To enable us to assess the ability of a single PRNP genotype to support various TSEs with distinct pathological characteristics, data is presented for comparison from AHQ/AHQ animals orally challenged with BSE (cases 10-14) [22-24] and field cases of classical scrapie which have arisen naturally in AHQ/AHQ sheep (cases 15-17) [25,26]. This evidence concerns the gene PRNP and scrapie.