Narnaviridae

Narnaviridae is a family of positive single stranded RNA viruses. Members of this family have no capsid.[1] Fungi serve as natural hosts. There are currently seven species in this family, divided among 2 genera.[2][3]

Narnaviridae
Virus classification
(unranked): Virus
Realm: Riboviria
Phylum: incertae sedis
Family: Narnaviridae
Genera

Virology

The genome of these viruses is unipartate and between 2.3 and 3.5 kilobases in length. It encodes a single gene—the RNA dependent RNA polymerase. This protein is associated with the genome in the cytoplasm of the host.[4] The viruses do not have a capsid or envelop and do not form any infectious viral particles except lipid vesicles.[5]

They infect fungi (including yeast) and oomycetes.[6] Mitovirues appear to be among the most common fungi viruses.[5]

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
MitovirusNo structural proteinsNon-envelopedLinearMonopartite
NarnavirusNo structural proteinsNon-envelopedLinearMonopartite

Life cycle

Viral replication is cytoplasmic. Replication follows the positive stranded RNA virus replication model. Positive-stranded RNA-virus transcription is the method of transcription. The virus exits the host cell by cell to cell movement. Fungi serve as the natural host. Transmission routes are parental and sexual.[2]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
MitovirusFungiNoneHorizontal; verticalNoneCytoplasmCytoplasmHorizontal: mating; vertical: parental
NarnavirusFungiNoneHorizontal; verticalNoneCytoplasmCytoplasmHorizontal: mating; vertical: parental

Taxonomy

Two genera have been recognised to date. Mitoviruses infect the mitochondria of fungi while narnaviruses remain within the cytoplasm of the host cell.[5]

Group: ssRNA(+)

[3]

Other proposed members of the Mitovirus genus are OnuMV1c and OnuMV7.[7]

Their closest relatives among RNA viruses are plant-infecting viruses of genus Ourmiavirus, which, however, have a capsid and a number of other proteins. Other close relatives are bacteriophages of the family Leviviridae.[5]

References
  1. Dolja, V. V.; Koonin, E. V. (2012). "Capsid-Less RNA Viruses". ELS. doi:10.1002/9780470015902.a0023269. ISBN 978-0470016176.
  2. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  3. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  4. Solorzano A, Rodríguez-Cousiño N, Esteban R, Fujimura T (2000) Persistent yeast single-stranded RNA viruses exist in vivo as genomic RNA. RNA polymerase complexes in 1:1 stoichiometry. J Biol Chem 275(34):26428–35
  5. Hillman, B. I.; Cai, G. (2013). "The Family Narnaviridae". Mycoviruses. Advances in Virus Research. 86. pp. 149–76. doi:10.1016/B978-0-12-394315-6.00006-4. ISBN 9780123943156. PMID 23498906.
  6. Cai G, Myers K, Fry WE, Hillman BI (2011) A member of the virus family Narnaviridae from the plant pathogenic oomycete Phytophthora infestans. Arch Virol
  7. Hintz W, Kassatenko I, Varga A, James D (2013) Two novel mitoviruses from a Canadian isolate of the Dutch elm pathogen Ophiostoma novo-ulmi (93–1224). Virology Journal 10(252). DOI: 10.1186/1743-422X-10-252
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