T CELL RECEPTORS INVOLVED IN TMEV INDUCED DEMYELINATION

脑内接种泰勒氏小鼠脑脊髓炎病毒（TMEV）可导致易感小鼠慢性炎症性脱髓鞘导致临床症状。鉴于潜在的病毒病因和慢性脱髓鞘进展的相似性，TMEV系统被认为是一种相关的感染性动物模型，可以替代实验性自身免疫性脑脊髓炎（EAE）系统，用于研究人类多发性硬化症（MS）。在此之前，我们已经确定了占TMEV Th应答85%以上的主要Th表位。此外，我们已经确定了Th表位（VP1233-250和VP274-86，而不是VP324-37）参与脱髓鞘的发病机制，并与诱导相对高水平的Th反应相关。我们进一步观察到Jbeta1区域多态性与脱髓鞘易感性相关，并且易感的H-2Ds MHC位点可以覆盖TCR β链基因型的抗性作用。此外，我们最近选择了自发产生的非致病性变异病毒，该病毒在主要Th1表位VP1233-250的244位上含有单个氨基酸替代，从而导致Th2反应的转换。此外，由TMEV感染引起的初始脱髓鞘导致自身免疫对主要髓磷脂成分的Th反应的发展。我们最近对浸润性中枢神经系统T细胞的光谱分型和TCR CDR3分析的初步研究表明，某些T细胞群的克隆扩增早在病毒感染后7天就很明显。一些主要人群似乎在整个病程中持续存在。与已知特异性的杂交瘤的CDR3序列相比，这些T细胞代表病毒和/或自身抗原反应性群体。基于这些初步结果，我们建议将CNS中的TCR库与tmev诱导的脱髓鞘的发展联系起来。本研究提出了三个具体目的：(1)CNS中TCR库与tmev诱导脱髓鞘发病机制的相关性；(2)病毒特异性和自身反应性T细胞在脱髓鞘发病机制中的作用；(3)额外的Vbeta或耐药MHC I类基因对中枢神经系统TCR库选择的影响。我们相信，我们提出的研究将为浸润T细胞群及其在病毒诱导的T细胞介导脱髓鞘发病机制中的作用提供重要信息，从而最终导致对中枢神经系统自身抗原的自身免疫。

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) results in chronic inflammatory demyelination leading to clinical signs in susceptible mice. The TMEV system is considered to be a relevant infectious animal model, an alternative to the experimental autoimmune encephalomyelitis (EAE) system, for studying human multiple sclerosis (MS) in light of the potential viral etiology and similarities in the progression of chronic demyelination. Previously, we have identified major Th epitopes accounting for greater than 85 percent of the Th response to TMEV. In addition, we have identified the Th epitopes (VP1233-250 and VP274-86, but not VP324-37) involved in the pathogenesis of demyelination and their association to induce relatively high levels of Th responses. We have further observed that the Jbeta1 region polymorphism is associated with susceptibility to demyelination and that the susceptible H-2Ds MHC locus can override the resistant effect of the TCR beta-chain genotype. Furthermore, we have recently selected spontaneously arising non-pathogenic variant viruses containing a single amino acid substitution at position 244 within the major Th1 epitope, VP1233-250, resulting in a switch to Th2 response. Moreover, the initial demyelination induced by TMEV infection leads to the development of autoimmune Th response to a major myelin component. Our recent preliminary studies for spectratyping and TCR CDR3 analyses of infiltrating T cells in the CNS indicate that clonal expansion of certain T cell populations is apparent as early as 7 d after viral infection. Some of the major population appear to be persistent throughout the disease course. In comparison with CDR3 sequences of hybridomas with known specificity, these T cells represent virus- and/or autoantigen-reactive populations. Based on these preliminary results, we propose to correlate the TCR repertoire in the CNS with the development of TMEV-induced demyelination. Three specific aims are proposed in this application: (1) Correlation of the TCR repertoire in the CNS with the pathogenesis of TMEV-induced demyelination; (2) Role of virus- specific and autoreactive T cells in the pathogenesis of demyelination; and (3) Influence of additional Vbeta or resistant MHC class I genes in the selection of TCR repertoire in the CNS. We believe that our proposed studies will yield important information on the role of infiltrating T cell populations and their expansion in the pathogenesis of virus-induced, T cell-mediated demyelination, leading to the eventual development of autoimmunity to CNS autoantigens.