Prion Protein Gene (Prp) Polymorphism in Iranian Ghezel, Harki and Makoei Sheep Breeds Using PCR-SSCP Technique and Sequencing

Scrapie or transmissible spongiform encephalopathy (TSE), is an infectious fatal disease of sheep and goats which affects the central nervous system. In the present study, 300 blood samples were collected from three breeds of Iranian indigenous Ghezel, Harki and Makoei sheep breeds. A DNA fragment with the length of 173 bp from exon 3 of PrP gene was amplified with specific primer pairs. The banding pattern of each sample in the study population was identified by means of PCR-SSCP. Then, after sequencing, comparison and analysis of the observed polymorphism between different breeds were performed at codons: 136, 154 and 171. In the present study, tow haplotypes of ARR and ARQ were identified and the wild type scrapie-susceptible ARQ was the most frequent haplotype. In this study more than 98% of animals were with the genotype ARQ/ARQ which was classified as low resistance to this disease.
Three novel alleles (L178, E147and L173) were observed for the first time in this study. The comparison of genotype frequency between Makoei-Ghezel and Makoei-Harki sheep breeds were statistically signi ficant (P