| Totivirus | |
|---|---|
 | |
| L-A helper virus capsid protein structure and homodimer of the gag capsid protei | |
Virus classification | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Duplornaviricota |
| Class: | Chrymotiviricetes |
| Order: | Ghabrivirales |
| Family: | Orthototiviridae |
| Genus: | Totivirus |
| Synonyms[2] | |
| |
Totivirus is a genus ofdouble-stranded RNA viruses in the familyOrthototiviridae. Fungi serve as natural hosts. The name of the group derives fromLatintoti which means undivided or whole. There are 32 species in this genus.[3][4]
Viruses in the genusTotivirus are non-enveloped, withicosahedral symmetry, and T=2 architecture. The diameter is around 40 nm.[3]
Totiviruses have agenome of 4700–6700nucleotides in length and only a single copy of the genome is present in the particle. Thenucleic acid content of a totivirus capsid is usually of one segment but can also contain three or four segments of lineardouble stranded RNA. Thegenome contains two large overlappingopen reading frames (ORFs). Theseopen reading frames (ORFs) code for a capsid protein (CP) and anRNA-dependent RNA polymerase (RdRp). The 5' end of the positive strand of the dsRNA genome has no cap and is very structured. Totiviruses contain a long 5' untranslated region (5' UTR) which functions as aninternal ribosome entry site (IRES). Totiviruses can have satellite RNAs encoding atoxin.[citation needed]
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. FungiSaccharomyces cerevisiae andsmut serve as the natural host. The virus is transmitted during cell division, sporogenesis, and cell fusion.[3]
The genusTotivirus contains the following species:[4]