Woolly monkey sarcoma virus
Woolly monkey sarcoma virus, with synonym Simian sarcoma virus is a species of gammaretrovirus that infects primates. First isolation was from a fibrosarcoma in a woolly monkey. For its reproduction the virus needs a helper or associated virus which is called Simian sarcoma associated virus, also known as woolly monkey virus.
The WMSV/SSV genome is nearly identical to the WMV/SSAV genome, except the part corresponding to the env gene on the WMV/SSAV genome is replaced by an oncogene called p28/v-sis. The lack of an env renders it reliant on the SSAV for reproduction while the presence of the oncogene makes it sarcoma-causing. v-sis is derived from a primate PDGFB gene that the ancestral WMSV/SSV had picked up instead of its own env gene.
Simian sarcoma associated virus
WMV/SSAV is its own independently-replicating retrovirus. It is usually lumped into the same species as the gibbon ape leukemia virus. It was originally detected in woolly monkeys co-housed in the same cage as gibbons, so the detection may have been due to a gibbon-to-monkey transmission rather than indicating the true natural host of the virus. Cladistically, the WMV/SSAV branch of the GALV-WMV clade also includes many rodent virues, including the Melomys burtoni retrovirus, melomys woolly monkey retrovirus, and complete melomys woolly monkey retrovirus. cMWMV is a complete endogenous retrovirus found in some populations of Melomys leucogaster, still very capable of producing infectious virions, in contrast to earlier Melomys-harbored relatives which were incomplete.