On the Brink of a Watershed Moment for HIV Vaccine R&D
By: Margaret McGlynn and David Cook
In late 2009, researchers from Thailand’s Ministry of Health and the United States Military HIV Research Program caused quite a stir when they announced that a vaccine regimen they evaluated in a large clinical trial in Thailand was modestly effective in preventing HIV. It was the first experimental demonstration that a vaccine can protect people from HIV, but it wasn’t at all clear why the regimen tested in that trial, known as RV144, had worked. So a global team of researchers was quickly convened to find the answer.
Their efforts were not in vain. In September, the team revealed at the international AIDS Vaccine 2011 Conference in Bangkok what it had learned from its analysis of the blood samples collected in the RV144 trial. The conclusion of their analysis capped another year of extraordinary productivity in a number of areas of AIDS vaccine research. From antibody discovery to the evaluation of new methods to deliver HIV vaccine candidates, researchers have lately made remarkable headway against some of the toughest scientific challenges the virus has presented – generating unprecedented momentum and optimism in the field.
Vaccinologists know very little about how exactly an AIDS vaccine should engage the immune system to prevent infection by HIV. Of course, a truly preventive HIV vaccine will probably have to activate both a broadly effective antibody response, which stops viruses from slipping into their target cells, and the cell-mediated response, which destroys cells that have already been commandeered by the virus. But the devil, as always, is in the details – what are the particular identities and roles of the scores of molecular and cellular supporting actors essential to this response? Vaccinologists call those details the correlates of protection, and they remain in large measure a mystery even for existing vaccines. The slightest hint about what they might be for HIV would be a big help to AIDS vaccine designers.
