IFN-α/β levels in HUVECs
For validation of IFN expression change at protein level,we quantified the IFN-α/β in response to H9N2 virus and viral particles using human IFN-α and IFN-β ELISA Kits. HUVECs were inoculated with H9N2 virus or viral particles at a MOI of 5,and then supernatants were collected at 6,12,24 and 36 h postinfection for ELISA assays.The results showed that there were no significant differences in released IFN-α/β levels between experimental and control groups at each time point.