Fig. 6

Overexpression of galectin-3 enhances the RdRp activity of IAV. a–d A549 cells that had been transfected with the Flag-tagged galectin-3 expression vector or the control vector were infected with IAV at an MOI of 1 for 5 h. Detection of Flag-tagged galectin-3 proteins by immunoblotting with the anti-Flag antibody in A549 cells (a). Expression of β-actin served as the loading control. Quantification of vRNA (b), mRNA (c), and cRNA (d) of the viral NP by RT-qPCR and normalization to GAPDH mRNA levels (n = 3). Ratios of vector control cells (b–d) were arbitrarily set to 1. e, f Galectin-3-overexpressing and vector control 293T cells were cotransfected with pPolI-Luc and four expression vectors individually encoding IAV proteins (PA, PB1, PB2, and NP) for assessing viral polymerase activity by the minireplicon assay. Luciferase activities were determined at 48 h post-transfection and expressed as light units/µg protein (n = 3). Detection of Flag-tagged galectin-3 proteins by immunoblotting with the anti-Flag antibody (e) and viral polymerase activity (f) in 293T cells