French autochthonous scrapied sheep without the 136Val PrP polymorphism.
Blood samples were obtained from 22 Lacaune, 11 Manech and 4 Préalpes du Sud sheep with clinical signs of scrapie and from 37 apparently healthy sheep, and DNA was extracted. The polymerase chain reaction was used to amplify DNA, with 2 primers corresponding to genes encoding prion protein (PrP). The amplified DNA was digested with BspH1, which cleaves the DNA when codon 136 encodes valine, and enables a PrP polymorphism to be identified. Only 1 sheep (a Lacaune ewe with scrapie) carried the 136Val allele, which had previously been shown to be associated with susceptibility to natural scrapie. Thus, valine at position 136 is not required for the development of scrapie in these breeds.