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United States Department of Agriculture

Agricultural Research Service

Title: Scrapie: the Very Model of An Infectious(protein)isoform

Author
item Silva, Christopher

Submitted to: Association Official Analytical Chemists Annual Intrl Meeting & Exposition
Publication Type: Abstract Only
Publication Acceptance Date: March 14, 2005
Publication Date: May 2, 2005
Citation: Silva, C.J. 2005. Scrapie: The Very Model of an Infectious (Protein) Isoform [abstract]. 96th AOCS Annual Meeting & Expo. Salt Lake City, UT, May 2, 2005.

Interpretive Summary: Scrapie is a fatal disease of sheep. It was first described in the 18th century. Since its initial discovery, it has become endemic in most of the world. It is the most intensely studied example of a class of diseases called transmissible spongiform encephalopathies (TSEs). TSEs include scrapie, chronic wasting disease (CWD), bovine spongiform encephalopathy (BSE), Kuru, and Creutzfeld-Jakob Disease (CJD). Research in the 20th century showed scrapie to be caused by a novel infectious agent, the prion. Prions are infectious proteins. They are structural variants of the highly conserved and naturally occurring cellular prion protein called the prion protein. A prion is able to convert the normal cellular prion protein into the infectious form, thus propagating the infection. An infectious dose is estimated at between 100,000 to 1,000,000 molecules. Prions are remarkably stable and survive many forms of sterilization, including autoclaving. It can survive years in the environment. Fields grazed by infected animals will remain infectious for years. Prions possess the worst properties of persistent toxins and virulent pathogens. This presentation will include a historical review of how this obscure sheep pathology leads to the discovery of the prion. It will highlight current research on the structure, detection and pathology of the prion.

Technical Abstract: Scrapie is a fatal neurodegenerative disease of sheep. It was first described in the 18th century. Since its initial discovery, it has become endemic in most of the world. It is the most intensely studied example of a class of diseases called transmissible spongiform encephalopathies (TSEs). TSEs include scrapie, chronic wasting disease (CWD), bovine spongiform encephalopathy (BSE), Kuru, and Creutzfeld-Jakob Disease (CJD). Research in the 20th century showed this disease to be caused by a novel infectious agent, the prion (PrPSc). PrPSc is an infectious isoform of the highly conserved and naturally occurring cellular protein called the prion protein (PrPC). PrPSc is able to convert PrPC into PrPSc, thus propagating the infection. An infectious dose(ID50)is estimated at between 105 to 106 molecules. PrPSc is remarkably stable and survives many forms of sterilization, including autoclaving. It can survive years in the environment. Fields grazed by infected animals will remain infectious for years. Prions possess the worst properties of persistent toxins and virulent pathogens. This presentation will include a historical review of how this obscure sheep pathology lead to the discovery of the prion. It will highlight current research on the structure, detection and pathology of PrPSc.

Last Modified: 10/21/2014
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