Background:  Primate lentiviruses are a diverse group that naturally infect at least 33 nonhuman African primate species. Initially, 6 distinct lineages (SIV_cpz, SIV_sm, SIV_agm, SIV_syk, SIV_lhoest, and SIV_col) have been described. More recently, a number of potential recombinant lineages have been also described highlighting the increasing complexity of phylogenetic relationships among primate lentiviruses. Here we report the full-length and partial sequences of SIVtal strains from two talapoins monkeys (Miopithecus oguensis) wild-caught in Cameroon and from 4 captive animals obtained from different U.S. zoos.

Methods:  By PCR we amplified viral pol sequences (650 bp) from uncultured PBMC DNA from these animals and for one willd-caught animal, we obtained the entire genome (SIV_tal266) using long PCR method by targeting unintegrated circular DNA. All sequences were compared to previously reported SIV sequences. Phylogenetic tree analyses of pol sequences showed that all viruses from talapoins monkeys cluster together forming a monophyletic species-specific SIV_tal lineage and thus indicating that these monkeys are the natural hosts for SIV_tal. Full-length genome analysis revealed that SIV_tal266 had a genomic organization characteristic for most primate lentiviruses (i.e. lacking vpu and vpx). While, overall, the SIV_tal lineage was more closely related to the recently described SIV_gsn lineage present in greater spot-nosed, mustached and mona monkeys in Cameroon and to the SIV_syk lineage. Using a neighbor-joining method, the clustering of these 3 lineages was significant in Gag and Pol trees as well as in the Env tree when excluding the SIVcpz lineage which has been recently shown to be recombinant between SIV_gsn and SIV_rcm.

Conclusions:  The geographic range of the gabon talapoin (Miopithecus oguensis) is from the Cameroon, south of the River Sanaga, and Rio Muni, Gabon. Although talapoin monkeys belong to the Miopithecus genus while Syke's, greater spot-nosed, mustached and mona monkeys are from Cercopithecus species, these data suggest that SIV_tal, SIV_syk, and SIV_gsn/mon/mus evolved from a common ancestor.

Keywords: SIV