Figure 5.

Lungs of E1-vaccinated mice exhibit more severe histopathological changes upon influenza virus infection. Representative histologic sections of the lung tissues from the mice harvested on day 3 and 5 post-inoculation were stained with H&E. The level of inflammatory infiltrate and thickening of the alveolar septum (as alveolar damage) was detected in samples from mice vaccinated with PBS (A,B), E1 (C,D), E2 (E,F), and HA (G,H). Lung tissues from the uninfected normal mice were included for comparisons (I,J). The black arrows indicate inflammatory cell infiltration. Scale bars represent 20 μm. (K,L) Pathological changes were scored as the criteria indicated in Section “Materials and Methods” (*P < 0.05; **P < 0.01).