Molecular Biological Studies on Demyelination Induced by Theiler's Virus Tohoku University School of Medicine

塞勒病毒（TV）被分为两个亚群。GDVII亚群菌株可引起小鼠脊髓急性脑脊髓炎，而DA亚群菌株可引起持续性脱髓鞘疾病，尽管在血清和脑脊液中存在高滴度的TV抗体。关于脱髓鞘活性，作为区分两个亚群的可能机制，对少突胶质细胞（OL）的不同嗜细胞性被提出。本项目的主要目标是利用这些亚群菌株的重组病毒和OL原代培养来澄清这一点。首先，我们从已经报道的三个重叠克隆中获得了DA菌株的全长cDNA （Virology 164: 245-255, 1988）。由转录本转染衍生的病毒产生脱髓鞘疾病，与野生型病毒的脱髓鞘疾病难以区分。传染性克隆为株间重组病毒的产生提供了关键试剂，有助于鉴定OL和脱髓鞘中嗜细胞性的遗传位点。另一方面，将DA和GDVII两种菌株接种于C3H小鼠OL原代培养物中，研究其感染和繁殖情况。抗半乳糖脑苷和抗tv抗体双染色显示两株菌株均感染OL。此外，两个菌株的无细胞和细胞相关感染动力学无显著差异。这些体外观察表明，无论是复制还是细胞相关感染性都不是区分这两个亚群菌株的唯一因素。

Theller's virus (TV) is divided into two subgroups. GDVII subgroups strains cause acute polloencephalomyelitis in the spinal cords of mice, whereas DA subgroup strains cause a persistent demyelinating disease in spite of the presence of high antibody titers against TV in the sera and CSF. As a possible mechanism to discriminate two subgroups with regard to the demyelinating activity, different cytotropism to oligodendrocytes (OL) has been proposed. The major goal of this project is to clarify this point by using recombinant virus from those subgroup strains and by using primary culture of OL.AL first, we generated a full-length cDNA of DA strain from three overlapping clones which had been already reported (Virology 164 : 245-255, 1988). Virus derived from transfection of transcripts produced a demyelinating disease indistinguishable from that of wild-type virus. The infectious clone provides a critical reagent for the production of interstrain recombinant viruses to help indentify genetic loci responsible for the cytotropism in OL and demyelination as well.On the other hand, two strains, i. e. DA and GDVII, were inoculated into the primary culture of OL derived from C3H mice and the infection and the propagation were studied. Double staining using anti-galactocerebroside and anti-TV antibodies revealed both strains infected OL. In addition, the kinetics of cell-free and cell-associated infectivity were not significantly different between two strains. These in vitro observation suggests that neither replication nor cell-associated infectivity is a sole factor in discriminating those two subgroup strains.