Search

The ancestry of human immunodeficiency virus-1 (HIV-1) has been traced to simian immunodeficiency virus (SIVcpz) infecting chimpanzees (Pan troglodytes) in west central Africa, but the origin of SIVcpz itself remains unknown. Species- specific strains of SIV have been identified in more than 20 species of African primates. The known strains of SIV cluster into six distinct major lineages, whose order of divergence has been difficult to disentangle. SIV phylogeny is complicated by a number of viruses that occupy different positions in the evolutionary tree dependent on the region of genome analyzed, indicative of recombination events among viruses from different major lineages. Two recently characterized viruses, SIVrcm, from red-capped mangabeys (Cercocebus torquatus), and SIVgsn, from greater spot-nosed monkeys (Cercopithecus nictitans), are most closely related to SIVcpz, but only in certain genomic regions, and so both have been interpreted as recombinant viruses. The finding of a hybrid origin of SIV in chimpanzees has important implications.

Examines the prevalence and detection of simian immunodeficiency virus (SIVcpz) on wild-living apes in Africa. Development of noninvasive methods to detect and characterize SIVcpz; Origins and evolutionary history of HIV-1 and SIVcpz; Absence of SIVcpz infections in chimpanzees from the Tai Forest.

Plasmodium vivax is the leading cause of human malaria in Asia and Latin America but is absent from most of central Africa due to the near fixation of a mutation that inhibits the expression of its receptor, the Duffy antigen, on human erythrocytes. The emergence of this protective allele is not understood because P. vivax is believed to have originated in Asia. Here we show, using a non-invasive approach, that wild chimpanzees and gorillas throughout central Africa are endemically infected with parasites that are closely related to human P. vivax. Sequence analyses reveal that ape parasites lack host specificity and are much more diverse than human parasites, which form a monophyletic lineage within the ape parasite radiation. These findings indicate that human P. vivax is of African origin and likely selected for the Duffy-negative mutation. All extant human P. vivax parasites are derived from a single ancestor that escaped out of Africa.