SIVs and Human Crossovers in West and Central Africa
Moderator: Mark Siddall (Division of Invertebrate Zoology, American Museum of Natural History)Beatrice Hahn (University of Pennsylvania)
"Origins of HIV-1 in the Congo River Basin"
Acquired immunodeficiency syndrome (AIDS) of humans is caused by two lentiviruses, human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2). Both HIVs are the result of multiple cross-species transmissions of simian immunodeficiency viruses (SIVs) naturally infecting African primates. Most of these transfers resulted in viruses that spread to only a limited extent. However, one transmission event, involving SIVcpz from chimpanzees about a century ago in southeastern Cameroon, gave rise to HIV-1 group M – the principal cause of the AIDS pandemic. I will discuss how host restriction factors have shaped the emergence of new SIV infections by imposing adaptive hurdles to cross-species transmission and/or secondary spread. I will also show that AIDS has likely afflicted chimpanzees long before the emergence of HIV. Tracing the genetic changes that occurred as SIVs crossed from monkeys to apes and from apes to humans provides a new framework to examine the requirements of successful host switches and to gauge future zoonotic risk.
