Research On ‘Elite Controllers’ To Improve AIDS Vaccine Design

Mexico City: A tiny group of people, also found in India, with a rare gift – they are infected with HIV but manage to stay healthy – may soon become the centre of attraction for the world’s top AIDS scientists, looking to find a vaccine against the deadly HIV virus.

A new roadmap announced by the International AIDS Vaccine Initiative at the International AIDS conference here has asked scientists to solve the Cell Mediated Immunity (CMI) problem while developing a candidate vaccine. The recommendation says, "We know that there are rare individuals, known as elite controllers, who are infected with HIV, but are able to keep the virus in check for decades without any sign of disease. More resources should be devoted to studying the mechanisms behind this phenomena which could provide vital clues for improved vaccine design."

It adds, "What’s more, nonhuman primates vaccinated with a live, but weakened form of the simian equivalent of HIV (known as SIV) mount an immune response that protects them from SIV disease. More attention should be paid to study this mechanism too. Canadian and American scientists have been working on finding what makes these elite controllers special and genetically what makes them so strong against HIV.

Experts say these controllers account for about 1 out of 300 people infected with HIV but have been largely invisible to AIDS researchers because they do not get sick and therefore do not qualify for clinical studies.

Koutenya Sinha, for The Times of India

The roadmap puts forth a series of recommendations to help guide research to answer the critical scientific questions that have hampered AIDS vaccine development to date. Its has asked scientists working on developing the elusive AIDS vaccine to dump their candidate vaccines and not cling onto them with hope, if it fails to demonstrate superiority.

On the other hand, if a candidate vaccines does show promise, scientists have been asked to test it rapidly, in smaller, more focused trials before moving them into conventional largescale efficacy trials contrary to what is done at present.

According to IAVI, current and future AIDS vaccine candidates need to be compared and prioritised in comparison to tested vaccines. Those vaccines that cannot demonstrate superiority should be dropped.

"Resources from these candidates should be freed and redirected towards solving the key scientific problems currently impeding the development of the next generation of AIDS vaccine candidates," IAVI said.

More than 25 years have passed since the AIDS epidemic started and scientists have failed to find an effective vaccine against the virus that infects 7,500 people each day. To date, more than 25 million lives have been claimed by AIDS and 33 million people are estimated to have HIV. The world at present only has 20 anti-retroviral (ART) drugs in the market to suppress the virus for some time and control its symptoms.

Dr Seth Berkley, CEO of IAVI, said the development of an AIDS vaccine continued to be one the greatest needs of the 21st century and one of science’s greatest challenges. "Developing an AIDS vaccine may take more time and innovation than we might have once imagined, but we are confident that science will prevail. The necessary direction for the field is clear," Berkley said. "Strong scientific evidence in both human and animal models suggests that developing an AIDS vaccine is possible," said Dr Wayne Koff, senior VP (research and development) at IAVI.

Out of the 50 candidates that have been evaluated among humans till now, only two vaccines have made it through all three phases of trials, and both were rejected as quite ineffective.

Despite the failures, about 30 vaccines remain in the pipeline, looking at different ways of stimulating the immune system. However, only one is in the phase III stage.



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