Figure 5. Lung histopathology of mice infected with wild-type (WT) or H274Y mutant isolates of pH1N1.

Groups of mice were euthanized on days 3, 6 and 12 post-infection and one pulmonary lobe was removed and fixed with 10% formalin. Thin sections of paraffin-embedded lung tissues were cut and stained with hematoxylin and eosin. The degree of lung inflammation (mean histopathological score) was evaluated for bronchial, peribronchial, perivascular, interstitial, pleural and intra-alveolar inflammation. ^* P<0.05 between the WT and H274Y lung histopathological scores.