TUESDAY, March 18, 2003 (HealthDayNews) -- Scientists are getting their first glimpses of the fancy footwork that takes place between the rear guards of the immune system and their nemesis, HIV.
The AIDS virus appears to stay several steps ahead of its pursuers by anticipating their every move, researchers say in a study in this week's issue of the Proceedings of National Academy and Sciences.
The immune system's struggle to keep up with the savvy virus is reminiscent of the unfortunate plight of the Red Queen in Alice in Wonderland, who had to "run as hard as she could to stay in the same place," says study co-author Dr. Douglas D. Richman, a virologist at the University of California at San Diego.
Scientists are well aware of HIV's stunning ability to mutate into new forms, a skill that lets it escape attacks from the body's defenders. However, scientists don't fully understand how the different parts of the immune system react separately to the threat of the virus.
Antibodies, the specialists of the body's anti-germ forces, are a major part of the mystery. They mop up after the immune system's first assaults on invaders, adapting themselves to attack specific types of germs.
Richman and his colleagues developed a new method to directly observe how antibodies interact with HIV. They used the technique to study bits of virus cloned from samples taken from 19 patients who were in the early stages of infection.
Over a 39-month period, researchers found the antibodies continually adapted to the changing structure of the virus. But the virus would just mutate into a new form, making the antibodies useless. It's as if an army designed new artillery to combat a specific enemy, only to produce the weapons and belatedly discover they are obsolete.
Richman says the next step is to examine how antibodies act in the later stages of HIV infection. One bit of good news in the study is the fact that the AIDS virus is clearly threatened by the antibodies, he adds.
"We have to assume that the antibodies are having an effect on the virus. Otherwise, there would be no pressure for the virus to mutate and escape from them," says Dr. Laurence Peiperl, director of the Center for HIV Information at the University of California at San Francisco. "If the antibodies were irrelevant, the virus wouldn't need to change."
He adds the study findings don't mean that antibodies sit around uselessly when HIV attacks the body. They do appear to keep the virus under some control, at least for a while.
"If you look at people who've become recently infected, there's a huge increase in viral load (the strength of the virus) when someone becomes infected," he says. "Then it comes down at about the time that you start to see the antibody response come up."
According to Peiperl, antibodies could become a main ingredient of a successful AIDS vaccine -- but only if the vaccine uses antibodies "in a way that the body hasn't thought of."
At this point, however, scientists appear to be far from developing a working vaccine against AIDS.
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