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Recently Discovered Antibody Offers New Avenue in AIDS Vaccine Research

By L.K. Regan

Last week we brought you news from the 18th annual World AIDS Conference, where for the first time evidence was presented of the efficacy of topical gel in preventing HIV. But we wanted to bring you the other big news in HIV prevention that took place outside the conference recently: the discovery of a new direction in research for an HIV vaccine.

An article published in Science Express in July shows a remarkable result. Researchers from the National Institutes of Health (NIH) found antibodies that appear able to neutralize 91% of HIV strains. The antibodies were found in the blood of a 60-year-old African American man who has been positive for 20 years. The most effective of the antibodies is called VRC01, and the donor's body produces them naturally. VRC01's potency far outstrips previously identified antibodies, which were never able to neutralize more than about 40% of strains. "This is the first antibody found for HIV that is capable of neutralizing the a wide variety of strains of the HIV virus," says our HIV/AIDS expert, Dr. Raphael Landovitz, MD, Assistant Professor in the Division of Infectious Diseases at the Center for Clinical AIDS Research & Education at the University of California, Los Angeles. "In that sense," Dr. Landovitz says, "this is the first time there has really been a clear target to go after in making a vaccine—part of the reason we've been unable to create an effective vaccine is that we've been a little unclear what pathway to go down—which means there's a tremendous amount of trial-and-error."

The change the new antibody offers isn't just the introduction of a new material; rather, its importance lies in an entirely new method of tackling vaccine research with regard to HIV. Previous vaccine attempts had tried to prompt the body's immune system use it's own immune cells to attack the HIV virus itself. The identification of an existing antibody at this degree of efficacy, however, means that there is the potential for a vaccine to work by prompting the body to produce a defensive antibody that can block infection by HIV at the cellular level. The patient who produced the antibody VRC01 himself has HIV—probably because he contracted the virus before producing the antibodies. The hoped-for vaccine would reverse this order, effectively "poking" the immune system to produce the antibody that would then block potential HIV receptors. This would prevent the virus from ever taking hold.

Says Dr. Landovitz, "This is a major redirection of focus of vaccine research. It is important to remember, however, that it is a long way from identifying the antibody to making an effective vaccine—and no one knows yet how to get there. But this sends scientists back into the lab with a new direction: to find a method to prompt the body to produce this antibody. It is a new target." It is also a new avenue of hope in vaccine research that has stalled, despite the massive resources directed at the problem.