Scientists closer to developing more effective HIV vaccine

Washington: Scientists have tracked the earliest days of a man's robust immune response to HIV which may lead to a potential new vaccine for the deadly virus. The research team, led by Barton F Haynes from Duke Human Vaccine Institute and John Mascola of the NIH Vaccine Research Center, has for the first time described the co-evolution of antibodies and virus in a person with HIV whose immune system mounted a broad attack against the pathogen.

Most vaccines work by inducing this antibody response, but the HIV virus has proved to be a difficult vaccine target, according to the findings published in the journal Nature. When HIV antibodies are produced, they typically have a limited range, and the virus changes rapidly to escape harm, leading to an arms race that the virus usually wins. The current research was aided by new technologies that can detect early infection and track the subsequent immune response and virus evolution, 'Medicalxpress' reported.

It fills gaps in knowledge that have impeded development of an effective vaccine for a virus that has killed more than 30 million people worldwide. "For the first time, we have mapped not only the evolutionary pathway of the antibody, but also the evolutionary pathway of the virus, defining the sequence of events involved that induce the broadly neutralising antibodies," said Haynes. The key to this finding was a person in Africa whose HIV infection was detected so early that the virus had not yet mutated to avoid the immune assault.

The individual also exhibited a fortuitous trait that occurs in only about 20 per cent of people infected with HIV, an immune system that produces broadly neutralising antibodies. These immune weapons attack vulnerable sites of the virus that are conserved despite mutations. In identifying the early viral infection, the team found the outer envelope, the viral surface glycoprotein, which triggered the start of the broadly neutralising antibody development.

By tracking the precise virus and antibody pathways involved, the researchers now have a detailed road map for development of a potential vaccine, which involves immunogens with an outer envelope specifically selected to stimulate the production of broadly neutralising antibodies. "The next step is to use that information to make sequential viral envelopes and test them as experimental vaccines," Haynes said.