FIG 3.

Progressive accumulation of misfolded PrP isoforms in gradient fractions 8 and 2 for three mouse Prnp genotypes. (A) Sequential appearance of total PrP^Sc and rPrP^Sc in fraction 8 containing low-M_r species plotted versus dpi. (B) Sequential appearance of total PrP^Sc and rPrP^Sc in fraction 2 containing high-M_r species plotted versus dpi. Note the different y axes for panels A and B. Each data point is an average ± the SEM of triplicate independent CDI measurements in three to four mice brains. As in Fig. 2, the CDI values for PrP^Sc in Tg20 mice at 30 and 45 days lay below the assay threshold.