Unité de Virologie et Immunologie Moléculaires, Unité de Recherche 892 Institut National de la Recherche Agronomique, Domaine de Vilvert, Jouy-en-Josas, France.
J Immunol. 2010 Oct 15;185(8):4812-23. doi: 10.4049/jimmunol.0903952. Epub 2010 Sep 15.
The PB1-F2 protein of the influenza A virus (IAV) contributes to viral pathogenesis by a mechanism that is not well understood. PB1-F2 was shown to modulate apoptosis and to be targeted by the CD8(+) T cell response. In this study, we examined the downstream effects of PB1-F2 protein during IAV infection by measuring expression of the cellular genes in response to infection with wild-type WSN/33 and PB1-F2 knockout viruses in human lung epithelial cells. Wild-type virus infection resulted in a significant induction of genes involved in innate immunity. Knocking out the PB1-F2 gene strongly decreased the magnitude of expression of cellular genes implicated in antiviral response and MHC class I Ag presentation, suggesting that PB1-F2 exacerbates innate immune response. Biological network analysis revealed the IFN pathway as a link between PB1-F2 and deregulated genes. Using quantitative RT-PCR and IFN-β gene reporter assay, we determined that PB1-F2 mediates an upregulation of IFN-β expression that is dependent on NF-κB but not on AP-1 and IFN regulatory factor-3 transcription factors. Recombinant viruses knocked out for the PB1-F2 and/or the nonstructural viral protein 1 (the viral antagonist of the IFN response) genes provide further evidence that PB1-F2 increases IFN-β expression and that nonstructural viral protein 1 strongly antagonizes the effect of PB1-F2 on the innate response. Finally, we compared the effect of PB1-F2 variants taken from several IAV strains on IFN-β expression and found that PB1-F2-mediated IFN-β induction is significantly influenced by its amino acid sequence, demonstrating its importance in the host cell response triggered by IAV infection.
流感 A 病毒（IAV）的 PB1-F2 蛋白通过一种尚未完全了解的机制促进病毒发病机制。已经表明 PB1-F2 调节细胞凋亡，并成为 CD8(+) T 细胞反应的靶标。在这项研究中，我们通过测量人肺上皮细胞中受感染时细胞基因的表达，研究了 IAV 感染期间 PB1-F2 蛋白的下游效应。野生型病毒感染导致与先天免疫有关的基因显著诱导。敲除 PB1-F2 基因强烈降低了抗病毒反应和 MHC Ⅰ类 Ag 呈递涉及的细胞基因的表达幅度，表明 PB1-F2 加剧了先天免疫反应。生物网络分析显示 IFN 途径是 PB1-F2 和失调基因之间的联系。使用定量 RT-PCR 和 IFN-β基因报告基因测定，我们确定 PB1-F2 介导 IFN-β表达的上调，该上调依赖于 NF-κB，但不依赖于 AP-1 和 IFN 调节因子-3 转录因子。敲除 PB1-F2 和/或非结构病毒蛋白 1（IFN 反应的病毒拮抗剂）基因的重组病毒提供了进一步的证据，表明 PB1-F2 增加了 IFN-β的表达，而非结构病毒蛋白 1强烈拮抗 PB1-F2 对先天反应的作用。最后，我们比较了来自几种 IAV 株的 PB1-F2 变体对 IFN-β表达的影响，发现 PB1-F2 介导的 IFN-β诱导明显受其氨基酸序列的影响，证明了其在 IAV 感染触发的宿主细胞反应中的重要性。
