Results of the phase one clinical trials to develop a vaccine for the Acquired Immunodeficiency Syndrome (AIDS) are out.
The Pune-based National AIDS Research Institute (NARI) took up two possible vaccines for trial in February 2005. The results were analysed after completion of one year’s follow-up this year of the last vaccinated volunteer.
The results indicate that the first vaccine, which used adeno-associated viral (AAV) vector, failed to generate desired results. The second vaccine using the modified vaccinia Ankara (MVA) vector was on par with scientists’ expectations.
The vector is a virus that is used as a vehicle to carry human immunodeficiency virus (HIV) genes of interest. “We have analysed the results and found that MVA vaccines have matched our expectations on the safety parameters,” said NARI Deputy Director Dr Sanjay M. Mehendale. “But the other vaccine, AAV, was not very much successful in generating desired immune response."
Now scientists at NARI, the Indian Council of Medical Research, the National AIDS Control Organisation and the International AIDS Vaccine Initiative, are discussing how to go ahead with further trials of the so-far successful vaccine. The phase two trials may take off in six months if the Union Health Ministry gives its clearance.
The phase one trial was meant to study the safety of the vaccine in humans and its ability to stimulate immune responses against HIV/AIDS. The 30 healthy candidates who underwent the trials did not show any adverse effects on safety parameters, but the immunity response using the AAV vector vaccine was below expectations. In the trials, data was also collected on the ideal dosage. The 30 volunteers were split into three groups to receive three different dosages - low, medium and high - of the vaccine candidate.
“After the results, we are also discussing the success and failure of these vaccines with our international counterparts,” said Dr Mehandale. Last year in Chennai, too, the phase one clinical trial of an AIDS vaccine candidate using the MVA vector was initiated at the Tuberculosis Research Centre. In Chennai, 32 volunteers will be enrolled for tests.
The AIDS vaccine trials work on two strategies - either neutralising antibodies or cell mediated immune response.
In the first case, the vaccine would be able to prime the immune system to kill HIV even as it enters the body, while in the second approach a cell would perform the protective function.