Research On Prion Protein Gene (PRNP) In Chinese Local Sheep Breeds

Amino acid polymorphisms of the prion protein (PrP) gene (PRNP), particularly those occurring at codons 136, 154, and 171, have a significant influence on scrapie pathogenesis in many sheep breeds. We isolate blood samples from 668 sheep representing the twenty-four main local sheep breeds in 10 provinces of our country, to identify the PRNP polymorphisms and to determine whether these breeds are at risk for developing scrapie. three new PRNP polymorphisms encoding either valine(V) or alanine (A) at codon 21, glycine (G) or arginine(R) at codon 85 and tyrosine (Y) or cysteine (C) at condon 153 as well as ten previously reported polymorphisms at codons 101, 112, 127, 138, 141, 143, 146, 154, 171and 189 in other sheep breeds are detected. Interestingly, the A/V polymorphism at codon 136 is not observed in this study, all sheep being homozygous for A at this position. While the previously identified polymorphism of R or histidine (H) at codon 154 is detected, the H polymorphism is rare (6.89%). Four polymorphisms at codon 171 encoding glutamine (Q), R, H or lysine (K) are detected. The predominant susceptible ARQ allele occurred at a high frequency of 78.14%, suggesting an increased risk of scrapie in Chinese local sheep breeds.In order to identify the ovine PRNP Genotypes, a real-time fluorescence PCR based on TaqMan probe technique is build to detect the ovine PRNP SNP polymorphisms at nucleotide position 407, 461, 512 and 513 which lead to polymorphisms at codon 136, 154, 171 and 171 respectively. The PRNP genotyping method established in this study is greatly suited for a broad range of ovine genotyping projects. It provides an exact, efficient and inexpensive SNPs analysis at nucleotide position 407, 461,...