Mad Cow Disease Detected in Blood

For the first time, researchers have found a way to detect in blood the proteins called prions that cause bovine spongiform encephalopathy (BSE), known as mad cow disease.

The discovery is expected to lead to a much more effective detection method for BSE and its human variant, Creutzfeldt-Jakob disease (vCJD). A blood test would make it much easier to keep BSE-infected beef out of the human food supply, ensure that blood transfusions and organ transplants do not transmit vCJD, and give researchers their first chance to discover how many people may be incubating the disease.

"The concentration of infectious prion protein in blood is far too small to be detected by the methods used to detect it in the brain, but we know it's still enough to spread the disease,” said senior author Claudio Soto, professor of neurology at the University of Texas Medical Branch (Galveston, USA).

Prof. Soto and the other authors applied a method they call protein misfolding cyclic amplification (PMCA) to blood samples taken from 18 prion-infected hamsters that had developed clinical symptoms of prion disease. PMCA uses sound waves to vastly accelerate the process that prions use to convert normal proteins to misshapen infectious forms. Successive rounds of PMCA led to the discovery of prions in the blood of 16 of the 18 infected hamsters. No prions were found in blood samples taken from 12 healthy controls and subjected to the same treatment.

"The next step, which we're currently working on, will be detecting prions in the blood of animals before they develop clinical symptoms and applying that technology to human blood samples,” added Prof. Soto.

Tests for infectious prions in cattle and human blood are badly needed, because current tests require post-slaughter brain tissue for analysis. "Who knows what the real situation is in cattle in the United States? And with people, we could be sitting on a time bomb, because the incubation period of this disease in humans can be up to 40 years,” warned Prof. Soto.




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U. of Texas Medical Branch