Figure 6.

Nucleoprotein (NP) staining of bronchi and alveoli indicates that bacillus Calmette–Guérin (BCG) does not reduce influenza virus replication. 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 the 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 influenza NP. Representative images of influenza A NP-stained lungs of mice treated with vehicle versus BCG-treated mice are depicted (A,B). NP-staining was scored from absent to 3: score “0” (absent), score “1” (minimal), score “2” (moderate), and score “3” (marked) (C). Results were statistically analyzed using the Cochran–Mantel–Haenszel test. Data are shown as mean ± SEM.