Tymoviridae

Tymoviridae is a family of single-stranded positive sense RNA viruses in the order Tymovirales. Plants serve as natural hosts. There are currently 37 species in this family, divided among 3 genera.[1][2]

Tymoviridae
Virus classification
(unranked): Virus
Realm: Riboviria
Phylum: incertae sedis
Order: Tymovirales
Family: Tymoviridae
Genera

Taxonomy

The largest of three genera is Tymovirus with 27 species, whereas the other genera, Marafivirus and Maculavirus have 7 and 1 species respectively.[2]

Group: ssRNA(+)

[2]

Proposed Viruses
  • Culex tymovirus[3]
  • Fig fleck-associated virus

Virology

The virions are non-enveloped and isometric with a diameter of around 30 nm, with an icosahedral structure and a triangulation number T=3.[1]

The linear genome is between of 6-7.5 kilobases in length[1] and encodes one large open reading frame. It is capped at the 5’ terminus. The 3’ terminus may have a tRNA-like structure or a polyA tract, depending upon the species. The genome is relatively cytosine rich.

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
MaculavirusIcosahedralT=3Non-envelopedLinearMonopartite
MarafivirusIcosahedralT=3Non-envelopedLinearMonopartite
TymovirusIcosahedralT=3Non-envelopedLinearMonopartite

Life cycle

Viral replication is cytoplasmic, and is lysogenic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. Translation takes place by leaky scanning. The virus exits the host cell by monopartite non-tubule guided viral movement. Plants serve as the natural host. The virus is transmitted via a vector (insects). Transmission routes are vector and mechanical.[1]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
MaculavirusPlantsNoneViral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: pseudococcid mealybugs; Mechanical inoculation: aphids
MarafivirusPlantsNoneViral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: pseudococcid mealybugs; Mechanical inoculation: aphids
TymovirusPlantsNoneViral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical: beetles; sap

References
  1. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  2. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  3. Wang L, Lv X, Zhai Y, Fu S, Wang D, Rayner S, Tang Q, Liang G (2012) Genomic characterization of a novel virus of the family tymoviridae isolated from mosquitoes. PLoS One 7(7):e39845.

Further reading
  • Martelli GP. Sabanadzovic S. Abou-Ghanem Sabanadzovic N. Edwards MC. Dreher T. (2002). The family Tymoviridae. Archives of Virology. 147(9):1837-46
  • University of Leicester Microbiology
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