An international team of researchers has discovered a pair of powerful new antibodies to HIV, providing fresh leads in the quest for a vaccine against AIDS.
The two HIV antibodies, reported in a study to appear in the journal Science on Friday, are the first of their kind to have been identified in more than a decade. They are 'broadly neutralizing,' which means they can target most of the many thousands of HIV strains.
Any potential vaccine is still a long way off, however. Researchers now have to work out how these antibodies bind to HIV, the virus that causes AIDS, and use that property as the basis for a vaccine. As a result, animal or human trials are likely to be years away.
Nonetheless, the new antibodies are deemed to be much more powerful than the handful of similar ones found before. They attach to a potentially more accessible part of the HIV virus, which could make vaccine design easier.
'We hope that we have a bit of a breakthrough and that the drought is over,' said Dennis Burton of the Scripps Research Institute in La Jolla, Calif., the senior author of the study.
The search for an HIV vaccine has been one of modern medicine's biggest challenges -- and disappointments. There have been about 100 vaccine trials since 1987, but not a single notable success.
Released by the immune system, antibodies are proteins that stick to the surface of a virus and stop it from entering a cell. HIV researchers hope to make a vaccine from a substance -- usually a piece of the virus itself -- that will provoke the immune system into releasing virus-fighting antibodies.
Until now, four broadly neutralizing antibodies had been isolated from HIV-positive patients in the Americas, Europe and Australia. But scientists have struggled to design a vaccine around them.
The newest two were isolated from a single person in Africa, where a high proportion of new infections occur and a vaccine is most keenly needed. The two antibodies are believed to be about 10 times more powerful than the previously discovered ones. But, Dr. Burton cautioned, such power 'doesn't necessarily translate into an ability to protect humans.'
A global hunt for new HIV antibodies has been under way for some time. The search that snared the latest two proteins was led by the nonprofit International AIDS Vaccine Initiative, or IAVI. IAVI provided most of the funding via its donors, while the U.S. National Institutes of Health, the world's biggest funder of HIV vaccine research, contributed a smaller amount.
