Viral Gene Screen; August 1999; Scientific American Magazine; by Netting; 2 Page(s)

Thanks to serological tests and rigorous screening, the U.S. blood supply is safer than ever before. But that doesn't mean there isn't any bad blood in the nation: although there is only a one-in-676,000 chance that blood containing HIV will slip by standard tests, as many as 14 million units are donated every year. The liverravaging hepatitis C virus can elude standard tests with a frequency nearly seven times greater than that for HIV. The chances may be slim, but the public "demands zero risk for blood and plasma donations," says Edward Tabor, associate director for medical affairs at the Food and Drug Administration's Office of Blood Research and Review. To work toward that goal, blood centers around the country began evaluating a technique this past March that could cut the risks by half or more-by looking for the viral genes themselves.

Currently U.S. blood banks interview potential donors, rejecting those with even small risk factors, such as having traveled to certain countries. Technicians generally test donated blood by identifying viral antigens (distinctive proteins on the surface of a virus) or the antibodies mobilized by the body against an infection.