Megabirnaviridae

Megabirnaviridae is a family of double-stranded RNA viruses with one genus Megabirnavirus which infects fungi.[1] The group name derives from member's bipartite dsRNA genome and mega that is greater genome size (16 kbp) than families Birnaviridae (6 kbp) and Picobirnaviridae (4 kbp). There is only one species in this family: the type species Rosellinia necatrix megabirnavirus 1. Diseases associated with this family include: reduced host virulence.[2][3]

Megabirnavirus
Virus classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Duplornaviricota
Class: Chrymotiviricetes
Order: Ghabrivirales
Family: Megabirnaviridae
Genus: Megabirnavirus
Type species
Rosellinia necatrix megabirnavirus 1

Structure

Viruses in the family Megabirnaviridae are non-enveloped, with icosahedral geometries, and T=1 symmetry. The diameter is around 50 nm.

Genome
Genome organization of Rosellinia necatrix megabirnavirus 1

The genome is composed of two double-stranded RNA segments of 7.2–8.9 kbp each and of a total length of 16.1 kbp. The genome codes for four proteins.[2][3]

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the double-stranded RNA virus replication model. Double-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][3]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
MegabirnavirusFungiNoneCytoplasmic exchange; hyphal anastomosisCytoplasmic exchange; hyphal anastomosisCytoplasmCytoplasmCytoplasmic exchange; hyphal anastomosis

Taxonomy
Phylogenetic tree of family Megabirnaviridae

The family Megabirnaviridae has one genus which has one species:[4]

  • Megabirnavirus
    • Rosellinia necatrix megabirnavirus 1

References
  1. Sato, Y; Miyazaki, N; Kanematsu, S; Xie, J; Ghabrial, SA; Hillman, BI; Suzuki, N; ICTV Report, Consortium (September 2019). "ICTV Virus Taxonomy Profile: Megabirnaviridae". The Journal of General Virology. 100 (9): 1269–1270. doi:10.1099/jgv.0.001297. PMID 31418675.
  2. "ICTV Report Megabirnaviridae".
  3. "Viral Zone". ExPASy. Retrieved 13 August 2015.
  4. "International Committee on Taxonomy of Viruses (ICTV)". talk.ictvonline.org. Retrieved 8 October 2020.
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