Newly isolated HIV antibody could lead to vaccine

Researchers announced Thursday that they have figured out how a rare antibody sees past the disguises of HIV--a finding that may lead to a vaccine that will finally work against the killer virus. The antibody, taken from a unusual patient whose body can resist the virus, recognizes and attacks HIV, unlike most of the body's other natural immune system defenses. "Nothing like this has ever been seen before," said Ian Wilson of the Scripps Research Institute in La Jolla, Calif., who led the research. Writing in the journal Science, Wilson and his colleagues report that they isolated an HIV-fighting antibody called 2G12 in a patient who has been infected with HIV for many years but has never developed immune system damage--what researchers call a long-term nonprogressor. HIV usually is able to shield itself from antibodies by disguising itself with sugar molecules, but 2G12 apparently sees through this defense by recognizing that the sugars are not arranged in a human-like way.

Antibodies are an important arm of the body's defenses against germs. They are usually able to recognize an invader by structures on its surface, called antigens, and can either summon other components of the immune system to fight the pathogens or can neutralize them directly by latching onto the antigens. Most vaccines in use today stimulate the production of these neutralizing antibodies. The human body makes antibodies against HIV, but the virus disguises itself with its sugar coating, which shields the antigens, allowing HIV to slip unrecognized past the immune defense.

The California researchers say the next step is to use the structure of the antibody as a template to design an antigen to stimulate the production of 2G12 or another similar antibody that will recognize and destroy HIV in the body. With as many as 42 million people in the world currently infected with HIV, the only real hope for stemming the epidemic is to create a vaccine against the virus, but efforts so far have been unsuccessful.

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