Nonstructural proteins NS1 and NS2 of bovine respiratory syncytial virus block activation of interferon regulatory factor 3
Nonstructural proteins NS1 and NS2 of bovine respiratory syncytial virus block activation of interferon regulatory factor 3
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DOI：
10.1128/jvi.77.16.8661-8668.2003
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发表时间：
2003-08-01
影响因子：
5.4
通讯作者：
Conzelmann, KK
中科院分区：
文献类型：
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作者：
Bossert, B;Marozin, S;Conzelmann, KK
我们先前已经表明，牛呼吸道合胞病毒（BRSV）的非结构（NS）蛋白NS1和NS2介导了对α/β-干扰素（IFN）介导的抗病毒反应的耐药性。在这里，我们表明它们还能够防止病毒感染或双链RNA刺激后诱导βIFN（IFN-beta）。在BRSV感染的MDBK细胞中，未发生IFN刺激基因（ISG）（例如MXA）的上调，尽管发现通过JAK/STAT进行IFN信号传导完好无损。相比之下，缺乏或两个NS基因的重组BRSV的感染导致ISG的有效上调。仅在感染了NS缺失突变体的细胞上清液中检测到生物IFN活性和IFN-β，但不在野生型（WT）BRSV中检测到。随后对IFN-β启动子活性的分析表明，具有双重缺失突变体BRSV Deltans1/2的细胞感染，但没有BRSV WT，导致IFN-β基因启动子活性显着增加。 IFN-β启动子的诱导取决于三个不同的转录因子NF-kappab，ATF-2/C-JUN和IFN调节因子3（IRF-3）的激活。尽管NF-KAPPAB和ATF-2/C-JUN活性在WT BRSV和BRSV和BRSV deltans1/2感染的细胞中均可易于检测，并且可以在BRSV deltans1/deltans1/deltans1/ 2感染。 NS蛋白介导的IRF-3激活抑制和IFN诱导应对BRSV的发病机理和免疫原性产生相当大的影响。
We have previously shown that the nonstructural (NS) proteins NS1 and NS2 of bovine respiratory syncytial virus (BRSV) mediate resistance to the alpha/beta interferon (IFN)-mediated antiviral response. Here, we show that they, in addition, are able to prevent the induction of beta IFN (IFN-beta) after virus infection or double-stranded RNA stimulation. In BRSV-infected MDBK cells upregulation of IFN-stimulated genes (ISGs) such as MxA did not occur, although IFN signaling via JAK/STAT was found intact. In contrast, infection with recombinant BRSVs lacking either or both NS genes resulted in efficient upregulation of ISGs. Biological IFN activity and IFN-beta were detected only in supernatants of cells infected with the NS deletion mutants but not with wild-type (wt) BRSV. Subsequent analyses of IFN-beta promoter activity showed that infection of cells with the double deletion mutant BRSV DeltaNS1/2, but not with BRSV wt, resulted in a significant increase in IFN-beta gene promoter activity. Induction of the IFN-beta promoter depends on the activation of three distinct transcription factors, NF-kappaB, ATF-2/c-Jun, and IFN regulatory factor 3 (IRF-3). Whereas NF-kappaB and ATF-2/c-Jun activities were readily detectable and comparable in both wt BRSV- and BRSV DeltaNS1/2-infected cells, phosphorylation and transcriptional activity of IRF-3, however, were observed only after BRSV DeltaNS1/2 infection. NS protein-mediated inhibition of IRF-3 activation and IFN induction should have considerable impact on the pathogenesis and immunogenicity of BRSV.