HIV Is Always a Step Ahead of the Immune Response

A recent study has revealed how the body's antibody response stimulates the HIV virus to mutate and escape destruction by the immune system. The study was published March 18, 2003, in the online edition of the Proceedings of the National Academy of Sciences.

Investigators from the University of California, San Diego (USA), cultured viral samples from HIV patients along with antibody-containing plasma samples from the same patients. As blood plasma contains antibodies but no white blood cells, the researchers were able to evaluate the effects of antibodies alone on the virus, independent of the rest of the immune system.

The results from 19 patients over a period of 39 months showed that most patients developed a high titer of antibodies to HIV within a few months, and the antibodies continually evolved in their ability to recognize different antigens on the outer coating of the virus. This evaluation in antibody specificity was necessary because the virus in the plasma continually and rapidly evolved to escape neutralization.

"The neutralizing antibodies are exerting a very strong selective pressure on the virus, and the virus is continually mutating to avoid it,” explained Dr. Douglas D. Richman, a virologist at the University of California, San Diego. "The bad news is that the virus is always staying a step ahead, and the neutralizing antibody response can not control it.”



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