If you have an unorthodox, unproven idea that can prevent HIV infection or help protect against infectious diseases, one of the richest men in the world wants to hear from you.

The Bill & Melinda Gates Foundation has set aside $100 million US to encourage innovation in global health research, offering grants to those with innovative ideas on four topics: tuberculosis, HIV, infectious diseases and drug resistance.

The foundation's new Grand Challenges Explorations program plans to give $100,000 US each to about 60 projects in the first round of what is expected to be a five-year program.

Proposal applications are short — only about two pages long — and preliminary data is not required for the submissions, due at the end of May. They'll be accepted beginning March 31.

Of course, each applicant will need to be a scientist and have a lab in which to do the work, foundation officials said. But there won't be many more restrictions.

Foundation officials say it's one of the most open-ended requests for proposals they've ever issued, but it fits well with the organization's quest to be innovative.

"We push ourselves to be as creative as we can," said Martha Choe, who is slated to become the foundation's new chief administrative officer.

The foundation has no plans to open the door to unorthodox ideas for its other focus areas — global development, libraries, education, and support for children and families in the Pacific Northwest — although unsolicited grant requests arrive in the mail daily.

The world's largest philanthropy, which was established by Bill Gates, the co-founder of Microsoft Corp., paid out 1,322 grants totalling more than $2 billion US in 2007, compared with 1,283 grants totalling more than $1.54 billion US in 2006.

The Grand Challenges Explorations program is an outgrowth of an effort launched by the foundation in 2003 to help foster innovation in global health.

The foundation is already spending about $450 million US to support 40 bigger projects focused on preventing infectious diseases, creating drugs or delivery systems that limit resistance, creating new ways to prevent or cure HIV infection, and understanding latent TB infection.

The smaller grants announced this week will focus on the same research areas. The foundation expects to make several requests for proposals each year, officials said.