Vaccine Hope: Antibodies Neutralise HIV's Prick

Image SourceThe envelope of HIV has pricks, or spikes made up of proteins gp120 and gp41. These proteins are highly variable, and therefore difficult for vaccines to pin down. But two particular antibodies (PG9 and PG16) researched by Scripps and IAVI (International Aids Vaccine Initiative) seem to target sections of the HIV prick which are less variable -- and would thus neutralise a much wider range of HIV strains around the world.

NEW YORK, NY, LA JOLLA and SAN FRANCISCO, CA, SEATTLE, WA, September 3, 2009—Researchers at and associated with the International AIDS Vaccine Initiative (IAVI), at The Scripps Research Institute, and at the biotechnology companies Theraclone Sciences and Monogram Biosciences have discovered two powerful new antibodies to HIV that reveal what may be an Achilles heel on the virus. They published their work in Science this week.

...The two new antibodies target a region of the viral spike used by HIV to infect cells. The viral spike glycoproteins, termed gp120 and gp41, are highly variable and have evolved to thwart immune attack. But biochemical studies suggest that PG9 and PG16 target regions of gp120 that do not change, which probably accounts for their breadth of neutralization. Now researchers at the IAVI-organized Neutralizing Antibody Consortium (NAC), a scientific network focused on designing vaccines capable of eliciting broadly neutralizing antibodies, will turn their attention to studying the molecular structure of PG9 and PG16 and that of the region they target on the HIV spike. _IAVI_via_MachinesLikeUs

The approach to an HIV vaccine is necessarily more difficult than for most other viruses. This is not only because HIV's viran envelope is highly variable, but also has to do with the way HIV attacks the immune system. Traditional approaches to activating the immune system can actually make the disease syndrome worse, leading to the infection of many more immune cells.

That is why scientists grasp at any conceivable approach that may either block or blunt the effect of HIV on the immune system. In this case, it looks as if an effective "blunting" maneuver may have been discovered.