Virulent Poxviruses Inhibit DNA Sensing by Preventing STING Activation.
Virulent Poxviruses Inhibit DNA Sensing by Preventing STING Activation.
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DOI：
10.1128/jvi.02145-17
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发表时间：
2018-05-15
影响因子：
5.4
通讯作者：
Maluquer de Motes C
中科院分区：
文献类型：
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作者：
Georgana I;Sumner RP;Towers GJ;Maluquer de Motes C
DNA的胞质识别已经成为病原体入侵时宿主免疫激活的关键细胞机制。中央细胞溶质DNA传感器cGAS激活STING，STING被磷酸化、二聚化并从内质网（ER）易位到核周区域以介导IRF-3激活。痘病毒是在胞质溶胶中复制的双链DNA病毒，因此可能触发胞质溶胶DNA传感。在这里，我们研究了激活先天免疫信号的4种不同的原型痘病毒痘苗病毒（VACV）在细胞系精通DNA传感。用减毒VACV毒株MVA感染经由cGAS和STING激活IRF-3，并且因此在MVA感染期间STING二聚化并磷酸化。相反，VACV株哥本哈根和Western Reserve在感染期间和响应于转染的DNA和环状GMP-AMP抑制STING二聚化和磷酸化，从而有效地抑制DNA传感和IRF-3活化。缺乏蛋白质C16的VACV缺失突变体，被认为是唯一作用于STING上游的病毒DNA传感抑制剂，保留了阻断STING活化的能力。对于牛痘和鼠痘病毒，也观察到DNA诱导的STING活化的类似抑制。我们的数据表明，毒性痘病毒具有在cGAS-STING轴水平靶向DNA传感的机制，并且这些机制在复制缺陷型菌株如MVA中不起作用。这些发现揭示了细胞DNA传感在痘病毒-宿主相互作用中的作用，并将开辟新的途径来确定其对VACV免疫原性和毒力的影响。痘病毒是双链DNA病毒，感染范围广泛的脊椎动物，包括天花（天花病毒）及其疫苗牛痘病毒（VACV）的病原体。尽管天花被根除，VACV仍然是一种令人感兴趣的治疗药物。减毒菌株是流行的候选疫苗，而具有复制能力的菌株正在成为病毒治疗中有效的溶瘤剂。VACV的成功治疗应用取决于对其调节宿主先天免疫应答能力的详细了解。DNA传感是病原体检测和先天免疫激活的关键细胞机制，其由内质网驻留蛋白STING集中协调。在此，STING显示响应于MVA介导免疫活化，但不响应于毒性VACV毒株或其他毒性痘病毒，其在感染期间和DNA转染后阻止STING活化和DNA感测。这些结果为痘病毒的免疫逃避提供了新的见解，并对基于VACV的治疗方法的合理设计产生了影响。
Cytosolic recognition of DNA has emerged as a critical cellular mechanism of host immune activation upon pathogen invasion. The central cytosolic DNA sensor cGAS activates STING, which is phosphorylated, dimerizes and translocates from the endoplasmic reticulum (ER) to a perinuclear region to mediate IRF-3 activation. Poxviruses are double-stranded DNA viruses replicating in the cytosol and hence likely to trigger cytosolic DNA sensing. Here, we investigated the activation of innate immune signaling by 4 different strains of the prototypic poxvirus vaccinia virus (VACV) in a cell line proficient in DNA sensing. Infection with the attenuated VACV strain MVA activated IRF-3 via cGAS and STING, and accordingly STING dimerized and was phosphorylated during MVA infection. Conversely, VACV strains Copenhagen and Western Reserve inhibited STING dimerization and phosphorylation during infection and in response to transfected DNA and cyclic GMP-AMP, thus efficiently suppressing DNA sensing and IRF-3 activation. A VACV deletion mutant lacking protein C16, thought to be the only viral DNA sensing inhibitor acting upstream of STING, retained the ability to block STING activation. Similar inhibition of DNA-induced STING activation was also observed for cowpox and ectromelia viruses. Our data demonstrate that virulent poxviruses possess mechanisms for targeting DNA sensing at the level of the cGAS-STING axis and that these mechanisms do not operate in replication-defective strains such as MVA. These findings shed light on the role of cellular DNA sensing in poxvirus-host interactions and will open new avenues to determine its impact on VACV immunogenicity and virulence. IMPORTANCE Poxviruses are double-stranded DNA viruses infecting a wide range of vertebrates and include the causative agent of smallpox (variola virus) and its vaccine vaccinia virus (VACV). Despite smallpox eradication VACV remains of interest as a therapeutic. Attenuated strains are popular vaccine candidates, whereas replication-competent strains are emerging as efficient oncolytics in virotherapy. The successful therapeutic use of VACV depends on a detailed understanding of its ability to modulate host innate immune responses. DNA sensing is a critical cellular mechanism for pathogen detection and activation of innate immunity that is centrally coordinated by the endoplasmic reticulum-resident protein STING. Here, STING is shown to mediate immune activation in response to MVA, but not in response to virulent VACV strains or other virulent poxviruses, which prevent STING activation and DNA sensing during infection and after DNA transfection. These results provide new insights into poxvirus immune evasion and have implications in the rational design of VACV-based therapeutics.