An experimental gel appeared to help protect some women from HIV infection, researchers said Monday.

The international trial of about 3,100 women showed the gel may have protected 30 per cent of the women from infection, Dr. Salim Abdool Karim of the Center for the AIDS Program of Research in South Africa told the 16th Conference on Retroviruses and Opportunistic Infections in Montreal.

The study, funded by the U.S. National Institutes of Health, was conducted in South Africa, Malawi, Zambia, Zimbabwe and the United States.

Researchers hope gels and other microbicide creams could help protect women whose partners refuse to wear condoms.

"This is the first study that now shows we have a promising candidate," said Karim.

In the study, designed to test the safety of the vaccine, participants were divided into four groups, and were all counselled to have their partners use condoms:

• The first group used the Indevus gel, called PRO 2000 in women, made by Massachusetts-based Indevus Pharmaceuticals Inc.
• A second group was given a gel made by Baltimore-based ReProtect Inc.
• A third group used a placebo gel.
• The last group used no gel at all.

The Invedus gel is designed to block HIV, the virus that causes AIDS, from attaching to certain white blood cells.

Those using the Invedus gel had a 30 per cent lower rate of HIV infection, but the results could have occurred by chance, the researchers said.

"We do not regard it as a definitive conclusion that PRO 2000 is a microbicide, but we certainly view it as very promising," Karim told a news conference.

There were no signs that ReProtect helped.

Larger trials are needed to tell if the gel is effective. One trial underway among 9,400 women in Africa is set to end in August.

With files from Associated Press