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| Vol. 24, No. 15 | February 16, 1999 |
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| Vol. 24, No. 15 | February 16, 1999 |
BY BOB NELSON
Researchers who announced last week that they had traced the AIDS virus to an endangered subspecies of chimpanzee found only in Central Africa drew extensively on genetic sleuthing conducted by Columbia scientists.
The Columbia team included Don J. Melnick, a molecular evolutionary geneticist, professor of anthropology and biological sciences and director of the Center for Environmental Research and Conservation (CERC), based at Columbia, and Juan Carlos Morales, associate research scientist at CERC.
The genetic research redefined the geographic boundaries among the three commonly accepted subspecies of chimpanzee, clarified relationships among the branches of the chimpanzee family tree and showed that genetic differences indicated a fourth subspecies. It also called for renewed conservation efforts on behalf of Central African chimps, which along with other primates increasingly are being hunted for food.
The findings were published in 1997 in the British journal Nature by a team that also included scientists from Hunter College and NYU.
That research allowed a team headed by Beatrice Hahn of the University of Alabama at Birmingham to pinpoint the geographical area-Gabon, southern Cameroon and the northern half of the Congo Republic-where humans acquired the HIV virus and to say from precisely which species: the chimpanzee subspecies known as Pan troglodytes troglodytes. The new research appears in the Feb. 5 issue of Nature.
The Alabama researchers sequenced the DNA from four samples of an immunodeficiency virus that had been acquired by chimpanzees in the wild. The scientists identified one strain of the virus that was closely related to HIV-1, the strain that causes most cases of AIDS in humans.
The scientists then turned to Columbia's research. By using the phylogenetic tree published by Melnick and his colleagues, they demonstrated which subspecies of chimpanzee harbors that strain of the virus and where in Africa it lives.
Melnick points to this important discovery in AIDS research as evidence of the critical need for basic science research: "What might seem like an arcane activity can have tremendous value. In this case, it took only a year for our study to prove its worth to an entirely different field of research."
The repeated or extensive contact required to transmit a virus from animal to human has only been possible since logging roads have been built through the region, offering poor villagers the opportunity both to hunt primates and to transport the meat to urban markets. As humans continue to disturb natural ecosystems, especially those of closely related primates, chances increase that they will be exposed to new disease agents, Melnick said.
"And if you kill off the previous hosts of a microorganism, where the two had evolved some kind of symbiosis, and destroy the habitat, you give that microorganism no place to go but into the immunologically naive human population," Melnick said.
"We've already had Ebola virus in Africa, hantavirus in the southwestern United States and Lyme disease in the Northeast, all of which are examples of disease being transferred to humans when ecosystems are disturbed. If we continue in this direction, we're just asking for trouble."
Even though chimpanzees can become infected with a virus similar to AIDS, they don't seem to become ill, and that fact might point to new ways to control the spread of AIDS.