SMAD2 and infection: p-Smad2/3 quantitation in lung tissues (Figure 9(b)) and relative expression levels (Figure 9(c)) showed that compared with the PBS group, the expression level of p-Smad2/3 proteins in mice in each infection group increased to a certain extent, but only in the CO and PRE groups, and the expression level of p-Smad2/3 proteins in the lung was significantly higher than in the other groups, confirming the activation of the TGF-β/Smad pathway in mice with simultaneous SEZ and CIV.