FIG. 1.

Wild-type avian influenza A virus strains induce different amounts of IFN-β in A549 cells. An A549 IFN-βLuc reporter cell line was infected with high- (A) or low- (B) pathogenicity avian influenza viruses at an MOI of 5 PFU/cell. Human- or mammalian-adapted viruses were included for comparison. Luciferase activity was measured 8 h postinfection. (C) A549 cells were infected with viruses at an MOI of 5 PFU/cell. At 24 h postinfection, the amount of IFN-β released into the culture supernatant was measured by ELISA.