When a group of black teens asks you if the AIDS virus was developed to get rid of African Americans and homosexuals, how do you answer?

If you're Patrick Allen, the nation's only black microbiologist leading an HIV investigation, you answer very gingerly.

"I don't think it's likely," Allen told a group of high-achieving Students at Denver Montbello High School on Monday. "I wasn't there at the beginning, so I don't know. But it's hard for me to imagine there's a small group of people who can do something like that and trick all the rest of the scientists.

Afterward, Allen, 36, said, "You wouldn't believe how many times I get that question." The first time, when he dismissed the conspiracy theory out of hand, the audience turned against him, decided he was someone schooled too long in a white world. "A lot of black people feel they're very much on the outside. The fear and the mistrust is so deeply rooted that it's not going away soon."

Allen, a University of Colorado researcher, is on a mission. He is determined to raise black peoples' awareness of their own health.

Sure, it would be great if more blacks - maybe somebody in Monday's audience - went into microbiology.

But that's more likely to happen when blacks get into the mainstream of health. That means jogging and bicycling and eating well so they live long enough to close the 14-year longevity gap between blacks and whites in Colorado.

And it means volunteering for clinical trials, especially involving hypertension and other diseases that disproportionately hit African Americans, said Allen, who has a $1.2 million National Institutes of Health grant to define the structure of the HIV virus.

"Blacks know they're at risk for high-blood pressure and cardiovascular problems," Allen said.

"Yet, they're the least likely group to go to the free health fairs and get their cholesterol checked."