As IL-6 and IL-13 were the main cytokines upregulated in mouse lungs during the early infection phase, we aimed to detect the protein levels of these two cytokines in the lungs of mice that died at 1 dpi and found that the protein level of IL-6 was significantly elevated but that of IL-13 showed only a slight increase (Fig 4D). This evidence concerns the gene IL13 and infection.