The Indian Government has recently approved human volunteer trials for the country's second preventive vaccine against HIV, the virus that leads to AIDS. A vaccine for the developing world, where anti-retroviral drugs are out of reach for millions of HIV-infected people, would be the ultimate prize in the fight against AIDS. But efforts to find one have been hampered by the virus's ability to mutate.
After South Africa , India has the second-largest number of people living with the killer virus .In its efforts to further prevent the spread of the deadly disease India started human trials on its first preventive vaccine in February this year, since the first vaccine has been making good progress , the government has received all clearances for the human trials of a second vaccine. Scientists say they need to test different vaccines on the same or separate strains of a virus to develop the most effective antibodies.
In February, researchers began trials on 34 healthy adult volunteers for tgAAC09 vaccine that targets HIV subtype C, widely prevalent in India, South Africa and China. The trials for the second vaccine -- called the Modified Vaccinia Ankara (MVA) -- will be carried out at the Tuberculosis Research Centre in the southern city of Madras. The MVA will also target HIV subtype C.
During the first phase of such trials, vaccines are usually tested on healthy volunteers who are given a controlled dosage of the HIV subtype C virus to create resistance after a consent id obtained from the volunteer due to the risk of possible HIV infection.
In the second phase, the vaccine is given to a smaller group of high-risk individuals -- sex workers, drug users and homosexuals -- to check for the efficacy of the dosage. They are not asked to alter their regular lifestyles. If the vaccine is seen to work on both groups, it is then given to a larger group of up to 1,000 people. Most importantly at every stage of the trial all volunteers have to be HIV-negative when they sign up.
In the fourth and last phase -- if the results of earlier phases are found to be satisfactory -- marketing of the vaccine is done and post-marketing surveillance carried out. Experts say it takes years for a successful vaccine to be developed.
The International AIDS Vaccine Initiative (IAVI), which coordinates the global search for a vaccine, says India is important because of its advanced biomedical research facilities and strong pharmaceutical industry which has developed cheap and effective AIDS drugs that are exported across the globe.