Detection of Susceptible and Resistant Allelic forms to Scrapie Disease in Prion Protein Locus in Iran Black and Arman Sheep Breeds

Zoonotic diseases or transmittable diseases between humans and animals, both for economic and public health are very important. Scrapie is a deadly degenerative central nervous system disease that takes place in this category. Polymorphisms in sheep PrP gene are related to scrapie resistance and susceptibility. The aim of this study was to genotype the PrP locus in Iran Black and Arman sheep breeds. Blood samples were collected from 100 Iran Black and Arman sheep and DNA was extracted using the modified salting out method. A DNA fragment with the length of 173 bp from exon 3 of PrP gene was amplified with a specific primer pairs. Then the obtained genotypes for each sample were genetically evaluated by means of PCR-SSCP and sequencing techniques. In overall, four haplotype alleles of ARR, ARQ, AHQ, and ARH and five haplogenotype combinations of ARQ/ARQ, ARR/ARQ, ARR/ARR, ARQ/AHQ, and AHQ/ARH were detected in studied populations. The ARQ with the mean frequency of 74.5 percent and the ARQ/ARQ with the mean frequency of 59 percent were the most frequent haplotype allele and haplogenotype, respectively. The comparison of allele and genotype frequency between Iran Black and Arman sheep breeds were statistically significant (P<0.05). Based on the obtained results more than seventy percent of sheep genotyped in the present study was categorized in low resistant group (R3). Therefore, adopting the appropriate strategy in the selection and breeding programs can be effective to reduce the risk of the disease.