Isolation and partial characterization of a lentivirus from talapoin monkeys (Myopithecus talapoin)

We have identified a novel lentivirus prevalent in talapoin monkeys (Myopit hecus talapoin), extending previous observations of human immunodeficiency virus-1 cross- reactive antibodies in the serum of these monkeys. We obtain ed a virus isolate from one of three seropositive monkeys initially availab le to us. The virus was tentatively named simian immunodeficiency virus fro m talapoin monkeys (SIVtal). Despite the difficulty of isolating this virus , it was readily passed between monkeys in captivity through unknown routes of transmission. The virus could be propagated for short terms in peripher al blood mononuclear cells of talapoin monkeys but not in human peripheral blood mononuclear cells or human T cell lines. The propagated virus was use d to infect a naive talapoin monkey, four rhesus macaques (M. mulatta), and two cynomolgus macaques (M. fascicularis). All animals seroconverted and v irus could he reisolated during a short period after experimental infection . A survey of SIVtal-infected captive talapoin monkeys revealed a relative decrease in CD4+ cell numbers in chronically (>2 years) infected animals. N o other signs of immunodeficiency were observed in any of the infected anim als. PCR amplification followed by DNA sequencing of two fragments of the p olymerase gene revealed that SIVtal is different from the presently known l entiviruses and perhaps most related to the SIV from Sykes monkeys. (C) 199 9 Academic Press.