TLR4 and infection: mRNA expression of both TLRs in the S. Gallinarum group was downregulated at 6 h post-infection, but this showed a peak at 24 h post-infection with fold-change being greater for TLR4 (6.82-fold) than for TLR21 (2.5-fold) (Fig. 6a and Supplementary Table S3).