RAPID GENOTYPING OF PRNP GENE POLYMORPHISMS TO ASSESS SCRAPIE SUSCEPTIBILITY IN BRAZILIAN SHEEP

Objective: Our study aimed to develop and validate a low-density SNP panel for 15 PRNP gene polymorphisms for genotyping sheep from 15 breeds in Brazil, incorporating samples from the Brazilian Animal Germplasm Biobank (BBGA). It was estimated both allelic, genotypic and haplotypic frequencies for the selected markers. Theoretical Framework: The study hypothesis centers on the need to validate a cost-effective reduced SNP panel, enhance genotyping accuracy, and support selective breeding against scrapie in Brazilian sheep. Method: The methodology adopted comprises a reduced SNP panel, with markers associated with scrapie, designed to genotype DNA samples of Brazilian sheep breeds. Results and Discussion: The panel achieved a success rate of 73%, as out of the 15 genotyped markers, only four were excluded by the call rate. Moreover, 73% (845) of the initial 1,152 samples were successfully genotyped. Analyzing the three most important PRNP polymorphisms, we found that genotype ARQ/ARQ, associated with susceptibility to scrapie, was the most frequent in all breeds. In contrast, genotype ARR/ARR (resistance) was found only in the BBGA (4%). Research Implications: Overall, the low-density SNP panel can be a rapid, dependable, and cost-effective tool for enhancing genetic selection in Brazilian sheep. However, further technology optimization is necessary, which can be achieved by excluding and replacing non-functional markers. Originality/Value: This study presents valuable insights by providing a cost-effective, validated genotyping tool tailored to SNP markers associated with scrapie in Brazilian sheep, which can streamline genetic selection in breeding programs.