HISTORY OF PRION PROTEIN GENE (PRNP) POLYMORPHISM IN SHEEP AND SCIENTIFIC FINDINGS

Scrapie is basically a kind of disease that originally was specific to European countries, but from England it spread all over the world to Canada, South Africa, Australia, New Zealand and many other countries. Scrapie is a prion disease which is fatal and results in or can be characterized by the degeneration of the nervous system. It belongs to transmissible spongiform encephalopathies (TSEs) infecting small ruminants including sheep and goat. Sheep susceptibility or resistance to classical scrapie is highly supervised by the polymorphisms at codons 136, 154 and 171 of the PRNP. In this review, we found that countries like Romania, Finland, Italy, Slovakia, Germany, Greece, Spain, Poland, Turkey, Iran, Brazil, England, Portugal, Hungary, Austria, and Czech Republic, are susceptible to scrapie, while in Pakistan, China, Algeria, West Africa, America, Burkina Faso, and Niger are those countries where sheep are not susceptible to this disease. From these studies, we can clearly conclude that China and Pakistan are the countries where sheep show more resistance to scrapie. We focused to summarize the PRNP polymorphism at 136, 154, and 171 in sheep and some important findings in major parts of the world.