TRANSCRIPTION ANALYSIS OF THE JC VIRUS ENHANCER

人类乳头状病毒，JCV，与人类 脱髓鞘障碍进行性多灶性 白质脑病。在组织培养中，病毒主要是 仅限于在原代人类胎儿神经胶质细胞中生长。在这 研究中，我们展示了对病毒宿主的两种水平的调节 射程。早期JCV mRNA的表达，它编码 主要的病毒蛋白，大肿瘤抗原(T抗原)，依赖于 关于组织识别早期增强子/启动子元件- 在人类和啮齿动物的神经胶质细胞中都发现了特定的因子。在 JCVT抗原的存在，病毒DNA复制需要 物种特异性因子，可能是DNA的一个组成部分 聚合酶，广泛存在于灵长类细胞中。我们 进一步证明猴病毒40T抗原具有足够的 同源基因高效替代同源JCV蛋白 在启动病毒DNA复制方面。我们已经使用了底漆 JC病毒5‘末端的延伸和S1分析定位 不同时间感染原代人神经胶质细胞的(JCV)早期RNA 感染后和稳定的JCV转化地鼠胚胎的时间 神经胶质细胞。在感染后的早期(第1-5天)，两个早期 转录起始于核苷酸5122和5082。一位少校 在较晚的时间5‘末端的移位导致新的 起始于核苷酸35上游的一系列早期mRNAs和 下游的核苷酸5047,5037，公元5012。在 然而，转化的仓鼠细胞只对RNA物种有影响 检测到，从5122号核苷酸开始。其背后的机制 JCV早期RNA在裂解过程中起始位置的转移 感染情况尚不清楚，但似乎与 发生在SV40裂解循环中。因为这种变化发生在DNA 复制，当T抗原处于最大水平时，就有可能 T抗原与JCV DNA结合和/或改变 染色质结构促成了这一现象。

Human papovavirus, JCV, is associated with the human demyelinating disorder progressive multifocal leukoencephalopathy. In tissue culture, the virus is largely restricted to growth in primary human fetal glial cells. In this study, we demonstrate two levels of regulation of the viral host range. Expression of early JCV mRNA, which encodes the essential viral protein, large tumor antigen (T-antigen), depends on recognition of the early enhancer/promoter elements by tissue- specific factors found in both human and rodent glial cells. In the presence of JCV T-antigen, viral DNA replication requires a species-specific factor, presumably a component of DNA polymerase, which is found in a wide range of primate cells. We further demonstrated that simian virus 40 T-antigen has sufficient homology to efficiently substitute for the analogous JCV protein in initiating viral DNA replication. We have used primer extension and S1 analysis to localize the 5'-termini of JC virus (JCV) early RNAs in infected primary human glial cells at various times postinfection and in stable JCV-transformed hamster fetal glial cells. At early times postinfection (days 1-5), two early transcripts are initiated at nucleotides 5122 and 5082. A major shift in 5'-ends at later times results in the synthesis of a new series of early mRNAs beginning upstream at nucleotide 35 and downstream at nucleotides 5047, 5037, ad 5012. In the transformed hamster cells, however, only on RNA species was detected, starting at nucleotide 5122. The mechanism underlying the shift in the initiation site of JCV early RNAs during a lytic infection remains unclear but appears analogous to that which occurs in the SV40 lytic cycle. Since the shift occurs during DNA replication, when T-antigen is at maximal levels, it is possible that T-antigen binding to JCV DNA and/or alterations in chromatin structure contribute to this event.