Abstract
Scrapie is the transmissible spongiform encephalopathy or prion disease that causes fatal degenerative damages in the central nervous system of affected sheep. To-date two forms of scrapie are known: classical, and atypical, or Nor98. Genetic susceptibility to classical scrapie is determined by allele polymorphisms in codons 136, 154 and 171 of the PRNP gene. Thus, A136R154R171 allele is associated with resistance while V136R154Q171 is linked with susceptibility. The F allele in 141 PRNP codon is responsible for susceptibility to Nor98. In this regard, the aim of our research was to analyze PRNP polymorphisms in 136,141, 154 and 171 codons in five Russian locally derived sheep breeds including Altai Mountain (n=16), Kuibyshev (n=16), North Caucasian (n=19), Russian Longhaired (n=14) and Tsigai (n=21). Identification of the alleles in the codons 136 (A/T/V), 141 (L/F), 154 (R/H) and 171 (Q/R/H/K) of PRNP was performed by pyrosequencing on the PSQ96MA (Qiagen, USA). We found eight different PRNP genotypes in five Russian breeds. The most frequent genotypes were ARR/ARQ (G2, genetically resistant) in the Kuibyshev (50.0%), North Caucasian (47.4%), Russian Longhaired (42.9%) and ARQ/ARQ (G3, little genetic resistance) in Altai Mountain (43.8%) and in Tsigai (42.9%). Sheep of the most genetically resistant class G1 were detected in all studied breeds with frequency varying from 4.8% in Tsigai to 35.7% in Russian Longhaired. The allele VRQ was found in all breeds (from 3.6 to 7.1%) except for North Caucasian. The F141 allele presented in two animals belonging to North Caucasian breed and with satisfactory genotypes for classical scrapie as ARQ/ARR and ARQ/ARQ. Thus, we demonstrated the necessity to test genetic susceptibility for both scrapie forms in sheep herds. The research was performed within the framework of the Federal Agency of Scientific Organizations No. 0600-2018-0014. Key Words: