Awareness and understanding of HIV has led many to be more "protected" from the disease, either through safe sex practice and abstinence or by engaging in advocacy campaigns to educate those from high-risk groups. And such a positive response to the disease has ushered in its better management, as well as an improvement in the number of infected individuals over the years. But a lot has happened since HIV-AIDS became an epidemic, killing hundreds of thousands of people worldwide, with the majority coming from highly-affected countries in Africa.

Recent developments in the study of HIV has revealed additional information about the disease. A new study conducted by an international team of researchers found that the rapid evolution of HIV is also slowing the virus's ability to cause AIDS. Researchers said that HIV's adaptation to protective genes reduces its ability to replicate significantly.

The availability of antiretroviral (ARV) therapy is also linked to HIV's slower progression to AIDS, according to the study which was led by researchers from the University of Oxford, and scientists from South Africa, Canada, Tokyo, Harvard University and Microsoft Research.

The research, recently published in the journal Proceedings of the National Academy of Sciences (PNAS), was undertaken in South Africa and Botswana and was participated by over 2,000 women with chronic HIV infection.

Reports said that the first part of the study looked at whether the interaction between the body's natural immune response and HIV leads to the virus becoming less virulent.

Proteins in the blood called the human leukocyte antigens (HLA) were relevant in the study as these enable the immune system to differentiate between the human body's proteins and the proteins of pathogens.

The findings showed that people with a gene that expresses a particular HLA protein called HLA-B*57, are known to benefit from a 'protective effect' to HIV. Infected patients with the HLA-B*57 gene progress more slowly to AIDS than usual, reports said.

The 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.

The authors showed that viral adaptation to protective gene variants, such as HLA-B*57, is driving down the virulence of transmitted HIV and slowly eliminates the virus.

The second part of the study involved the impact of antiretrovirals on HIV virulence.

The researchers 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," a news report explained.

"This research highlights the fact that HIV adaptation to the most effective immune responses we can make against it comes at a significant cost to its ability to replicate," said lead scientist, Professor Phillip Goulder from the University of Oxford.