An antibody that gains hold of the HIV/AIDS virus has revealed a new potential target for developing a vaccine for the virus, a Scripps Research Institute study showed.
PGT 128, one of more than a dozen antibodies that work against the various strains of the HIV/AIDS virus, can block the ability of 70 percent of global HIV strains to infect cells, in smaller concentrations than any of its predecessors.
"What's unexpected and unique about this antibody is that it not only attaches to the sugar coating of the virus but also reaches through to grab part of the virus's envelope protein," said lead study author Dennis Burton, a professor at The Scripps Research Institute and scientific director of the International AIDS Vaccine Initiative's (IAVI) Neutralizing Antibody Center at Scripps Research's La Jolla campus.
Using X-ray crystallography, a research associate of co-author Ian Wilson, the Hansen Professor of Structural Biology and member of the Skaggs Institute for Chemical Biology at Scripps Research. showed that PGT 128 binds to sugars known as glycans that surround the surface of the virus, preventing it from being attacked by the body's immune system. More importantly, at the same time PGT128 reaches through the cluster of glycans surrounding HIV's envelope protein to take hold of a structure called the V3 loop.
Knowledge of these binding sites of PGT 128 could give researchers ways to develop vaccines that stimulate a lifelong antibody against vulnerable sites.
"We'll probably need multiple targets on the virus for a successful vaccine, but certainly PGT 128 shows us a very good target," said Burton.
The study appeared online Oct. 13 in the journal Science Express:
