New "Mad Cow" Test
Cuts Time By Months

SAN FRANCISCO —(AP)— Scientists have developed a lab technique that might allow rapid screening of slaughtered cows for the rogue proteins that cause mad cow disease and a similar human illness.

A rapid test could ease consumer fears about eating beef or other cattle products. Such products are blamed for some rare cases of Creutzfeldt-Jakob disease in people.

Right now, the test for finding the proteins, or prions, requires too much time and labor for large-scale use on cattle, said researcher Dr. Fred Cohen. Further work will be needed to produce a workable screening kit, he said Monday.

The test-tube technique, used on hamsters so far, would be applied to cow brain tissue. It gives an answer in eight hours, versus the months needed for the standard means of detecting low levels of prions in tissue, Cohen said. The standard technique involves injecting tissue into the brains of lab animals and waiting to see if disease appears.

The work was reported in the October issue of the journal Nature Medicine by researchers at the University of California at San Francisco, including Cohen, Dr. Jiri Safar and Dr. Stanley Prusiner. Prusiner won a Nobel Prize last year for discovering prions.

The test involves treating a tissue sample with substances that unfold the prions. That exposes a section that proteins called antibodies can grab onto, allowing the prions to be detected.