Science / Medicine : AIDS Blocked in Drug Experiment

An experimental drug prevented AIDS virus infections in two chimpanzees, suggesting it might be able to block transmission of the virus from mothers to babies, a study says.

Researchers at Genentech Inc. of San Francisco started treatment before the chimps were exposed to the virus, an opportunity that may also exist in trying to protect babies, said study co-author Rebecca Ward.

Ward presented the work last week in the journal Nature with scientists at her company and elsewhere.

Experts cautioned that the laboratory-grown AIDS virus strain used in the experiment is particularly vulnerable to the drug, so that the therapy may not work as well against strains found in people.

Previous studies have shown that vaccines also can protect chimps against AIDS virus infection.

The experimental drug is called CD4 immunoadhesin. It is made from parts of two natural proteins: CD4, which the AIDS virus latches onto to infect cells, and immunoglobulin, a protein of the disease-fighting immune system.

The drug is designed to act as a decoy, so that the AIDS virus will attach itself to the CD4 portion rather than infecting cells of the body.