Nonstructural Protein 1 of Variant PEDV Plays a Key Role in Escaping Replication Restriction by Complement C3
Nonstructural Protein 1 of Variant PEDV Plays a Key Role in Escaping Replication Restriction by Complement C3
复制标题
变体 PEDV 的非结构蛋白 1 在通过补体 C3 逃避复制限制中发挥关键作用
DOI：
10.1128/jvi.01024-22
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发表时间：
2022-08-29
影响因子：
5.4
通讯作者：
Li, Bin
中科院分区：
文献类型：
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作者：
Fan, Baochao;Peng, Qi;Li, Bin
人畜共患冠状病毒是对公共卫生的持续威胁。猪流行性腹泻病毒(PEDV)最早出现于20世纪70年代初。自2010年以来，PEDV高毒力变异株的暴发给全球养猪业造成了巨大的经济损失。然而，PEDV变异株逃避宿主免疫反应的策略尚不完全清楚。补体成分3(C3)被认为是三种补体激活途径的中心成分，在预防病毒感染中起着至关重要的作用。在这项研究中，我们发现C3在体外显著抑制PEDV的复制，并且PEDV变异株和经典株都能诱导Huh7细胞产生高水平的白介素1β(IL-1β)。然而，与PEDV经典株相比，PEDV变异株降低了IL-10诱导的C3转录和蛋白水平。对C3转录信号通路关键分子的检测表明，变异的PEDV通过抑制CCAAT/增强子结合蛋白β(C/EBP-β)的磷酸化来减少C3。PEDV非结构蛋白1(NSP1)通过50个氨基酸残基抑制C/EBP-β的磷酸化。最后，我们构建了重组PEDV，以验证NSP1的50位氨基酸在C3表达调控中的关键作用。综上所述，我们确定了C3在抑制PEDV复制方面的新的抗病毒作用以及PEDV变异体的病毒免疫逃避策略。我们的研究揭示了PEDV-宿主相互作用的新信息，并进一步了解了该病毒的致病机制。重要的是，补体系统在天然免疫和获得性免疫之间起着至关重要的作用，具有识别和中和各种病原体的能力。补体系统的激活就像一把双刃剑，适当水平的激活可以防止病原体感染，但过度的反应可能会引发戏剧性的炎症反应，导致组织损伤，导致病理过程，这通常出现在新冠肺炎患者中。然而，作为引起仔猪腹泻的最严重的冠状病毒，PEDV如何调节补体系统的研究尚未见报道。在这项研究中，我们首次发现了PEDV变异体抑制C3表达的新机制，表明不同的冠状病毒甚至不同的亚型毒株对C3表达的调节是不同的。此外，本研究还对PEDV变异在免疫逃逸和增强毒力方面的机制提供了更深入的理解。
Zoonotic coronaviruses represent an ongoing threat to public health. The classical porcine epidemic diarrhea virus (PEDV) first appeared in the early 1970s. Since 2010, outbreaks of highly virulent PEDV variants have caused great economic losses to the swine industry worldwide. However, the strategies by which PEDV variants escape host immune responses are not fully understood. Complement component 3 (C3) is considered a central component of the three complement activation pathways and plays a crucial role in preventing viral infection. In this study, we found that C3 significantly inhibited PEDV replication in vitro, and both variant and classical PEDV strains induced high levels of interleukin-1 beta (IL-1 beta) in Huh7 cells. However, the PEDV variant strain reduces C3 transcript and protein levels induced by IL-10 compared with the PEDV classical strain. Examination of key molecules of the C3 transcriptional signaling pathway revealed that variant PEDV reduced C3 by inhibiting CCAAT/enhancer-binding protein beta (C/EBP-beta) phosphorylation. Mechanistically, PEDV non-structural protein 1 (NSP1) inhibited C/EBP-beta phosphorylation via amino acid residue 50. Finally, we constructed recombinant PEDVs to verify the critical role of amino acid 50 of NSP1 in the regulation of C3 expression. In summary, we identified a novel antiviral role of C3 in inhibiting PEDV replication and the viral immune evasion strategies of PEDV variants. Our study reveals new information on PEDV-host interactions and furthers our understanding of the pathogenic mechanism of this virus.IMPORTANCE The complement system acts as a vital link between the innate and the adaptive immunity and has the ability to recognize and neutralize various pathogens. Activation of the complement system acts as a double-edged sword, as appropriate levels of activation protect against pathogenic infections, but excessive responses can provoke a dramatic inflammatory response and cause tissue damage, leading to pathological processes, which often appear in COVID-19 patients. However, how PEDV, as the most severe coronavirus causing diarrhea in piglets, regulates the complement system has not been previously reported. In this study, for the first time, we identified a novel mechanism of a PEDV variant in the suppression of C3 expression, showing that different coronaviruses and even different subtype strains differ in regulation of C3 expression. In addition, this study provides a deeper understanding of the mechanism of the PEDV variant in immune escape and enhanced virulence.