Rooting out hidden HIV

Science News, Sept 10, 2005

Drugs currently used to suppress HIV, the AIDS virus, work only on actively replicating viral particles in the blood. When viruses lie dormant in a cell, they can escape the drugs' dragnet.

Researchers report in the Aug. 13 Lancet that a novel combination of drugs can significantly reduce the number of these cellular safe houses in patients.

The new, three-step strategy combines a standard "cocktail" of HIV drugs to knock down active virus circulating in a patient, another drug that blocks viral entry into uninfected cells, and finally a drug intended to root out dormant HIV.

David M. Margolis, a physician and virologist at the University of North Carolina at Chapel Hill, and his colleagues recruited four HIV-positive volunteers who had been taking a standard regimen of drugs for at least 2 years. For 4 weeks, each patient received twice-daily injections of enfuviritide, which inhibits HIV from invading fresh CD4 T cells--the primary cells that HIV commandeers. Then, the patients took valproic acid pills for 3 months. Previous lab tests had suggested that valproic acid could rouse HIV resting in CD4 T cells.

In three of the four volunteers, the number of CD4 T cells harboring HIV dropped by three-fourths. In the other volunteer, the decrease was closer to one-fourth.

The goal, Margolis says, "is to get rid of [all] infected CD4 T cells." Leaving any cells behind could allow the infection to reemerge, he notes.

"These results, though preliminary, merit further urgent study," says Jean-Pierre Routy of Royal Victoria Hospital in Montreal, writing in the journal issue reporting the new results.--N.S.