To establish whether HUVECs support H9N2 virus infection,the titers of viruses in the supernatant of HUVECs were measured by PFUs. First,the replication of H9N2 viruses with different MOI was
observed in HUVECs grown in 6-well plates. When HUVECs were treated with H9N2 viruses at different MOI for 24h, viral infection caused adose-dependent increment in titer levels, as shown in With a MOI of 5 or 10, virus titers reached of 5.67104 PFU/mL and 1.57105 PFU/mL, respectively.