The first human clinical trial of an HIV vaccine in South Africa begins this week, researchers said on Monday.
The drug, which is also being tested in the US, is one of about two dozen potential vaccines being tested by some 12,000 human volunteers in experiments around the world.
But it is the only one that contains genetic material from the HIV strain most prevalent in South Africa -- the country with the most people infected with HIV in the world.
4.7 million South Africans, 11 percent of the population, are infected with the AIDS-causing virus. An estimated 600 to 1,000 South Africans die every day from AIDS-related complications.
The tests beginning this week are the first of a series planned by the South African AIDS Vaccine Initiative, established by the government three years ago to develop an affordable, effective and locally relevant vaccine.
"An HIV vaccine is our best hope of eradicating HIV from the globe," said Tim Tucker, who heads the initiative. "It is an extremely exciting time."
The first drug being tested contains parts of a weakened strain of Venezuelan equine encephalitis and a harmless gene from a South African HIV strain.
By entering human cells, scientists hope to stimulate the production of antibodies that will fight off AIDS infections, and also train specialized cells -- dubbed "killer T-cells" -- to identify and eliminate infected cells after the virus is contracted.
Animal studies have shown significant immune responses of both types, researchers say.
The first human trials are aimed at establishing the safety of the drug and are expected to last two years. If successful, they will be widened to take in more volunteers and determine the vaccine's effectiveness.
AIDS is notoriously successful at beating the body's immune system and so far has resisted every drug tried. In February, VaxGen Inc reported that the world's most advanced human vaccine experiment, involving 5,000 volunteers, had failed.
Tucker predicted it would be at least 10 years before an effective vaccine was ready for distribution.
The global HIV Vaccine Trials Network, funded by the National Institute of Allergy and Infectious Diseases of the US National Institutes of Health, is conducting the preliminary trials.
A total of 48 volunteers -- 24 each in the US and South Africa -- are participating.
Each group has been randomly divided into two groups of 12 people, 10 of whom will be injected with the vaccine and two of whom will receive a placebo. The first group in each country is being administered a lower dosage than the second.
The first 12 US volunteers received their vaccinations in July at Johns Hopkins University, Columbia University, the University of Rochester and Vanderbilt University.