New drugs help battle HIV. (Treatment).

Three potential drugs in development rely on novel tactics for attacking HIV, the virus that causes AIDS.

A compound dubbed BMS-806 blocks the entry of HIV into cells, reports Richard J. Colonno of Bristol-Myers Squibb in Wallingford, Conn. In test tubes, the compound inhibits the replication of HIV, including strains already resistant to other drugs.

BMS-806 binds to an HIV protein that's part of the virus' envelope and is responsible for recognizing a molecular marker on many immune cells. Once HIV latches on, the virus then binds to a second set of molecules before gaining entry to the cell.

At the meeting, another team reported that a compound called SCH C, which blocks this second set of molecules, reduced the blood concentrations of HIV by 68 percent in 10 of 12 people with moderately advanced HIV infection.

Before HIV can turn a cell into a factory for new viruses, it must insert its genetic material into the cell's DNA. That's why researchers have been struggling to find compounds to block integrase, the enzyme that inserts HIV genes, says Tamio Fujiwara of Shionogi USA, a drug company based in Florham Park, N.J.

Fujiwara and his colleagues report they've found an integrase inhibitor, called S-1360. In mice, the drug was as effective at blocking the replication of HIV as other drugs now on the market are, says Fujiwara. The company has already begun a small trial with 36 people to test the safety of S-1360.

"Finding new drugs is a lot like fishing," says Carl W. Dieffenbach of the National Institute of Allergy and Infectious Diseases in Bethesda, Md., "and we're finally getting some hits." Even if the drugs themselves prove ineffective in clinical studies, he says, they pave the way for future advances against HIV using these novel approaches. --D.C.