Figure 5.

Bacillus Calmette–Guérin (BCG) vaccination does not lead to reduction of histopathological damage and inflammation. Female BALB/c mice were challenged with a dose of 4MLD₅₀ influenza A/Anhui/1/2013 (H7N9) on day 0. Mice received 750 µg BCG or vehicle control (phosphate buffered saline) i.v. on day –7 (n = 8 per group). Three days after viral challenge, lungs were fixed in formalin. Paraffin-embedded tissue sections were then stained for hematoxylin and eosin. Representative histopathological image of vehicle versus BCG-treated mice are depicted (A,B). Lung sections were scored from absent to marked: score “0” (absent), score “1” (minimal), score “2” (moderate), and score “3” (marked) for epithelial necrosis (damage) (C), inflammation markers (D), and inflammatory cell types (E). Results were statistically analyzed using the Cochran–Mantel–Haenszel test. Data are shown as mean ± SEM.