Lentivirus infections and mechanisms of disease resistance in chimpanzees

One year after the human immunodeficiency virus (HIV) was pinpointed as the etiological agent of the acquired immunodeficiency syndrome (AIDS) in humans, chimpanzees were identified as one of the few living species also capable of sustaining persistent HIV-1 infection. During the mid to late 1980s, as the AIDS epidemic spread globally in humans, the chimpanzee was eagerly looked to for answers concerning effective AIDS therapies and a possible HIV vaccine. Although from the complicated inter-relationship of the AIDS virus with the human immune system, neither an effective vaccine nor a therapy has emerged, one remarkable observation has been that, unlike humans, chimpanzees are relatively resistant to the development of AIDS. In the meantime, HIV-1 vaccine and therapy research has moved on to the SHIV/SIVmac rhesus model as an alternative AIDS model for which disease intervention studies can be better performed, and chimpanzees are rarely studied anymore. However, pertinent questions about the mechanisms of resistance to AIDS in this species beg to be answered. After more than twenty years, the spotlight has recently been turned once again on to the chimpanzee, in the intense search for the origin of the AIDS epidemic. Here we review the history of HIV-1 infection in this species as well as the observations that have led to some of the current leading hypotheses regarding the resistance to AIDS in naturally infected African primates.