(A–C) Hectd3^–/– (KO) mice and littermate WT controls were intranasally infected with GFP-expressing BCG (7.5 × 10⁶ CFUs per mouse), and bacterial burden in the lung on day 2 was determined by BCG genomic DNA PCR (A) and CFU analysis (B). H&E staining of lung sections from WT and Hectd3^–/– mice on day 2 after infection (C). Arrowhead indicates infiltrated immune cells. (D–H) Hectd3^–/– mice and littermate WT controls were intraperitoneally infected with L. monocytogenes (6.0 × 10⁴ CFUs per mouse). Loss in body weight was determined (D), and bacterial burden in the spleen and liver was analyzed on day 2 after infection (E). (F) H&E staining of liver sections from WT and Hectd3^–/– mice on day 2 after infection with L. monocytogenes. Arrowhead indicates infiltrated immune cells. (G) Expression of genes encoding TNF-α, IL-6, and IFN-β was analyzed in liver tissues from WT and Hectd3^–/– mice on day 2 after infection with L. monocytogenes. (H) Liver tissue samples from WT and Hectd3^–/– mice on day 2 after infection with L. monocytogenes were homogenized, and lysates were analyzed for activation and expression of caspase-3, caspase-11, ZBP1, and HECTD3. GAPDH was used as loading control. (I–K) Hectd3^–/– mice and littermate WT controls were intraperitoneally infected with E. coli (1.0 × 10⁸ CFUs per mouse), and loss in body weight was determined (I), bacterial burden in the spleen and liver was analyzed on day 2 after infection (J), and production of TNF-α and IL-6 (K) was analyzed from WT and Hectd3^–/– mice on day 2 after infection with E. coli. Each symbol indicates an individual mouse (A, B, E, G, and J). Data represent 2 independent experiments and are presented as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001. Scale bars: 50 μm.