Scientists Find Clue to HIV Infection

After nearly 20 years of searching, scientists have reported isolating the structure of a key HIV protein that allows the virus to latch on to human cells and infect them. Using an X-ray beam, researchers in Boston obtained a three-dimensional image of the gp120 protein'part of the virus's outer membrane'taken before the protein rearranges its shape to enable it to bind to receptors on the surface of immune system cells. The 3-D image 'reveals the viral envelope at its potentially most vulnerable,' says AIDS expert Peter Kwong. Researchers had previously isolated and analyzed gp120's structure after it binds to human cells. 'We can now compare the bound and unbound forms and try to understand whether there are any immunologic properties that differ and that might provide a route to new vaccine or drug strategies,' says lead researcher Stephen Harrison. 'Knowing how gp120 changes shape is a new route to inhibiting HIV'by using compounds that inhibit the shape change.'