Western blot analysis. Healthy bovine used as negative control (C-), U.S. H-type BSE (1), Italian C-type BSE (2), Italian L-type BSE (3) and U.S. C-type BSE (4) samples, all examined by whole homogenate and SAF extraction methods. 10 milligrams of tissue equivalent were loaded per lane. All samples were proteinase K treated. Blots were probed with mAbs 6H4 (A) and P4 (B), respectively.