Totivirus
| Totivirus | |
|---|---|
| Virus classification | |
| Group: | Group III (dsRNA)
|
| Family: | Totiviridae
|
| Genus: | Totivirus
|
The genus Totivirus is a member of the Totiviridae family. These are a family of icosahedral nonenveloped viruses. The double-stranded RNA (dsRNA) genomes are packaged in isometric particles 40 to 50 nm in diameter.
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 that encoding a toxin.
Species
One species infects the fungus Saccharomyces cerevisiae. A second Helminthosporium victoriae 190S virus (Hv190SV) infects the phytopathogenic fungus Helminthosporium victoriae.