Protein Finding Bolsters AIDS Vaccine Hopes

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At the same time, the researchers were investigating an immune system antibody called b12. This antibody, while rare, appears to help protect a tiny minority of HIV-exposed people from infection with various strains of the virus. In fact, b12 carriers "neutralize an extremely broad range of HIV isolates (types)," Kwong said.

Further study brought these two strands of research together. The NIAID team, along with experts at the Scripps Institute in La Jolla, Calif., and the Dana-Farber Cancer Institute in Boston, discovered that b12 actually binds to the gp120 site on HIV during that "weak handshake" stage, where it does not change its shape.

Using high-tech crystallography imaging, the researchers actually watched this interaction in detail. "This gives us the resolution to know exactly what's going on," Kwong said.

Because the b12-gp120 hookup does not change its configuration, regardless of the HIV strain it is found on, it's exactly the type of non-mutating "site of vulnerability" that AIDS vaccine researchers have hoped for.

"But we also needed to find that there's no barrier in humans to getting antibodies to go against that site," Kwong said. The fact that b12 is already active in just this way in a few HIV-resistant people suggests that it can be tweaked for wider use in much larger populations, he said.

The next step is to test that notion in animals. "If you get those antibodies to be produced in animals, it should then be straightforward to do something similar in humans," Kwong said.

Fauci stressed, however, that success in AIDS research is never guaranteed.

"There are many steps to go," he said. "You have to make it into a stable form that could immunize people. Then the body has got to recognize (the vaccine) and make a good neutralizing antibody against it. Those are all 'ifs.' On the other hand, we have no reason to believe that all this won't happen."

"I'm sure there are going to be many bumps along the way," Fauci said, "but, nonetheless, this is a major step forward."

More information

Find out more about HIV/AIDS at the U.S. National Institute of Allergy and Infectious Diseases.