Figure 4.

Lung histopathology. Groups of female Balb/c mice (n = 6) were immunized subcutaneously with 20 μg FilF formulated with CFA/IFA adjuvant on day 1, 14, and 21, and intra-tracheally challenged with 10⁸ CFU of A. baumannii ATCC 19606 at day 29. The mice were sacrificed at 12 and 24 h post-challenge and lungs were collected for histopathology. (A) The lung from an unimmunized uninfected mouse showing normal histological characters. (B) Unimmunized infected mouse lung showing increased inflammatory cell infiltration in the perivascular and peribronchial areas, and within the airway lumen (arrows) 12 h postinfection. (C) The lung from an immunized infected mouse showing mild inflammatory cell infiltration in the perivascular and peribronchial areas (arrows) 12 h postinfection. (D) The lung from an immunized infected mouse showing significantly reduced infiltration of inflammatory cells 24 h postinfection. H&E, Magnification 100X.