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Are we on the brink of an AIDS vaccine?


AIDS Vaccine Trials
A researcher operates an LSR II, an advanced sample analyzing machine, at the opening of the Internaional AIDS Vaccine Initiative's new laboratory in New York City.
A researcher operates an LSR II, an advanced sample analyzing machine, at the opening of the Internaional AIDS Vaccine Initiative's new laboratory in New York City.
Chris Hondros/Getty Images

­ In preclinical trials, 23 monkeys received the vaccine. Seven months later, they were injected with a highly powerful, simian version of HIV. Twenty-two out of 23 monkeys never developed any clinical symptoms of the virus -- after three and a half years, there was no immune-system damage, no clinical signs of AIDS. Five out of the six monkeys in the control group died of AIDS within eight months. In the experimental group, the virus was there, but it appeared to be deactivated. For a potential AIDS vaccine, a 96 percent success rate is unheard of. The one monkey in the experimental group that did develop and die of AIDS had been given only a partial dose of the vaccine.

The fact that the vaccine was so effective at warding off the progression of HIV to AIDS could mean the vaccine may also work as a kind of cure for people already infected with HIV. The virus would still be there, but it would basically go into indefinite remission. And the fact that it would also vaccinate people against smallpox is an added benefit, considering the widespread view that smallpox would be an effective and attainable biological weapon.

In Phase I human trials, which are intended to find out if the vaccine is safe, not if it protects against HIV, nine people received partial doses of the vaccine. It caused no side effects, and it resulted in the same type of boosted immune response as that seen in the monkeys. The vaccine is now in the final stages of Phase I, in which researchers inject subjects with full doses of the vaccine. Phase II human trials, using uninfected but high-risk volunteers, could begin at the end of 2007. If Phase II reveals that the vaccine is effective against HIV in humans, Phase III (which uses a larger number of volunteers -- in the thousands) could begin sometime in 2008, and the drug could be in distribution by 2011.

But that's if everything goes exactly as planned, which is seldom the case in vaccine development.

As of March 2007, there were more than two dozen potential AIDS vaccines in various stages of testing. Two of the vaccines in human trials are similar in structure to the GeoVax vaccine but use a genetically modified form of adenovirus for the live-virus injection instead of smallpox.

For more information on AIDS, potential vaccines and related topics, check out the next page.


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