Totivirus

Totivirus is a genus of viruses, in the family Totiviridae. Fungi serve as natural hosts. There are seven species in this genus including the type species Saccharomyces cerevisiae virus L-A.[3][4]

Totivirus
Virus classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Duplornaviricota
Class: Chrymotiviricetes
Order: Ghabrivirales
Family: Totiviridae
Genus: Totivirus
Type species
Saccharomyces cerevisiae virus L-A
Species[1]
  • Saccharomyces cerevisiae virus L-A
  • Saccharomyces cerevisiae virus LBCLa
  • Scheffersomyces segobiensis virus L
  • Tuber aestivum virus 1
  • Ustilago maydis virus H1
  • Xanthophyllomyces dendrorhous virus L1A
  • Xanthophyllomyces dendrorhous virus L1B
Synonyms[2]
  • Saccharomyces cerevisiae virus group

Species details

One species infects the fungus Saccharomyces cerevisiae. Helminthosporium victoriae virus 190S which was initially included in this genus has been moved to a new genus—the Victorivirus.

Species of this genus commonly infect the human pathogen Trichomonas vaginalis.[5]

Structure

Viruses in Totivirus are non-enveloped, with icosahedral symmetry, and T=2 architecture. The diameter is around 40 nm. Genomes are linear, around 4.6-6.7kb in length. The genome has 2 open reading frames.[3]

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
TotivirusIcosahedralT=2Non-envelopedLinearMonopartite

Genome

Totivirus have a genome of 4700–6700 nucleotides in length and only a single copy of the genome is present in the particle. The nucleic acid content of Totivirus is usually of one molecule but can also contain three or four segments of linear double stranded RNA. The genome contains two large overlapping open reading frames (ORFs). These open reading frames (ORFs) code for a capsid protein (CP) and an RNA-dependent RNA polymerase (RDRP). The 5' end of the positive strand of the dsRNA genome has no cap and is very structured. Totivirus contains a long 5' untranslated region (5' UTR) which functions as an internal ribosome entry site (IRES). Totiviruses can have satellite RNAs encoding a toxin.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by virus remains intracellular. Replication follows the double-stranded RNA virus replication model. Double-stranded RNA virus transcription is the method of transcription. Translation takes place by -1 ribosomal frameshifting. The virus exits the host cell by cell-to-cell movement. Fungi serve as the natural host.[3]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
TotivirusFungi: saccharomyces cerevisiae; fungi: smut fungiNoneCytoplasmic exchange, sporogenesis; hyphal anastomosisCytoplasmic exchange, sporogenesis; hyphal anastomosisCytoplasmCytoplasmCell division; sporogenesis; cell fusion

References
  1. "Virus Taxonomy: 2018b Release" (html). International Committee on Taxonomy of Viruses (ICTV). March 2019. Retrieved 11 February 2020.
  2. "MINUTES OF THE SIXTH MEETING OF THE ICTV, SENDAI, 5th SEPTEMBER 1984" (PDF). International Committee on Taxonomy of Viruses (ICTV). 5 September 1984. Retrieved 11 February 2020.
  3. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  4. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  5. Parent, K. N; Takagi, Y; Cardone, G; Olson, N. H; Ericsson, M; Yang, M; Lee, Y; Asara, J. M; Fichorova, R. N; Baker, T. S; Nibert, M. L (2013). "Structure of a Protozoan Virus from the Human Genitourinary Parasite Trichomonas vaginalis". mBio. 4 (2): e00056–13. doi:10.1128/mBio.00056-13. PMC 3622925. PMID 23549915.
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