KwaZulu-Natal woman opens new window for HIV vaccine

South African researchers say they are a step closer to finding a way to treat and prevent HIV, after scientists found an antibody in a KwaZulu-Natal woman that effectively kills half of all the viruses it encounters.

Researchers believe that if a vaccine could elicit potent antibodies to a specific conserved site in the 'V1V2' region of the virus, one of a handful of sites that remains constant on the fast-mutating virus, then the vaccine could protect people from HIV infection.

Analyses of the results of a clinical trial of the only experimental HIV vaccine to date to have modest success in people suggest that antibodies to sites within V1V2 were protective.

The new findings point the way towards a potentially more effective vaccine that would generate V1V2-directed HIV neutralising antibodies, the researchers said.

In the study, led by the National Institute of Allergy and Infectious Diseases (NIAID) in Pretoria, scientists began by identifying an HIV-infected volunteer who naturally developed V1V2-directed HIV neutralising antibodies, named CAP256-VRC26, after several months of infection.

Using techniques similar to those employed in an earlier study of HIV-antibody co-evolution, the researchers analysed blood samples donated by the volunteer between 15 weeks and 4 years after becoming infected.

This enabled the scientists to determine the genetic make-up of the original form of the antibody; to identify and define the structures of a number of the intermediate forms taken as the antibody mutated towards its fullest breadth and potency.

It also allowed them to describe the interplay between virus and antibody that fostered the maturation of CAP256-VRC26 to its final, most powerful HIV-fighting form.

The study showed that after relatively few mutations, even the early intermediates of CAP256-VRC26 can neutralise a significant proportion of known HIV strains.

This improves the chances that a V1V2-directed HIV vaccine developed based on the new findings would be effective, according to scientists, who have begun work on a set of vaccine components designed to elicit V1V2 neutralising antibodies and guide their maturation.

Their report was published by the internationally respected science journal Nature.

An estimated 30 per cent of all people in the world being treated for HIV/Aids live in South Africa. Efforts to understand, treat and eventually cure the life-threatening illness have rapidly increased over the years.

Now, with the research done by local scientists in a region where the disease is most endemic, the way the virus is tackled medically may drastically change and it's all because of a broadly neutralising antibody found in some HIV patients.