New glimmer of hope for HIV vaccine

Currently, RV144 vaccine from Thailand is the only HIV preventive vaccine htat has shown efficacy in the last 30 years of vaccine research. The vaccine, which took 16 years of research, showed 31 per cent efficacy level after three years of following up the participants. Although, the efficacy is not much, it provide s a glimmer of hope for scientists working in the field of vaccine research.

The correlate study conducted by the US Military along with Duke University has found clues that will enable scientists to improve the current vaccine’s efficacy level. The conclusions announced at the International AIDS Vaccine Conference held at Bangkok from September 12 till September 15, is a significant development since it will offers answers to why the vaccine was effective on some people and why the efficacy level only this much.

Explaining the importance of this new findings, Dr Barton Haynes of Duke Human Vaccine Institute, USA, who was part of the leading team, said that biomarkers or correlates have given them directions, signals on the hypothesis. “We did not have vaccine trials that worked but then RV144 did that. Then we wanted to know what did work and what we have found,” he said. The study found that that high concentration of antibodies that bind to V1 and V2 regions of the correlates, that keep changing, have reduction in infection rate by 43 per cent but high plasma IgA envelope indicated 54 per cent increase in the infection rate. In other words, this enables the scientists to understand why the vaccine worked the well in some people and in what way its efficacy could be increased.

According to Col Jerome Kim, Walter Reed Army Institute of Research, US, who was also part of the lead group for the study, apart from the current four doses of vaccines that were given to subjects in the phase III clinical trials in Thailand, they are planning to give a booster does after six months to increase the strength of the vaccine. This will be done by carrying out clinical studies with a booster dose in Thailand and South Africa.

The correlates study is considered as a pioneer in getting various agencies together. A total of 35 investigators from 20 institutes and 32 tests were run on over 4000 blood samples collected during RV144 clinical trials.

The samples were shipped to Duke University from Thailand and the study was conducted November 2009 till last month. “We have been looking for correlates (targets in the virus where vaccines can be aimed penetrate and weaken it) for protection for the last 25 years.

With RV144 showing efficacy we have been able to find them. But since it was such a difficult problem to find these correlates, everyone came forwards and joined hands to get a solution,” said Col Kim.

More trials in the offing

Sanofi Pasteur announed the P5 (Pox Poretin public private partnership) between US National Institute of Health, Bill and Melinda Gates Foundation, US Military, HIV Vaccine Trial Network (HVTN), Sanofi Pasteur and Novartis Vaccine. The object of this partnership would be to take the RV144 vaccine regimen and create a more effective vaccine.
Thailand is gearing up for two clinical trials in the coming months. Mahidol University that created the RV144 vaccine will carrying out RV305, an extension of the earlier vaccine, from October.

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