UCSF develops faster, more sensitive mad cow detector

By Paul Elias
Monday October 21, 2002

SAN FRANCISCO – Scientists at the University of California, San Francisco have developed a new mad cow disease detector they claim is faster and more accurate than existing models and could “significantly reduce human exposure” to the fatal brain-destroying malady. 

UCSF researchers said their test can detect 10,000 more abnormal prions – the disease-causing proteins – per gram of tested tissue than more conventional tests. 

Such sensitive readings could spare cattle wrongly diagnosed as having the disease, known as bovine spongiform encephalopathy. The readings could also detect infected cows now misdiagnosed with false negative results, said Dr. Jiri Safar, who was lead author on a scientific paper discussing the research published online Sunday in the scientific journal Nature Biotechnology. 

Other prion disease experts agree the UCSF test is the most sensitive reported, but question how it will improve upon the current methods of diagnosing mad cow disease. Tests already available are sensitive enough to detect most occurrences of mad cow disease, they said. 

“This is a Cadillac when a Pinto is all you really need,” said Dr. Pierluigi Gambetti at Case Western Reserve University in Cleveland. 

Still, Gambetti said the UCSF test is impressive and could open the door to blood testing, which would allow diagnosis of mad cow disease while the cow is still alive. Currently, mad cow disease is only diagnosed by examining the brains of dead cows. 

More than 100 Europeans have died of the brain-destroying Creutzfeld-Jakob disease linked to eating infected cattle. Some 179,000 cattle have been found to have mad cow disease since 1986. 

One of the biggest challenges in testing for prion-related disease is distinguishing the abnormal prions from naturally occurring healthy prions. 

The UCSF test employs antibodies genetically engineered to seek out and bind with abnormal prions in tissue samples. Safar said the test performed flawlessly on 1,729 samples. 

Safar works in the lab of Dr. Stanley Prusiner, who co-wrote the paper and who won the 1997 Nobel Prize in Medicine for discovery that abnormal prions cause mad cow disease. The research was funded by the National Institutes of Health. 

Safar and Prusiner also hope to profit from the new test, which is being considered for commercial use by the European Commission. Both are investors in InPro Biotechnology Inc., a tiny South San Francisco startup launched by Prusiner in 2001 and which owns the commercial rights to the UCSF test. 

The company hopes to have the test on the European market by sometime next year, said InPro president Scott McKinlay. McKinlay estimated the commercial market for such a test in Europe to be about $200 million.