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. Neither an effective vaccine nor a therapy has emerged probably because of the complicated inter-relationship of the AIDS virus with the human immune system. Nevertheless, one remarkable observation is that, unlike humans, chimpanzees are relatively resistant to the development of AIDS. In the meantime, HIV-1 vaccine and therapy research has moved to SHIV/SIVmac infection in rhesus macaques as a model of AIDS for which disease intervention studies can be better performed. Chimpanzees are very rarely used in applied HIV-1 research anymore. However, pertinent questions about the mechanisms of resistance to AIDS in this species beg to be answered. Furthermore, after more than twenty years of intense search for the origin of the AIDS epidemic, the spotlight has recently been turned once again on to the chimpanzee. 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.