Recently, several studies have shown that the ARR allele at codons 136, 154 and 171 of the PRNP gene is associated with a highly protective effect against natural or experimental infection with classical scrapie and BSE, while the VRQ and ARQ alleles of the PRNP gene are susceptible to classical scrapie and BSE in sheep3,31–33. This evidence concerns the gene PRNP and scrapie.