Complex Protein may Help HIV Vaccine Development

Scientists at Duke University have taken aim at what may be an Achilles' heel of the HIV virus.

Combining expertise in biochemistry, immunology and advanced computation, researchers at Duke University have determined the structure of a key part of the HIV envelope protein, the gp41 membrane proximal external region (MPER), which previously eluded detailed structural description.

The research will help focus HIV vaccine development efforts, which have tried for decades to slow the spread of a virus that currently infects more than 33 million people and has killed 30 million more. The team reported the findings online in the Jan. 13 early edition of Proceedings of the National Academy of Sciences.

"One reason vaccine development is such a difficult problem is that HIV is exceptionally good at evading the immune system," said Bruce Donald, an author and professor in Duke's computer science and biochemistry departments. "The virus has all these devious strategies to hide from the immune system."

One of those strategies is a dramatic structural transformation that the virus undergoes when it fuses to a host cell. The envelope protein complex is a structure that protrudes from HIV's membrane and carries out the infection of healthy host cells. Scientists have long targeted this complex for vaccine development, specifically its three copies of a protein called gp41 and closely associated partner protein gp120.

The authors said they think about a particular region of gp41, called MPER, as an Achilles' heel of vulnerability.

"The attractiveness of this region is that, number one, it is relatively conserved," said Leonard Spicer, senior author and a professor of biochemistry and radiology. In a virus as genetically variable as HIV, a successful vaccine must act on a region that will be conserved, or similar across subtypes of the virus.

"Second, this region has two particular sequences of amino acids that code for the binding of important broadly neutralizing antibodies," said Spicer. The HIV envelope region near the virus membrane is the spot where some of the most effective antibodies found in HIV patients bind and disable the virus.

Source: Eurekalert