Single Nucleotide Polymorphism (SNP) in Prion Protein Alleles renders Essay

Single Nucleotide Polymorphism (SNP) in Prion Protein Alleles renders susceptibility or resistance to Natural Scrapie in sheep - Essay Example Among these 3 codons there are 5 alleles generated that causes resistance and 3 alleles generated that causes susceptibility to the disease. Therefore, genotype of the breeds may dictate susceptibility or resistance to scrapie. Scrapie can be highly infectious and transmissible among similar species. But being a genetic disease, only individuals that are susceptible in the prion protein (PrP) gene could be infected, regardless of any environmental factors. The objective of this research is to analyze each species genotype as to their genetic make up for alleles. Single nucleotide polymorphism (SNP) in the genotype of the three codons mentioned earlier, renders sheep susceptible or resistant to the disease. The research will involve the genotypic comparison of two breeds of sheep: The Awassi flock and The North Country Cheviot flock, to see which genotype of the two breeds resembles the disease allele the most. DNA extraction and amplification will be done through PCR amplification. F urthermore, identification of the nucleotide sequences that closely resemble those of the disease allele will be determined using methods of restriction enzymes and specific primer binding sites. PROJECT SUMMARY The purpose of this study is to identify sheep susceptibility and resistance for scrapie from two different breeds based strictly on genotypic variations due to single nucleotide polymorphism (SNP) at codons 136, 154 and 171. The primary reason for carrying out this research is to increase awareness about the fatal neurological disease in order to encourage farmers and breeders to take proper measurements in identifying the correct symptoms and to use proper sterile techniques to minimize transmission of the disease from environmental factors. More drastically, with no treatment or cure for scrapie, breeders can anticipate selective breeding to eradicate scrapie by mating a resistant ram (ARR) with any ewe. Thus, it will assure a resistant genotype for scrapie in the offspri ngs. Although selective breeding showed to have a few successes in the past, the method is not guaranteed to work every time, since factors such as mutation and single nucleotide polymorphism (SNP) render the animal susceptible to acquiring the disease upon interaction. INTRODUCTION Scrapie is a dangerous, degenerative disease affecting the central nervous system (CNS) of sheep and goats. The disease is also referred to as la tremblante (French: trembling), Traberkrankheit (German: trotting disease), or rida (Icelandic: ataxia or tremor) (Detwiler 1992). The disease was first recognized as affecting sheep in Great Britain and other countries of Western Europe over 250 years ago. The earliest definite record of the incidence of scrapie was in Britain in 1732. Following this event, there were accounts of a scrapie-like disease occurring in the Dorset Horn, Wiltshire Horn and Norfolk Horn breeds in England between 1750 and the early 1800s. Scrapie progressed in becoming a major problem in the English Suffolk breed around 1950, leading to successive financial loss in flocks. In 1938, first report of the disease was identified in Canada and since then there have been over 167 flocks in 6 Canadian provinces with confirmed cases of classical scrapie (Plummer 1946). In general, there is a gradual development of clinical cases of scrapie that have been recorded in many regions around the world; notable exceptions are Australia and New Zealand. This is due