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prion (1)

pri·on [ pr òn, pr ən ] (plural pri·ons)


noun 
Definition:
 
infectious protein particle: an infectious particle of protein that, unlike a virus, contains no nucleic acid, does not trigger an immune response, and is not destroyed by extreme heat or cold. These particles are considered responsible for such diseases as scrapie, bovine spongiform encephalopathy, kuru, and Creutzfeldt-Jakob disease.

[Late 20th century. < proteinaceous + infectious + -on1]
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