Histopathology of pulmonary infection with CO92 or CO92Δ yopH.
CD1 mice were infected IN with 2 × 104 CFU of CO92 or CO92ΔyopH for 24 or 48 hours. Representative 20× images of lungs are presented. A) Mouse mock infected for 24 hours with saline. B) Mouse infected with CO92 for 24 hours. C) Mouse infected with CO92ΔyopH for 24 hours with black arrow pointing out vacuolated bronchial epithelium. D) Mouse infected with CO92 for 48 hours. Black arrows denote robust neutrophilic inflammation, bacteria, and dead cells. E) 100× image of free bacteria in the airways of mice infected with CO92 for 48 hours (black arrow). F-H) Mouse infected with CO92ΔyopH for 48 hrs. F) Vacuolization in conjunction with exudates denoted by the double black arrows and an area of sub-mucosal necrosis denoted by the single black arrow. G) Large infiltration of PMNs adjacent to bronchiole. Note that there are no bacteria evident at this time point. H) 100× image of infiltration of the bronchial epithelium with PMNs. Data is representative images of 8-10 mice per time point.