Fig. 4

Changes in SAMHD1 protein and RNA levels in A549 cells infected with H1N1. A549 cells were infected with H1N1 at MOIs of 0.5 (A) and 1.5 (B), respectively. The cells were harvested at the indicated time points. IB analysis of H1N1 NP, SAMHD1 and phosphorylated SAMHD1(SAMHD1-P) in cells was performed, with GAPDH as a loading control. The expression levels of SAMHD1 protein were quantified as described before (A, B). A549 cells were infected with H1N1 at an MOI of 0.2, 1.0, or 1.5 (D). The cells were harvested at 48 h post infection. IB analysis of H1N1 NP and SAMHD1 in cells was performed, with GAPDH as a loading control. The expression levels of SAMHD1 protein were quantified as described before (D). SAMHD1 RNA levels in cell lysates were detected by RT‒qPCR and normalized to GAPDH, and the RNA level in A549 cells at 0 h post infection was set as 1 (C, E). Data are the mean ± SD of three independent experiments. The results are representative of those from three independent repeats (mean ± SD, *p < 0.05, **p < 0.01, paired t test)