“…The species tropism of HIV-1 is narrower than that of viruses of the HIV-2 subgroup (HIV-2, SIV~A c and SIVMN E of the macaque monkey and SIVsM of the sooty mangabey, Cercocebus atys). Only higher primates [humans, chimpanzees (Pan troglodytes), gibbons (Hylobates lar)] and pig-tailed macaques (M. nemestrina) are susceptible to HIV-1 infection in vivo (Agy et al, 1992;Alter et al, 1984;Fultz et al, 1986;Gajdusek et al, 1985;Lusso et al, 1988;Nara et al, 1987), whereas various primates [humans, rhesus monkeys (Macaca mulatta), cynomolgus monkeys (M. fascicularis), pig-tailed monkeys, and sooty mangabeys] are productively infected with viruses of the HIV-2 subgroup (Benveniste et al, 1988;Daniel et al, 1985;Dewhurst et al, 1990;Franchini et al, 1990;Letvin et al, 1985;Naidu et al, 1988). In cultured peripheral blood mononuclear cells (PBMC), growth of HIV-1 is similarly restricted .…”