Phillips J J, Chua M M, Lavi E, Weiss S R
Departments of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6076, USA.
J Virol. 1999 Sep;73(9):7752-60. doi: 10.1128/JVI.73.9.7752-7760.1999.
The mouse hepatitis virus (MHV) spike glycoprotein, S, has been implicated as a major determinant of viral pathogenesis. In the absence of a full-length molecular clone, however, it has been difficult to address the role of individual viral genes in pathogenesis. By using targeted RNA recombination to introduce the S gene of MHV4, a highly neurovirulent strain, into the genome of MHV-A59, a mildly neurovirulent strain, we have been able to directly address the role of the S gene in neurovirulence. In cell culture, the recombinants containing the MHV4 S gene, S4R22 and S4R21, exhibited a small-plaque phenotype and replicated to low levels, similar to wild-type MHV4. Intracranial inoculation of C57BL/6 mice with S4R22 and S4R21 revealed a marked alteration in pathogenesis. Relative to wild-type control recombinant viruses (wtR13 and wtR9), containing the MHV-A59 S gene, the MHV4 S gene recombinants exhibited a dramatic increase in virulence and an increase in both viral antigen staining and inflammation in the central nervous system. There was not, however, an increase in the level of viral replication in the brain. These studies demonstrate that the MHV4 S gene alone is sufficient to confer a highly neurovirulent phenotype to a recombinant virus deriving the remainder of its genome from a mildly neurovirulent virus, MHV-A59. This definitively confirms previous findings, suggesting that the spike is a major determinant of pathogenesis.
小鼠肝炎病毒（MHV）刺突糖蛋白S被认为是病毒致病机制的主要决定因素。然而，在缺乏全长分子克隆的情况下，很难确定单个病毒基因在致病机制中的作用。通过使用靶向RNA重组技术，将高神经毒力毒株MHV4的S基因导入低神经毒力毒株MHV-A59的基因组中，我们得以直接研究S基因在神经毒力中的作用。在细胞培养中，含有MHV4 S基因的重组体S4R22和S4R21表现出小斑表型，且复制水平较低，类似于野生型MHV4。用S4R22和S4R21对C57BL/6小鼠进行颅内接种，结果显示致病机制发生了显著改变。相对于含有MHV-A59 S基因的野生型对照重组病毒（wtR13和wtR9），MHV4 S基因重组体的毒力显著增加，中枢神经系统中的病毒抗原染色和炎症均有所增加。然而，脑中的病毒复制水平并未升高。这些研究表明，仅MHV4 S基因就足以赋予一种重组病毒高神经毒力表型，该重组病毒的基因组其余部分来自低神经毒力病毒MHV-A59。这明确证实了先前的研究结果，表明刺突是致病机制的主要决定因素。
