Department of Virology 1, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan.
Virology. 2010 Jan 20;396(2):298-304. doi: 10.1016/j.virol.2009.10.035. Epub 2009 Nov 14.
We previously reported that the Japanese encephalitis virus (JEV) strain Mie/41/2002 has weak pathogenicity compared with the laboratory strain Beijing-1. To identify the determinants of its growth nature and pathogenicity, we produced intertypic viruses, rJEV(EB1-M41), rJEV(nEB1-M41) and rJEV(cEB1-M41), which contained the entire, the N-terminal, and the C-terminal half, respectively, of the Beijing-1 E region in the Mie/41/2002 background. The growth of rJEV(EB1-M41) in mouse neuroblastoma N18 cells and virulence in mice were similar to those of Beijing-1. rJEV(nEB1-M41) propagated in N18 cells to the same extent as did Beijing-1. Furthermore, we produced mutant viruses with single amino acid substitutions in the N-terminal half of the Mie/41/2002 E region. A Ser-123-Arg mutation in the Mie/41/2002 E protein exhibited significantly increased growth rate in N18 cells and virulence in mice. These results indicate that the position 123 in the E protein is responsible for determining the growth properties and pathogenicity of JEV.
我们之前报道称，与实验室株北京-1 相比，日本脑炎病毒（JEV）株 Mie/41/2002 的致病性较弱。为了确定其生长特性和致病性的决定因素，我们构建了嵌合病毒 rJEV(EB1-M41)、rJEV(nEB1-M41)和 rJEV(cEB1-M41)，它们分别在 Mie/41/2002 背景下含有北京-1 E 区的全长、N 端和 C 端半区。rJEV(EB1-M41)在小鼠神经母细胞瘤 N18 细胞中的生长和对小鼠的毒力与北京-1 相似。rJEV(nEB1-M41)在 N18 细胞中的增殖程度与北京-1 相同。此外，我们还在 Mie/41/2002 E 区的 N 端半区构建了单点突变病毒。 Mie/41/2002 E 蛋白中的 Ser-123-Arg 突变显著提高了在 N18 细胞中的生长速度和对小鼠的毒力。这些结果表明，E 蛋白的第 123 位决定了 JEV 的生长特性和致病性。
