FIGURE 2.

Transition of PrP^Sc in scrapie-passaged mice during the long term PK (LTPK) resistance assay. Brain homogenates prepared from the first to fifth passages of scrapie in mice were digested with 100 μg/ml PK for 1, 3, or 6 h. The transition of PK resistance of PrP^core was monitored by ELISA (see “Experimental Procedures”). The A_{450 nm} of PrP^core (1 h) was defined as 1.0 and used as a basis for calculating the degree of PK resistance of PrP^core after 3 and 6 h of digestion. All values except that after the second passage were significantly lower (*, p < 0.01) than those after the first passage (n = 3 for each analysis).