AIDS: Microbicide gel 'highly encouraging' in lab tests

The dogged search for a vaginal gel to thwart the AIDS virus earned some good news on Wednesday as scientists announced that a cheap, commonly-used compound shielded monkeys from a lethal cousin of HIV.

They cautioned that a long road lies ahead before the microbicide can be verified as safe and effective for humans but hailed the outcome as a tremendous boost.

A cream that blocks or kills the human immunodeficiency virus HIV is a cornerstone of efforts in the fight against AIDS. It would be especially useful for women in sub-Saharan Africa, at risk from coercive sex from HIV-infected partners.

But the quest has suffered many blows. They include two trials that, dismayingly, found women who used a prototype gel ran a greater risk of HIV than those who used a dummy lookalike.

In a study published in Nature, researchers at the University of Minnesota tested a compound called glycerol monolaurate GML.

GML exists naturally in the human body but is already licensed as an antimicrobial and anti-inflammatory agent in cosmetics and toiletries and as an emulsifier in foods.

Their hunch was that GML interferes with signalling processes in the immune system, thus blocking HIV's rampage at a key stage.

When the virus enters the body, defence systems unleash a cascade of orders, dispatching so-called T immune cells to the site of the infection.

It is these cells that are then hijacked by HIV and turned into virus-making mini-factories, enabling the agent to proliferate throughout the bloodstream.

"Even though it sounds counter-intuitive, halting the body's natural defence system might actually prevent transmission and and rapid spread of the infection," said chief investigator Ashley Haase.

The team gave a vaginal application of GML gel to five rhesus macaque monkeys and exposed them and a comparison group of five other animals to two large doses of simian immunodeficiency virus SIV -- the monkey equivalent of HIV.

Over the next two weeks, four of the control group contracted SIV. But none of the GML-treated group showed any acute infection, even though they were given up to two further shots of the virus.

GML, said the paper, breaks a "vicious cycle" of immune-system signalling and inflammatory response in the cervix and vagina.

"This result represents a highly encouraging new lead in the search for an effective microbicide to prevent HIV-1 transmission that meets the criteria of safety, affordability and efficacy," it declared.

Each dose of GML used in the experiment cost less than one US cent 0.75 of a euro cent.

GML's use as a microbicide and anti-inflammatory was discovered by one of the researchers, Pat Schlievert, when he probed so-called toxic shock syndrome in the use of menstrual tampons.

He found that GML inhibited the toxin-making mechanism of the germ Staphylococcus aureus. Tampons coated with GML protected women from the bacterium and eased vaginal inflammation.

Around 33 million people around the world have HIV, two-thirds of them south of the Sahara. Globally, women make up 50 percent of all HIV-infected people, but in Africa, this rises to nearly 60 percent.









March 4. REUTERS/Hannibal Hanschke