Fig. 3: B. pseudolongum NjM1 and acetate protect WT but not Nlrp3^−/− mice against IAV infection.

a–d WT and Nlrp3^−/− mice were given: (a) either 1.48 × 10⁹ B. pseudolongum NjM1 or mGAM medium control for each mouse by gavage 3 times (WT, n = 11 or 13; Nlrp3^−/−, n = 10 or 10), (b) either 50 µL B. pseudolongum NjM1 conditioned supernatant or mGAM medium for each mouse by intranasal route twice (WT, n = 10 or 10; Nlrp3^−/−, n = 12 or 10), (c) drinking water with or without 50 mM sodium acetate (WT, n = 14 or 14; Nlrp3^−/−, n = 10 or 10), (d) either diet HAMS or HAMSA for 5 weeks (WT, n = 8 or 8; Nlrp3^−/−, n = 8 or 8), and then intranasally infected with influenza A virus PR8 (H1N1). Body weight changes in percentage and survival rates of such mice post-infection were assessed. e The lungs from infected WT and Nlrp3^−/− mice treated as in (c) were harvested on day 7 post-infection, sectioned, and stained with hematoxylin and eosin. Representative images and peribronchial inflammation scores are shown. f Viral loads and relative Ifna1 expression in the lung homogenates from infected WT and Nlrp3^−/− mice were determined with the standard plaque assay and qPCR, respectively, on day 7 post-infection. Results represent two (a, b, d–f) or three independent experiments (c). Changes in body weights shown in (a–d) are presented as mean ± SEM, two-tailed Student’s t test. Survival rates shown in (a–d) are analyzed with Log-rank (Mantel–Cox) test. Data in (e–f) are presented as mean ± SEM, one-way ANOVA with Dunnett’s post-hoc test. Significant values are defined by *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Source data are provided as a Source Data file.