Read Online The Chimp and the River: How AIDS Emerged from an African Forest by David Quammen - Free Book Online Page A
Authors: David Quammen
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National Park, in Tanzania, where Jane Goodall had done her historic field study, beginning back in 1960. That trace of virus didn’t match quite as closely with HIV-1 as Feng Gao’s had done, and it came from a chimp of a different subspecies, the eastern chimpanzee, Pan troglodytes schweinfurthii . But it was SIV cpz nonetheless.
The advantage of sampling at Gombe, Hahn told me, was that those chimps didn’t run away. They were truly wild but, after four decades of study by Goodall and her successors, well habituated to human presence. For use elsewhere, the urine-screening method wasn’t practical. “Because, you know, non-habituated chimps don’t stay close enough so you can catch their pee.” Youcould collect their poop from the forest floor, of course, but fecal samples were useless unless preserved somehow; fresh feces contain an abundance of proteases, digestive enzymes, which would destroy the evidence of viral presence long before you got to your laboratory. These are the constraints within which a molecular biologist studying wild animals labors: the relative availability and other parameters of blood, shit, and piss.
Another of Hahn’s young wizards, Brandon F. Keele, soon solved the problem of fecal sample decay. He did it by tinkering with a liquid stabilizer called RNAlater, a commercial product made by a company in Austin, Texas, for preserving nucleic acids in tissue samples. The nice thing about RNAlater is that its name is so literally descriptive: The stuff allows you to retrieve RNA from a sample . . . later. If it worked with RNA in tissues, Keele reasoned, maybe it could work also with antibodies in feces. And indeed it did, after he and his colleagues untangled the chemical complications of getting those antibodies released from the fixative. This technique vastly enlarged the scope of screening that was possible on wild chimpanzees. Field assistants could collect hundreds of fecal samples, scooping each into a little tube of RNAlater, and those samples—stored without refrigeration, transported to a distant laboratory—would yield their secrets later. “If we find the antibodies, we know that chimps are infected,” Hahn told me. “And then we can home in on those we know are infected, and try to get the viruses out.” Antibody screening is easy and quick. Performing PCR amplification and the other requisite steps to probe for fragments of viral RNA is far more laborious. The new methods allowed Hahn and her group to look first at a large number of specimens and then work more concertedly on a select few. They could separate the Shinola from the shit.
And they could expand their field surveying beyond Gombe.They could turn their attention back to Pan troglodytes troglodytes, the subspecies of chimp whose SIV cpz most closely matched HIV-1. Working now with Martine Peeters of Montpellier, plus some contacts in Africa, they collected 446 samples of chimpanzee dung from various forest sites in the south and southeast of Cameroon, after which Brandon Keele led the laboratory analysis. DNA testing showed that almost all the samples came from P. t. troglodytes (though a couple dozen derived from a different chimp subspecies, P. t. vellerosus , whose range lay just north of a major river). Keele then looked for evidence of virus. The samples yielded two surprising results.
11
T ohear about those surprises, I visited Brandon Keele, who by this time had finished his postdoc with Hahn and gone off to a research position at a branch of the National Cancer Institute, in Frederick, Maryland. He was still studying viral phylogenetics and AIDS, as head of a unit devoted to viral evolution. His new office and lab were on the grounds of Fort Detrick, a high-security installation that once housed the U.S. biological weapons program and still encompasses USAMRIID, the big army research institute on infectious diseases. Since I was entering without an escort, soldiers at the guardhouse searched the
The advantage of sampling at Gombe, Hahn told me, was that those chimps didn’t run away. They were truly wild but, after four decades of study by Goodall and her successors, well habituated to human presence. For use elsewhere, the urine-screening method wasn’t practical. “Because, you know, non-habituated chimps don’t stay close enough so you can catch their pee.” Youcould collect their poop from the forest floor, of course, but fecal samples were useless unless preserved somehow; fresh feces contain an abundance of proteases, digestive enzymes, which would destroy the evidence of viral presence long before you got to your laboratory. These are the constraints within which a molecular biologist studying wild animals labors: the relative availability and other parameters of blood, shit, and piss.
Another of Hahn’s young wizards, Brandon F. Keele, soon solved the problem of fecal sample decay. He did it by tinkering with a liquid stabilizer called RNAlater, a commercial product made by a company in Austin, Texas, for preserving nucleic acids in tissue samples. The nice thing about RNAlater is that its name is so literally descriptive: The stuff allows you to retrieve RNA from a sample . . . later. If it worked with RNA in tissues, Keele reasoned, maybe it could work also with antibodies in feces. And indeed it did, after he and his colleagues untangled the chemical complications of getting those antibodies released from the fixative. This technique vastly enlarged the scope of screening that was possible on wild chimpanzees. Field assistants could collect hundreds of fecal samples, scooping each into a little tube of RNAlater, and those samples—stored without refrigeration, transported to a distant laboratory—would yield their secrets later. “If we find the antibodies, we know that chimps are infected,” Hahn told me. “And then we can home in on those we know are infected, and try to get the viruses out.” Antibody screening is easy and quick. Performing PCR amplification and the other requisite steps to probe for fragments of viral RNA is far more laborious. The new methods allowed Hahn and her group to look first at a large number of specimens and then work more concertedly on a select few. They could separate the Shinola from the shit.
And they could expand their field surveying beyond Gombe.They could turn their attention back to Pan troglodytes troglodytes, the subspecies of chimp whose SIV cpz most closely matched HIV-1. Working now with Martine Peeters of Montpellier, plus some contacts in Africa, they collected 446 samples of chimpanzee dung from various forest sites in the south and southeast of Cameroon, after which Brandon Keele led the laboratory analysis. DNA testing showed that almost all the samples came from P. t. troglodytes (though a couple dozen derived from a different chimp subspecies, P. t. vellerosus , whose range lay just north of a major river). Keele then looked for evidence of virus. The samples yielded two surprising results.
11
T ohear about those surprises, I visited Brandon Keele, who by this time had finished his postdoc with Hahn and gone off to a research position at a branch of the National Cancer Institute, in Frederick, Maryland. He was still studying viral phylogenetics and AIDS, as head of a unit devoted to viral evolution. His new office and lab were on the grounds of Fort Detrick, a high-security installation that once housed the U.S. biological weapons program and still encompasses USAMRIID, the big army research institute on infectious diseases. Since I was entering without an escort, soldiers at the guardhouse searched the
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