Prion gene analysis of the Turkish crosbred sheep

Scrapie is an infectious spongiform encephalopathy fatal disease of sheep and goat that effects the prions of cells of central nervous system. It?s an hard to stop the outspread because the infectious agent is contagious and resistant to many disinfectant. Polymorphism in the PrP gene of the sheep related to scrapie susceptibility. Selection programmes of European sheep breeds for scrapie based on PrR genotypes are available and supported by European Union. So far these genotyping data for Turkish sheep breeds are insufficient.The aim of the thesis was the genotyping of PrP gene in crossbreds of Turkish native breeds and foreign breeds- Black headed German-Kivircik, Hampshire-Merinos and Rambouillet-Daglic and find out their risk groups. Therefore these crossbreds genotyped by means of PCR and direct sequencing in this thesis.The polymorphic alleles were ARR, ARQ, ARK, ARL, TRR, TRQ, VRR and 9 genotypes were ARR/ARR, ARQ/ARQ, ARR/ARQ, ARQ/TRQ, ARQ/ARL, ARR/VRR, ARR/TRR, ARK/ARK and ARL/ARL. Also 7 different additional polimorphism were identified on PrP gene M112T, K113N, A116E, A116D, M173V, S173N and V179E. According to our PrP genotype analysis data the crossbreds are high variable and most of the genotypes belong to risk group 1 and 2 for their resistance of scrapie. The investigated breeds found to be not 100% resistant against classical scrapie.