Porcine Reproductive and Respiratory Syndrome Virus Nonstructural Protein 4 Antagonizes Beta Interferon Expression by Targeting the NF-κB Essential Modulator
Porcine Reproductive and Respiratory Syndrome Virus Nonstructural Protein 4 Antagonizes Beta Interferon Expression by Targeting the NF-κB Essential Modulator
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DOI：
10.1128/jvi.01396-14
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发表时间：
2014-09-01
影响因子：
5.4
通讯作者：
Feng, Wen-hai
中科院分区：
文献类型：
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作者：
Huang, Chen;Zhang, Qiong;Feng, Wen-hai
猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus，PRRSV）是一种高度传染性的病原体，在世界范围内引起严重的疾病，给养猪业造成巨大的经济损失。I型干扰素（IFN）在抗病毒免疫中起着至关重要的作用。在本研究中，我们证明了感染高致病性PRRSV株JXwn06拮抗聚（I. C）诱导的猪肺泡巨噬细胞（PAM）和血液单核细胞衍生的巨噬细胞（BMo）中的I型IFN的表达。随后，我们表明，抑制聚（I. C）诱导的IFN-β的生产由PRRSV依赖于NF-κ B信号通路的阻断。通过筛选PRRSV非结构蛋白和结构蛋白，我们证明了非结构蛋白4（nsp4），病毒3C样丝氨酸蛋白酶，显着抑制IFN-β的表达。此外，我们证实nsp4抑制由信号分子（包括RIG-I、VISA、TRIF和IKK β）诱导的NF-κ B活化。显示nsp 4在E349-S350位点靶向NF-κ B必需调节剂（NEMO）以介导其切割。重要的是，具有缺陷蛋白酶活性的nsp4突变体消除了其切割NEMO和抑制IFN-β产生的能力。这些发现可能对我们理解PRRSV的发病机制及其逃避宿主免疫反应的机制具有重要意义。重要性猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus，PRRSV）是猪呼吸道疾病的主要病原。与许多其他病毒一样，PRRSV已经进化出多种策略来逃避宿主的抗病毒先天免疫以存活和繁殖。在这项研究中，我们表明，PRRSV nsp4是一种新的NF-κ B B信号通路的拮抗剂，这是负责调节I型干扰素和其他关键细胞因子的表达。然后，我们研究了nsp4抑制NF-κ B介导的IFN-β产生的潜在机制。我们发现nsp4通过在E349-S350位点切割NEMO（NF-κ B信号传导的关键调节因子）来干扰NF-κ B信号传导途径，导致poly（I. C）诱导的IFN-β产生下调。这些数据有助于我们更好地了解PRRSV的发病机制。
Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly infectious pathogen that causes severe diseases in pigs and great economic losses to the swine industry worldwide. Type I interferons (IFNs) play a crucial role in antiviral immunity. In the present study, we demonstrated that infection with the highly pathogenic PRRSV strain JXwn06 antagonized type I IFN expression induced by poly(I.C) in both porcine alveolar macrophages (PAMs) and blood monocyte-derived macrophages (BMo). Subsequently, we showed that the inhibition of poly(I.C)-induced IFN-beta production by PRRSV was dependent on the blocking of NF-kappa B signaling pathways. By screening PRRSV nonstructural and structural proteins, we demonstrated that nonstructural protein 4 (nsp4), a viral 3C-like serine protease, significantly suppressed IFN-beta expression. Moreover, we verified that nsp4 inhibited NF-kappa B activation induced by signaling molecules, including RIG-I, VISA, TRIF, and IKK beta. nsp4 was shown to target the NF-kappa B essential modulator (NEMO) at the E349-S350 site to mediate its cleavage. Importantly, nsp4 mutants with defective protease activity abolished its ability to cleave NEMO and inhibit IFN-beta production. These findings might have implications for our understanding of PRRSV pathogenesis and its mechanisms for evading the host immune response.IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) is a major agent of respiratory diseases in pigs. Like many other viruses, PRRSV has evolved a variety of strategies to evade host antiviral innate immunity for survival and propagation. In this study, we show that PRRSV nsp4 is a novel antagonist of the NF-kappa B signaling pathway, which is responsible for regulating the expression of type I interferons and other crucial cytokines. We then investigated the underlying mechanism used by nsp4 to suppress NF-kappa B-mediated IFN-beta production. We found that nsp4 interfered with the NF-kappa B signaling pathway through the cleavage of NEMO (a key regulator of NF-kappa B signaling) at the E349-S350 site, leading to the downregulation of IFN-beta production induced by poly(I.C). The data presented here may help us to better understand PRRSV pathogenesis.