DEAD-box解旋酶21对猪传染性胃肠炎病毒复制的调控作用

Regulatory Role of DEAD-box Helicase 21 on Transmissible gastroenteritis virus Replication

旨在探究DEAD-box解旋酶21(DDX21)对猪传染性胃肠炎病毒(TGEV)复制的调控作用。首先通过蛋白免疫印迹(Western Blot)分析了TGEV感染对DDX21表达的影响;进一步构建了猪DDX21真核表达质粒以及建立稳定敲低DDX21的PK-15细胞系,运用荧光定量PCR(RT-qPCR)、蛋白免疫印迹、间接免疫荧光(IFA)和半数细胞培养物感染量(TCID 50)探究外源过表达DDX21及敲低DDX21对TGEV体外复制的调控作用;构建一系列DDX21截短突变体真核表达质粒,鉴定了DDX21调控TGEV增殖的关键功能域。Western Blot分析显示,在TGEV WH-1株感染早期,PK-15细胞内源性DDX21蛋白的表达水平显著上调;RT-qPCR、Western Blot、IFA和TCID 50试验显示,超表达DDX21可以显著提高TGEV N基因的mRNA水平、N蛋白的表达及病毒滴度,且呈剂量依赖性,其601-784 aa区域是其影响TGEV复制的关键;与阴性对照相比,在相应DDX21敲低细胞系中TGEV的增殖显著被抑制,而回补试验逆转了DDX21敲低细胞系中TGEV的滴度。该研究首次揭示了猪DDX21对TGEV增殖的促进作用并鉴定了其调控TGEV复制的关键结构域,为今后研究DDX21蛋白的功能及TGEV的致病机理提供了理论依据。

To investigate the regulatory effect of DEAD-box helicase 21(DDX21)on the replication of Transmissible gastroenteritis virus(TGEV).Firstly,Western Blot was utilized to analyze the effect of TGEV infection on DDX21 expression.Furthermore,we constructed eukaryotic expression plasmids of porcine DDX21 and established knockdown stable cell lines.RT-qPCR,Western Blot,Indirect immunofluorescence(IFA)and TCID 50 assays were used to investigate the regulatory effect of DDX21 on TGEV replication in vitro.Western Blot analysis showed that the protein levels of DDX21 were significantly up-regulated in PK-15 cells at the early stage of TGEV infection.RT-qPCR,Western Blot,IFA and TCID 50 experiments showed that over-expression of DDX21 significantly increased the mRNA level and protein of TGEV N in a dose-dependent manner.And the amino acids 601-784 aa of DDX21 were critical for promoting TGEV replication.Otherwise,the titer of TGEV was significantly down-regulated in DDX21 knockdown cell lines,whereas the titer of TGEV in DDX21 knockdown cell lines was reversed under the rescue experiment.This study revealed for the first time that DDX21 promotes the proliferation of TGEV and identified the key domain of DDX21 in regulating TGEV replication,which provided a theoretical a basis for future research on the function of DDX21 protein and the pathogenesis of TGEV.