Fig. 1: Efb inhibits host pro-inflammatory responses.

a Quantitative polymerase chain reaction (qPCR) analysis of Tnf, Il1b, Il6, and Il12p40 mRNA from alveolar macrophage (MH-S) infected with Newman, ΔEfb, or ΔEfb + Flag − Efb for indicated times (MOI = 25; **P = 0.0014, 0.0052, ****P < 0.0001, ***P = 0.0003 in sequence, Tnf; ****P < 0.0001, Il1b; ****P < 0.0001, <0.0001, <0.0001, ***P = 0.0001, ****P < 0.0001, ***P = 0.0002, in sequence, Il6; **P = 0.0019, *P = 0.0126, 0.0391, 0.0118, **P = 0.0020, 0.0020, in sequence, Il12p40). b ELISA quantification of TNF-α, IL-1β, IL-6, and IL-12 levels in lung tissue homogenized in 1 ml PBS 24 h after infection with Newman, ΔEfb, or ΔEfb + Flag − Efb. C57BL/6 mice were infected by intratracheal administration with the test strains (2 × 10⁸ CFUs per mouse) for the indicated times (**P = 0.0095, ****P < 0.0001, in sequence, TNF-α; *P = 0.0109, ****P < 0.0001, in sequence, IL-1β; *P = 0.0187, ***P = 0.0008, in sequence, IL-6; *P = 0.0206, ***P = 0.0002, in sequence, IL-12). c Quantification of the bacterial CFUs of lung tissue homogenates obtained in b (***P = 0.0001, ****P < 0.0001). d, e Histopathology of lung tissues was assessed in H&E sections stained from mice infected for 24 h; scale bars, 1,000 μm (top) and 200 μm (bottom), the boxed areas at the top are enlarged below (**P = 0.0036, *P = 0.0110). Student’s two-tailed unpaired t-test (a, b, d) or two-tailed Mann–Whitney U test (c) was used for statistical analysis. Data are representative of three experiments with at least three independent biological replicates. The bars show the mean and standard deviation of n = 3 (a), n = 9 (b, c), and n = 5 (d) per group. Source data are provided as a Source Data file.