Nuclear localization of Japanese encephalitis virus core protein enhances viral replication
Nuclear localization of Japanese encephalitis virus core protein enhances viral replication
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DOI：
10.1128/jvi.79.6.3448-3458.2005
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发表时间：
2005-03-01
影响因子：
5.4
通讯作者：
Matsuura, Y
中科院分区：
文献类型：
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作者：
Mori, Y;Okabayashi, T;Matsuura, Y
流行性乙型脑炎病毒(JEV)感染哺乳动物和昆虫细胞株，在核仁和细胞质中均检测到JEV核心蛋白。突变分析表明，核心蛋白中的Gly(42)和Pro(43)是核仁和核仁定位所必需的。通过以质粒为基础的反向遗传学方法，获得了一株Gly(42)和Pro(43)均被Ala取代的M4243病毒突变株。在C6/36蚊虫细胞中，M4243病毒表现出与野生型JEV相当的RNA复制和蛋白质合成，而在Vero细胞中的繁殖受到损害。在感染M4243病毒的C6/36和Vero细胞系的细胞质中检测到突变的核心蛋白，但在细胞核中未检测到突变的核心蛋白。野生型核心蛋白的反式表达可以恢复M4243在哺乳动物细胞中的增殖，而突变的核心蛋白则不能。虽然M4243变异病毒显示出与野生型JEV相当的高水平的神经毒力，尽管JCL：ICR株小鼠脑内接种的病毒繁殖能力降低了约100倍，但经腹腔接种该变异病毒后，脑内未发现病毒。这些结果表明，乙脑病毒核心蛋白的核定位不仅在哺乳动物细胞的体外复制中起重要作用，而且在乙脑病毒诱发的体内脑炎的发病机制中也起着重要作用。
Japanese encephalitis virus (JEV) core protein was detected in both the nucleoli and cytoplasm of mammalian and insect cell lines infected with JEV or transfected with the expression plasmid of the core protein. Mutation analysis revealed that Gly(42) and Pro(43) in the core protein are essential for the nuclear and nucleolar localization. A mutant M4243 virus in which both Gly(42) and Pro(43) were replaced by Ala was recovered by plasmid-based reverse genetics. In C6/36 mosquito cells, the M4243 virus exhibited RNA replication and protein synthesis comparable to wild-type JEV, whereas propagation in Vero cells was impaired. The mutant core protein was detected in the cytoplasm but not in the nucleus of either C6/36 or Vero cell lines infected with the M4243 virus. The impaired propagation of M4243 in mammalian cells was recovered by the expression of wild-type core protein in trans but not by that of the mutant core protein. Although M4243 mutant virus exhibited a high level of neurovirulence comparable to wild-type JEV in spite of the approximately 100-fold-lower viral propagation after intracerebral inoculation to 3-week-old mice of strain Jcl:ICR, no virus was recovered from the brain after intraperitoneal inoculation of the mutant. These results indicate that nuclear localization of JEV core protein plays crucial roles not only in the replication in mammalian cells in vitro but also in the pathogenesis of encephalitis induced by JEV in vivo.