New knowledge on mad cow disease emerges as researchers across the Atlantic claim to have developed a faster test for identifying the disease, possibly even in living cows.
The standard immunoassay tests used to identify the infectious prion proteins that cause mad cow disease have been criticised by some as inadequate for large scale screening of cattle - accused as producing false readings and can also take a week to yield results.
The new test - the conformation-dependent immunoassay (CDI) - can detect prion proteins with 100 per cent accuracy at much smaller levels than conventional tests and only takes about five hours to produce results, according to researchers at the University of California-San Francisco who presented their findings this week at the 226th national meeting of the American Chemical Society.
Like conventional tests, the new test is designed for detecting prions in the brain tissue of cows only upon autopsy. It also shows promise for detecting the proteins in muscle tissue and even blood while the animal is still alive, claim the scientists. If so, it could be used to identify precisely which animals are infected before they show symptoms and could help end the current practice of slaughtering whole herds, the scientists say.
"This represents a new generation of prion tests," said project leader Dr. Jiri G. Safar, an associate adjunct professor at UCSF.
He added that the test - funded in part by the UK's Department for Environment, Food and Rural Affairs - has been used in a field trial to check for signs of the disease in the brains of 11,000 slaughtered cows in Spain, the United Kingdom and Germany. Results were compared to those from standard immunoassays performed on the same animals. There were no discrepancies between the tests, he says.
The research group plans to use the test on an even larger scale among European cattle herds within the next year, checking them for signs of the disease upon autopsy. If further tests prove successful, Safar hopes it will eventually be used to evaluate dead cows in the US for mad cow disease, also known as bovine spongiform encephelopathy, or BSE.
CDI technology is now licensed to InPro Biotechnology, of San Francisco.