AIDS vaccines showing promise in human trials

A pair of vaccines designed to mobilise the immune system to protect against HIV and AIDS have completed first stage human testing and are now to undergo intermediate human testing in more than 100 volunteers in the UK. Second-stage trials of the vaccines are scheduled to begin in sub-Saharan Africa by the end of the year.

The two vaccines – one a naked DNA formulation and the other constructed from a weakened pox virus, MVA – are the only ones in human testing that are tailored for variants of HIV common in sub-Saharan Africa – subtype A – where the infection rate is highest. They have been shown to be well tolerated and to stimulate the immune system eliciting anti-HIV CD8+ T cell-mediated responses as measured by Elispot T assays.

The vaccines were developed and are being tested by a cross-national partnership that includes the International AIDS Vaccine Initiative (IAVI); the University of Oxford and UK Medical Research Council (MRC); and the University of Nairobi and Kenya AIDS Vaccine Initiative (KAVI).

The nonprofit IAVI is financing and coordinating the project, and all partners have agreed that if the vaccines ultimately prove successful, they will rapidly be made available to developing countries at reasonable prices. If the vaccines continue to perform well, the research partners plan to commence final-stage, multi-year trials within two or three years.

IAVI's strategy is to fast-track a diverse portfolio of drug possibilities, and more than half a dozen AIDS vaccines are currently being developed with IAVI support.

'IAVI is accelerating the Oxford-Nairobi DNA-MVA candidates while at the same time aggressively pursuing many other, entirely different designs,' said Dr Wayne Koff, IAVI's senior vice president for research and development. 'No one knows the magic recipe for an AIDS vaccine. The surest path is to try multiple approaches at once, comparing them against each other to see which are best.'

By 2007, IAVI plans to move between eight and 12 AIDS vaccine candidates through early human trials and see the most promising two or three into final-stage studies. IAVI-sponsored vaccines are poised to begin testing within the next few years in South Africa, Uganda, India and China, and in Europe and the US.