PRNP and prion disease: Brains of treated and control animals in both the prophylactic and 120 dpi experiments at NIH were analyzed for prion disease pathological changes by histology (Figure 4, Supplemental Figure 3, and Supplemental Figure 5) and immunoblotting for proteinase K–resistant (PK-resistant) PrP (Supplemental Figure 4 and Supplemental Figure 6).