Paraffin sections of spleen and liver from those negative controls and seven monkeys with clinical signs of TSE (SQ-BSE 721, 722, 735, 736, 737, 738 and 739) were probed with PrP monoclonal antibodies 6H4 and 3F4; brain from SQ 659 served as negative control and brain from SQ-BSE 739 as positive control. Here, PRNP is linked to human prion disease.