A. P1 and P2, biotinylated and coupled to streptavidin magnetic beads, were used to capture PrP from the brain homogenates of CJD patients, as well as unaffected controls (Non-CJD). Beads with no conjugated peptide, but blocked with 0.1 % BSA, were used as a negative control (None). An unrelated peptide was biotinylated and conjugated to streptavidin magnetic beads, as a second negative control (Unrelated).