Differential Expression Of IFN-? Subtypes During Influenza Virus Infection

Influenza is an acute respiratory infection disease caused by influenza virus.The type ? interferon induced by influenza virus through pattern recognition receptor is essential for innate defense against influenza virus.The cells infected by influenza virus could produce IFN-?,which is secreted by paracrine or autocrine manner and binds to the cell surface interferon receptor(IFNAR).The binding can activate the downstream transcription factors and induce large amount of IFN-? production.There are 13 subtypes of IFN-? in human and 14 subtypes of IFN-? in mice.Although there are many IFN-? subtypes,the expression pattern of IFN-? subtypes during influenza virus infection is less studied.In this study,we analyzed the amino acid sequences,base sequences,spatial structures and the binding position of related transcription factor on their gene promoters of human and mouse IFN-? subtypes.Then we detected the mRNA expression levels of IFN-? subtypes and related transcription factors in the in vitro cultured lung epithelial cells and monocytes/macrophages infected by influenza virus and the lung tissues in the influenza model mice using qRT-PCR,and found there were different in the expression of different IFN-? subtypes after influenza virus infection.The results are as below:1.The expression of IFN-? subtypes in the epithelial cells and immune cells infected by influenza virus.The mRNA levels of IFN-? subtypes in human and mouse epithelial cells and monocytes/macrophages infected by influenza virus were elevated in a tendency over the infectious time.The IFNA1,14 and 16 in influenza virus infected human epithelial cell A549 cells reached the peak on 9h and started to decrease on 12 h post-infection,in which the mRNA level of IFNA16 was the highest.IFNA5,6,10 and 21 were increased along with the infectious time,and reached the peak on 12 h post-infection.The above results were also displayed in influenza virus infected human monocyte U937 cells and showed that,the mRNA levels of IFNA1,5,6,10,14,16 and 21 on 9h were higher than that on 6h post-infection.And the mRNA levels of almost all IFN-? subtypes,except for IFNA16,in infected U937 cells were higher than that produced by infected A549 cells.The high expression level of IFNA16 in A549 cells and barely expression of that in U937 cells may due to the difference responses between epithelial cells and immune cells.In the influenza virus infected RAW264.7 cells,the mRNA expression of Ifna were overall increased.The mRNA levels of Ifna13 and 16 were increased along with the infectious time,and that of Ifna1,2 and 9 were decreased in 9h while increased on 12 h post-infection.The mRNA expression of Ifna4 was decreased along with the infectious time.In general,the expression levels of IFN-? subtypes in epithelial cells were entirely lower than that in monocytes/macrophages.2.The expression of IFN-? subtypes in the lung tissues of influenza model mice.In the lung tissues of influenza model mice,the mRNA levels of Ifna1,2,4,9 and 16 were decreased on day 5 post-infection compared with that on day 3 post-infection and the levels of Ifna1,2,4,9 and 16 were similar.The expression levels of Ifna13 were opposite since the mRNA expression of Ifna13 on day 5 post-infection were higher than that on day 3 post-infection.3.The effect of interferon regulatory factors(IRF)on the influenza virus infection.We detected the mRNA expression levels of IRF3,5,7 and 9,and NF-?B in the influenza virus infected human and mouse cells and mouse lung tissues,and found that IRF7 is the major regulator.In A549 cells,the IRF3 and IRF5 were barely expressed on 6h and 12 h post-infection,whereas the mRNA levels of IRF7 and IRF9 were increased along with infectious time,and the level of IRF7 was about 4-fold increased than that of IRF9 and 15-fold increased than that of IRF3 and IRF5.It was similar in U937 cells,but the expression levels of IRF7 and IRF9 were about 4 to 5-fold increased than that of IRF3 and IRF5.In the influenza virus infected RAW264.7 cells,the mRNA expression levels of Irf3,5,7 and 9 were increased along with the infectious time.Irf7 and Irf9 displayed the major effects and Irf5 were barely expressed.The extent of Irf3 mRNA expression was similar with NF-?B mRNA level.Since the lung tissues of mice were detected on day 3 and day 7 post-infection,the mRNA levels of all IRFs were decreased,and IRF7 was still the main regulatory factor.Like RAW264.7,the expression trend of IRF3 mRNA was consistent with that of NF-? B,but the difference was that the expression level of IRF5 mRNA was higher than that of RAW264.7 cells.4.Cloning,expression and activity study of human IFNA21.According to the results of bioinformatics analysis of IFN-? subtypes,we cloned and expressed the recombinant human IFNA21 protein,and found that the recombinant IFNA 21 had antiviral effect.In conclusion,the study focused on the relationship between the influenza virus infection and the differential expression and regulation of IFN-? subtypes and explored the mechanism of the antiviral response induced by influenza viruses in the body from another aspect.The study provides the valuable experimental data for the prevention and treatment of immune damage caused by influenza virus infection.