Thailand - Thai research team tests HIV vaccine

A Thai research team is working on two new studies to see how a vaccine can boost people's immunity against HIV.

"These studies will help us determine if a vaccine can strengthen immunity against the virus," Prof Dr Punnee Pitisuttithum, chief of Mahidol University's Vaccine Research Centre, said.

About 500,000 to 600,000 people are living with HIV/Aids in Thailand, and though the situation has improved in terms of treatment, the efficiency of preventative measures has been below expectation and the annual average of 10,000 new patients is higher than projected.

The trials, divided into two, will involve a total of 632 volunteers. The first study, called RV305, will evaluate immunity boosting strategies for noninfected participants.

In 2009, the HIVvaccine efficacy trial, RVI44, tested a combination of two vaccines - ALVAC HIV (prime vaccine) and AIDSVAX B/E (the booster) - on more than 16,000 HIV-negative men and women from Chon Buri and Rayong provinces. The outcome of the trial showed that the combined vaccine lowered the rate of HIV infections by 31.2 per cent, but had no effect on the amount of the virus in the blood.

The results of RV144 trial also showed that the efficacy rate of primeboost vaccine, one year after being administered, was approximately 60 per cent.

A recent discovery suggested that the potential immune correlatesantibody so called V1/V2 region is likely to be protective leading to further studies using similar regimen.

"The previous trial helped us to learn more about the type of antibodies that could improve a human's immunity to fight against HIV. This was why we are conducting two studies to find out more details about the efficacy of the HIV vaccine," Dr Punnee, who is leading the studies, said.

About 167 people, who were part of the previous RV144 trial, will participate in the RV305 trial and receive eight shots of the combined vaccine in one year. The RV305 trial began last month and the result should be ready in two years.

The second study, named RV306, will focus on the efficacy of the HIV vaccine on 465 volunteers who are not at a high risk of getting infected. The trial will evaluate different booster vaccines one year after the volunteers have received either AIDSVAX B/E or ALVACHIV alone or a combination of both. The trial will also study specific immunity responses to various bodily fluids, including secretions from the cervix and the anus. The results of this trial should be ready in three years, though the research team is awaiting approval from the university's ethics committee.

"We don't know if these vaccines are capable of activating the immune system in other parts of the body," Dr Punnee said.

The two studies will be conducted in collaboration with several institutions, namely the Public Health Ministry, Vaccine Trial Centre, Mahidol University's Faculty of Tropical Medicines, the US Armed Forces Research Institute of Medical Sciences, Research Institute for Health Science, the Chulalongkorn University and the Thai Red Cross Society. The World Health Organisation (WHO), Vaxgen Inc and the Military HIVVaccine Research Programme are also supporting the trials.

Pongphon Sarnsamak

The Nation