HVTN - Vaccines in HIV Prevention

The 2010 International Microbicides Conference (M2010) has come and gone.

The conference that brought together about 1100 delegates from close to 47 countries sought to brigde the gap between researchers, advocates, the community, the media and regulators.

Appropriately located M2010 whose theme was "Building bridges in HIV Prevention," was held in Pittsburgh, the city of bridges. Pittsburgh is argued to be the city with the highest number of bridges in North America.

An area of special focus during the conference was the Thai vaccine trial whose recently released results resonated with hope for a vaccine that can help fight AIDS. Vaccines have historically been the tried and tested way of fighting and eradicating disease.

Pittsburgh is also home to the Inactivated Polio Vaccine (IPV), also called the Salk vaccine developed by Dr. Jonas Salk in 1952. The vaccine is a clear, colorless sterile suspension for subcutaneous injection. IPV contains strains of the 3 types of polioviruses (Types 1, 2, and 3), originally grown in monkey kidney cell culture and inactivated by exposure to formaldehyde. Clinical trials of IPV began in 1954, and results were dramatic: the cases of polio in the vaccinated test groups fell amazingly, and permission for IPV distribution was quickly granted by the US government in 1955. In 1987, a new, more potent version of inactivated poliovirus vaccine was introduced that is grown on human cell culture and contains greater antigenic content than the original vaccine.

Unfortunately, HIV has proven to be a challenging virus to vaccinate against during the close to 3 decades of HIV vaccine research efforts. Products tested to date have not worked much to the satisfaction of researchers.The HVTN 505 study will use a DNA prime/rAd5 boost vaccine regimen developed by the Vaccine Research Center at the National Institute of Health (NIH). Parts of the vaccine regimen are similar to the vaccine used in Step and Phambili. However, this vaccine is not on the path to licensure and is not expected to prevent HIV infection but the results of the HVTN 505 study will go a long way in bringing a better understanding and development of T-cell-based vaccines.

On Thursday, September 24, initial results were released from an AIDS vaccine phase III trial in Thailand, which showed, for the first time, that the risk of HIV infection can be reduced by a vaccine.On October 20, at the annual AIDS Vaccine Conference, the investigators for the Thai prime-boost AIDS vaccine trial presented the results of additional data analyses. The Thai prime-boost AIDS vaccine trial was the largest AIDS vaccine trial to date, with over 16,000 participants. It evaluated the efficacy of a vaccine regimen consisting of two candidates, known as ALVAC HIV and AIDSVAX B/E.

The trial data indicated that the vaccine regimen reduced HIV risk by approximately 30 percent. This is the first time a trial has found evidence that it is possible to
reduce the risk of HIV infection with a vaccine. While this does not mean that an AIDS vaccine will be available in clinics anytime soon, the evidence that a vaccine
can protect against infection is unprecedented. Scientists will spend the coming months reviewing the data, and testing blood samples from the trial to discover how
the vaccine may have protected some trial participants.

Researchers are already working hard to understand what these findings mean and to identify key next steps.