PRP GENOTYPE CONTRIBUTES TO DETERMINING SURVIVAL TIMES OF SHEEP WITH NATURAL SCRAPIE

Several allelic variants of the sheep PrP gene are associated with scr apie susceptibility, However, it is not known whether, and to what ext ent, the PrP genotype contributes to determining survival times of scr apie sheep, We therefore determined the PrP genotype and life spans of over 50 Flemish and Swifter sheep within a single scrapie-affected fl ock, Eighty-three per cent of the scrapie sheep were homozygous for th e PrPVQ allele (polymorphic amino acids at codons 136 and 171 are indi cated) and these sheep died from scrapie at a mean age of 25 months, I n sheep heterozygous for PrPVQ, development of scrapie was delayed or did not occur, Sheep with at least one prp(AR) allele, including prp(V Q)/prp(AR) sheep, did not develop scrapie, Ho scrapie sheep were found without a PrPVQ allele, We conclude that the PrP genotype contributes to determining survival times of sheep with natural scrapie, Addition ally, we describe two novel sheep PrP allelic variants.