PrP genotype contributes to determining survival times of sheep with natural scrapie.
The PrP genotype and life spans were determined for more than 50 Flemish and Swifter sheep within a single scrapie-affected flock. 83% of the scrapie sheep were homozygous for the PrPVQ allele (polymorphic amino acids at codons 136 and 171 are indicated) and these sheep died from scrapie at a mean age of 25 months. In sheep heterozygous for PrPVQ, development of scrapie was delayed or did not occur. Sheep with at least one PrPAR allele, including PrPVQ/PrPAR sheep, did not develop scrapie. No scrapie sheep were found without a PrPVQ allele. It is concluded that the PrP genotype contributes to determining survival times of sheep with natural scrapie. Additionally, 2 novel sheep PrP allelic variants are described.