title: A novel mycovirus from Aspergillus fumigatus contains four unique dsRNAs as its genome and is infectious as dsRNA.
abstract: We report the discovery and characterization of a double-stranded RNA (dsRNA) mycovirus isolated from the human pathogenic fungus Aspergillus fumigatus, Aspergillus fumigatus tetramycovirus-1 (AfuTmV-1), which reveals several unique features not found previously in positive-strand RNA viruses, including the fact that it represents the first dsRNA (to our knowledge) that is not only infectious as a purified entity but also as a naked dsRNA. The AfuTmV-1 genome consists of four capped dsRNAs, the largest of which encodes an RNA-dependent RNA polymerase (RdRP) containing a unique GDNQ motif normally characteristic of negative-strand RNA viruses. The third largest dsRNA encodes an S-adenosyl methionine-dependent methyltransferase capping enzyme and the smallest dsRNA a P-A-S-rich protein that apparently coats but does not encapsidate the viral genome as visualized by atomic force microscopy. A combination of a capping enzyme with a picorna-like RdRP in the AfuTmV-1 genome is a striking case of chimerism and the first example (to our knowledge) of such a phenomenon. AfuTmV-1 appears to be intermediate between dsRNA and positive-strand ssRNA viruses, as well as between encapsidated and capsidless RNA viruses.
authors.affiliation: Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom;
authors.forename: Lakkhana
authors.initials: L
authors.lastname: Kanhayuwa
authors.affiliation: Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom;
authors.forename: Ioly
authors.initials: I
authors.lastname: Kotta-Loizou
authors.affiliation: Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom;
authors.forename: Selin
authors.initials: S
authors.lastname: Özkan
authors.affiliation: Institute of Food Research, Norwich Research Park, Colney Lane, Norwich NR4 7UA, United Kingdom.
authors.forename: A Patrick
authors.initials: AP
authors.lastname: Gunning
authors.affiliation: Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom; r.coutts@herts.ac.uk.
authors.forename: Robert H A
authors.initials: RH
authors.lastname: Coutts
mesh_terms: D001232:Aspergillus fumigatus / Q000302:isolation & purification / Q000821:virology*; D002999:Clone Cells; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D016679:Genome, Viral; D054884:Host-Pathogen Interactions; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D012330:RNA, Double-Stranded / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014779:Virus Replication; D014780:Viruses / Q000737:chemistry / Q000235:genetics* / Q000472:pathogenicity*
chemical_list: D018076:DNA, Complementary; D012330:RNA, Double-Stranded
keywords: capping enzyme; infectious dsRNA; mycovirus; protoplast transfection; virus evolution