Scientists in Australia's tropical north are collecting blood from crocodiles in the hope of developing a powerful antibiotic for humans, after tests showed that the reptile's immune system kills the HIV virus.
Natural immunity to the AIDS virus
Throughout the history of the AIDS epidemic, a few lucky people have avoided infection despite being exposed again and again. Now, researchers are traveling back in evolutionary time to understand why some people are resistant -- and in some cases virtually immune -- to the AIDS virus.
Studies released this week and last year suggest that the roots of AIDS immunity extend back for centuries, long before the disease even existed. Our ethnic backgrounds and the illnesses suffered by our distant ancestors appear to play a crucial role in determining whether our genes will allow HIV to take hold in our bodies.
Genetic resistance to AIDS works in different ways and appears in different ethnic groups. The most powerful form of resistance, caused by a genetic defect, is limited to people with European or Central Asian heritage. An estimated 1 percent of people descended from Northern Europeans are virtually immune to AIDS infection, with Swedes the most likely to be protected. One theory suggests that the mutation developed in Scandinavia and moved southward with Viking raiders.