USDA Licenses Rapid Assays for BSE

MAD COW TESTING

The Department of Agriculture has licensed two rapid tests for use in detecting mad cow disease, known technically as bovine spongiform encephalopathy (BSE). The tests, made by Bio-Rad Laboratories in Hercules, Calif., and Idexx Laboratories in Westbrook, Maine, produce results in four to five hours.

USDA had announced in mid-March that it would for the first time use rapid assays in its BSE testing program, which aims to examine brain tissue from 201,000 to 268,000 slaughtered cattle over a 12- to 18-month period (C&EN, March 22, page 7). USDA's National Veterinary Services Laboratories in Ames, Iowa, as well as NVSL facilities in 25 states, will use the Bio-Rad and Idexx kits for the testing. The program is expected to start in June.

The Bio-Rad kit is the most widely used BSE assay in Europe and is used almost exclusively in Japan to test all its slaughtered animals. The Idexx kit has been submitted to the European Union for approval.

Both kits employ the enzyme-linked immunosorbent assay, or ELISA, technique to detect the presence of the protease-resistant form of prion protein—the cause of BSE.

Positive results obtained with the screens will be confirmed with an immunohistochemistry assay, an expensive test that requires five days for results.

In a related development, Creekstone Farms, a beef processor in Arkansas City, Kan., has asked USDA to allow the firm to voluntarily test all of its cattle for BSE. It wants to sell beef to Japan, which is demanding that all beef imports be tested. So far, USDA has refused Creekstone's request.