The Human Immunodeficiency Virus, HIV, is evolving rapidly and this is weakening its ability to cause Acquired Immunodeficiency Syndrome, AIDS, according to a new University of Oxford-led study.
The study concluded that the decreasing virulence of HIV could lead to the end of the AIDS pandemic.
According to the study titled, “Impact of HLA-driven HIV adaptation on virulence in populations of high HIV seroprevalence,” funded by the Wellcome Trust and published in the journal Proceedings of the National Academy of Sciences (PNAS), the decreasing virulence of HIV due to its evolution could be one of the major factors causing the recently observed slowing of the AIDS pandemic.
The team of researchers, which included scientists from the Oxford University in the UK, South Africa, Canada, Tokyo, Harvard University and Microsoft Research, conducted a study involving over 2,000 women with chronic HIV infection from Botswana and South Africa, two countries most affected by the AIDS pandemic.
The study found that the body’s natural immune response to HIV infection has contributed to the lowering of the virulence of HIV over the decades and slowing of the AIDS pandemic.
Previous studies have confirmed that people with a gene that synthesizes a variant of the human leukocyte antigen (HLA), called HLA-B*57, have an increased ability to resist HIV infection.
Antigens are special types of proteins that mediate the response of the human immune system to infection by helping the immune system to distinguish the body’s proteins from the proteins of the pathogens.
The extra resistance to HIV infection conferred by HLA-B*57 helps to slow down the progress of HIV infection to AIDS; that is, people with the HLA-B*57 protein progress to AIDS much slower than people who do not have the gene.
However, the study found that after three decades of the pandemic, HIV has evolved to adapt to the special resistance or extra immunity induced by HLA B*57 so that people with the variant protein no more enjoy the benefit of the protective effect of the protein. But the researchers noted that the adaptation of HIV to HLA-B*57 was more pronounced among HIV-infected people from Botswana than among those from South Africa.
Further analysis of the effect of the HLA-B*57 protein revealed that the cost to HIV of its adaptation to the novel protein was a reduction in its ability to multiply or replicate. According to Philip Goulder, professor at Oxford, who was involved in the study, the weakening of the ability of HIV to replicate reduces its virulence.
“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. 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 explained further that the study also looked at the effect of the widespread use of antiretroviral therapy (ART) drugs on the virulence of HIV and found that aggressive treatment of people with virulent forms of the infection encourages the emergence of variants of the virus that have a weaker ability to replicate.
Mike Turner, expert in immunobiology at Wellcome Trust, noted that widespread use of ART has contributed significantly to the gradual eradication of HIV and AIDS.
“The widespread use of ART is an important step towards the control of HIV. This research is a good example of how further research into HIV and drug resistance can help scientists to eliminate HIV.”
The WHO estimated in 2013 that in the last three decades, about 35 million people have been infected with HIV worldwide and that about 40 million have died from HIV infection leading to full-blown AIDS.