de Andrade Caroline P, de Almeida Laura L, de Castro Luiza A, Driemeier David, da Silva Sérgio C
Setor de Patologia Veterinária, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
J Vet Diagn Invest. 2013 Jan;25(1):120-4. doi: 10.1177/1040638712471343.
Scrapie is a transmissible spongiform encephalopathy of sheep and goats and is associated with the deposition of an abnormal isoform of prion protein (PrP(sc)). This isoform presents an altered conformation that leads to its aggregation in the host's central nervous and lymphoreticular systems. A predisposition to the prion-agent infection can be influenced by specific genotypes that are related to polymorphisms in the ovine prnp gene. The most characterized polymorphisms occur at codons 136, 154, and 171, with genotype VRQ being the most susceptible and ARR the most resistant. In the current study, a real-time quantitative polymerase chain reaction (qPCR) technique based on allele-specific TaqMan probes was developed to identify single nucleotide polymorphisms in the prnp gene from Brazilian herds. Specific primers and TaqMan probes were designed for all 3 codons of interest. Samples from a total of 142 animals were analyzed by qPCR, followed by DNA sequencing of the amplicons. All of the genotypes determined by qPCR were in agreement with the data determined by DNA sequencing. In all 3 of the analyzed breeds, the majority of the animals were AA homozygous for the 136 codon. The most frequent genotype for codon 154 was RR, and genotypes QQ and QR were the most frequent for codon 171. The results are discussed in relation to establishing scrapie control measures and breeding programs for Brazilian herds.
羊瘙痒病是绵羊和山羊的一种传染性海绵状脑病，与朊病毒蛋白（PrP(sc)）的异常异构体沉积有关。这种异构体呈现出改变的构象，导致其在宿主的中枢神经和淋巴网状系统中聚集。朊病毒感染的易感性可能受与绵羊prnp基因多态性相关的特定基因型影响。最具特征性的多态性发生在第136、154和171密码子处，基因型VRQ最易感，ARR最具抗性。在本研究中，开发了一种基于等位基因特异性TaqMan探针的实时定量聚合酶链反应（qPCR）技术，以鉴定巴西畜群prnp基因中的单核苷酸多态性。针对所有3个感兴趣的密码子设计了特异性引物和TaqMan探针。通过qPCR分析了总共142只动物的样本，随后对扩增子进行DNA测序。qPCR确定的所有基因型均与DNA测序确定的数据一致。在所有3个分析品种中，大多数动物在第136密码子处为AA纯合子。第154密码子最常见的基因型是RR，第171密码子最常见的基因型是QQ和QR。结合为巴西畜群制定羊瘙痒病控制措施和育种计划对结果进行了讨论。
