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Nobel To Prion Professor

By Sean Henahan, Access Excellence 

San Francisco, CA (10/6/97)-  Stanley Prusiner (pictured), whose suggestion of a new infectious particle called the prion was originally greeted with skepticism has received the ultimate vindication, the Nobel Prize for Medicine and Physiology. 

The Nobel Committee cites Prusiner " for his pioneering discovery of an entirely new genre of disease-causing agents and the elucidation of the underlying principles of their mode of action." Prusiner, a professor of biochemistry at the University of California, San Francisco, was the first to suggest the existence of prions and to suggest that they were the causative agents of the spongiform encephalopathies- among them kuru and bovine spongiform encephalopathy ("mad cow disease".) 

Prions are rogue proteins that wreak havoc in the brains of  infected animals and people. They contain no nucleic acid (DNA or RNA). These hard to classify biological objects consist of a single molecule containing about 250 amino acids, termed the PrP protein. They are abnormal variant of proteins that occur normally in cells, such as human brain cells. The abnormal PrP proteins, when they enter the body, are able to convert their normal counterparts into more of the abnormal forms. 

Prusiner's research showed that the difference between the normal and abnormal proteins did not lie in their primary structure (the sequence of their amino acids), but rather in their folding -the abnormal PrP proteins are folded in a way that allows them to resist normal protease degradation so that over time this leads to the build up of aggregates of PrP, especially in neurons in the brain. These aggregates resemble the tangles of abnormal protein found in neurons in Alzheimer s disease patients. 

"Prions are the only "life forms" that break the great "central dogma" of biology. That is, we have come to expect that all life forms from viruses to bacteria to plants to humans to hand down the blueprints for all their progeny via their DNA (except for some viruses which carry their blueprints as an RNA genome), and we expect that the process for converting the blueprints into building blocks must involve replication of DNA, transcription of the message into RNA, and translation of the RNA s message to form proteins, the building blocks of cells, tissues, organs and whole organisms. Here we have life forms where abnormal proteins, the PrP proteins, direct the refolding of normal proteins just by direct contact," explained Dr. Frederick A. Murphy, former  Dean of the School of Veterinary Medicine, University of California, Davis, in an interview with AE. 

Prions have been implicated in a number of spongiform encephalopathies, including: scrapie, a disease of sheep; bovine spongiform encephalopathy (BSE), a disease of cattle; and Creutzfeldt-Jakob disease (CJD), a disease of humans. Prions jumped to the front pages when epidemiological and post-mortem pathology studies confirmed an apparent link between BSE (mad cow disease) and the human disorder CJD. 

"Stanley Prusiner's discovery provides important insights that may furnish the basis to understand the biological mechanisms underlying other types of demential-related disease, for example Alzheimer's disease, and establishes a foundation for drug development and new types of medical treatment strategies," the Nobel Committee notes. 

Dr. Prusiner provides an update on prion science in the October 10, 1997 issue of Science 

Related information on the Internet
Nobel Announcement
AE: Prion Interview
AE: Quick BSE Test
AE: Mad Cow BSE Connection
AE: Prion Puzzle Pieces
Illustrated Presentation

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