Promising multistrain HIV vaccine candidate emerges.(Brief Article)

2002 SEP 18 - (NewsRx.com & NewsRx.net) -- AIDS researchers have developed a candidate vaccine strategy that, for the first time, demonstrates an ability to elicit antibodies that block the infection of multiple HIV virus strains - an elusive scientific goal that has been pursued for a decade.

The candidate vaccine - still early in developmental stages at the Institute of Human Virology (IHV) - is described in a report in the Proceedings of the National Academy of Sciences USA. It is authored by Drs. Timothy Fouts, Anthony Devico, and colleagues at the IHV, a center of the University of Maryland Biotechnology Institute and affiliated with the University of Maryland Medical Center, and Dr. Ranajit Pal and colleagues at Advanced BioScience Laboratories, Inc., (ABL) in Kensington, Maryland.

One of the major challenges in developing an effective AIDS vaccine has long been the fact that the virus that causes AIDS, much like the influenza virus, exists as multiple strains that present many different faces to the immune system, said the authors. The surface of the AIDS virus, HIV, is coated with a protein called gp120 that has chemical features that vary from strain to strain. It has been difficult for researchers to find a single vaccine component that is able to generate antibodies that recognize the many forms of gp120 that exist in nature.

The IHV/ABL research team approached the problem by recognizing that all gp120 molecules have a shared characteristic that allows all HIV strains to bind a molecule on human target cells called CD4. Importantly, once gp120 forms a complex with CD4, it undergoes structural and chemical changes that reveal features shared by all HIV strains.

Taking advantage of this knowledge, the team produced artificial gp120-CD4 complexes that were chemically treated in order to glue or "crosslink" them together. The complexes were then used to generate antibodies in small animals and monkeys.

"The gp120-CD4 complex has shown a consistent ability to generate antibodies that neutralize a wide range of HIV-1 isolates," said Devico, ...