Hope Found in First Vaccine to Stop HIV

nuclearfm · 09-24-2009

http://abcnews.go.com/Health/AIDS/ho...ory?id=8663206

After 20 Years of Dead Ends, a New Vaccine Can Protect Some From HIV
By MICHAEL SMITH
MedPage Today North American Correspondent

For the first time, an investigational HIV vaccine has shown it can protect people from the virus.
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Dr. Richard Bresser explains how the vaccine could prevent some types of HIV.

In a large phase III trial, the vaccine reduced the risk of infection by 31.2 percent compared with a placebo.

"I am very encouraged at these results -- the first such encouragement in two decades," said Dr. James Curran, a professor of epidemiology at Emory University who was not involved in the trial. "While this does not merit immediate application, this will reinvigorate interest in the crucial goal of seeking a highly effective vaccine."

The trial, conducted among more than 16,000 people in Thailand, enrolled volunteers from the community, rather than high-risk groups, as many other vaccine studies have done.

In the final analysis, there were 74 infections in the placebo group, compared with 51 in the vaccine group.

"This is the first HIV vaccine candidate to successfully reduce the risk of HIV infection in humans," said Lt. Gen. Eric Schoomaker, the Surgeon General of the U.S. Army.
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The army was one of the partners on the trial, along with the Thai Ministry of Public Health, the National Ins ute of Allergy and Infectious Diseases, Sanofi Pasteur, and Global Solutions for Infectious Diseases.

"We are very excited and pleased with the outcome of this trial and congratulate all those who participated in it," Schoomaker said in a statement.

He added that the study is "an outstanding example of international, and interagency, collaboration."

The trial tested a so-called "prime-boost strategy" using two different medications.

The first, dubbed ALVAC-HIV, was a canarypox virus, engineered so it could not cause disease and modified to carry synthetic versions of three HIV genes, known as gag, env, and pro.

A Primer Vaccine May Help Fight HIV Infection

Volunteers were either given four injections of ALVAC-HIV over six months, or a matching placebo.

At the last two injections, the volunteers were also given a placebo shot or a shot of AIDSVAX B/E -- a vaccine candidate that was proved safe but not effective in an earlier trial. The AIDSVAX B/E contains an HIV protein known as gp120.

The idea was to prime the immune system with the first vaccine and then boost it with the second. Researchers hoped to elicit both antibodies to HIV and killer T cells that would destroy the virus.