Sequence of simian immunodeficiency virus and its relationship to the human immunodeficiency viruses

The characterization of HIV-1 (HTLV-III/LAV)1,2, the human retrovirus associated with AIDS (acquired immune deficiency syndrome) 3 has led to the identification of a group of related human and simian retroviruses which also infect CD4-bearing T lymphocytes. Simian T-lymphotropic virus type III (simian immodeficiency virus) from macaques (STLV-IIIMAC) induces symptoms similar to those of AIDS in infected macaques4,5, but isolates from African green monkeys (STLV-IIIAGM) 6 and mangabeys (STLV-IIMM) 7,8 appear to be non-pathogenic in these animals. A human virus immunologically related to STLV-IIIAGM (HTLV-IV), reported to have been isolated from healthy humans9, has been shown to be almost identical to STLV-IHAGM10,11, which has called into question the independent origin of these viruses11. Here we report the complete DNA sequence of STLV-IIIAGM and analyse its relationship with the genomes of the HTLV -IIIB strain of HIV-1, HIV-2ROD (previously called LAV-2) 12–15 and several ungulate lentiretroviruses. STLV-IIIAGM and HIV-2 are closely related, and more distantly related to HIV-1.