With no hope of an AIDS vaccine anytime soon, activists have pinned their hopes on research to test if antiretroviral drugs can protect HIV negative people from the virus.

Called pre-exposure prophylaxis or PrEP, the research involves HIV negative people taking a combination of ARVs before engaging in potentially risky sex.

Also on trial is a gel (called a microbicide) containing an ARV which can be inserted vaginally or anally to prevent infection.

Seven PrEP trials are either underway or in the process of being launched, and involve a diverse range of people from African sex workers to gay Americans and Thai intravenous dug users.

‘€œAlthough still unproven human clinical research, PrEP is considered one of the promising clinical interventions against HIV currently in development,” said Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition (AVAC).

AVAC believes there is reason to hope that PrEP can offer some protection against HIV.

Firstly, ARVs given to pregnant women with HIV during labour and delivery have ‘€œsignificantly reduced’€ HIV transmission to their babies.

In addition, ARVs given to health workers soon after exposure to HIV are believed to reduce the chances of HIV infection.

Finally, PrEP studies in monkeys have shown that the ARVs ‘€œsignificantly reduces risk of infection by HIV-like viruses’€.

“By mid-2009, more people will be enrolling in PrEP studies than in both HIV vaccine and microbicide efficacy trials combined,’€ Warren said.

‘€œAdvocates and communities affected by HIV need to understand PrEP and its implications for the AIDS advocacy and global health agendas, and government and private funders committed to global health must step forward now to ensure that PrEP research is fully funded.”

The earliest results from the trials are expected late next year, while most trials will be completed by 2012.

The ARV drugs tenofovir (TDF) and a combination drug called FTC are currently being tested in clinical trials for use as PrEP. They work by making it more difficult for HIV to replicate in the body, by interfering with an enzyme (reverse transcriptase) that the virus needs to reproduce itself.

AVAC’s report identifies a number of priorities in the run-up to the PrEP trial results, including that:

* the trials are well run and produce clear results;

* a plan of action to rollout PrEP is made now in case it works, and that this includes procurement and delivery plans.

However, the coalition warns that PrEP is unlikely to be 100% effective and would need to be used with other prevention methods such as condoms. ‘€“ health-e news.