For years researchers have been trying to understand how a few HIV-infected patients naturally defeat a virus that otherwise overwhelms the immune system. Last year, a research team at the University of Rochester Medical Center confirmed that such patients, called long-term non-progressors, maintain higher than normal levels of the enzyme called APOBEC-3G (A3G) in their white blood cells, which function to stave off infections. Now, the same group has teamed up with a structural biologist to provide the first look at the A3G structure. Such information represents an early step toward the design of a new class of drugs that could afford to all the same natural protection enjoyed by few, according to a study published today in The Journal of Biological Chemistry.