Notes on Genus: Totivirus


Type member: Saccharomyces cerevisiae virus L-A


General Description

This genus contains those members of the family Totiviridae that infect yeasts and smut fungi. The name reflects the fact that the genome is undivided (Latin: totus).


Virions isometric, 40 nm in diameter, with T=1 and a dimer of the coat protein as the asymmetric unit.


Monopartite, linear, double stranded DNA of 3200-6700 base pairs. Satellite or defective RNAs occur in some isolates.

Genus Genomic Organization

The genome usually has two large, overlapping ORFs on the positive strand. The first encodes the coat protein. The second ORF is an RNA-dependent RNA polymerase and is believed to be expressed as a fusion protein via a translational frameshift with ORF1.

Type Member Genomic Organization

There are two large, overlapping ORFs on the positive strand:
1. 76 kDaCoat protein (gag)
2.   88-99 kDa Polymerase (pol): RNA-dependent RNA polymerase expressed as a 171 kDa fusion protein with gag by a -1 ribosomal frameshift