Figure 7. CCR2 contributes to host defense from primary pneumonic plague following intranasal challenge with Y. pestis CO92 yopK.

A) WT C57BL/6 and Ccr2^−/− mice were challenged by intranasal infection with 5×10⁶ CFU of Y. pestis CO92 yopK and monitored for development of disease for 14 days. Data shown are representative; n = 10 mice per group, data were collected in two independent experiments. *p<0.05, evaluated by Log rank test. B) Bacterial titers collected from lungs of C57BL/6 (white circles) and C57BL/6 Ccr2^−/− mice (grey circles) infected intranasally with 5×10⁶ CFU CO92 yopK at 72 hpi, data shown from two independent experiments, n = 9–12 mice per group. (C–D) H&E stains of formalin fixed lungs from mice challenged by intranasal infection with 5×10⁶ CFU of Y. pestis CO92 yopK at 72HPI: (C) C57BL/6, (D) C57BL/6 Ccr2^−/−. Images are representative; boxes show 4× magnified section of indicated area. Data were collected in two independent experiments (n = 9–12 mice per group).