SWALEDALE SHEEP AFFECTED BY NATURAL SCRAPIE DIFFER SIGNIFICANTLY IN PRP GENOTYPE FREQUENCIES FROM HEALTHY SHEEP AND THOSE SELECTED FOR REDUCED INCIDENCE OF SCRAPIE

PrP glycoprotein gene polymorphisms were examined in Swaledale sheep a ffected by natural scrapie, in healthy sheep and in Swaledales selecte d for low susceptibility to scrapie. The three groups differed signifi cantly in frequencies of PrP genotypes detected by the restriction enz ymes EcoRI, HindIII and BspHI, the latter being indicative of a PrP pr otein amino acid difference at codon 136. These frequency differences were confirmed in a single-flock study and present good evidence that scrapie susceptibility and resistance are associated with PrP gene var iants in Swaledale sheep.