FIG 4 .
De novo prions display and propagate distinct conformational stabilities. We assessed three replicates of brain homogenates from all mice in each group (n = 5). (A) Western blots of brain extracts denatured with increasing guanidine hydrochloride (GdnHCl) concentrations and treated with 50 μg/ml·PK. (B) Corresponding denaturation curves quantify remaining PrPRES. To the right of each curve is the concentration of GdnHCl required to denature 50% of the PrPRES [(GdnHCl)50]. De novo prions exhibited conformational stability similar to that of D10 prions serially amplified (Amp D10) or passaged into cervidized mice (D10 p1), but the corresponding data were statistically significantly different from D10 data (P < 0.01). Passage of de novo prions into cervidized mice produced prions (de novo p1) whose incredibly stable conformation was much greater than that seen with the original de novo prions, while passaging the original D10 (D10 p1) or amplified D10 (Amp D10 p1) through mice produced prions with comparatively decreased stability.