A misfolded protein can spread disease with no DNA or RNA at all

Every infectious agent known was assumed to need genetic material to replicate — until Stanley Prusiner proposed that a misfolded protein alone could trigger identical proteins nearby to misfold too, causing diseases like mad cow disease and CJD. The idea was ridiculed for years before winning him the 1997 Nobel Prize.

— Stanley B. Prusiner, Prion — Science, 1982 (named "prion"); Nobel Prize, 1997