FIGURE 3.

miR-194 negatively regulates IAV-induced type I interferons in A549 cells. Cells were transfected with miR-194 mimic or mimic negative control and miR-194 inhibitor or inhibitor negative control as indicated. For FGF2 reintroduction, PCDNA3. 1 (+)-FGF2 or vector were cotransfected with miR-194 mimic. After 24 h, cells were infected by BJ501 at a multiplicity of infection (MOI) = 1 for the indicated time. The results are presented as the means ± SDs of values obtained in three independent experiments. Statistical significance is indicated as follows: ^∗P <0.05, ^∗∗P <0.01, and ^∗∗∗P <0.001. (A,F,K) The IAV titers in infected A549 cells as measured by qPCR. (B,G,L) The virus titers in infected A549, determined using the 50% tissue infectious dose (TCID₅₀) assay. (C,H,M) Interferon B1 (IFNB1) transcriptional activity assay measured by dual luciferase reporter assay in HEK-293T cells. (D,I,N) IFN-α and IFN-β mRNA expression after 24 h post-infection determined by qPCR. (E,J,O) Levels of IFN-α and IFN-β cytokines in the cell culture supernatant, determined by enzyme-linked immunosorbent assay (ELISA).