FIG. 2.

ELISA measurements of serum IgG and mucosal IgA responses in immunized mice. (A and B) Serum IgG responses against rPspA (A) and S. Typhimunium LPS (B) were measured using pooled sera from neonates and infants born to either naïve (N) or immunized (I) mothers. (C) Mucosal IgA responses against rPspA were measured in pooled vaginal washes. Mice were immunized orally with either χ9558(pYA4088) (pspA) or χ9558(pYA3493) (control) or were mock immunized with BSG on either day 7 (7d) or day 21 (21d) after birth. Only mice from naïve mothers were inoculated with χ9558(pYA3493). Mice were boosted 3 and 6 weeks after the primary immunization. Error bars represent differences between triplicate wells. Significant differences between groups are indicated (*, P < 0.05; **, P < 0.01). No immune responses to PspA were detected in mice immunized with χ9558(pYA3493). No antibody to PspA or LPS was detected in mice inoculated with buffer only or in preimmune sera from vaccinated mice (reciprocal titer, <1:50).