Genetic organization of a chimpanzee lentivirus related to HIV-1

SIMIAN immunodeficiency viruses have been isolated from four species of monkey, the 'captive' macaque 1 and mangabey 2–4 and the 'feral' African green monkey 5 and mandrill 6 . While none of these viruses is a replica of HIV-1, the macaque 7 and mangabey 8 viruses represent correct genetic models for HIV-2, possessing exactly the same complement of genes. Recently a lentivirus has been identified in two wild chimpanzees ( Pan troglodytes troglodytes ) in Gabon, west equatorial Africa, and isolated from one of them 9 . This virus is referred to as SIV CPZ . Sera from these animals cross reacted with all the HIV-1 proteins including the envelope glycoproteins. Here, we describe the molecular cloning and sequencing of an infectious proviral clone of SIV CPZ . The overall genetic organization was the same as that of HIV-1, but phylogenetic analysis revealed that the sequence was more divergent than any HIV-1 sequence reported so far. The vpu gene product, found only in the type 1 viruses, was particularly different (64% divergent to HIV-1 BRU ) suggesting that the SIV CPZ represents a distinct subtype. These findings indicate that there is a larger pool of simian lentiviruses than previously suspected and revives debate as to the origins of HIV-1.