INFECTION OF A YELLOW BABOON WITH SIMIAN IMMUNODEFICIENCY VIRUS FROM AFRICAN-GREEN MONKEYS - EVIDENCE FOR CROSS-SPECIES TRANSMISSION IN THEWILD

Many African primates are known to be naturally infected with simian i mmunodeficiency viruses (SIVs), but only a fraction of these viruses h as been molecularly characterized. One primate species for which only serological evidence of SIV infection has been reported is the yellow baboon (Papio hamadryas cynocephalus). Two wild-living baboons with st rong SIVAGM seroreactivity were previously identified in a Tanzanian n ational park where baboons and African green monkeys shared the same h abitat (T. Kodama, D. P. Silva, M. D. Daniel, J. E. Phillips-Conroy, C . J. Jolly, J. Rogers, and R. C. Desrosiers, AIDS Res. Hum. Retrovirus es 5:337-343, 1989). To determine the genetic identity of the viruses infecting these animals, we used PCR to examine SIV sequences directly in uncultured leukocyte DNA. Targeting two different, nonoverlapping genomic regions, we amplified and sequenced a 673 bp gag gene fragment and a 908-bp env gene fragment from one of the two baboons. Phylo-gen etic analyses revealed that this baboon was infected with an SIVAGM st rain of the vervet subtype. These results provide the first direct evi dence for simian-to-simian cross-species transmission of SIV in the wi ld.