Delayed Cytosolic Exposure of Japanese Encephalitis Virus Double-Stranded RNA Impedes Interferon Activation and Enhances Viral Dissemination in Porcine Cells
Delayed Cytosolic Exposure of Japanese Encephalitis Virus Double-Stranded RNA Impedes Interferon Activation and Enhances Viral Dissemination in Porcine Cells
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DOI：
10.1128/jvi.00233-11
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发表时间：
2011-07-01
影响因子：
5.4
通讯作者：
Morita, Kouichi
中科院分区：
文献类型：
--
作者：
Espada-Murao, Lyre Anni;Morita, Kouichi
干扰素是宿主抗病毒防御系统的主要成分。在这项研究中，日本脑炎病毒（JEV）在灵长类动物细胞中流产的病灶形成伴随着干扰素的早期诱导，而在猪细胞中产生病灶形成与干扰素应答的晚期相关。针对干扰素的中和抗体缓解了灵长类细胞的限制性感染，并且随着外源性干扰素治疗的延迟，产生越来越大的病灶，从而建立了干扰素应答与病毒传播之间的坚实相关性。然而，在没有病毒主动抑制的情况下，干扰素在感染乙脑的猪细胞中的延迟诱导发生。我们进一步证明了乙脑病毒通过双链RNA和细胞质模式识别受体介导干扰素激活。免疫荧光和亚细胞分离研究表明，双链RNA在感染早期隐藏在细胞膜内，但最终在后期出现在细胞质中，然后可以被细胞质模式识别受体检测到。有趣的是，与灵长类动物细胞相比，猪细胞中双链RNA的细胞质暴露延迟，与总双链RNA水平无关，并与干扰素反应的时间相关。此外，当双链RNA被人工引入猪细胞的细胞质中时，干扰素激活比病毒感染时更快、更强。因此，乙脑病毒双链RNA的细胞质暴露对于干扰素诱导是必要的，但在细胞质双链RNA出现延迟的细胞系（例如猪细胞）中，干扰素反应较晚，因此病毒传播增强。
Interferon is a principal component of the host antiviral defense system. In this study, abortive focus formation by Japanese encephalitis virus (JEV) in primate cells was accompanied by early interferon induction, while productive focus formation in porcine cells was associated with a late interferon response. Neutralization antibodies against interferon relieved the restricted infection in primate cells, and increasingly larger foci were generated as treatment with exogenous interferon was delayed, thereby establishing a solid correlation between interferon response and viral dissemination. However, delayed interferon induction in JEV-infected porcine cells occurred in the absence of active inhibition by the virus. We further demonstrated that JEV mediates interferon activation through double-stranded RNA and cytosolic pattern recognition receptors. Immunofluorescence and subcellular fractionation studies revealed that double-stranded RNA is concealed in intracellular membranes at an early phase of infection but eventually appears in the cytosol at later periods, which could then allow detection by cytosolic pattern recognition receptors. Interestingly, cytosolic exposure of double-stranded RNA was delayed in porcine cells compared to primate cells, independent of total double-stranded RNA levels and in correlation with the timing of the interferon response. Furthermore, when double-stranded RNA was artificially introduced into the cytosol of porcine cells, more rapid and robust interferon activation was triggered than in viral infection. Thus, cytosolic exposure of JEV double-stranded RNA is imperative for interferon induction, but in cell lines (e.g., porcine cells) with delayed emergence of cytosolic double-stranded RNA, the interferon response is late and viral dissemination is consequently enhanced.