Viral and host factors contributing to the neuro-virulence of rabies virus.

为了明确狂犬病病毒神经毒力的分子基础，我们从病毒粒子和细胞两个方面对致病因子进行了分析和表征。结果如下：1)对成年小鼠缺乏致死能力的RC-HL株在乳鼠脑内传代22次。2)获得部分毒力的突变株在G蛋白和M蛋白上各有一个氨基酸替换。与RC-HL株全基因组比较，M基因3‘端非编码区有1个核苷酸替换。3)对在病毒中和单抗(N-MAb)存在下选择的具有细胞融合抑制活性的抗原变异体进行比较分析，发现融合活性对应于G蛋白第35位的半胱氨酸。4)任何由N-MAb识别的抗中和突变体(与狂犬病病毒毒力相关的333位氨基酸不能从强毒病毒、西原株、5)狂犬病病毒感染小鼠神经母细胞瘤NA细胞，导致Na~+电流和延迟整流钾通道的功能表达降低；1+&gt；电流，并提供了可能参与狂犬病发病机制的细胞膜特性改变的证据。

In this study, to definite the molecular bases of neurovirulence in rabies virus, we have analyzed and characterized the pathogenic factors in the both virion and cells. The results run as follows :1) The RC-HL strain lacking the capacity to kill adult mice was passaged intracerebrally 22 times in suckling mice. Each passaged virus failed to regain lethal virulence for adult mice, although the viruses were increased to level of mouse pathogenicity.2) The revertant strain acquired partially virulence had each one amino acid substitution in G and M proteins. and one nucleotide substitution in non-coding region of 3' end in M gene when compared with full genome of the RC-HL strain. These changed positions of a nucleotide and two amino acids may necessary for mouse virulence.3) A comparative analysis of antigenic variants selected in the presence of virus-neutralizing monoclonal antibody (N-MAb) with cell-fusion inhibition activity, revealed that fusion activity corresponded to cystine at position 35 of the G protein.4) Any neutralization-resistant mutants by a N-MAb recognized an amino acid at position 333 of the (3 protein that related to virulence of rabies virus could not be selected from virulent virus, the Nishigahara strain, suggesting that arginine at the position is necessary for replication of virulent rabies virus.5) It was suggested that infection of mouse neuroblastoma NA cells with rabies virus causes reduction of functional expression of ion channels responsible for Na^+ current and delayed rectifier K^<1+> current, and provided evidence for possible involvement of the change in membrane properties in the pathogenesis of rabies disease.