MYD88 and infection: In the current study, infection with S. Typhimurium upregulating ileal TLR4, MyD88, NF-κB, IFN-γ, TNF-α, pIgR, and the negative regulators (Tollip and PI3K) mRNA levels at the early stage of infection; which was in similar with observations of previous studies in chickens infected with S. Typhimurium [4, 5, 53, 66–71].