Woolly monkey sarcoma virus

Woolly monkey sarcoma virus (WMSV), with synonym Simian sarcoma virus (often abbreviated by SSV, but this may also stand for some species called Sulfolobus spindle-shaped virus, that belong to different genera in family Fuselloviridae) is a species of gammaretrovirus that infects primates. First isolation was from a fibrosarcoma in a woolly monkey (Legothrix lagothrica). For its reproduction the virus needs a helper or associated virus which is called Simian sarcoma associated virus (SSAV), also known as woolly monkey virus (WMV).

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 (c-sis) gene that the ancestral WMSV/SSV had picked up instead of its own env gene.