鼠诺如病毒感染RAW264.7细胞中干扰素和干扰素激活基因转录水平研究

Comparison on Transcriptional Levels of Interferons and Interferon-stimulated Genes in RAW264.7 Cells Infected with Murine Norovirus

诺如病毒（Norovirus,NoV）是全球急性胃肠炎散发病例和暴发疫情的主要致病原。鼠诺如病毒（Murine norovirus,MNV）是研究诺如病毒的理想研究模型。本研究通过实时定量荧光PCR检测急性感染毒株MNV-CW1和持续性感染毒株MNV-SH1603感染Balb/c小鼠后的排毒情况以及感染RAW264.7细胞后不同时间点病毒RNA扩增、干扰素（Interferon,IFN）和干扰素激活基因（Interferon-stimulated gene,ISG）转录水平,以探讨不同的MNV毒株感染诱导IFNs和ISGs基因表达的特征。研究显示MNV-CW1和MNV-SH1603病毒感染Balb/c小鼠后排毒时间不同。MNV-CW1和MNV-SH1603病毒感染RAW264.7细胞后,6h后出现明显扩增,48h达到病毒复制高峰,随后复制速度减慢。MNV-SH1603增殖比MNV-CW1快。两种病毒感染RAW264.7细胞后能上调IFN-β,IFN-λ2,ISG15和ISG54转录水平。MNV-CW1感染后,诱导IFN-β,IFN-λ2和ISG15基因表达上调,而ISG54在感染24h后转录水平下降。MNV-SH1603感染初期IFN-β,IFN-λ2,ISG15和ISG54基因转录水平持续增高,感染24h后IFN-β和ISG54的转录水平明显降低,IFN-λ2和ISG15转录水平峰值在感染后72h。研究揭示MNV病毒感染RAW264.7细胞后能上调IFN和ISG基因表达,但是MNV-CW1和MNV-SH1603诱导的基因表达特征有异同。

Human noroviruses（HuNoVs）are the major cause of gastroenteritis and sporadic diarrhea worldwide.Murine norovirus（MNV）is an important model to study the biology and pathogenesis of HuNoVs.Using real-time reverse transcription-polymerase chain reaction（qRT-PCR）,viral RNA was detected in feces after infection by MNV-SH1603 and MNV-CW1 in Balb/c mice.In addition,the nucleic acids of the MNV and intracellular transcriptional level of interferons（IFNs）and interferon-stimulated genes（ISGs）were investigated at different times after MNVs infection of RAW264.7 cells.The time that MNV-SH1603 viral RNA was detected in the feces of Balb/c mice was longer than that of MNV-CW1.MNVs propagated significantly in RAW264.7 cells 10 hpost-infection（hpi）and the number of MNVs reached a maximum at 48 hpi,whereas MNV-SH1603 propagated faster than MNV-CW1. When RAW264.7 cells were infected with MNV-CW1,the mRNA levels of IFN-β,IFN-λ2 and ISG15 increased continuously,and that of ISG54 mRNA decreased at 24 hpi.At the early stage of MNV-SH1603 infection,the mRNA levels of IFN-β,IFN-λ2,ISG15 and ISG54 increased obviously.At 24 hpi,mRNA levels of IFN-βand ISG54 decreased distinctly,and peak expression of IFN-λ2 mRNA and ISG15 mRNA appeared at 72 hpi.These findings suggest that MNV infection could induce increases in the mRNA levels of IFNs and ISGs.However,the transcription characteristics of the mRNAs of IFNs and ISGs were different between MNV-CW1 and MNV-SH1603 infections.