LONDON — An Irish supermarket chain has become the first retailer in the world to sell beef tested for bovine spongiform encephalopathy (BSE), or mad cow disease, after it began evaluating carcasses with a prion diagnostic developed by Proteus International plc.

Shares in Proteus, of Macclesfield, U.K., rose 23 pence to 80 pence when the news was disclosed last week.

The testing is carried out at a cost of £20 per carcass by Enfer Scientific, a privately held Irish company based in Newbridge, which has an exclusive worldwide license for the diagnostic from Proteus. Proteus receives a 10 percent royalty.

SuperValu, which has 168 supermarkets, said all the beef it sells will be tested for prions, the infectious agents that are thought to cause BSE and its human counterpart, Creutzfeldt-Jakob disease.

David Gration, chairman of Proteus, said, "We hope this is the first step in the widespread acceptance of this test, which I am sure would be welcomed by consumers everywhere." — Nuala Moran