State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural Universitygrid.35155.37, Wuhan, Hubei, China.
Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural Universitygrid.35155.37, Wuhan, Hubei, People's Republic of China.
Microbiol Spectr. 2022 Jun 29;10(3):e0141722. doi: 10.1128/spectrum.01417-22. Epub 2022 Jun 13.
In flavivirus, the furin-mediated cleavage of prM is mandatory to produce infectious particles, and the immature particles containing uncleaved prM cannot undergo membrane fusion and release to the extracellular environment. However, the detailed relationship between viral replication or pathogenicity and furin in Japanese encephalitis virus (JEV) hasn't been clarified. Here, JEV with the mutations in furin cleavage sites and its nearby were constructed. Compared with WT virus, the mutant virus showed enhanced cleavage efficiency of prM protein and increased replication ability. Furthermore, we found that the mutations mainly promote genomic replication and assembly of JEV. However, the mutant formed smaller plaques than WT virus in plaque forming assay, indicating the lower cytopathogenicity of mutant virus. To assess the virulence of JEV mutant, an assay was performed using a mouse model. A higher survival rate and attenuated neuroinflammation were observed in JEV mutant-infected mice than those of WT-infected mice, suggesting the cleavage of prM by furin was closely related to viral virulence. These findings will provide new understanding on JEV pathogenesis and contribute to the development of novel JEV vaccines. Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis epidemics in Southeast Asia, affecting mostly children, with high morbidity and mortality. During the viral maturation process, prM is cleaved into M by the cellular endoprotease furin in the acidic secretory system. After cleavage of the prM protein, mature virions are exocytosed. Here, the mutant in furin cleavage sites and its nearby was constructed, and the results showed that the mutant virus with enhanced replication mainly occurred in the process of genomic replication and assembly. Meanwhile, the mutant showed an attenuated virulence than WT virus . Our study contributes to understanding the function of prM and M proteins and provides new clues for live vaccine designation for JEV.
在黄病毒中，弗林介导的 prM 切割对于产生感染性颗粒是必需的，并且包含未切割 prM 的不成熟颗粒不能进行膜融合并释放到细胞外环境中。然而，日本脑炎病毒 (JEV) 中病毒复制或致病性与弗林之间的详细关系尚未阐明。在这里，构建了弗林切割位点及其附近突变的 JEV 及其突变体。与 WT 病毒相比，突变病毒显示出 prM 蛋白切割效率的提高和复制能力的增强。此外，我们发现这些突变主要促进 JEV 的基因组复制和组装。然而，在噬斑形成测定中，突变体形成的噬斑比 WT 病毒小，表明突变体病毒的细胞病变能力较低。为了评估 JEV 突变体的毒力，使用小鼠模型进行了一项 。与 WT 感染小鼠相比，JEV 突变体感染小鼠的存活率更高，神经炎症减轻，表明弗林对 prM 的切割与病毒毒力密切相关。这些发现将为 JEV 发病机制提供新的认识，并有助于开发新型 JEV 疫苗。日本脑炎病毒 (JEV) 是东南亚病毒性脑炎流行的主要原因，主要影响儿童，发病率和死亡率高。在病毒成熟过程中，prM 在酸性分泌系统中被细胞内内切酶弗林切割成 M。prM 蛋白切割后，成熟病毒被外吐。在这里，构建了弗林切割位点及其附近的突变体，结果表明增强复制的突变体主要发生在基因组复制和组装过程中。同时，与 WT 病毒相比，突变体表现出较弱的毒力。我们的研究有助于了解 prM 和 M 蛋白的功能，并为 JEV 的活疫苗设计提供新的线索。
