FIG 11.

Gross pathology and histopathology of lungs from ferrets infected with three representative P9-derived viruses (L2, N9, and L18). Lungs were isolated from ferrets directly infected with L2, N9, L18, and rH1N1 viruses at 8 dpi or from ferrets proximally exposed for 9 days (10 dpi) to infected ones. (A to C and E) Lungs from pigs directly infected L2, N9, and L18 viruses, along with lungs of L2 virus-exposed pigs, showed extensive edema, consolidation (white arrows), severe interstitial pneumonia with infiltration of erythrocytes, and inflammatory cells in the alveolar space. (D) The directly infected rH1N1 lung showed mild edema, emphysema, and mild bronchopneumonia. (F to H) Lungs of ferrets proximally exposed to ferrets directly infected with N9, L18, and rH1N1 viruses showed no obvious gross lesions or pathological damage. Images shown are representative of three ferrets from three independent experiments. Scale bar, 200 μm.