Monday, September 21, 2009
Scientists find HIV's 'missing link' in ill chimps
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WASHINGTON – Scientists believe they have found a "missing link" in the evolution of the virus that causes AIDS. It bridges the gap between the infection that does no harm to most monkeys and the one that kills millions of people. That link is a virus that is killing chimpanzees in the wild at a disturbingly high rate, according to a study in Thursday's journal Nature.
Chimpanzees are the first primate besides man shown to get sick in the wild in significant numbers from a virus related to HIV. Chimps are also man's closest relative among primates.
And chimps are already endangered.
But the discovery of the disease killing chimps may help doctors come up with better treatments or a workable vaccine for humans, experts said.
The monkey version of the virus that causes AIDS is called simian immunodeficiency virus (SIV), but most apes and monkeys that have it show no symptoms or illness. So "if we could figure out why the monkeys don't get sick, perhaps we could apply that to people," said study lead author Beatrice Hahn, a professor of medicine at the University of Alabama at Birmingham.
The nine-year study of chimps in their natural wild habitat at Gombe National Park in Tanzania found chimps infected with SIV had a death rate 10 to 16 times higher than uninfected chimps. And necropsies of dead infected chimps showed unusually low counts of T-cell white blood proteins that are just like the levels found in humans with AIDS, Hahn said in a phone interview.
And when scientists looked at the particular strain, they found that it was the closest relative possible to the virus that first infected humans.
"From an evolutionary and epidemiological point of view, these data can be regarded as a 'missing link' in the history of the HIV pandemic," AIDS researcher Dr. Daniel Douek of the National Institute of Allergy and Infectious Diseases wrote in an e-mail. Douek was not involved in the Nature study.
Monkeys and apes - except for chimps - seem to survive the virus because of some kind of evolutionary adaptation, probably on the cell receptors, Douek wrote. The infection of chimps is more recent so they haven't adapted, he wrote.
Hahn said chimps and people probably caught the virus the same way, by eating infected monkeys. And they both spread it the same way, through sexual activity.
Many factors are causing Africa's chimp population to dwindle, said study co-author Michael Wilson, a professor of anthropology at the University of Minnesota and former director of field research at the Jane Goodall Institute in Tanzania. Hunting, loss of habitat and disease are decreasing chimp numbers and it's hard to figure out how much of a factor SIV is, he said.
"It is a concern," Wilson said. "The last thing these chimps need is another source of mortality."
Wilson, who spent years observing chimps in Tanzania as part of the study, said that when researchers realized the virus was fatal and they knew which chimps were infected, it became hard to watch some of their activities in the wild.
He recalled wanting to warn one female chimp, "Don't mate with those guys." Wilson said. "But of course I can't do that."
By SETH BORENSTEIN, AP Science Writer
Labels: aids, simian immunodeficiency virus, trends newsletter
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Monday, February 9, 2009
Early study shows AIDS-fighting gel promising
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ATLANTA - An experimental vaginal gel has shown some promise in preventing infection from the AIDS virus - the first study to offer hope that a microbicide may soon join the medical arsenal in the international battle against HIV, scientists announced Monday.
The results were not conclusive in this preliminary study, but they were welcome news considering the failure of other similar products. The multi-country study suggests a gel made by Massachusetts-based Indevus Pharmaceuticals Inc. cut HIV infection to a slight degree, a researcher said Monday at a medical conference.
Scientists have been trying to develop gels and other microbicides for women to use as protection in parts of the world where their partners may refuse to use condoms.
"This is the first study that now shows we have a promising candidate," said Salim Abdool Karim, the South African researcher who presented the results.
About 3,100 women participated in the study, which was designed mainly to test whether it was safe. The women were divided into four groups. One-quarter of them used the Indevus gel, which is supposed to block the AIDS virus from attaching to certain white blood cells.
Another quarter were put on a gel made by Baltimore-based ReProtect Inc. The rest were given a placebo gel, or no gel at all.
All the women were counseled to have their partners use condoms. The study was done in South Africa, Malawi, Zambia, Zimbabwe and the United States, and was funded by the U.S. National Institutes of Health.
Researchers found that women who used the Indevus-made gel had a 30 percent lower rate of HIV infection than the other women in the study. But the difference was not statistically significant, meaning the results could have occurred by chance.
Health officials say larger studies are needed to better assess effectiveness. Such a study of the Indevus gel, involving 9,400 African women, is to conclude in August.
The results were presented at a medical conference on retroviruses in Montreal.
By MIKE STOBBE, AP Medical Writer
The results were not conclusive in this preliminary study, but they were welcome news considering the failure of other similar products. The multi-country study suggests a gel made by Massachusetts-based Indevus Pharmaceuticals Inc. cut HIV infection to a slight degree, a researcher said Monday at a medical conference.
Scientists have been trying to develop gels and other microbicides for women to use as protection in parts of the world where their partners may refuse to use condoms.
"This is the first study that now shows we have a promising candidate," said Salim Abdool Karim, the South African researcher who presented the results.
About 3,100 women participated in the study, which was designed mainly to test whether it was safe. The women were divided into four groups. One-quarter of them used the Indevus gel, which is supposed to block the AIDS virus from attaching to certain white blood cells.
Another quarter were put on a gel made by Baltimore-based ReProtect Inc. The rest were given a placebo gel, or no gel at all.
All the women were counseled to have their partners use condoms. The study was done in South Africa, Malawi, Zambia, Zimbabwe and the United States, and was funded by the U.S. National Institutes of Health.
Researchers found that women who used the Indevus-made gel had a 30 percent lower rate of HIV infection than the other women in the study. But the difference was not statistically significant, meaning the results could have occurred by chance.
Health officials say larger studies are needed to better assess effectiveness. Such a study of the Indevus gel, involving 9,400 African women, is to conclude in August.
The results were presented at a medical conference on retroviruses in Montreal.
By MIKE STOBBE, AP Medical Writer
Labels: aids, aids drug, hot trends 2009, indevus gel
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