HIV not eradicated by drug cocktail.

HIV, the virus responsible for AIDS, isn't eliminated entirely by combinations of medications--even when doctors catch it early. Although drugs kept the virus at bay in many patients for up to 30 months, HIV was still present and potentially active, according to three new studies.

Scientists warn that people getting today's most effective anti-HIV cocktails of expensive drugs may be destined to take them indefinitely. Side effects include vomiting and diarrhea.

The virus was present in all patients tested, reported two teams--one led by researchers at Johns Hopkins Medical Institutions in Baltimore and the other by scientists at the University of California, San Diego School of Medicine in La Jolla--in the Nov. 14 Science.

"The bad news is we still found the virus present; the good news is, in the patients we looked at, it was still sensitive [to the drugs] and not resistant," says Diana Finzi of Johns Hopkins.

The third study indicates that HIV may be doing more than merely clinging to life in T cells, the immune cells that the virus invades. A team led by researchers at the National Institute of Allergy and Infectious Diseases (NIAID) examined 13 HIV-positive patients who were taking a triple-drug combination. It detected viral DNA that was not integrated into chromosomes in the infected cells, an indication that the virus might be slowly replicating. "If viral replication is shut off, that [form of DNA] would have disappeared," says coauthor Anthony S. Fauci, NIAID director. "It's not absolutely slam-dunk, but it's likely that replication is going on." The study appears in the Nov. 25 Proceedings of the National Academy of Sciences.

All three research teams used the most sensitive measures available to detect HIV. Long-term studies extending months or years into the future may show whether the drug onslaught causes the virus to dissipate, Fauci says.