Lung samples from euthanized animals 6 days post challenge were fixed in 10% formalin solution and stained with H & E. (A) Representative transverse section of the H & E stained lung images at 40× magnification showing pneumonitis (red arrow), alveolar epithelial injury (blue arrow) and inflammation (black arrow). The stained sections were assessed by blinded-trained histologist on the scale of 0–5 (where 0 represents no feature, while 5 represents the maximum score). (B) The histological scores for each pulmonary pathology was plotted as mean ± SEM. The disease index score was calculated by taking the average score of all pulmonary pathologies. Ther, therapeutic; NS, not statistically significant.