IFN-λ1 mRNA expression levels in SL3- and SL2-stimulated Huh7-S10-3 cells under RIG-I knockdown conditions. Huh7-S10-3 cells were transfected with control siRNA (siCnt) or RIG-I siRNA (siRIG). At 24 h posttransfection, the cells were transfected with SL3 (a and c) or SL2 (b and d). The mRNA expression levels of IFN-λ1 and RIG-I were estimated using gene-specific RT-qPCR. The fold change was calculated compared to unstimulated cells (mock), using the 2−ΔΔCT method. RPS18 was used as a housekeeping control. (e) RIG-I protein levels in siCnt- and siRIG-transfected cells at 24 h posttransfection. **, P < 0.01 versus SL3/SL2-stimulated cells; a, P < 0.05; aa, P < 0.01 versus siCnt+SL3/SL2-stimulated cells; NS, not significant. Data represent means ± standard deviations (SDs) of results from two independent experiments.