Fig. 1: Commensal microbiota from Nlrp3^−/− mice enhances host defense against influenza A virus infection in WT animals.

a Nlrp3^−/− and WT mice either singly housed or co-housed were intranasally infected with PR8. The body weights and survival rates were assessed. Single-WT (n = 12), Single-Nlrp3^−/− (n = 12), Co-WT (n = 18), Co-Nlrp3^−/− (n = 18). b All groups of mice as in (a) were given antibiotics, then infected and assessed as in (a). Single-WT (n = 12), Single-Nlrp3^−/− (n = 9), Co-WT (n = 11), Co-Nlrp3^−/− (n = 11). c–g Fecal microbiota composition was assayed for mice in (a) by bacterial 16S rRNA gene V3–V4 region sequencing before PR8 infection: (c) Principal coordinate analysis (PCoA) plot (based on Bray–Curtis distance) of the gut microbiota; (d, e, g) Heatmaps for ASVs that were significantly altered between these groups, as identified using the algorithm LDA Effect Size (LEfSe) v1.0 (n = 5 per group). The cluster tree on the left of each heatmap shows associations among these ASVs, as determined by the Spearman correlation coefficient based on their relative abundances among all the samples. The heat maps show the relative abundance (log₁₀ transformed) of each ASV in a sample from an individual mouse; (f) Venn diagram of differential ASVs in relative abundance. h A phylogenetic tree constructed with the 16S rRNA genes of B. pseudolongum NjM1 (red), other bacteria within the family Bifidobacteriaceae (blue) and typical bacterial strains within the phylum Actinobacteria. Results represent three (a) or two independent experiments (b). Changes in body weights shown in (a, b) are presented as mean ± SEM, one-way ANOVA with Tukey’s post-hoc test. Survival rates shown in (a, b) are analyzed with Log-rank (Mantel–Cox) 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.