Notes on Genus: Epsilonretrovirus
Type member: Walleye dermal sarcoma virus
This is one of the genera in the family Retroviridae
. Members are distinguished from those of the other genera by the presence of more than 4 (up to 7) ORFs and a genome of more than 10 kb. All known members infect fish.
Virions are spherical and enveloped, 80-100 nm in diameter, with suface projections of glycoprotein.
A dimer of linear, positive sense, ssRNA molecules, each 11-13 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), up to three additional genes of unknown function are encoded. A spliced mRNA is used to generate the env while the pro and pol are translated after readthrough of the gag stop codon.
Type Member Genomic Organization
The major genes are
- ORFC: unknown function (14.2 kDa)
- gag: structural polyprotein of 65.7 kDa
- pro: protease
- pol: polymerase (the gag-pro-pol polyprotein is 196.3 kDa)
- env: envelope proteins (139.6 kDa)
- ORFA: 33.1 kDa
- ORFB: 45.0 kDa