There are more than 50 different Simian Immunodeficiency Viruses (SIVs), named after their cognate wild African primate host species. For example, SIVs infecting wild chimpanzees are called SIVcpz, SIVs infecting wild gorillas are called SIVgor, etc. Although the human immunodeficiency viruses, HIV-1 and H1V-2, have a seemingly narrow host range which is limited to humans, these viruses are now known to represent examples of species cross-over . The first evidence for this was obtained for HIV-2, when a close relationship between HIV-2 and a virus isolated from a sooty mangabey (Cercocebus atys) from West Africa was demonstrated (Fig. 4). The close relationship between humans and sooty mangabeys, and the clear origin of HIV-2 cases in a geographic region where sooty mangabeys are common, supported the idea that HIV-2 was derived from a species cross-over event . Subsequently, all HIV-1 strains known to infect humans were shown to be closely related to viruses isolated from the chimpanzee subspecies Pan troglodytes troglodyte, supporting the notion that the spread of this chimpanzee retrovirus into humans was the origin of the major HIV pandemic that now affects some 35 million people worldwide.
Global Perspectives on the Transmission of Zoonotic RNA Viruses from Wild Animal Species to Humans Zoonotic, Epizootic, and Anthropogenic Viral Pathogens 2023, Pages 65-79,