Sequence of a novel simian immunodeficiency virus from a wild-caught African mandrill

SINCE the isolation of an HIV-2-related virus from captive macaques (SIV_MAC), the origin of human immunodeficiency viruses, a much debated subject, has been attributed to monkeys. The sequence of SIV_AGM, which is derived from a naturally infected African green monkey, shows equal relatedness to HIV-1 and HIV-2, suggesting that the derivation of these viruses from SIV_AGM is unlikely. Recent sequence analysis of SIV from a captive sooty mangabey (SIV_SM), however, shows its close relatedness to HIV-2 and SIV_MAC, indicating a possible origin of HIV-2 and SIV_MAC from SIV_SM (refs 4, 7, 9). We report here the sequence of a novel simian lentivirus, SIV_MND, isolated from a wild-caught mandrill in Africa. It is distinct from the three other main groups, HIV-1, HIV-2/SIV_MAC/SIV_SM and SIV_AGM, and therefore represents a fourth main group of primate lentiviruses. Phylogenetic analysis indicates that these four main virus groups might have diverged from a common ancestor at about the same time, long before the spread of AIDS in humans.