Figure 1. Immunoblots obtained for reference brain samples by discriminatory Western blot method. The first membrane (A, B) was probed with Bar233 antibody. The second membrane (C, D) was probed with monoclonal antibody P4. The 2 immunoblots were loaded with a natural classical bovine spongiform encephalopathy (BSE) isolate (lane 1); an isolate from a sheep experimentally infected with classical BSE 4 (SB1, lanes 2, 6); 2 sheep-passaged scrapie isolates (SSBP/1, lanes 3, 5; CH1641, lane 4); and an isolate from a goat experimentally infected with classical BSE (CH41x76, lane 7).