prion2
Pronunciation: /ˈpriːɒn/
noun
Microbiology- a protein particle that is believed to be the cause of brain diseases such as BSE, scrapie, and CJD. Prions are not visible microscopically, contain no nucleic acid, and are highly resistant to destruction. Compare with virino.

Origin:
1980s: by rearrangement of elements from pro(teinaceous) in(fectious particle).