T CELL RECEPTORS INVOLVED IN TMEV INDUCED DEMYELINATION

脑内接种泰勒氏小鼠脑脊髓炎病毒(TMEV)可导致慢性炎症性脱髓鞘，导致易感小鼠出现临床症状。TMEV系统被认为是一种相关的感染动物模型，可替代实验性自身免疫性脑脊髓炎(EAE)系统，根据潜在的病毒病因学和慢性脱髓鞘进展的相似性来研究人类多发性硬化症(MS)。在此之前，我们已经确定了主要的Th表位，占TMEV应答的85%以上。此外，我们还确定了参与脱髓鞘发病机制的Th表位(VP1233-250和VP274-86，而不是VP324-37)，以及它们之间的关联，以诱导相对高水平的Th反应。我们进一步观察到，Jbeta1区域的多态与脱髓鞘的易感性有关，易感的H-2DS MHC基因座可以盖过TCRβ链基因的抗性效应。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的第244位含有单一氨基酸替代，导致切换到Th2反应。此外，TMEV感染引起的初始脱髓鞘导致对主要髓鞘成分的自身免疫性Th反应的发展。我们最近对CNS中浸润性T细胞的分型和TCR CDR3分析的初步研究表明，某些T细胞群体的克隆性增殖早在病毒感染后7d就出现了。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CDR3序列相比，这些T细胞代表了病毒和/或自身抗原反应群体。基于这些初步结果，我们建议将中枢神经系统中的TCR谱系与TMEV诱导的脱髓鞘的发展联系起来。在这一应用中提出了三个特定的目标：(1)中枢神经系统中TCR谱系与TMEV诱导的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类基因在中枢神经系统TCR谱系选择中的影响。我们相信，我们提出的研究将提供重要的信息，在病毒诱导的T细胞介导的脱髓鞘的发病机制中，渗透的T细胞群体及其扩张的作用，最终导致对CNS自身抗原的自身免疫的发展。

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.