Assay for Prions Responsible for Mad Cow Disease

An assay is being developed to determine the presence of prions in humans before symptoms of variant Creutzfeldt-Jakob disease (vCJD) appear. Since the silent vCJD phase can last 40 years in humans, such an assay would reveal the extent of the problem and stop further infection via transfusions and transplants.

In the July 7, 2006, issue of the journal Science, Professor Claudio Soto and colleagues at the University of Texas Medical Branch at Galveston (UTMB, Galveston, TX, USA) described experiments they expect will lead to a test that will enable them to estimate how many people are infected with the human form of mad cow disease. The scientists detected prions--the infectious proteins responsible for such brain-destroying disorders as bovine spongiform encephalopathy (BSE) in cattle and vCJD in humans--in the blood of hamsters in as few as 20 days after the animals had been infected. That discovery occurred about three months before the hamsters began showing clinical symptoms of the disease.

To detect the very small quantities of prions found in blood samples, Professor Soto, assistant professor Joaquin Castilla, and research assistant Paula Saá used a technique known as protein misfolding cyclic amplification (PMCA), invented by the group. PMCA greatly accelerates the process by which prions convert normal proteins to misshapen infectious forms.

"With this method, for the first time we have detected prions in what we call the silent phase of infection,” said Prof. Soto. "This result is an important step toward a practical biochemical test that will determine how common variant CJD is, and keep contaminated blood and organs from spreading it further.” In a move toward making a human test commercially available, Prof. Soto and UTMB recently formed a startup company dubbed "Amprion.”

"All our effort so far has been to prove the scientific concepts, so we're building this company to go into issues of development, scalability and practicality,” Prof. Soto said. "We are hopeful that development of this technology into a useful blood test will be a pretty straightforward process.”





Related Links:
University of Texas Medical Branch at Galveston