Studies on a mechanism of hantavirus persistent infection in central nervous system and immune system

1.通过加入特异性结合N-乙酰半乳糖胺的凝集素（DBA和SBA），汉坦病毒感染增强约10倍。这种增强被认为是由于凝集素将受体与病毒粒子交联而引起的.建立了两个Vero E6细胞亚克隆，一个在汉坦病毒感染后诱导低pH依赖性细胞融合，另一个抵抗引起细胞融合。利用这两个细胞克隆，探讨了细胞因子在诱导感染细胞融合中的可能作用.汉坦病毒外周感染小鼠后，强毒比弱毒早4 ~ 5天到达脑内。这种差异被认为是汉坦病毒在小鼠模型中毒力的一种机制.强毒汉坦病毒在脑微血管细胞和腹腔巨噬细胞中的生长速率较高，提示其毒力与在靶器官中的生长能力有关.建立了强毒与无毒毒之间的遗传互作病毒。通过对两株病毒毒力的比较，发现其毒力与包膜蛋白一个氨基酸的差异和聚合酶基因核苷酸的差异有关.将汉坦病毒强毒感染的SCID小鼠在感染后3周用免疫BALB/c小鼠的脾细胞被动转移。受体SCID小鼠在转移后4天表现出明显的体重减轻，表明免疫介导的致病性。克隆了汉滩病毒S和M基因组片段，分别编码核衣壳蛋白和囊膜糖蛋白，并在哺乳动物细胞中表达.克隆了编码聚合酶的整个L基因组片段。L克隆的表达正在进行中。

1. Hantavirus infection was enhanced about 10 times by addition of lectins (DBA and SBA) which specifically bind to N-acetylgalactosamine. This enhancement was considered to caused by the cross linking between receptor to virion by the lectins.2. Two Vero E6 cell subclones, one induce low pH dependent cell fusion after hantavirus infection and the other resistant to cause cell fusion, were established. By using the two cell clones, the possible role for the cellular factor for responsible for induce infected cell fusion was considered.3. After peripheral infection of hantavirus to mice, virulent virus reached to brain 4 to 5 days earlier than that of avirulent virus. This difference was considered as a mechanism which define the virulence of hantavirus in the mouse model.4. Virulent hantavirus showed higher growth rate in the brain micro vascular cells and peritoneal macrophage, suggesting that virulence relates to the growth ability in the target organs.5. Genetic reassortant virus between virulent and avirulent viruses were established. The comparison of the virulence of the reassortant viruses indicated that one amino acid difference at enveloped protein and nucleotide difference in the polymerase gene are related to the virulence.6. Virulent hantavirus infected SCID mice were passively transferred with spleen cells of immunized BALB/c mice 3 weeks after infection. The recipient SCID mice represented apparent weight loss 4 days after the transfer, indicating the immune mediated pathogenicity.7. Hantaan virus S and M genome segment which encoding nucleocapsid protein and enveloped glycoprotein, respectively were cloned and expressed in the mammalian cells.8. Entire L genome segment which encodes polymerase was cloned. The expression of the L clone is under going.