HIV's "Mising link" in chimps

Source TOI July 24 , 2009

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 one that kills millions of people. That link is a virus that is killing chimpanzees in the wild a disturbingly high rate, according to a study in Nature.

Chimpanzees are the first primates besides man shown to get sick in the wild in significant numbers from a virus related to HIV. The discovery of disease killing chimps may help doctors come up with a workable vaccine for humans.

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 lead author BEAtrice Hahn, a professor at the University of Alabama at Birmingham.

The study found chimps infected with SIV had death rate 10 to 16 time higher than uninfected chimps. Necropsies of dead infected shows low counts of T-cell white blodd protiens that are just like the levels found in humans with AIDS. And when experts looked at a particular strain, they found that it wa closest relative possible to the virus that first infected humans.

AIDS virus weakening, says a study

LONDON: The HIV virus that causes AIDS, the fatal disease of the immune system, is becoming less aggressive, researchers have said in a landmark new study, amid surging speculation about the implications for the global fight against a pandemic that has killed an estimated 30 million people worldwide.

Researchers at the Institute of Tropical Medicine in Antwerp, Belgium, compared HIV-1 samples from 1986-89 and 2002-03 and found that 75 per cent of the newer samples appeared less fit than those of 15 years ago both in terms of spread within individuals and transmission to others.

Speaking to TOI from Antwerp, Dr Kevin Arien, who wrote the paper and is one of the lead researchers said: "From our study, based on 24 patient HIV-1 isolates, we have observed that historical viruses were more fit than recent HIV-1 isolates".

In layman's terms, explained Keith Alcorn, Senior Editor of National AIDS Manual, the UK's best scientific reference on HIV, that means "the virus is weakening and may be in 50 or a 100 years, it will adapt to living with its human host but cause less disease".

The study, titled 'Replicative fitness of historical and recent HIV-1 isolates suggests HIV-1 attenuation over time', is published in AIDS the official Journal of the International AIDS Society.

Source: Times of India (New Delhi)