TNFSF15 and infection: Compared to uninfected birds, NE infection significantly (P < 0.05) decreased mucin-2 (at 14 DPI), TLR2 (at 7 and 14 DPI), TLR4 (at 7 and 14 DPI), TNFSF15 (at 7 and 14 DPI), LYZ (at 14 DPI), and fowlicidin-2 (at 7 and 14 DPI) gene mRNA levels, whereas a significant (P = 0.001) increase in IFN-γ mRNA levels (at 7 DPI) was observed.