No headway on HIV vaccine after 20 years

Global efforts over the last two decades to produce an HIV vaccine have made little headway. Here’s why: Vaccine trials on monkeys and chimpanzees have routinely failed to elicit a satisfactory immune response against the human immuno-deficiency virus, the cause behind acquired immuno-deficiency syndrome (Aids).
Monkeys and chimpanzees, normally used for clinical trials, have medical parameters close to humans.

“Efforts to produce a vaccine against HIV have not been succeeding due to unavailability of suitable animal species for clinical trials,’’ Dr Ramesh Paranjape, director, National Aids Research Institute (Nari) said. Polio and malaria are other diseases that took longer periods for vaccine development.
On the use of monkeys in clinical trials, Paranjape said monkeys are used in HIV vaccine trials as they get the infection simian immuno-deficiency virus, which is 60% identical to that of the HIV virus found in humans.

“We infect them to see the vaccine’s efficacy and check whether it prevents the subject from getting the virus. But every time the animals are vaccinated, they get the infection.

This means the vaccine was unsuccessful in saving the animal and that will be case with humans,” he said.

According to Paranjape, the animal model has been found unsuitable across the globe. On an ideal animal model needed for HIV trials, he said researchers need an animal model that, after vaccination, generates immune response against the virus and does not get infected with the potent HIV virus.

NARI, established under the Indian Council of Medical Research in 1992 at Bhosari near Pune, has been at the forefront of attempts to develop a HIV vaccine in India. Its first phase of human trials began in 2005 and was called off in 2006 as the vaccine Adeno-Associated Virus Vector failed to bring results.

One human trial began at the end of last year at NARI, while three research studies are on currently to assess the response of patients who take anti-retroviral therapy (ART). While one study includes ART clinical trials for treatment, another includes ART trials in prevention of HIV transmission and ART in HIV and TB combined.

Dr Atmaram Bandivdekar, assistant director, National Institute for Research in Reproductive Health, Mumbai, which is associated with NARI in medical research, had a similar opinion as Paranjape. He said 20-25 trials have failed globally so far, besides four in India.