TORONTO (AP) – Empowering women in developing countries to protect themselves against HIV with hopeful preventative drugs could be the “next big breakthrough” in combating the virus that has already claimed 25 million lives, Bill and Melinda Gates told a global conference.

The couple joined more than 24,000 scientists, activists, celebrities, and health workers from 132 countries Sunday at the opening of the week-long 16th International AIDS Conference.

The Microsoft founder – flush with a US$30 billion (euro23.5 billion) commitment from Warren Buffet to fight such diseases as AIDS – recently announced he would step down from his day-to-day duties at the company to devote more time to philanthropy.

He told the opening ceremonies that the search for a vaccine to prevent the virus that causes AIDS, and universal treatment for those infected with HIV, were now top priorities.

“At the same time, we have to understand that the goal of universal treatment – or even the more modest goal of significantly increasing the percentage of people who get treatment – cannot happen unless we dramatically reduce the rate of new infections,” he said.

Gates noted that between 2003 and 2005, the number of people in low- and middle-income countries on antiretroviral drugs increased by 450,000 each year. Yet over the same period, the number of people who became infected with HIV averaged more than 4 million a year.

“In other words, for each new person who got treatment for HIV, more than 10 people became infected,” he said. “Even during our greatest advance, we are falling behind.”

The Bill & Melinda Gates Foundation has given US$1.9 billion (euro1.5 billion) to support HIV/AIDS projects worldwide since 1995 and announced last week a US$500 million (euro391 million) grant to the Global Fund to fight AIDS.

“We want to call on everyone here and around the world to help speed up what we hope will be the next big breakthrough in the fight against AIDS – the discovery of a microbicide or an oral prevention drug that can block the transmission of HIV,” Gates said.

“This could mark a turning point in the epidemic, and we have to make it an urgent priority,” he added.

Microbicides are gels or creams women can use to block infections and disease. Sixteen microbicides are being clinically evaluated; five are in major advanced studies.

The couple also called for greater advocacy to break the “cruel stigma” of AIDS for women in impoverished nations who typically have little say over their own sex lives or health.