Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore; Laboratory of Primate Model, Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, Kyoto 606-8517, Japan.
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore.
Biochem Biophys Res Commun. 2014 May 23;448(1):95-100. doi: 10.1016/j.bbrc.2014.04.081. Epub 2014 Apr 21.
ISGylation, an ubiquitin-like post-translational modification by ISG15, has been reported to participate in the interferon (IFN)-mediated antiviral response. In this study, we analyzed the functional role of ISGylation in dengue virus 2 (DENV-2) replication. Overexpression of ISG15 was found to significantly suppress the amount of extracellular infectious virus released, while intracellular viral RNA was unaffected. This effect was not observed with a conjugation-defective ISG15 mutant. In addition, extracellular virus infectivity was decreased by ISG15 overexpression. To further clarify the role of ISGylation in the anti-DENV-2 response, we depleted endogenous ISG15 by RNA interference and analyzed the virus production in the absence or presence of type-I IFN. Results showed a significant reduction in extracellular DENV-2 RNA levels for cells treated with IFN, and that these DENV-2 RNA levels could be partially restored by the ISG15 knockdown. Among various DENV-2 proteins, NS3 and NS5 were subjected to the ISGylation. These results demonstrate that IFN-inducible ISGylation suppresses DENV-2 particle release, and that ISG15 is one of the mediators of IFN-induced inhibition of DENV-2 replication. ISG15 therefore functions as a host antiviral factor against DENV-2 infection.
ISGylation，一种由 ISG15 介导的泛素样翻译后修饰，已被报道参与干扰素 (IFN) 介导的抗病毒反应。在这项研究中，我们分析了 ISGylation 在登革热病毒 2 (DENV-2) 复制中的功能作用。发现过表达 ISG15 可显著抑制细胞外传染性病毒的释放量，而细胞内病毒 RNA 不受影响。这种效应在具有连接缺陷的 ISG15 突变体中观察不到。此外，过表达 ISG15 可降低细胞外病毒感染力。为了进一步阐明 ISGylation 在抗 DENV-2 反应中的作用，我们通过 RNA 干扰耗尽内源性 ISG15，并在存在或不存在 I 型 IFN 的情况下分析病毒产生情况。结果显示，用 IFN 处理的细胞中细胞外 DENV-2 RNA 水平显著降低，而这些 DENV-2 RNA 水平可通过 ISG15 敲低部分恢复。在各种 DENV-2 蛋白中，NS3 和 NS5 受到 ISGylation 的影响。这些结果表明，IFN 诱导的 ISGylation 抑制 DENV-2 颗粒释放，而 ISG15 是 IFN 诱导的 DENV-2 复制抑制的介质之一。因此，ISG15 作为一种针对 DENV-2 感染的宿主抗病毒因子发挥作用。
