Analysis of Neurovirulence of Japanese encephalitis virus based on Eprotein-receptor interaction

分析了参与乙型脑炎病毒致病性的因素。用大鼠脑原代培养和建立的细胞系得到以下结果：1. 乙型脑炎病毒能在神经元中感染和复制，但不能在神经胶质细胞中感染和复制。2. 乙型脑炎病毒可以在未成熟神经元上吸附和复制，但不能在完成突触形成的分化成熟神经元上吸附和复制。3. 乙型脑炎病毒能在易感细胞上有效吸附和内化，而在不易感细胞上则不能。4. 日本脑炎病毒可以在不敏感细胞中复制，将感染性RNA直接注入细胞质。5. 从易感细胞的膜组分中分离到一个与乙型脑炎病毒E蛋白结合的候选75Kd受体分子。通过对日本脑炎病毒颗粒形成机制的分析，得到以下结果。1. 多蛋白在内质网腔内表达加工后形成包膜上的prM- e异二聚体，prM蛋白在高尔基复合体中加工后，包膜上的M-E异二聚体作为成熟病毒粒子从感染细胞中释放出来。2. M-E异二聚体在低pH条件下转化为E同三聚体。3. 这种发生在E蛋白上的结构变化，在病毒粒子与细胞受体结合完成后，可诱导病毒粒子的包膜与易感细胞的细胞膜融合。4. prM蛋白的C端部分具有prM-E异源二聚体的形成、E蛋白结构的构建和E蛋白在细胞内的转运所必需的空穴。5. 在中和性表位上替换氨基酸可降低病毒的神经毒力。这些结果表明，乙型脑炎病毒的部分神经毒力取决于病毒粒子与易感细胞上的细胞受体与E蛋白的结合效率，而prM蛋白在E蛋白结构的构建中起关键作用，该结构负责与受体和细胞膜的反应性。少

Factors which participated in the pathogenicity of Japanese encephalitis virus were analyzed.The following results were obtained using primary rat brain culture and established cell lines. 1. Japanese encephalitis virus could infect and replicate in neurons but not in glial cells. 2. Japanese encephalitis virus could be adsorbed and replicate on immature neurons but not on differentiated mature neurons which completed synapse formation. 3. Japanese encephalitis virus could be adsorbed and internalized effectively on susceptible cells but not on unsusceptible cells. 4. Japanese encephalitis virus could replicate in unsusceptible cells which were received the infectious RNA directly into the cytoplasm. 5. A candidate 75Kd receptor molecule which could bind with the E protein of Japanese encephalitis virus was detected and isolated from membrane fractions of susceptible cells.The following results were obtained from an analysis on the mechanism of particle formation of Japanese encephalit … More is virus. 1. A prM-E heterodimer on an envelope was formed after expression and processing of polyprotein in ER lumen and the prM protein was processed in golgi complex and then the M-E heterodimer on the envelope was released from infected cells as a mature virion. 2. The M-E heterodimer was converted to E homotrimer under low pH conditions. 3. This structural change occurred on the E protein could induce a fusion between the envelope of the virion and cell membranes of susceptible cells after the virion and the cellular receptor binding was completed. 4. The C terminal part of prM protein had essential Hole for the formation of the prM-E heterodimer and the construction of the E protein structure and the transport of the E protein in the cells. 5. Amino acid replacements at the neutralizing epitope induced decreased neurovirulence on the virus.These results indicate that a part of neurovirulence of Japanese encephalitis virus is determined the binding efficiency between the cellular receptor on the susceptible cells and the E protein of the virion and prM protein has a critical role on the construction of the E protein structure responsible on the reactivity with the receptor and the cell membranes. Less