Glitscher Mirco, Himmelsbach Kiyoshi, Woytinek Kathrin, Schollmeier Anja, Johne Reimar, Praefcke Gerrit J K, Hildt Eberhard
Department Virology; Paul-Ehrlich-Institut; D-63225 Langen, Germany.
Department Biological Safety; German Federal Institute for Risk Assessment; Berlin, D-10589 Berlin,; Germany.
J Virol. 2021 Mar 10;95(7). doi: 10.1128/JVI.01564-20. Epub 2021 Jan 20.
This study aims to gain deeper insight into HEV-induced innate immunity by characterizing the crosstalk between the virus and the host factor guanylate-binding protein 1 (GBP1). We observe that the amount of GBP1 is elevated upon infection, although number of transcripts is decreased, which is explained by a prolonged protein half-life. Modulation of GBP1 levels via overexpression significantly inhibits the viral life cycle. Use of various GBP-1 mutants revealed that the antiviral effect of GBP-1 on HEV is independent from the GTPase-activity, but depends on the capacity of GBP-1 to form GBP1 homodimers. This connects GBP-1 to the autophagosomal pathway. Indeed, dimerization competent GBP1 targets the viral capsid protein to the lysosomal compartment leading to inactivation of the viral particle. Most importantly, silencing of GBP1 abolishes the antiviral effect of IFNγ on HEV. In IFNγ treated cells the virus is targeted to lysosomal structures and destroyed therein. This process depends in part on GBP1. These observations about the relevance of GBP1 for type II interferon-mediated innate immunity against HEV could be a base for tailoring novel antivirals and improvement of disease management. Although HEV represents a worldwide public health problem with 20 million infections and 44.000 death cases per year, there are still no specific antivirals available and many aspects of the viral life cycle are not well understood. Here we identify the guanylate binding protein 1 (GBP1) as a restriction factor affecting life cycle of HEV. Surprisingly, the antiviral effect of GBP1 does not depend on its GTPase function, but on its capacity to homodimerize. We revealed that GBP1 exerts its antiviral activity by targeting HEV to the lysosomal compartment where the virus is inactivated. Most importantly, we observed that the antiviral effect of interferon-γ on HEV strongly depends on GBP1. Our observation that GBP1 impairs HEV and is crucial for the antiviral effect of interferons on HEV extends understanding of host defense-mechanisms. As the interferon-system represents a universal defense-mechanism, our study could help to design novel antivirals targeting.
本研究旨在通过表征病毒与宿主因子鸟苷酸结合蛋白1（GBP1）之间的相互作用，更深入地了解戊型肝炎病毒（HEV）诱导的固有免疫。我们观察到，感染后GBP1的量增加，尽管转录本数量减少，这可通过延长的蛋白质半衰期来解释。通过过表达调节GBP1水平可显著抑制病毒生命周期。使用各种GBP-1突变体表明，GBP-1对HEV的抗病毒作用独立于GTPase活性，但取决于GBP-1形成GBP1同二聚体的能力。这将GBP-1与自噬体途径联系起来。实际上，具有二聚化能力的GBP1将病毒衣壳蛋白靶向溶酶体区室，导致病毒颗粒失活。最重要的是，沉默GBP1可消除IFNγ对HEV的抗病毒作用。在IFNγ处理的细胞中，病毒被靶向溶酶体结构并在其中被破坏。这个过程部分依赖于GBP1。这些关于GBP1对II型干扰素介导的针对HEV的固有免疫的相关性的观察结果，可能成为定制新型抗病毒药物和改善疾病管理的基础。尽管HEV是一个全球性的公共卫生问题，每年有2000万例感染和44000例死亡病例，但仍然没有可用的特异性抗病毒药物，并且病毒生命周期的许多方面尚未得到很好的理解。在这里，我们确定鸟苷酸结合蛋白1（GBP1）是一种影响HEV生命周期的限制因子。令人惊讶的是，GBP1的抗病毒作用不依赖于其GTPase功能，而是依赖于其同二聚化的能力。我们发现GBP1通过将HEV靶向溶酶体区室发挥其抗病毒活性，在该区域病毒被灭活。最重要的是，我们观察到干扰素-γ对HEV的抗病毒作用强烈依赖于GBP1。我们观察到GBP1损害HEV并且对干扰素对HEV的抗病毒作用至关重要，这扩展了对宿主防御机制的理解。由于干扰素系统代表一种普遍的防御机制，我们的研究可能有助于设计新型靶向抗病毒药物。
