Novel proteinaceous infectious particles cause Scrapie.

In 1997 Prusiner was awarded the Nobel Prize in Physiology or Medicine "for his discovery of Prions - a new biological principle of infection."

In his 1982 paper Prusiner proposed a completely novel explanation for the cause of bovine spongiform encephalopathy ("mad cow disease") and its human equivalent, Creutzfeldt–Jakob disease.To describe the cause of the disease in this paper Prusiner coined the term prion, which comes from the words "proteinaceous" and "infectious," to refer to a previously undescribed form of infection, due to protein misfolding, with no DNA or RNA involved. This new concept "violated all the rules" and failed to convince the scientific community, most of whom initially thought that Prusiner was "totally insane."
See also Nos. 10842, 12835 and 7624.