July 9, 2010 -- National Institutes of Health (NIH) scientists now have "proof" that the search for an AIDS vaccine can succeed.

In the blood of an HIV infected person, the researchers discovered two powerful antibodies that neutralize 91% of HIV strains.

"The discoveries we have made may overcome the limitations that have long stymied antibody-based HIV vaccine design," Peter D. Kwong, PhD, chief of structural biology at the NIH Vaccine Research Center, says in a news release.

The finding has implications far beyond HIV and AIDS. The new techniques used to find the anti-HIV antibodies can be used to spur research into vaccines against other diseases that have long stymied researchers.

It's major news that humans are capable of making antibodies that neutralize the AIDS virus. But finding antibodies -- even such powerful antibodies as these -- is not the same as finding a vaccine capable of eliciting the antibodies. It will be years, at least, before the discovery leads to a vaccine that can be tested in people.

Even so, the discovery of the antibodies was a major scientific feat. The researchers, led by Kwong, Vaccine Research Center Director Gary J. Nabel, MD, PhD, and Vaccine Research Center Deputy Director John R. Mascola, MD, used newly developed molecular techniques to build "resurfaced" protein probes to trap the antibodies.

It seems surprising that a person with HIV infection can carry powerful anti-HIV antibodies and not be cured. But other recent studies suggest that as many as one in four people with HIV infection may carry such antibodies.

The problem is that the antibodies appear naturally only long after HIV has established a death grip on the body. Because the virus replicates often and mutates quickly, people don't just carry a single strain of HIV -- their blood swarms with a vast number of HIV "quasi-species." By the time a person develops neutralizing antibodies, the virus has had time to evolve escape variants.

But if a vaccine were able to elicit neutralizing antibodies before a person was exposed to HIV, it's very likely the antibodies would keep the virus from taking root.

That's the hope, anyway. And because of the new findings -- announced just before the 18th International AIDS Conference -- there's a lot more of that hope than there was before.

The study findings are reported in the July 8 online issue of Science Express.