Manivanh Richard, Mehrbach Jesse, Knipe David M, Leib David A
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA.
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
J Virol. 2017 Nov 14;91(23). doi: 10.1128/JVI.01156-17. Print 2017 Dec 1.
During viral infection, pattern recognition receptors (PRRs) and their associated adaptors recruit TANK-binding kinase 1 (TBK1) to activate interferon regulatory factor 3 (IRF3), resulting in production of type I interferons (IFNs). ICP0 and ICP34.5 are among the proteins encoded by herpes simplex virus 1 (HSV-1) that modulate type I IFN signaling. We constructed a recombinant virus (ΔXX) that lacks amino acids 87 to 106, a portion of the previously described TBK1-binding domain of the γ34.5 gene (D. Verpooten, Y. Ma, S. Hou, Z. Yan, and B. He, J Biol Chem 284:1097-1105, 2009, https://doi.org/10.1074/JBC.M805905200). These 20 residues are outside the γ34.5 beclin1-binding domain (BBD) that interacts with beclin1 and regulates autophagy. Unexpectedly, ΔXX showed no deficit in replication in a variety of tissues and showed virulence comparable to that of wild-type and marker-rescued viruses following intracerebral infection. ΔXX was fully capable of mediating the dephosphorylation of eIF2α, and the virus was capable of controlling the phosphorylation of IRF3. In contrast, a null mutant in γ34.5 failed to control IRF3 phosphorylation due to an inability of the mutant to sustain expression of ICP0. Our data show that while γ34.5 regulates IRF3 phosphorylation, the TBK1-binding domain itself has no impact on IRF3 phosphorylation or on replication and pathogenesis in mice. Interferons (IFNs) are potent activators of a variety of host responses that serve to control virus infections. The have evolved countermeasures to IFN responses. Herpes simplex virus 1 (HSV-1) encodes the multifunctional neurovirulence protein ICP34.5. In this study, we investigated the biological relevance of the interaction between ICP34.5 and TANK-binding kinase 1 (TBK1), an activator of IFN responses. Here, we establish that although ICP34.5 binds TBK1 under certain conditions through a TBK1-binding domain (TBD), there was no direct impact of the TBD on viral replication or virulence in mice. Furthermore, we showed that activation of IRF3, a substrate of TBK1, was independent of the TBD. Instead, we provided evidence that the ability of ICP34.5 to control IRF3 activation is through its ability to reverse translational shutoff and sustain the expression of other IFN inhibitors encoded by the virus. This work provides new insights into the immunomodulatory functions of ICP34.5.
在病毒感染期间,模式识别受体(PRRs)及其相关接头招募TANK结合激酶1(TBK1)以激活干扰素调节因子3(IRF3),从而产生I型干扰素(IFN)。ICP0和ICP34.5是单纯疱疹病毒1(HSV-1)编码的调节I型IFN信号传导的蛋白质。我们构建了一种重组病毒(ΔXX),其缺少氨基酸87至106,这是γ34.5基因先前描述的TBK1结合域的一部分(D. Verpooten、Y. Ma、S. Hou、Z. Yan和B. He,《生物化学杂志》284:1097 - 1105,2009年,https://doi.org/10.1074/JBC.M805905200)。这20个残基位于γ34.5与beclin1相互作用并调节自噬的beclin1结合域(BBD)之外。出乎意料的是,ΔXX在多种组织中的复制没有缺陷,并且在脑内感染后显示出与野生型和标记拯救病毒相当的毒力。ΔXX完全能够介导eIF2α的去磷酸化,并且该病毒能够控制IRF3的磷酸化。相比之下,γ34.5的缺失突变体由于无法维持ICP0的表达而未能控制IRF3的磷酸化。我们的数据表明,虽然γ34.5调节IRF3磷酸化,但TBK1结合域本身对IRF3磷酸化或小鼠中的复制和发病机制没有影响。干扰素(IFNs)是多种宿主反应的有效激活剂,用于控制病毒感染。病毒已经进化出针对IFN反应的对策。单纯疱疹病毒1(HSV-1)编码多功能神经毒力蛋白ICP34.5。在本研究中,我们研究了ICP34.5与IFN反应激活剂TANK结合激酶1(TBK1)之间相互作用的生物学相关性。在此,我们确定尽管ICP34.5在某些条件下通过TBK1结合域(TBD)与TBK1结合,但TBD对小鼠中的病毒复制或毒力没有直接影响。此外,我们表明TBK1的底物IRF3的激活与TBD无关。相反,我们提供的证据表明,ICP34.5控制IRF3激活的能力是通过其逆转翻译关闭并维持病毒编码的其他IFN抑制剂表达的能力。这项工作为ICP34.5的免疫调节功能提供了新的见解。