Notes on Genus: Spumavirus
Type member: Simian foamy virus 1
This is one of the genera in the family Retroviridae
. Members are distinguished from those of the other genera by the presence of 6 ORFs, a genome of more than 10 kb, and because they infect mammals.
Virions are spherical and enveloped, 80-100 nm in diameter, with suface projections of glycoprotein.
A dimer of linear, positive sense, ssRNA molecules, each 10.5-13.5 kb long and with a 3'-polyA tail.
Genus Genomic Organization
In addition to the standard 4 genes of the family (gag, pro, pol and env), two other regulatory genes are encoded at the 3'-end of the genome. The pro and the pol are translated from a single spliced mRNA and the other genes downstream are translated from separate spliced mRNAs.
Type Member Genomic Organization
The major genes are
- gag: structural polyprotein of 70.7 kDa
- pro: protease
- pol: polyprotein (pro-pol of 129.9 kDa)
- env: envelope proteins (113.3 kDa)
- taf: transactivating factor of 33.8 kDa
- bet: > 48 kDa