FIG. 1.
Neonatal mice show prolonged resistance to orogastric Y. enterocolitica infection and prolonged antigen persistence compared to adult mice. Seven-day-old neonatal (NEO) and adult (AD) BALB/c mice were infected orogastrically with 5 × 107 CFU (A), 5 × 106 CFU (B), or 2 × 105 CFU (C) of Y. enterocolitica. Survival curves were generated by Kaplan-Meier Survival analysis. The survival curves depict pooled data from three experiments (10 neonates and 14 adults) (A), two experiments (9 neonates and 10 adults) (B), or 6 experiments with 78 neonates and 51 adults (C). The survival kinetics were compared using the Mantel-Haenszel log rank test. n.s., not significant; *, P ≤ 0.046. (D) Fecal pellets from individual mice infected orogastrically with 2 × 105 CFU of Y. enterocolitica (Ye) were collected at 19 days p.i. and enriched for the presence of Y. enterocolitica bacteria. Each symbol represents the percentage of mice with stools positive for Y. enterocolitica from five separate experiments with 5 to 13 neonates per experiment (total of 48 mice) and 3 to 9 adults per experiment (total of 31 mice). Symbols on the dashed line are from experiments with samples with undetectable bacteria, and the line indicates the mean for the pooled data.