Villmann Carmen, Sandmeier Barbara, Seeber Silke, Hannappel Ewald, Pischetsrieder Monika, Becker Cord-Michael
Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany.
J Agric Food Chem. 2007 Aug 22;55(17):7114-23. doi: 10.1021/jf0707278. Epub 2007 Jul 13.
Spreading transmissible spongiform encephalopathies (TSE) have been widely attributed to transmission by ingestion of mammalian central nervous system (CNS) tissue. Reliable exclusion of this epidemiological important route of transmission relies on an effective surveillance of food contamination. Here, myelin proteolipid protein (PLP) is identified as a specific and largely heat-resistant marker for detection of food contaminations by CNS tissue. PLP is a component of oligodendritic glial sheaths of neuronal processes that is specifically expressed in the CNS. A highly selective polyclonal antibody was developed directed against an epitope present in the full-length PLP protein, but absent from the developmentally regulated splice variant DM-20. In combination with a hydrophobic extraction of PLP from tissue samples, the antibody reliably detected PLP from spinal cord, cerebellum, and cortex of different mammalian species. Consistent with earlier reports on PLP expression, no cross-reactivity was observed with peripheral nerve or extraneural tissue, except for a very faint signal obtained with heart. When applied to an artificial CNS contamination present in sausages, the antibody reliably detected a low concentration (1%) of the contaminant. Application of heat, as used during conventional sausage manufacturing, led to a predominant alteration of arginine residues in the PLP protein and a partial loss of immunoreactivity. In contrast, a stretch of hydrophilic amino acids(112-122) proved to be heat-resistant, preserving the immunogenicity of this PLP epitope during heating. Taken together, the excellent CNS specificity of PLP immunodetection and the presence of a heat-resistant epitope have permitted the development of a highly sensitive immunoassay for CNS contamination in routine food control.
传播性可传播海绵状脑病（TSE）被广泛认为是通过摄入哺乳动物中枢神经系统（CNS）组织而传播的。可靠排除这一重要的流行病学传播途径依赖于对食品污染的有效监测。在此，髓鞘蛋白脂蛋白（PLP）被鉴定为检测中枢神经系统组织对食品污染的一种特异性且在很大程度上耐热的标志物。PLP是神经元突起少突胶质鞘的一个组成部分，在中枢神经系统中特异性表达。针对全长PLP蛋白中存在但发育调控剪接变体DM - 20中不存在的一个表位，开发了一种高度选择性的多克隆抗体。结合从组织样本中对PLP进行疏水提取，该抗体能可靠地检测出不同哺乳动物物种脊髓、小脑和皮质中的PLP。与早期关于PLP表达的报道一致，除了心脏获得的非常微弱的信号外，未观察到与外周神经或神经外组织的交叉反应。当应用于香肠中存在的人工中枢神经系统污染时，该抗体能可靠地检测出低浓度（1%）的污染物。在传统香肠制作过程中使用的加热处理导致PLP蛋白中精氨酸残基的主要改变以及免疫反应性的部分丧失。相比之下，一段亲水性氨基酸序列（112 - 122）被证明是耐热的，在加热过程中保留了该PLP表位的免疫原性。综上所述，PLP免疫检测出色的中枢神经系统特异性以及耐热表位的存在使得在常规食品检测中开发出一种用于检测中枢神经系统污染的高灵敏度免疫测定法成为可能。
