Scientists fill a gap in AIDS research.

While much of AIDS research has focused on preventing HIV replication, scientists also have long sought a way to prevent the virus from entering human cells altogether. That approach, according to a report in the October 1 issue of the journal Cell, may now have opened the door to an entirely new way to design HIV drugs.

Using computerized images of HIV proteins, researchers have found a pocket on the surface of the virus that is exposed only when HIV attaches to a healthy cell. The pocket is probably open for just a second--maybe even less. And researchers say that if they can develop a drug that would fill this pocket, they could theoretically stop HIV in its tracks.

"That pocket gets filled back up right away during the rearrangement of proteins [that occurs when HIV attaches to a human cell]," explains study coauthor Stephen Harrison, a researcher at Harvard University and the Howard Hughes Medical Institute. "So if you put something into the pocket, it will prevent completion of that rearrangement and hence prevent fusion and hence prevent infection."

Now, Harrison says, drug development experts must step up to the plate. "We've opened up a maim of possibility that the professional pharmaceutical companies can now try to capitalize upon."