Histopathological findings in the lungs
Haematoxylin and eosin staining of lung tissues from mice at 3, 7, and
10 days post-infection is shown in Fig. 4 . Inflammatory cell
infiltration was prominently observed in A(H1N1)pdm09-infected mice,
whereas this was rarely observed in mice infected with seasonal H1N1 at
3 days post-infection (Fig. 4A ). The lung inflammation was
clearly observed in A(H1N1)pdm09- and seasonal H1N1-infected mice at 7
days post-infection, but was more severe in A(H1N1)pdm09-infected mice
(Fig. 4B ). In contrast, the magnitude of inflammation was
attenuated by 10 days post-infection (Fig. 4C ).