Analysis of mechanisms of demyelination in progressive multifocal leukoencephalopathy

JC病毒(JCV)可引起人类一种脱髓鞘疾病-进行性多灶性白质脑病(PML)，但其脱髓鞘机制尚不清楚。为了研究JCV感染的早期事件，包括附着、穿透和转运到发生病毒复制的细胞核，我们使用半定量PCR、ISH、激光扫描共聚焦显微镜和病毒复制分析了15种不同细胞系对感染的敏感性。所有细胞株在接种后10min内均可观察到JCV进入。用抗JCV VP1抗体和唾液酸酶处理来去除唾液酸残基来抑制病毒进入，证明JCV VP1作为配体发挥作用，JCV受体是含有唾液酸的细胞表面分子。此外，氯丙嗪，一种依赖于笼蛋白的途径抑制剂，显著地抑制了JCV进入细胞核，这表明JCV在进入细胞的过程中利用了一条笼蛋白途径。FR…由于最近的临床病理分析表明人类T淋巴细胞嗜T病毒I型(HTLV-I)可能是PML的潜在疾病，我们研究了HTLV-I编码的调节蛋白Tax是否激活了JCV的转录。通过双荧光素酶分析和凝胶迁移率改变分析，我们发现HTLV-I Tax的表达以一种依赖于NF-κB的方式激活了人类神经细胞中JCv早期和晚期启动子的转录潜能。此外，我们还发现了非神经细胞中存在的税收结合蛋白(S)。我们还发现，JCV晚期蛋白中的不可知蛋白能够增强JCV启动子本身。这些结果为基于病毒感染和神经细胞增殖机制的PML的有效治疗提供了可能。较少

JC virus (JCV) causes in humans a demyelinating disease, progressive multifocal leukoencephalopathy (PML), but mechanisms of demyelination by JCV remain unknown.To investigate early events of JCV infection including attachment, penetration, and transport to the nuclei where viral replication occurs, we have analyzed the susceptibility of 15 different cell lines to infection using a semi-quantitative PCR assay, ISH, laser scanning confocal microscopy and a viral replication assay. JCV entry was observed in all cell lines within 10 min after inoculation. Inhibition of viral entry both by an anti-JCV VP1 antibody and sialidase treatment to remove sialic acid residues argues in favor that JCV VP1 functions as ligand and that JCV receptor is the cellular surface molecules containing sialic acids. In addition, chlorpromazine, a clathrin-dependent pathway inhibitor, significantly suppressed entry of JCV into nuclei, suggesting that JCV utilizes a clathrin pathway during the entry to cells. Fr … More om these observations it has been proved that JCV receptor is broadly expressed in the cells originated from various tissues and species.Because the recent clinicopathological analyses have disclosed that human T-lymphotropic virus type I (HTLV-I) could be an underlying disease of PML, we have examined whether the HTLV-I encoded regulatory protein Tax activates JCV transcription. Using a dual luciferase assay and an electrophoretic mobility shift assay (EMSA), we found the expression of HTLV-I Tax activated the transcriptional potential of both early and late promoters of JCV in human neural cells in a NF-κB-dependent manner. In addition, we demonstrated the presence of Tax-bound protein(s) which were specifically present in non-neural cells.We also found that agnoprotein, one of the JCV late proteins, enhanced the JCV promoter itself. These results make it possible to establish an effective therapy against PML based on the mechanism of viral infection and multiplication in the neural cells. Less