[LINK] On the possible evolution of HIV towards decreased virulence

[rfmcdonald]

Livejournal's robby pointed me to the New Scientist article suggesting that HIV is becoming less virulent over time in many populations.

To track how HIV has been evolving, Philip Goulder of the University of Oxford and his colleagues compared HIV samples taken from 842 pregnant women in Botswana and South Africa. In Botswana, the epidemic took off in the mid-1980s, compared with the mid-90s in South Africa – so HIV in Botswana has had about a decade longer to evolve.

When tested on cells grown in a lab, the HIV from Botswana reproduced more slowly than that from South Africa, which should mean it takes longer to destroy people's immune systems and result in AIDS.

"To show it's adapting so rapidly is very significant," says José Borghans of the University Medical Center Utrecht in the Netherlands.

One reason for the change could be the growing use of HIV drugs, says Goulder. People with the most virulent form of the virus get sick sooner and start drug treatment. This reduces the level of the virus in their blood and sexual fluids almost to zero, so they are unlikely to pass it on. This means that a more aggressive virus is less likely to be transmitted.

"It's a benefit of therapy that nobody thought of," says Goulder. "That's another reason to provide it."

The study in question, "Impact of HLA-driven HIV adaptation on virulence in populations of high HIV seroprevalence", is available here from the Proceedings of the National Academy of Sciences.