AIDS Information Services >> Lemons & AIDS >> Latest News

Starting to gel - by Helen Pilcher (Edited highlights) - Published online: 07 July 2004 - From: NEWS @ NATURE.COM

In sub-Saharan Africa, there's an urgent need for creams or gels that can protect women from infection with HIV. Now the first large-scale trials are getting under way. Helen Pilcher reports.

Microbicides are creams or gels that can be applied to the vagina before sex to help prevent HIV infection. It is hoped that they will be undetectable to male partners, so that women will be able to protect themselves discreetly. With condom use patchy and any successful vaccine some way off, hopes are pinned on these compounds' prophylactic powers.

But so far, only one has been fully tested in people, and that proved to be a resounding flop....... The detergent molecule nonoxynol-9.

At best, microbicide gels are likely to be only partially effective. "But this could make a big difference in places such as Africa," says Charlotte Watts, who works on the epidemiology of HIV at the London School of Hygiene and Tropical Medicine. Her team has calculated that even a microbicide that was 60% effective could prevent 2.5 million infections worldwide over a three-year period.

Today, microbicide research is receiving relatively generous funding, after years of being the poor relative of vaccine studies. Over the past six years, the US government has quadrupled its microbicide expenditure and will spend a further $88 million this year. Worldwide, public- and private-sector spending on microbicides totalled $530 million over the same period. "But it's not enough," says Polly Harrison, director of the Alliance for Microbicide Development, an advocacy group based in Silver Spring, Maryland. It costs about $35 million to develop and test a single microbicide.

When a product finally does make it to the market, it will have to be affordable.

With 3 billion people living on less than $2 a day, microbicides will have to be a lot cheaper if they are to be effective.

Fruitful enquiry
Given these concerns, and the fact that the commercial microbicides won't be available until 2010 at the earliest, reproductive biologist Roger Short of the University of Melbourne, Australia, is looking for a cheaper, more readily available alternative. He thinks that the answer may grow on trees.

Roger Short: believes citrus fruit may offer a cheap and convenient barrier to HIV infection.

In a paper to be presented at the XV International AIDS Conference in Bangkok, Thailand, Short and his colleagues will report that a 20% solution of lemon juice takes just two minutes to achieve 90% inactivation of HIV in lab culture.

Historically, citrus fruit juices have been used as contraceptives. About 300 years ago, Mediterranean women used lemon juice in the vagina to help prevent pregnancy. Today, Nigerian prostitutes douche with dilute lemon juice in the hope that it will protect them against sexually transmitted diseases.

Short points out that in South Africa, five lemons can be bought for the price of one condom. And the juice of just one fruit goes a long way. A single lemon yields enough juice for ten sexual acts, and can be kept at room temperature for up to a month.

As long as the vagina is free of lesions, using lemon juice is virtually painless. It could also be applied to the foreskin after sex to help protect men from HIV infection. And because it's natural, it can't be patented. But the flipside is that with no profit motive for drug companies, funding for clinical trials is hard to come by.

Nevertheless, the Thai government recently agreed to launch an initial clinical study. Because limes — manao in Thai — grow widely in southeast Asia, the manao trial will focus on limes rather than lemons. The study, which should begin shortly, will assess the acceptability, safety and efficacy of lime juice against pregnancy and sexually transmitted infections, including HIV. "We've been looking for the microbicidal Cadillac," claims Short, "when all along we've been overlooking the humble push bike."

Whether the answer lies with Short's low-tech approach, gels such as dextrin sulphate, or advanced rational drug design won't be known until the results from clinical trials are in. But with no sign of an effective AIDS vaccine on the horizon, microbicides may offer the best hope for millions of young women.