HIV Is Becoming Milder And Its Ability To Cause AIDS Is Slowing

Chuck Bednar for redOrbit.com – Your Universe Online
The ability of HIV to cause AIDS is weakening, and the virus is becoming less deadly and less infectious as it adapts to our immune systems, according to new research published Monday in the journal Proceedings of the National Academy of Sciences (PNAS).
The study, which was led by scientists at the University of Oxford, indicates the virus is becoming “watered down” and is taking longer for HIV infection to cause AIDS. In addition, the changes in the pathogen could not only help efforts to contain the pandemic, but could one day cause it to evolve to an “almost harmless” state.
In addition, the research revealed that people infected by HIV are likely to progress to AIDS more slowly due to the widespread availability of antiretroviral therapy (ART), the university explained in a statement. When combined, both factors could go a long way to the ultimate goal of controlling and eventually eradicating the HIV epidemic, the study authors noted.
As part of the study, which also involved scientists from South Africa, Canada, Japan and the US, the authors recruited more than 2,000 women with chronic HIV infection from two of the countries that have been affected the worst by the spread of the disease: Botswana, which has long had an HIV problem, and South Africa, where the disease arrived over a decade later.
The first part of the study examined whether the interaction between the body’s natural immune response and HIV leads to the virus becoming less virulent. This part of the investigation focused on human leukocyte antigens (HLA), proteins in our blood that enable the immune system to tell the difference between natural proteins and those of pathogens. Specifically, they looked at a gene for a particular HLA protein called HLA-B*57.
The researchers explained that infected patients with HLA-B*57 are known to benefit from a “protective effect” to HIV, meaning that they tend to progress more slowly than usual to AIDS. Their investigation revealed that in Botswana, HIV had evolved to adapt to HLA-B*57 more than in South Africa, and that patients no longer benefitted from the protective effect of the gene, but that adaptation “significantly reduced” the virus’ ability to self-replicate.
“It is quite striking. You can see the ability to replicate is 10 percent lower in Botswana than South Africa and that’s quite exciting,” Professor Philip Goulder told BBC News. “We are observing evolution happening in front of us and it is surprising how quickly the process is happening. The virus is slowing down in its ability to cause disease and that will help contribute to elimination.”
In the second part of the study, Goulder and his colleagues probed the impact of ART on HIV virulence. They created a mathematical model which suggested that the way treatment is provided to those with more virulent HIV is accelerating the evolution of HIV viruses with a weaker ability to replicate. The paper demonstrated that these drugs would primarily target the most dangerous forms of the virus, thus encouraging the weaker ones to thrive.
“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,” Goulder said. “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.”
“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,” added Dr. Mike Turner, Head of Infection and Immunobiology at the Wellcome Trust, which helped fund the study.
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