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5 December 2013 11:26 am ,
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An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
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Study Pushes AIDS Origins Back to 1930s
9 June 2000 6:00 pm
The strain of virus responsible for nearly all cases of AIDS first appeared in the 1930s, say scientists who used a "molecular clock" to date the origin of HIV. The finding, reported in the 9 June issue of Science, casts doubt on the controversial idea that contaminated polio vaccines seeded the AIDS pandemic in the late 1950s.
The origin of AIDS is much clearer today than it was in the early 1980s, when the new disease blindsided the scientific establishment. Virologists have identified the chimpanzee virus that probably gave rise to HIV, while epidemiologists have rummaged through old samples and forgotten medical records to identify early cases. Still, the trail of direct evidence stops with an HIV-positive blood sample drawn in 1959 in what is now the Democratic Republic of Congo. How and when the chimpanzee virus entered humans remains uncertain.
To look farther into HIV's murky past, theoretical biologist Bette Korber of Los Alamos National Laboratory in New Mexico and her colleagues used a statistical model to clock the evolution of HIV's envelope gene, which codes for one of the spiky proteins jutting from the virus's surface. With help from a supercomputer, Korber's group compared 159 gene sequences from viruses in the so-called M group, which causes the majority of AIDS cases worldwide. Assuming that differences between genes accumulate at a constant rate, the researchers calculated that the common ancestor of all the M group viruses arose between 1915 and 1941--most likely in 1931. They believe the virus had already jumped to humans at this time; a later invasion would require that multiple viral strains entered people before spreading from person to person--a scenario Korber calls very unlikely.
The study impresses other scientists in the field. "It's the best analysis by a long way that's been carried out in this area," says molecular evolutionist Paul Sharp of the University of Nottingham in the United Kingdom. If confirmed, the early date would squash the hypothesis--described recently in a book called The River (Science, 12 November 1999, p. 1305)--that the AIDS pandemic was triggered by an oral polio vaccine inadvertently contaminated with the chimpanzee virus.