New Insights into Mad Cow May Improve Tests

A new procedure that should improve the sensitivity of current tests for mad cow and other prion diseases has been developed by researchers at Serono Pharmaceutical Research Institute (Geneva, Switzerland). The research was reported in the June 14, 2001, issue of Nature.

The new procedure is termed Protein Misfolding Cyclic Amplification (PMCA). According to the researchers, this marks the first time the abnormal prion protein has been cultivated in vitro, with a greater efficiency than the conversion process postulated to occur in vivo with prion diseases. The procedure suggests that the abnormal prion protein can be detected in blood.

The research has many applications in the diagnosis of prion diseases. These include the identification of abnormal prion proteins in the brains of dead cattle under 30 months of age or those recently infected with bovine spongiform encephalopathy (BSE), the identification of abnormal prion protein in live cattle, and the detection of Creutzfeldt-Jakob (CJD and nvCJD), using spinal fluid or blood. The procedure may also be applicable to the detection of other protein-misfolding diseases such as Alzheimer's disease.

In the procedure, minute samples of abnormal prion protein (PrPsc) were taken from the brains of scrapie-infected hamsters and mixed with large excess amounts of normal prion protein (PrPc). This resulted in a rapid conversion of the normal prion protein into many aggregates of the abnormal prion protein. The aggregates were then treated with ultrasound. This cycle of amplification can be repeated many times within a day in a laboratory, say the researchers, to produce quantities of the abnormal prion protein that are several hundred times greater than those currently available in the brain tissue of dead animals or humans.

"The procedure mimics the replication of abnormal prion proteins in the body in ‘fast forward' mode, compressing years of real-life time into a few hours in the laboratory,” said Silvano Fumero, senior executive vice president, research & pharmaceutical development, Serono. "This is a major scientific breakthrough and has potential applications in improving tests for prion diseases, as well as identifying targets against which future drugs could be aimed.”




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