PK-resistant fragment (PrPTSE) of the prion protein in Bov6 mice challenged with BSE-H, 581 days p.i. (lanes 1 and 2), BASE, 610 days p.i. (lanes 3 and 4) and BSE-C, 604 days p.i. (lanes 5 and 6). Lanes 1, 3 and 5 represent untreated brain homogenate and lanes 2, 4 and 6 show PK-treated brain homogenate. Anti-PrP mAb 6H4 was used to detect bands.