PRNP and scrapie: [1] Most scrapie infections are presumably acquired by the oral route. Exposure to the scrapie agent initiates an autocatalytic, templated conversion of the highly conserved, host-encoded, membrane-anchored glycoprotein PrPC to the abnormally folded PrPSc. The clinical and pathological hallmarks of scrapie develop as PrPSc gradually accumulates in the central nervous system (CNS) months or years after initial exposure.