New HIV vaccine concept may extend hope to those already infected

VIDEO CNN's Holly Firfer reports on the HIV vaccine approach Windows Media 28K 80K

August 29, 1999
Web posted at: 7:42 p.m. EDT (2342 GMT)

From Medical Correspondent Holly Firfer

BALTIMORE (CNN) -- Creating a vaccine against HIV, the virus that causes AIDS, has proven to be a tricky task. But a group of researchers is expressing excitement about a new approach that may also offer help to those already infected with the virus.

Shortly after someone is infected with HIV, the virus produces a protein called TAT, which binds to healthy immune cells and uses them to reproduce HIV. Without this protein, HIV can't reproduce in the body.

Now, scientists hope to use this information to create a vaccine that could not only prevent infection but also possibly help control HIV in those already infected.

"By vaccinating against TAT, you would inactivate TAT. You would block it so the immune system wouldn't be so impaired, and you would be better able to fight the virus," says Dr. Robert Gallo of the Institute of Human Virology, one of the researchers working on the study.

Other scientists say while the approach sounds promising, the research is still in the early stages.

"Theoretically, it makes sense," says Dr. Anthony Fauci of the National Institutes of Health. "But there are a lot of things that make sense theoretically that when you practically try them, they just don't work."

Dr. Daniel Zagury, of the University Pierre et Marie Curie in Paris, has done several clinical trials with a vaccine called TAT toxoid.

"The experiments in animals showed that the TAT toxoid was fully safe, well tolerated and induced antibodies in very high levels to antagonize, to neutralize the TAT that is reduced by infected cells," he says.

Last year, the first large scale HIV vaccine trial was launched, which is still ongoing. It could be years before the TAT vaccine is tested in large numbers of people.