3. Both virus groups (tentatively designated as Centivirus and Aphiglyvirus, respectively), together with arthropod virus-like TSAs, fill the phylogenetic gaps between the negeviruses and kitaviruses lineages. We also characterized the flavi/jingmen-like and tombus-like virus sequences as well as other RNA viruses, including six putative novel viruses, designated as barley aphid RNA viruses 5 to 10. Interestingly, we also discovered that some aphid-associated viruses, including nege/kita-like viruses, were present in different aphid species, raising a speculation that these viruses might be distributed across different aphid species with plants being the reservoirs. This study provides novel information on the diversity and spread of nege/kitavirus-related viruses and other RNA viruses that are associated with aphids. No potential conflict of interest relevant to this article was reported.

Humana Press Acta Medica Okayama 2014 Detection and analysis of non-retroviral RNA virus-like elements in plant, fungal, and insect genomes. 73 88 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Sotaro Chiba Institute of Plant Science and Resources (IPSR)Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University 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. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 1345-2630 79 5 2013 Biological and genetic diversity of plasmodiophorid-transmitted viruses and their vectors 307 320 EN Tetsuo Tamada Institute of Plant Science and Resources (IPSR)Okayama University Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University About 20 species of viruses belonging to five genera, Benyvirus, Furovirus, Pecluvirus, Pomovirus and Bymovirus, are known to be transmitted by plasmodiophorids. These viruses have all positive-sense, single-stranded RNA genomes that consist of two to five RNA components. Three species of plasmodiophorids are recognized as vectors: Polymyxa graminis, P. betae, and Spongospora subterranea. The viruses can survive in soil within the long-lived resting spores of the vector. There are biological and genetic variations in both virus and vector species. Many of the viruses are causal agents of important diseases in major crops such as rice, wheat, barley, rye, sugar beet, potato, and groundnut. Control is dependent on the development of resistant cultivars. During the last half century, several virus diseases have rapidly spread worldwide. For six major virus diseases, we address their geographical distribution, diversity, and genetic resistance. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 0304-8608 159 1 2013 Complete genome sequence of Habenaria mosaic virus, a new potyvirus infecting a terrestrial orchid (Habenaria radiata) in Japan 163 166 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Takanori Maeda College of Bioresource SciencesNihon University I Wayan Gara Institute of Plant Science and Resources (IPSR)Okayama University Sotaro Chiba Institute of Plant Science and Resources (IPSR)Okayama University Kazuyuki Maruyama Institute of Plant Science and Resources (IPSR)Okayama University Tetsuo Tamada Institute of Plant Science and Resources (IPSR)Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University 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. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 0304-8608 160 8 2015 Cymbidium chlorotic mosaic virus, a new sobemovirus isolated from a spring orchid (Cymbidium goeringii) in Japan. 2099 104 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Shogo Takemoto Institute of Plant Science and Resources (IPSR)Okayama University Kazuyuki Maruyama Institute of Plant Science and Resources (IPSR)Okayama University Sotaro Chiba Institute of Plant Science and Resources (IPSR)Okayama University Ida Bagus Andika Institute of Plant Science and Resources (IPSR)Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University 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. No potential conflict of interest relevant to this article was reported.

Elsevier Science Acta Medica Okayama 01681702 177 1 2013 Characterization of burdock mottle virus, a novel member of the genus Benyvirus, and the identification of benyvirus-related sequences in the plant and insect genomes. 75 86 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Shuichi Hirano Institute of Plant Science and Resources (IPSR), Okayama University Sotaro Chiba Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences Makoto Hirai Department of Parasitology, Graduate School of Medicine, Gunma University Takanori Maeda Formerly College of Bioresource Sciences, Nihon University Tetsuo Tamada Institute of Plant Science and Resources (IPSR), Okayama University The complete nucleotide sequence of the burdock mottle virus (BdMoV) isolated from an edible burdock plant (Arctium lappa) in Japan has been determined. BdMoV has a bipartite genome, whose organization is similar to RNA1 and RNA2 of benyviruses, beet necrotic yellow vein virus (BNYVV), beet soil-borne mosaic virus (BSBMV), and rice stripe necrosis virus (RSNV). BdMoV RNA1 (7038 nt) contains a single open reading frame (ORF) encoding a 249-kDa polypeptide that consists of methyl-transferase, helicase, papain-like protease, AlkB-like, and RNA-dependent RNA polymerase domains. The AlkB-like domain sequence is not present in the proteins encoded by other known benyviruses, but is found in replication-associated proteins of viruses mainly belonging to the families Alfaflexiviridae and Betaflexiviridae. BdMoV RNA2 (4315 nt) contains six ORFs that are similar to those of benyviruses: these are coat protein (CP), CP readthrough, triple gene block movement and cysteine-rich proteins. Phylogenetic analyses showed that BdMoV is more closely related to BNYVV and BSBMV than to RSNV. Database searches showed that benyvirus replicase-related sequences are present in the chromosomes of a chickpea plant (Cicer arietinum) and a blood-sucking insect (Rhodnius prolixus). Some other benyvirus-related sequences are found in the transcriptome shotgun libraries of a few species of plants and a bark beetle. Our results show that BdMoV is a distinct species of the genus Benyvirus and that ancestral and extant benyviruses may have infected or currently infect a wide range of hosts, including plants and insects. No potential conflict of interest relevant to this article was reported.

Elsevier Science Acta Medica Okayama 01681702 213 2016 Sequence and phylogenetic analyses of novel totivirus-like double-stranded RNAs from field-collected powdery mildew fungi 353 364 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Sakae Hisano Institute of Plant Science and Resources (IPSR), Okayama University Sotaro Chiba Institute of Plant Science and Resources (IPSR), Okayama University Kazuyuki Maruyama Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika Institute of Plant Science and Resources (IPSR), Okayama University Kazuhiro Toyoda Graduate School of Environmental and Life Science, Okayama University Fumihiro Fujimori Department of Environmental Education, Tokyo Kasei University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University The identification of mycoviruses contributes greatly to understanding of the diversity and evolutionary aspects of viruses. Powdery mildew fungi are important and widely studied obligate phytopathogenic agents, but there has been no report on mycoviruses infecting these fungi. In this study, we used a deep sequencing approach to analyze the double-stranded RNA (dsRNA) segments isolated from field-collected samples of powdery mildew fungus-infected red clover plants in Japan. Database searches identified the presence of at least ten totivirus (genus Totivirus)-like sequences, termed red clover powdery mildew-associated totiviruses (RPaTVs). The majority of these sequences shared moderate amino acid sequence identity with each other (<44%) and with other known totiviruses (<59%). Nine of these identified sequences (RPaTV1a, 1b and 2-8) resembled the genome of the prototype totivirus, Saccharomyces cerevisiae virus-L-A (ScV-L-A) in that they contained two overlapping open reading frames (ORFs) encoding a putative coat protein (CP) and an RNA dependent RNA polymerase (RdRp), while one sequence (RPaTV9) showed similarity to another totivirus, Ustilago maydis virus H1 (UmV-H1) that encodes a single polyprotein (CP-RdRp fusion). Similar to yeast totiviruses, each ScV-L-A-like RPaTV contains a -1 ribosomal frameshift site downstream of a predicted pseudoknot structure in the overlapping region of these ORFs, suggesting that the RdRp is translated as a CP-RdRp fusion. Moreover, several ScV-L-A-like sequences were also found by searches of the transcriptome shotgun assembly (TSA) libraries from rust fungi, plants and insects. Phylogenetic analyses show that nine ScV-L-A-like RPaTVs along with ScV-L-A-like sequences derived from TSA libraries are clustered with most established members of the genus Totivirus, while one RPaTV forms a new distinct clade with UmV-H1, possibly establishing an additional genus in the family. Taken together, our results indicate the presence of diverse, novel totiviruses in the powdery mildew fungus populations infecting red clover plants in the field. No potential conflict of interest relevant to this article was reported.

Academic Press Acta Medica Okayama 00426822 533 2019 Two novel fungal negative-strand RNA viruses related to mymonaviruses and phenuiviruses in the shiitake mushroom (Lentinula edodes) 125 136 EN Yu-Hsin Lin Institute of Plant Science and Resources (IPSR), Okayama University Miki Fujita Institute of Plant Science and Resources (IPSR), Okayama University Sotaro Chiba Graduate School of Bioagricultural Sciences, Nagoya University Kiwamu Hyodo Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika Institute of Plant Science and Resources (IPSR), Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Abstract There is still limited information on the diversity of (−)ssRNA viruses that infect fungi. Here, we have discovered two novel (−)ssRNA mycoviruses in the shiitake mushroom (Lentinula edodes). The first virus has a monopartite RNA genome and relates to that of mymonaviruses (Mononegavirales), especially to Hubei rhabdo-like virus 4 from arthropods and thus designated as Lentinula edodes negative-strand RNA virus 1. The second virus has a putative bipartite RNA genome and is related to the recently discovered bipartite or tripartite phenui-like viruses (Bunyavirales) associated with plants and ticks, and designated as Lentinula edodes negative-strand RNA virus 2 (LeNSRV2). LeNSRV2 is likely the first segmented (−)ssRNA virus known to infect fungi. Its smaller RNA segment encodes a putative nucleocapsid and a plant MP-like protein using a potential ambisense coding strategy. These findings enhance our understanding of the diversity, evolution and spread of (−)ssRNA viruses in fungi. No potential conflict of interest relevant to this article was reported.

Elsevier Science Acta Medica Okayama 01681702 262 2019 A novel insect-infecting virga/nege-like virus group and its pervasive endogenization into insect genomes 37 47 EN Hideki Kondo Institute of Plant Science and Resources (IPSR), Okayama University Sotaro Chiba Asian Satellite Campuses Institute, Nagoya University Kazuyuki Maruyama Institute of Plant Science and Resources (IPSR), Okayama University Ida Bagus Andika Institute of Plant Science and Resources (IPSR), Okayama University Nobuhiro Suzuki Institute of Plant Science and Resources (IPSR), Okayama University Insects are the host and vector of diverse viruses including those that infect vertebrates, plants, and fungi. Recent wide-scale transcriptomic analyses have uncovered the existence of a number of novel insect viruses belonging to an alphavirus-like superfamily (virgavirus/negevirus-related lineage). In this study, through an in silico search using publicly available insect transcriptomic data, we found numerous virus-like sequences related to insect virga/nege-like viruses. Phylogenetic analysis showed that these novel viruses and related virus-like sequences fill the major phylogenetic gaps between insect and plant virga/negevirus lineages. Interestingly, one of the phylogenetic clades represents a unique insect-infecting virus group. Its members encode putative coat proteins which contained a conserved domain similar to that usually found in the coat protein of plant viruses in the family Virgaviridae. Furthermore, we discovered endogenous viral elements (EVEs) related to virga/nege-like viruses in the insect genomes, which enhances our understanding on their evolution. Database searches using the sequence of one member from this group revealed the presence of EVEs in a wide range of insect species, suggesting that there has been prevalent infection by this virus group since ancient times. Besides, we present detailed EVE integration profiles of this virus group in some species of the Bombus genus of bee families. A large variation in EVE patterns among Bombus species suggested that while some integration events occurred after the species divergence, others occurred before it. Our analyses support the view that insect and plant virga/nege-related viruses might share common virus origin(s). No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 5 1 1997 Evaluation of Dot-Immunobinding Assay and Rapid Immunofilter Paper Assay for　Detection of Cymbidium Mosaic Virus in Orchids 39 46 EN Gara I Wayan Hideki Kondo Takanori Maeda Dot-immunobinding assay (DIA) on nitrocellulose membranes and rapid immunofilter paper assay (RIPA) were examind for their usefulness in the detection of cymbidium mosaic virus (CyMV) in orchids. The minimum detection levels of CyMV by these methods were 100 ng/ml in purified preparations and at 10-4 dilution of extracts from infected leaves of orchids could be detected by these methods. Although DIA took 5 to 6 hours for the detection of the virus, it was reliable method for diagnosis of a large-number of samples. On the other hand, RIPA, which enabled detection of CyMV within a few minutes with sensitivity similar to that of DIA, will be suitable as a rapid and handy tool for virus disease diagnosis in orchids. Moreover, by RIPA, we could detect CyMV and odontoglossum ringspot virus (ORSV) simultaneously form doubly infected plant. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 5 1 1997 Comparison of Biologically Different Isolates of Odontoglossum Ringspot Virus from Cymbidium in Japan by Peptide Mapping 31 38 EN Hideki Kondo Takanori Maeda Narinobu Inouye Symptoms on Cymbidium, double-stranded (ds) RNA pattern and peptide mapping of coat protein (CP) of five isolates of odontoglossum ringspot virus from Cymbidium in Japan were compared. One of the isolates, Cy-1, that produced unique symptoms on Cymbidium, showed a distinct peptide mapping pattern from those of the other four isolates by partial digestion of CP with pepsin. All the isolates produced three major dsRNA species of Mr=4.3,1.4 and 0.6×106 in the infected plants. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 4 2 1996 Characterization of Bean Yellow Mosaic Virus from Ixia hybrida 201 213 EN Toshiya Tsuji Takanori Maeda Hideki Kondo Narinobu Inouye A strain (Ixia-B) of bean yellow mosaic virus (BYMV) isolated from Ixia hybrida was characterized and compared with other isolates of BYMV and clover yellow vein virus (CYVV). Ixia-B was transmitted by aphids,Myzus presicae in a non-presistent manner and by sap-inoculation to 11 of 46 species in 5 of 10 families tested, and had a similar host range to that of some BYMV isolates, althrough some defferences were detected. Sap from diseased C. quinoa was infective after 10 min heating at 55℃ but not 60℃, after a dilution to 10-3 but not 10-4, and after 2 days but not 4 days at 20℃.The Virus particles were filamentous rods of about 13×820 nm. Ixia-B contaied a single protein species with a molecular weight of 34,000 and a single viral RNA with approximately 9,000 bases. In ultrahtin sections of leaf tissues from infected plants, the virus particles, cylindrical cytoplasmic inclusions and dense bodies were obsserved in the cytoplasm. The antiserum to Ixia-B produced by immunizing a rabbit had a titer of 1/512. A close serological relationship was revealed between Ixia-B and two strains of BYMV from crocus and gladiolus, but no relationship to clover yellow vein virus was found in agar gel diffusion tests. However,Ixia-B could be distinguished from two strains of BYMV by the formation of spurs among them in agar gel and by the differences in the patterns of peptide mapping of coat proteins. From these findings, Ixia-B was identified as a strain of BYMV. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 4 2 1996 エビネ（Calanthe spp.）から分離されたCymbidium mosaic virus 187 199 EN Jun-ichi Matsumoto Shinji Urabe Takanori Maeda Koji Mitsuhata Hideki Kondo Mochimu Tahara Narinobu Inouye Cymbidium mosaic virus(CyMV) was isolated from Calanthe spp. showing mosaic on the leaves, collected in Yamaguchi and Kyoto Prefectures in 1986～1993. CyMV, Cal. 90-1 isolate was transmitted by sapinoculation to 12 out of 37 species in 7 out of 9 families. Sap from diseaded Tetragonia expansa was infective to Chenopodium amaranticolor after dilution to 10-5 but not 10-6, after heating at 65℃ for 10 min but not 70℃, and after 1 month at 20℃ but not 2 months. The virus particles were flexuous rod, about 475 nm long. The virus was purified from diseased T. expansa leaves and contained a single protein species of Mr27,800. The Mr of the capsid proteins(Cal. 90-1) was similar to those of two ohter CyMV isolates(Cal. 90-4, Cal. 93-14).Cal. 90-1 and Cal. 93-14 reacted with antiserum to the Cymbidium isolate (Cy-16), suggesting that Cal. 90-1 was serologically very similar to the other two CyMV isolates. Two species of dsRNA were isolated from plants infected with Cal-1 and they were similar to those of two other CyMv isolates. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 4 2 1996 Further Characterization of Cymbidium Mosaic Virus from Vanda Orchid 164 174 EN I Wayan Gara Hideki Kondo Takanori Maeda Koji Mitsuhata Narinobu Inouye A virus causing necrotic spots and necrotic flecks on the leaves of Vanda orchids in Japan was identified as cymbidium mosaic virus(Cymv) on the basis of host range,stabilly in crude sap, particle morphology, serological test and physico-chemical properties. The virus was transmitted by sap inoculation to 12 of 57 species in 6 of 12 families tested, but not by aphid Mizus persicae or through seeds. Systemic infection occurred in all Orchidaceae plants tested and only one in non-orchidaceae (Sesamum indicum). In Tetragonia expansa sap, the infective at a dilution of 10-5 but not at 10-6, after heating at 65℃ for 10 min, and was still active after 1 month aging in vitro. Flexuous rod particles, c. 475×13nm, were observed.In ultrahtin sections of leaf tissues from diseased plants, virus particles were found to aggregate in the cytoplasm. The molecular weight of the protein submit and RNA determined by gel electrophoresis, was 27.8×103 and 2.2×106, respectively. Double-stranded RNAs with estimated molecular weight of 5.4×106, 4.0×106, 3.6×106 and 3.0×106 were isolated from infected plants. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 4 2 1996 東洋ランに発生するウイルスの検索・同定 149 162 EN Hideki Kondo Takanori Maeda Koji Mitsuhata Narinobu Inouye A survey of virus diseases occurring in Oriental Cymbidium collected from a commerical nursery and home garden in Japan was conducted in 1991-1994. Identification of the vurus was based on partcle morphology, symptomatology in indicator plants, ultrastructure of infected cells and serology. Four viruses, odontoglossum ringspot tabamovirus(ORSV), cymbidium mosaic potexvirus(CyMV), orchid fleck virus (ORV) and a previously underscribed spherical virus, were found in 27 out of 37 Cymbidium plants tested. ORSV was detected from 11 plants belinging to Cym. ensifolium, Cym. forrestii, Cym. goeringii, Cym. kanran, Cym. sinense and Cymbidium spp. showing chlorotic streaks and/or mild mosaic. CyMV was isolated from only one plant of Cymbidium sp. showing mosaic and necrotic spots on leaves. In negatibvely stained dip preparations from plants infected with ORSV and CyMV, rod shaped particles of ca. 310 nm and flexuous rod-shaped ca. 475 nm in length were observed, respectively. The viruses were reacted strongly with respective antiserum to each virus in immunosorbent electron microcopy and inderect ELISA. OFV was isolated from four plants of Cym. formosanum, Cym. kanran, Cym. sinense and Cymbidium sp. showing mosaic and necrotic flecks. The virus had non-enveloped, bullet-shaped particles about 40×120～150 nm in dip preparation. The undescribed spherical virus, ca. 28 nm diameter, was isolated from 11 plants of Cym. forrestii, Cym. goeringii and Cymbidium spp. showing stunting and chlorotic streaks on newly developed leaves. The virus was mechanically transmitted only to Cymbidium orchids. Previously, we designated it as cymbidium chlorotic mosaic sobemovirus(CyCMV)(Kondo et al,1994),as the virus was considered to be a new member of the genus Sobemovirsu. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 4 2 1996 エビネ類に発生する黄色斑紋モザイク病の病原，Orchid Fleck Virusについて 119 135 EN Narinobu Inouye Jun-ichi Matsumoto Takanori Maeda Koji Mitsuhata Hideki Kondo Mochimu Tahara Orchid fleck virus(OFV) was isolated from Calanthe spp.(Cal. discolor,Cal. Bicolor,Cal. Hizen,Cal. triplicata,Cal longicalcarata,Cal Satusma) showing light-green and/or yellowish fleck mosaic on the leaves, which different from previously known viruses of Calanthe. OFV caused systemic infection in Calanthe, Chenopodium quinoa and Beta vulgasis var. cicla, and local infection in C.amaranticolor, C. murale, Spinacia oleracea, Tetragonia expansa, Nicotiana tabacum, N. clevelandii, N. glutinasa, N. rustica, Vigna unguiculata. C quinoa and T expansa are useful as indecator hosts and as a source of virus for inoculation, diagnosis and purification. Sap from C. quinoa was infective after dilution to 10-3 but not 10-4, after 10 min at 45 but not 50℃, and after 1 hr at 20℃ but not 2 hrs. For sap inoculation, it is best to use the homogenate of OFV-onfected leaves within about 7-8 min after homogenization in summer and within about 15 min in winter. The virus particles were bullet-shape or bacilliform, approximately 45-50×105-125 nm in a negatively stained praparations. In ultrathin sections, the viroplasms were observed in the nuclei, and the virus particles and the chracteristic spokewheel structures were found both in the nuclei and the cytoplasm. Antiserum (precipitin tiner:1/512) against the present virus reacted strongly with the isolates of OFV-Cy-50, similar to that of homologous virus. In agar gel diffusion tests, no spur formation occurred among Cal. 94-16 and OFV-Cy-50. In SDS-polyacrylamide gel electrophoresis, one major band of Mr 55,000, probably viral nucleocapsid-protein, and three minor proteins were detected, similar to those of OFV･So from Cymbidium. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 3 2 1995 東洋ラン(Cymbidium sp.)から分離されたOrchid Fleck Virusの性状について 151 161 EN Hideki Kondo Jun-ichi Matsumoto Takanori Maeda Narinobu Inouye Orchid flck virus (OFV) was isolated from Oriental Cymbidium (Cymbidium sp.),showing chlorotic flecks on leaves. The virus was transmitted mechanically to Chenopodium quinoa,C.murale and Beta vulgaris by sap-inoculation and caused systemic infection. Local lesions were produced on C.amaranticolar, Petunia hybrida, Tetragonia expansa and Vigna sinensis. Sap from infected T.expansa was still infective after 10 mim at 40℃ but not after 10 min at 45℃, at a dilution of 10-3 but not 10-4, and after 30 min at room temperature but not after 60 min. The isolate of OFV had non-enveloped, bullet-shaped patricles measuring about 40×120－150 nm in dip preparations. However, bacilliform particles about 40×120-140 nm were observed in ultrathin sections. In ultrahtin sections of virus-infected tissues, virus patricles were detected both in the nuclei and in the cytoplasm. Moreover, the inclusions of low electron density(viroplasm) were also observed in the nuclei.Virus particles were found to attach at one end to the inner nuclear membrane. A number of particles surrounded by the inner membrane often showed an appearance like a spoked wheel. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 1 1 1992 東洋ラン・Cymbidium属植物から分離されたOdontoglossum ringspot Tobamovirus (ORSV)について 21 34 EN Hideki Kondou Takanori Maeda Narinobu Inouye Odontoglossum ringspot virus (ORSV)はJensen＆Gold（1951）によってOdontoglossum grandeにえそ輪紋を生じた病原ウイルスに命名されたが、CattleyaやCymbidiumを中心として広くラン科植物に発生していることが認められている。また、わが国では井上（1966、1983）がCymbidiumからORSVを分離し報告しており、日本でも多種属のラン科植物にORSVの発生が非常に多いことが認められている。シュンラン、カンラン、スルガランなどを含む東洋ラン・Cymbidium属では、かつて葉にモザイク斑を生じた斑紋を”金砂”と呼び非常に珍重されていたが、井上（1984、1990）はこの斑紋がORSVの感染によって生じたものであることを記載した。さらに、井上・呂（1983）は台湾においてもORSVが東洋ランに発生していることを報告している。これらの報告にはウイルスの診断と病徴の記載にとどまり、その病原ウイルスの諸性質についての詳細な記述がなされていなかった。本報告では、葉に軽いモザイク症状を示す東洋ランと呼ばれているスルガラン（Cymbidium ensifolium：蕙蘭）およびカンラン（Cymb. kanran）から検出されたウイルスについて病原学的研究を行ったところ、ORSVと同定されたので、これらの諸性質についての研究結果を報告するとともに、この東洋ラン分離株と既報の洋ランから分離されているORSVおよび同グループのtobacco mosaic virus （TMV）との比較研究を行ったので、それらの結果についても報告する。 No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2006 ランえそ斑紋ウイルスの生物学的性状とゲノム構造に関する研究 EN Hideki Kondo No potential conflict of interest relevant to this article was reported.