Fig. 1.

Neonatal Abx exposure alters the commensal microbiota and enhances food allergen sensitization. Abx treatment was initiated before weaning as described in Methods. (A and B) 3-wk-old mice were sensitized by intragastric administration of PN plus CT (PN/CT, open symbols) or CT only (closed symbols) and challenged on day 35; feces and serum were collected on day 36. Serum concentration of (A) PN-specific IgE and (B) PN-specific IgG1 was measured by ELISA (n = 4–9 mice per group from three independent experiments; each circle represents an individual mouse; bars depict mean and SEM). (C) Bacterial load in the feces or ileal contents of mice treated with Abx compared with no treatment (NT) controls. (n = 4–5 mice per group). (D) Bacterial diversity, as shown by operational taxonomic unit (97% identity) rarefaction curves in Abx-treated mice compared with NT controls: black lines, NT feces; gray lines, Abx feces; red lines, NT ileal contents; blue lines, Abx ileal contents. (E) Taxonomic classifications for the mice in C represented as proportion of total reads (Methods). *P < 0.05, **P < 0.01, ***P < 0.001 determined by Student t test (B) or one-way ANOVA with Tukey posttest (C).