Bridgen A, Weber F, Fazakerley J K, Elliott R M
Division of Virology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 5JR, Scotland, United Kingdom.
Proc Natl Acad Sci U S A. 2001 Jan 16;98(2):664-9. doi: 10.1073/pnas.98.2.664.
Bunyamwera virus (family Bunyaviridae, genus Bunyavirus) contains a tripartite negative-sense RNA genome. The smallest RNA segment, S, encodes the nucleocapsid protein N and a nonstructural protein, NSs, in overlapping reading frames. We have generated a mutant virus lacking NSs, called BUNdelNSs, by reverse genetics. Compared with the wild-type (wt) virus, BUNdelNSs exhibited a smaller plaque size and generated titers of virus approximately 1 log lower. In mammalian cells, the mutant expressed greatly increased levels of N protein; significantly, the marked inhibition of host cell protein synthesis shown by wt virus was considerably impaired by BUNdelNSs. When inoculated by the intracerebral route BUNdelNSs killed BALB/c mice with a slower time course than wt and exhibited a reduced cell-to-cell spread, and titers of virus in the brain were lower. In addition, the abrogation of NSs expression changed Bunyamwera virus from a noninducer to an inducer of an interferon-beta promoter. These results suggest that, although not essential for growth in tissue culture or in mice, the bunyavirus NSs protein has several functions in the virus life cycle and contributes to viral pathogenesis.
布尼亚姆韦拉病毒（布尼亚病毒科，布尼亚病毒属）含有一个由三条负链RNA组成的基因组。最小的RNA片段S在重叠阅读框中编码核衣壳蛋白N和一个非结构蛋白NSs。我们通过反向遗传学构建了一种缺失NSs的突变病毒，称为BUNdelNSs。与野生型（wt）病毒相比，BUNdelNSs的噬斑尺寸更小，产生的病毒滴度大约低1个对数级。在哺乳动物细胞中，该突变体表达的N蛋白水平大幅增加；值得注意的是，BUNdelNSs显著削弱了wt病毒对宿主细胞蛋白质合成的明显抑制作用。当通过脑内途径接种时，BUNdelNSs杀死BALB/c小鼠的时间进程比wt病毒慢，且细胞间传播减少，脑内病毒滴度也较低。此外，NSs表达的缺失使布尼亚姆韦拉病毒从干扰素-β启动子的非诱导剂转变为诱导剂。这些结果表明，尽管布尼亚病毒NSs蛋白对于在组织培养或小鼠体内生长并非必需，但它在病毒生命周期中具有多种功能，并对病毒致病性有贡献。
