Study of genetic resistance to scrapie in sheep of the southern meat breed

Introduction. In modern Russia, there is a change in the economic importance of the main types of sheep products. In this regard, new meat sheep breeds are being created in the country, one of which is the Southern Meat breed. In national sheep breeding, marker-assisted selection is evolving actively, aimed at improving productive traits and disease resistance. Scrapie is a prion disease of sheep. The resistance or susceptibility of animals is determined by the polymorphism of the prion protein gene (PRNP). To reduce the proportion of sheep susceptible to scrapie, it is necessary to genotype the PRNP gene polymorphism and, based on the results, select breeding strategies. The aim of our research was the genetic characterization of breeding rams of the Southern Meat breed by genotypes in the PRNP gene to determine resistance to classical and atypical scrapie.
Object. The research objects are samples of biological material from domestic sheep of the Southern Meat breed.
Materials and methods. The studies were carried out on the equipment of Center for Biological Resources and Bioengineering of Agricultural Animals (L.K. Ernst Federal Science Center for Animal Husbandry). A total of 77 Southern Meat rams were genotyped. The genetic resistance to scrapie was determined according to the methodological guidelines by Deniskova et al.
Results and conclusion. The study showed the presence of five haplotypes (ARR, ARQ, ARH, AHQ and AHH) and eleven PRNP genotypes (ARR/ARR, ARR/ARQ, ARR/ARH, ARR/AHQ, ARQ/ARQ, ARQ/ARH, ARQ/ AHQ, ARH/ARH, ARH/AHQ, ARH/AHH, AHQ/AHQ) in the Southern Meat breed. The most widespread haplotype among the animals in the study sample was ARQ, which occurred with a frequency of 39.6%. The AHH allele had the lowest frequency (2.6%). The most widespread genotype was ARQ/ARQ with frequency of 20.8% in the sample. The rarest genotype was ARH/AHQ, occurring with a frequency of 1.3%. The studied population was assigned to three classes of resistance to the classic scrapie (G1, G2 and G3). In the study group, most animals (71.4%) belonged to the G3 resistance class, while only two animals were the most genetically resistant to the classical form of scrapie (G1 class), which amounted to only 2.6% of the sample. The proportion of animals included in the G2 class was 26.0%. As for the atypical scrapie, all studied animals were resistant to it.

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