Western blot analysis of PrPSc deposition load in terminal brain samples. Samples: 1, Uninfected 129/Ola; 2, Schwann cell PrP knock-out; 3, floxed PrP control; 4, Cre control; and 5, nontransgenic control. Densitometry revealed no significant differences in the amount of PK-resistant PrP detectable between genotypes; similar results were obtained following oral and intraperitoneal challenges. Approximate protein molecular weight markers are given in kilodaltons.