An experimental HIV vaccine being studied by researchers in France was shown to be "promising" in animal tests in dramatically reducing the amount of virus in monkeys infected with the simian immunodeficiency virus, researchers say. The vaccine, which aims not to prevent HIV infection but instead to slow the virus in the body, was shown to drop viral levels in the animals' blood 50-fold and specifically in blood plasma by 1,000-fold, said Wei Lu of René Descartes University in Paris. For some of the animals, the decreases in viral levels persisted as long as 10 months.
The vaccine works by prompting the body's immune system to better recognize and attack the virus inside the body. In the experiment, 10 macaques that had been infected with SIV were vaccinated using a type of cell called dendritic cells, which had been exposed to chemically inactivated SIV. Dendritic cells produce antigens that battle diseases invading the body, and their exposure to the inactivated SIV primed them to attack real copies of the virus. The macaques were given five injections over two months. While the virus was not eliminated in any of the monkeys, it was sharply reduced in seven of them as long as 10 months later. "We are now working on an improved protocol aimed at immunologic eradication" of the virus, Lu said.
The full study appears in the online edition of the journal Nature Medicine.