Notes on Genus: Epsilonretrovirus

enveloped spheres
enveloped spheres

Type member: Walleye dermal sarcoma virus


General Description

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
  1. ORFC: unknown function (14.2 kDa)
  2. gag: structural polyprotein of 65.7 kDa
  3. pro: protease
  4. pol: polymerase (the gag-pro-pol polyprotein is 196.3 kDa)
  5. env: envelope proteins (139.6 kDa)
  6. ORFA: 33.1 kDa
  7. ORFB: 45.0 kDa