THE ASSOCIATION OF A CODON-136 PRP GENE VARIANT WITH THE OCCURRENCE OF NATURAL SCRAPIE

Incidence of both experimental and natural scrapie in sheep has been a ssociated with polymorphisms of the PrP gene. In case/control studies the PrP allele which encodes valine at codon 136 (Val(136)) is found i n 96-100% of naturally infected scrapie sheep of Shetland, Scottish Ha lfbred and Bleu du Maine breeds. In contrast, in healthy animals from the same flocks, the most frequent allele encodes Ala(136) (91-100% of sheep). However Val(136) does not correlate with incidence of scrapie in two other flocks - Poll Dorsets and Suffolks and there may therefo re be breed differences in PrP genotypes affected by scrapie.