ISG15 and influenza: To further investigate whether RUNX1 negatively regulate IFN-β signaling upon IAV infection in A549 cells is not strain specific, we infected the A549 cells with influenza A/Zhejiang/163/2020 (H3N2) (ZJ163), A/swine/Jiangsu/C1/2008 (H9N2) (JSC1) and A/California/04/2009(H1N1) (CA04) at MOI of 1, and then examined the IFNB1, MxA, and ISG15 expression at 9 h.p.i.