HIV ability to cause AIDS in decline

A new study has examined that HIV's ability to cause AIDS is slowing down.

The study led by researchers at the University of Oxford also indicated that people infected by HIV were likely to progress to AIDS more slowly i.e. the virus became less "virulent" because of widespread access to antiretroviral therapy (ART).

The research was carried out in Botswana and South Africa, two countries that have been worst affected by the HIV epidemic. Across those countries, researchers enrolled over 2000 women with chronic HIV infection to take part in the study.

This study showed that in Botswana, where HIV has evolved to adapt to HLA-B*57 more than in South Africa, patients no longer benefit from this gene's protective effect. However, the team's data show that the cost of this adaptation to HIV is that its ability to replicate is significantly reduced, therefore making the virus less virulent.

In the second part of the study the authors examined the impact of ART on HIV virulence as they developed a mathematical model, which concluded that selective treatment of people with low CD4 counts will accelerate the evolution of HIV variants with a weaker ability to replicate.

Lead scientist, Professor Phillip Goulder from the University of Oxford, said that this research highlighted the fact that HIV adaptation to the most effective immune responses they could make against it comes at a significant cost to its ability to replicate.

The study is published in the journal Proceedings of the National Academy of Sciences (PNAS).