摘要
The newly emerged Middle East respiratory syndrome coronavirus(MERS-CoV)is a highly pathogenic respira-tory virus with pathogenic mechanisms that may be driven by innate immune pathways.The goal of this study is to characterize the expression of the structural(S,E,M,N)and accessory(ORF 3,ORF 4a,ORF 4b,ORF 5)proteins of MERS-CoV and to determine whether any of these pro-teins acts as an interferon antagonist.Individual structural and accessory protein-coding plasmids with an N-terminal HA tag were constructed and transiently transfected into cells,and their native expression and subcellular localiza-tion were assessed using Wes tern blotting and indirect immunofl uorescence.While ORF 4b demonstrated majorly nuclear localization,all of the other proteins demonstrated cytoplasmic localization.In addition,for the fi rst time,our experiments revealed that the M,ORF 4a,ORF 4b,and ORF 5 proteins are potent interferon antagonists.Further exami-nation revealed that the ORF 4a protein of MERS-CoV has the most potential to counteract the antiviral effects of IFN via the inhibition of both the interferon production(IFN-βpromoter activity,IRF-3/7 and NF-κB activation)and ISRE promoter element signaling pathways.Together,our re-sults provide new insights into the function and pathogenic role of the structural and accessory proteins of MERS-CoV.
基金
This work was supported by the National Basic Research Program(973 Program)(No.2011CB504704)
the Ministry of Health of China(2014ZX10004-001,2013ZX10004601).
