Effect of NMB treatment on the expression of viral NP and cytokines in A549 cells. The A549 cells were mock-treated or treated with NMB after infection with PR8 (MOI = 1). NMB-treated cells were harvested at 16 hpi. A The mRNA levels of NP, IFN-α, and IL-6 were measured by RT-PCR. qRT-PCR measurement of NP (B), IFN-α (C) and IL-6 (D) mRNA expression. GAPDH was used as the reference housekeeping gene for internal standardization. **P < 0.01, *P < 0.05.