(RxWiki News) An AIDS vaccine has long been a holy grail for medical researchers. New experiments in monkeys are giving hope that a vaccine for humans is getting closer to reality.
Researchers have developed a vaccine that provided significant protection for Rhesus monkeys from SIV, the monkey equivalent of HIV. Monkeys that were given the vaccine reduced their likelihood of contracting SIV by 80 to 83 percent.
The researchers say that the experiments could provide important clues for designing an AIDS vaccine.
"Take preventative measures against AIDS, in lieu of a vaccine."
The study was led by Dr. Dan Barouch, associate professor of medicine at Harvard Medical School, and was published online in the journal Nature, in January 2012.
The study built on the results of a 2009 large scale HIV vaccine trial in Thailand, which was 31 percent effective in protecting humans against HIV.
Dr. Barouch and his colleagues tested the vaccine in 40 Rhesus monkeys against a control group that did not receive the vaccine. An important aspect of the study was that they used an especially strong dose of the virus – 100 times the strength that is usually seen in human exposure.
The monkeys got two doses of the vaccine, which contained SIV proteins. The vaccines had been designed to use harmless viruses to deliver the proteins to boost the monkey's immunity to the virus.
The vaccines also contained the “envelope” that the virus comes in, which had not been included in previous vaccines.
The monkeys were infected with SIV a week after each dose of the vaccine. The group that received the vaccine were far less likely to become infected – by 80 to 83 percent.
After repeated intentional exposures to the strong virus, all of the monkeys eventually became infected. But those who had been vaccinated fared much better, with less virus appearing in their blood than unvaccinated monkeys. Essentially, the vaccine was able to weaken the virus if it did make it into body.
According to Dr. Anthony Fauci, director of the National Institute on Allergies and Infectious Diseases, the study is significant because it showed the strength of the vaccine against a very robust strain of the virus.
The other important aspect of the study is that it demonstrated that a successful AIDS vaccine needs to provide protection against the “envelope” of the virus, Dr. Fauci told NPR's Shots blog.
The research group is currently raising the funds needed to test the safety of the vaccines in humans, and hopes to begin the trial next year.