Timothy Ray Brown is believed to be the only person to ever be cured of the AIDS-causing virus, HIV.
Once known as the "Berlin Patient", Brown was cured five years ago when doctors attempting to alleviate his leukemia infection used the bone marrow of a donor with a rare gene mutation.
Brown's cells have been HIV-resistant ever since and he has allowed his body to be used for tests.
He believes further research needs to be done to find a cure, and hopes his case will help to find a cure for others.
Al Jazeera's Kimberly Halkett reports from Washington.