FIGURE 1.

Co-infection of H9N2 AIV and E. coli increases mortality and aggravates acute lung injury. Seven-week-old female SPF BALB/c mice were mock infected, or intranasally infected with single H9N2 AIV (1 × 10⁴ PFU) and E. coli (1.5 × 10⁷ CFU), or co-infected with H9N2 and E. coli for indicated times (n = 10 mice/group). (A) The body weight changes of mice in four groups. The results are shown as mean percentage weight changes from three independent experiments. (B) The survival rate of mice in four groups (n = 10). Mice were monitored for up to 10 days. During this period, mice were sacrificed when they displayed severe unrelieved distress or excessive weight loss (25% weight loss from initial body weight). (C) Representative images (magnification, ×200) of mouse lungs in four groups after 48 h of infection followed by hematoxylin and eosin (HE) staining.