TGFB1 and infection: In the kidneys, the mRNA levels of IL-1β at 7 and 14 dpi and IL-6 at 7 dpi were lower in the infection group than those in the negative control group (P < 0.05), whereas the TGF-β and iNOS mRNA levels at 7 and 14 dpi and the IL-8 mRNA level at 14 dpi were higher in the infection group than those in the negative control group (P < 0.05).