Origin of HIV-1 Discovereda

Origin of HIV-1 Discovered

To place any conspiracy theory into perspective, consider the following media release from scientists at the University of Alabama at Birmingham, titled "Origin of HIV-1 Discovered" (posted on January 31, 1999 at 1:52 p.m.):

BIRMINGHAM, AL — Scientists at the University of Alabama at Birmingham (UAB) have discovered the origin of Human Immunodeficiency Virus Type 1 (HIV-1), the virus that causes AIDS in humans. This finding by an international team of scientists led by Dr. Beatrice H. Hahn of

UAB AIDS Researchers Dr. Beatrice Hahn and George Shaw, M.D., Ph.D. Image Source: UAB Media Relations

UAB, solves a 20-year-old puzzle regarding the beginnings of the AIDS epidemic which now afflicts some 30 million people worldwide. Hahn presented her study today at the 6th Conference on Retroviruses and Opportunistic Infections in Chicago. A paper detailing the discovery appears in the February 4 issue of the journal Nature.

Hahn, a professor of medicine and microbiology at UAB, is senior author of the paper. Dr. Feng Gao, research assistant professor of medicine at UAB, is the paper's lead author.

The researchers identified a subspecies of chimpanzee (Pan troglodytes troglodytes) native to West-Central Africa as the natural reservoir for HIV-1. "We have long suspected a virus from African primates to be the cause of human AIDS, but exactly which animal species was responsible was unknown," says Gao. Viruses related to HIV-1 had previously been found in chimpanzees and were given the designation SIVcpz (for Simian Immunodeficiency Virus). However, only three such infected animals were identified, and one of these harbored a virus so different from HIV-1 that most scientists questioned a direct relationship to the human virus.

The recent breakthrough came when Hahn and her colleagues identified a fourth SIVcpz infected chimpanzee and used sophisticated molecular techniques to analyze all four viruses and the animals from which they were derived. The researchers found that three of the four SIVcpz strains came from chimpanzees that belonged to one particular subspecies, termed Pan troglodytes troglodytes, which is native to West-Central Africa. The fourth virus strain, which was genetically divergent from the other three, came from an animal that belonged to a different chimpanzee subspecies, termed Pan troglodytes schweinfurthi, which is native to East Africa. The scientists then discovered that all known strains of HIV-1, including the major group M (responsible for the global AIDS epidemic) as well as groups N and O (found only in West-Central Africa), were closely related only to SIVcpz strains infecting Pan troglodytes troglodytes.

The final piece of the puzzle was put in place when the researchers realized that the natural habitat for Pan troglodytes troglodytes overlaps precisely with the region in West-Central Africa where all three groups of HIV-1(M, N, and O) were first recognized. Based on these findings, Hahn and her colleagues concluded that Pan troglodytes troglodytes is the origin of HIV-1 and has been the source of at least three independent cross-species transmission events of SIVcpz.