title: The family Tymoviridae.
abstract: The family Tymoviridae comprises the genus Tymovirus, from which it derives its name, the genus Marafivirus and the newly established genus Maculavirus. Members of the family share the following characteristics: (i) non-enveloped isometric particles c. 30 um in diameter, with a rounded contour and prominent surface structures, and clustering of coat protein subunits in pentamers and hexamers; (ii) the presence in preparations of purified virus particles of two centrifugal components, made up of non-infectious protein shells (T) that may contain small amounts of RNA (primarily subgenomic coat protein mRNA) and of infectious nucleoproteins (B), that contain the virus genome; (iii) possession of a positive-sense, single-stranded RNA genome with an unusually high cytidine content (32 to c. 50%), capped at the 5' terminus and containing a very large ORF encodes replication-related proteins analogous to those of other taxa of the "alpha-like" supergroup of ssRNA viruses; (iv) a replication strategy possibly encompassing posttranslational proteolytic cleavage of the polypeptide encoded by ORF1 by a papain-like virus-encoded protease, and coat protein expression via a subgenomic RNA; (v) the presence in infected cells of cytopathic structures, thought to be the sites of RNA replication, originating from severely altered chloroplasts and/or mitochondria, the periphery of which is lined with vesicles produced by the localized invaginations of the bounding membrane. There are 23, 4, and 2 known species in the genera Tymovirus, Marafivirus and Maculavirus, respectively. The genus Marafivirus also contains one tentative species.
authors.affiliation: Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi and Istituto di Virologia Vegetale del CNR, Bari, Italy.
authors.forename: G P
authors.initials: GP
authors.lastname: Martelli
authors.forename: S
authors.initials: S
authors.lastname: Sabanadzovic
authors.forename: N
authors.initials: N
authors.lastname: Abou-Ghanem Sabanadzovic
authors.forename: M C
authors.initials: MC
authors.lastname: Edwards
authors.forename: T
authors.initials: T
authors.lastname: Dreher
mesh_terms: D012367:RNA, Viral / Q000032:analysis / Q000096:biosynthesis; D017806:Tymovirus / Q000145:classification* / Q000235:genetics / Q000502:physiology; D014779:Virus Replication
chemical_list: D012367:RNA, Viral