In mammals, the interaction of flagellin with TLR5 induces a signaling cascade that utilizes MyD88 adaptor, IRAK family members, and downstream signaling mediators such as MAP kinases and NF-kB that regulate pro-inflammatory genes [Smith KD et al 2003].
The chicken tlr5 gene was cloned from the chicken NCSU macrophage cell line; It encodes a protein of 861 amino acids. The cloned chTLR5 showed 69% and 68% overall amino acid similarity to human and murine TLR5, respectively (Keestra AM et al, 2008). Chicken TLR5 mRNA is expressed in a broad range of tissues, immune cell subsets and chicken cell lines. The strongest signal was detected in colon, spleen, kidney, lung, heart, and testes (Iqbal M et al, 2005).
Comparisons of gene structure, genomic location, amino acid composition, and patterns of leucine-rich regions (LRR) consistent with the suggestion that chTLR5 is an orthologue of mammalian TLR5. Like its mammalian counterpart chTLR5 was reported to respond to bacterial flagellin (Iqbal M et al., 2005 and Keestra AM et al.,2008).