HIV may evolve to cause AIDS less frequently

LONDON – HIV may be evolving to become less aggressive, suggesting that one day it may infect humans without causing AIDS.

Women with HIV in South Africa are more likely to have AIDS than a similar group in Botswana, where the disease arrived a decade earlier. The comparison indicates that HIV eventually evolves into a less virulent form, according to the study published Monday in the Proceedings of the National Academy of Sciences.

“If this process is something we can see continuing as a trend, then the ability of HIV to cause disease will become less and less over time,” Philip Goulder, a professor of pediatric immunology at the University of Oxford and the study’s lead author, said in an interview.

About 35 million people are infected with HIV, according to the World Health Organization, and about one-third receive anti-retroviral therapies, the standard treatment. About 1.5 million people died from AIDS last year. Currently, about half of 1 percent of people with HIV will never develop AIDS, and that proportion will probably grow, Goulder said.

In the women in Botswana, HIV had evolved to adapt to a protein that shields the body from the virus. While patients lose the “protective effect” of the protein, the adaptation means the ability of the virus to replicate is significantly reduced.

The study indicates that treatment with anti-retroviral drugs speeds the evolution of HIV into a less virulent form.

“Anything we can do to increase the pressure on HIV in this way may allow scientists to reduce the destructive power of HIV over time,” Goulder said in a statement.

The prevalence of HIV and the genetic homogeneity of the population studied may have allowed the virus to adapt more quickly than it would in more ethnically diverse places such as North America and the U.K., Goulder said.

“If you have a very heterogeneous population, the genes acting on the virus are many and varied, and are not all working in the same direction,” he said.

The researchers studied more than 2,000 women with chronic HIV infection. The study, funded by the Wellcome Trust, was led by Oxford researchers, along with scientists from South Africa, Canada, Japan, Harvard University and Microsoft Research.

The changes in HIV are a rare opportunity for scientists, according to Goulder.

“We have the opportunity in HIV to see evolution happen before our eyes,” he said. “We haven’t ever really been able to view this evolution in so much detail.”