Mad Cow & Kreutzfeld-Jacob
Disease Prions Defined
Prions are a class of poorly understood proteins implicated in a number of exotic human neurological diseases and in some common animal diseases such as sheep scrapie and bovine spongiform encephalopathy in cattle ("mad cow disease"). One human disease in which prions have been strongly implicated is Creutzfeldt- Jakob disease, which appears to have a genetic basis in about 15% of the cases. What is remarkable about prions is that they behave as infectious agents, but they are 100 times smaller than viruses and their mechanism of replication is unclear. All the prion diseases are apparently associated with the accumulation in the brain of an abnormal protease-resistant isoform of the prion protein PrP. In other words, an abnormal variant of the normal PrP is somehow copied or produced by the disease process, which can be initiated by introducing infectious prion into the system. B. Chesebro (Rocky Mountain Labs., US), in a review of current research in prion diseases, points out that although the idea of prions as self-sufficient infectious proteins has received a great deal of publicity because of the recent award of the Nobel Prize in Medicine and Physiology to S. Prusiner for the discovery of prions, "at the present time the fact remains that there are no definitive data on the nature of prions." The author suggests it would be tragic if the recent Nobel Prize award were to lead to complacency regarding the obstacles still remaining in prion research, and that "it is not mere detail, but rather the central core of the problem, that remains to be solved." QY: Bruce Chesebro < (Science 2 Jan 98)

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