Structure of key protein in HIV 'uncovered'

In a breakthrough which may pave the way for a vaccine against AIDS, scientists have provided what they claim is the first-ever glimpse of the structure of a key protein, gp120, found on surface of a subgroup of HIV-1.

In addition, the scientists from California Institute of Technology demonstrated that a particular antibody to gp120 makes contact not only with the protein, but with CD4 receptor that gp120 uses to gain entrance into the body's T cells.

This three-dimensional understanding of how gp120 is built is more than just a basic scientific advance, they say.

"There's a tremendous continuing effort to develop a vaccine for HIV and most of those efforts use gp120. Having more structural information will facilitate better vaccine design," said lead scientist Ron Diskin.

The team looked specifically at gp120 from what is known as clade C HIV-1.

To explain what that means, here's a brief HIV family history: Most people who get HIV and proceed to AIDS are infected with a member of the HIV-1 family of viruses. HIV-1 is divided into groups; most AIDS-related strains of the virus come from group M. The groups are further subdivided into what are known as clades.

Clade B is the form of group M HIV-1 most often found in the United States and western Europe, and the one that is probably best-studied to date. Clade C, the clade studied by the Caltech team, is "the one that is devastating Africa and Asia," said Diskin. "It's the one that probably causes the largest number of infections worldwide."