Western immunoblot and antibody signal ratio of vole brain samples after primary passage of bovine scrapie and comparison with vole-adapted classical scrapie and BSE. WB analysis of PrPres in voles infected with P75-7 (primary passage) compared with a representative sample of P90-4 (primary passage), vole-adapted classical scrapie and BSE. Replica blots were developed with mAbs SAF84 (upper panel) and 12B2 (lower panel) to compare the antibody reactivity with each sample similar to the discriminative WB used for samples from small ruminants. The graph on the bottom shows the SAF84/12B2 signal ratio relative to the scrapie control. Values higher than 1 denote more C-terminal PK-cleavage and consequential loss of the epitope of 12B2.