FIGURE 5.

JAK/STAT/SOCS pathway and MAPK pathway are involved in aberrant expression of cytokines after viral-bacterial co-infection. Four groups of 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 48 h. Then the mice were euthanized, and the lungs were ground for the preparation of protein and RNA samples. (A) Protein samples were analyzed by western blotting with the indicated antibodies. Shown are representative data of three independent experiments with similar results. (B,C) Levels of p-STAT1 (B) and p-STAT3 (C) in (A) were quantitated by densitometry, and normalized to their total protein and β-actin levels. Plotted are the average levels from three independent experiments. The error bars represent the SE. (D,E) Quantitative real-time PCR was used for detecting the expression of SOCS1 (D) and SOCS3 (E) in mice lungs. (F) Western blotting was used to determine the phosphorylation level of ERK1/2, JNK, and p38 in mice lungs. The results are representative of three independent experiments. (G–I) Levels of p-ERK1/2 (G), p-JNK (H) and p-p38 (I) in (F) were quantitated by densitometry, and normalized to their total protein and β-actin levels. Plotted are the average levels from three independent experiments. The error bars represent the SE. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.