FIG 9.

The type 3 secretion system (T3SS) and/or Yops is required to elicit inflammation in neonates. Neonatal C57BL/6 mice were uninfected (○), infected with 5 × 10⁸ CFU wild-type Y. enterocolitica (●), or infected with 5 × 10⁸ CFU plasmid-cured Y. enterocolitica (◆). (A) Neutrophil recruitment to the MLN was evaluated by flow cytometry 24 h postinfection. (B) Il6, Il17a, and Ifng RNA expression was determined in MLN of individual mice 18 h postinfection by real-time RT-PCR. (C) Y. enterocolitica titers were determined in the MLN 18 h postinfection. Dotted line represents the limit of detection of Y. enterocolitica CFU. ns, not significant; *, P ≤ 0.05.