Is HIV Losing its Bite?

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HIV’s grip on the world is weakening, say scientists from UKZN, the University of Oxford as well as leading institutions in the United States, Japan and Botswana, who collaborated on a scientific study.

Findings in the study, Proceedings of the National Academy of Sciences, clearly indicate that the HI virus is evolving into a much milder form due to the introduction of antiretrovirals (ARVs) as well as the natural adaptation of the immune system to the virus.

Co-author of the study, UKZN’s Professor Thumbi Ndung’u, who is also an investigator at the KwaZulu-Natal Research Institute for Tuberculosis and HIV and the Victor Daitz Chair in TB and HIV, said: ‘We investigated the impact on HIV virulence of HIV adaptation to HLA molecules that protect against disease progression by analysing cohorts in Botswana and in Durban. Our findings indicate that in Botswana, where the epidemic started earlier, the viral replicative capacity is lower. These data suggest that the virus is evolving to a much milder form.’

Lowering of the viral replication capacity is also attributed to the effects of ARVs. One of the most successful public health interventions ever undertaken has been the provision of combination antiretroviral therapy (ART) to more than 6.2 million people in sub-Saharan Africa.

Professor Frank Tanser, a research Professor in UKZN’s College of Health Sciences at the Africa Centre for Health and Population Studies which is based in a rural community in northern KwaZulu-Natal severely affected by HIV, recently published a study in the journal Science which received substantial international recognition. The study found that the HIV epidemic could be reversed through increasing coverage of ART bringing about a decreased risk of onward transmission of HIV.  

Ndung’u says the new study provides some mechanistic explanation for the observations made in the previous Tanser study that ARVs were forcing HIV to evolve into milder forms. ‘Our study showed that the drugs primarily target the nastiest versions of HIV and encourage the milder ones to thrive. Our study also found that in Botswana, where 20 years ago the progression to AIDS following infection was 10 years, the period has now increased to 12.5 years given the increase in ARV roll-out and the adaptation of the virus to the immune system.’

Professor Jonathan Ball, a Virologist at the University of Nottingham, remarked: ‘If the trend continues then we might see the global picture change - a longer disease causing much less transmission. In theory, if we were to let HIV run its course then we would see a human population emerge that was more resistant to the virus than we collectively are today - HIV infection would eventually become almost harmless.’

The scientists however warned that even milder forms of HIV can lead to AIDS and cautioned the public to remember that HIV was still dangerous.

MaryAnn Francis