Simian immunodeficiency virus (SIV), also known as African Green Monkey virus and also as Monkey AIDS is a retrovirus able to infect at least 33 species of African primates. Virus strains from two of these primate species, SIVsmm in sooty mangabeys and SIVcpz in chimpanzees, are believed to have crossed the species barrier into humans, resulting in HIV-2 and HIV-1, respectively. Unlike HIV-1 and HIV-2 infections in humans, SIV infections in their natural hosts appear in many cases to be non-pathogenic. Alternative Names: Simian Immunodeficiency Virus glycoprotein 28 protein, SIV-1, SIV 1 protein, SIV 1, SIV-1 protein, SIV1, SIV p28 protein