DDX3X is a central regulator of the NLRP3 inflammasome, stress granules, and type I IFN responses during IAV infection.A, confocal microscopy imaging of Ddx3xfl/fl and Ddx3xfl/flLysMCre bone marrow–derived macrophages (BMDMs) infected with influenza A virus (IAV; MOI 5) or IAV–ΔNS1 (MOI 5), stained for G3BP1 and DDX3X to visualize stress granules and DAPI to visualize nuclei. The scale bars represent 10 μm (whole image) and 5 μm (magnified image). Representative images (n = 2). B, quantification of the number of cells with stress granules from confocal microscopy images. Each circle represents the percentage of cells in a field of view with stress granules. ∗∗∗p = 0.0004 (unpaired two-sided t test). Data are the mean ± SEM. (n = 2 independent experiments). C, immunoblot analysis of caspase-1 (CASP1) cleavage (pro-CASP1 (p45) and cleaved CASP1 (p20)) in Ddx3xfl/fl and Ddx3xfl/flLysMCre BMDMs infected with IAV–PR8 (MOI 20) and ELISA measurement of IL-1β and IL-18 in Ddx3xfl/fl and Ddx3xfl/flLysMCre BMDMs infected with IAV–PR8 (MOI 20). ∗∗p = 0.0054, ∗p = 0.0436 (unpaired two-sided t test; n ≥ 2). Data are the mean ± SEM. D, ELISA measurement of IFN-β in Ddx3xfl/fl and Ddx3xfl/flLysMCre BMDMs infected with IAV and IAV–ΔNS1 (MOI 5). ∗p = 0.0263, ∗∗p = 0.0054 (unpaired two-sided t test; n > 3). Data are the mean ± SEM. ΔNS1, NS1 deletion mutant; DDX3X, DEAD-box helicase 3 X-linked; G3BP1, GTPase-activating protein-binding protein 1.