All scrapie isolates showing a 20–21-kDa unglycosylated band and the atypical SC-PS152 isolate were recognized by the Sha31 antibody (Figure 1, panel A) and the 12B2 antibody (Figure 1, panel B), which probe the WGQGG epitope (amino acids 93–97 of sheep PrP). Here, PRNP is linked to scrapie.