An article in the November 9 issue of Nature reports the discovery of gorillas living in the wild in Central Africa infected with an HIV-related virus. The new data were completely unexpected and were presented by an international team headed by Martine Peeters, PhD, of the Institut de Recherché pour le Développement in Paris, and Eric Delaporte, MD, of the University of Montpellier.

Earlier this year, Drs. Peeters and Delaporte, along with Beatrice Hahn, MD, at the University of Alabama and other investigators, showed that chimpanzees living in the Congo Basin were the natural reservoir of HIV-1 virus group M, the source of the world pandemic and that of another, very rare variant, HIV-1 group N. Sooty mangabeys, a West African monkey, harbor a form of SIV that is closely related to HIV-2.

The reservoir of the third HIV-1 group, group O, which can also infect humans, has long been unidentified.

This new simian immunodeficiency virus, called SIVgor, has the special feature of being genetically close to an HIV-1 variant called group O. Although rarely found in humans, this variant has nevertheless been the source of cases of AIDS.

The discovery of SIVgor has prompted the research group to ask crucial questions regarding the source and route of the infection. In effect, it substantially broadens the scope of research regarding the ability of these viruses to cross over from one species to another.

The study involved an analysis of feces samples collected from different communities of gorillas found in remote areas of the Cameroon tropical forest. Some of the samples found to contain antibodies against SIVgor.

The genetic characteristics of the virus were present again in three gorillas living more than 400 kilometers apart. The analysis of SIVgor showed it to be related to HIV-1 group O found in humans, essentially in Cameroon and in neighboring countries.

This discovery of an HIV-1 related virus in wild gorillas does not, however, call into question the fact that chimpanzees are the primary reservoir of SIV/HIV viruses that crop up again in gorillas and in humans. According to Dr. Peeters, “the viruses of groups M and N are, very clearly, the consequence of inter-species transmission from chimpanzee to humans, whereas the origin of HIV-1 group O is less apparent. It cannot be excluded that chimpanzees infected by HIV-1 group O might have contaminated humans and the gorilla independently, or that the gorilla, having been contaminated by the chimpanzee, might have contaminated humans.”

These new data open up Pandora’s box of questions and speculations concerning the ability of these viruses to cross over from one species to another.

To further explore SIVgor as it relates to HIV-1 group O infection in humans, Dr. Peeters’ group will be conducting additional studies to determine the prevalence, geographical distribution, and biology of the virus in these great apes.