Notes on Genus: Metavirus

variable ovoid or spheroid
variable ovoid or spheroid

Type member: Saccharomyces cerevisiae Ty3 virus


General Description

This is one of the genera in the retroelement family Metaviridae. Members have 1 or 2 ORFs and a genome of less than 6 kb. The name is from the Greek metathesis = transposition.


Virus-like particles (VLPs) are poorly studied but seem to include irregular ovoid enveloped particles up to 100 nm in diameter and smaller non-enveloped particles.


Positive sense, ssRNA molecules, less than 6 kb long, flanked by Long Terminal Repeats (LTRs).

Genus Genomic Organization

Depending on the member, there is either one continuous ORF, or 2 in separate reading frames (gag and pol) and a frameshift to generate the pol. As in other genera of the family, the pol contains protease (PR), reverse transcriptase (RT) and integrase (IN) domains in that order.

Type Member Genomic Organization

There are 2 ORFs:
  1. gag: structural polyprotein of 36 kDa
  2. pol: polymerase of 146 kDa with protease (PR), reverse transcriptase (RT) and integrase (IN) domains