The only known difference between the cellular (PrP C) and scrapie-specific (PrP Sc)
isoforms of the prion protein is conformational. Because disruption of PrP Sc structure
decreases scrapie infectivity, restoration of the disease-specific conformation should restore
infectivity. In this study, disruption of PrP Sc (as monitored by the loss of proteinase K
resistance) by guanidine hydrochloride (GdnHCl) resulted in decreased infectivity. Upon
dilution of the GdnHCl, protease resistance of PrP was restored and infectivity was regained …