Western blot analysis in wild‐type mice. Western blot analysis of proteinase‐K‐digested PrPSc from UK‐1 and UK‐2 challenged RIII (A) and C57BL (B) mice, detected with Sha31 and 12B2 antibodies. Lanes 1 and 12: molecular mass markers (kDa), Lanes 2 and 11: blank, lane 3: unchallenged proteinase‐K digested mouse brain homogenate, lane 4: mouse challenged with ovine classical scrapie, lanes 5–6 and 8–9: mice challenged with UK‐1 or UK‐2, lane 7: mouse challenged with murine passaged ME7 strain, lane 10: mouse challenged with sheep bovine spongiform encephalopathy (BSE). Exposure time was1 minute for all blots.