Different breeding strategies for scrapie resistance depending on breed-specific PrP allele and genotype frequencies in the Polish sheep

摘要

The level of resistance of sheep to scrapie is modulated genetically by polymorphisms particularly in the three codons (136, 154, 171) of the ovine PrP gene. Scrapie resistance breeding of sheep aims at instant increase of the ARR haplotype frequency. The goal of undertaken studies was to detect PrP allele and genotype frequencies in four sheep breeds in Poland: lie de France, Berrichon du Cher, Suffolk and Polish Merino and to present the effectiveness of applying breed-specific scrapie eradication programs in these breeds. PCR-RFLP analyses were done in order to determine polymorphisms in the three codons: 136, 154 and 171. High frequencies of the ARR allele were detected in Ile de France (83.87%), Berrichon du Cher (87.5%) and Suffolk (63.64%) breeds. A simulation studies were undertaken in order to calculate expected ARR/ARR genotype frequencies in the next generations after applying scrapie resistance breeding. In general, according to simulation studies it was possible to reach high ARR/ARR genotype frequencies, ranging from 60.57% in Polish Merino to 99.57% in Berrichon du Cher in generation F-6.