Vaccari G, Conte M, Morelli L, Di Guardo G, Petraroli R, Agrimi U
Laboratory of Veterinary Medicine, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome 00161, Italy.
Mol Cell Probes. 2004 Feb;18(1):33-7. doi: 10.1016/j.mcp.2003.06.001.
Scrapie is a transmissible spongiform encephalopathy (TSE) which affects sheep and goats. TSEs are characterised by the conversion of the cellular prion protein (PrP(C)) into the pathological form PrP(Sc). The occurrence of scrapie in sheep is influenced by polymorphisms in the PrP gene; in particular, three codons (136, 154 and 171) are important in conditioning the susceptibility/resistance of sheep to the disease, with the Val/Val(136) Arg/Arg(154) Gln/Gln(171) genotype being the most susceptible and the Ala/Ala(136) Arg/Arg(154) Arg/Arg(171), the most resistant one. The latter genotype seems to confer, in sheep, resistance to the oral infection with bovine spongiform encephalopathy, as well. The selection of genetically resistant sheep populations represents the basis of the recent strategies against ovine TSE in the European Union (EU). Herein, we describe a rapid and simple method, based on the primer extension technique, for PrP genotype determination at codons 136, 154 and 171. Intra-laboratory validation of the method showed accuracy levels comparable to those of sequencing analysis. Such method could be used for both the application of the EU policies requiring PrP genotype analysis in all ovine TSE cases, and the large-scale genotyping claimed by the implementation of breeding programmes for genetic resistance to TSE in sheep.
羊瘙痒病是一种影响绵羊和山羊的传染性海绵状脑病（TSE）。TSE的特征是细胞朊蛋白（PrP(C)）转变为病理形式的PrP(Sc)。绵羊中羊瘙痒病的发生受PrP基因多态性的影响；特别是，三个密码子（136、154和171）在决定绵羊对该病的易感性/抗性方面很重要，其中Val/Val(136) Arg/Arg(154) Gln/Gln(171)基因型最易感，而Ala/Ala(136) Arg/Arg(154) Arg/Arg(171)基因型最具抗性。后一种基因型似乎也使绵羊对牛海绵状脑病的口服感染具有抗性。选择具有遗传抗性的绵羊群体是欧盟近期防治绵羊TSE策略的基础。在此，我们描述了一种基于引物延伸技术的快速简便方法，用于确定密码子136、154和171处的PrP基因型。该方法在实验室内的验证显示其准确性水平与测序分析相当。这种方法可用于欧盟要求对所有绵羊TSE病例进行PrP基因型分析的政策实施，以及绵羊TSE遗传抗性育种计划实施中所要求的大规模基因分型。
