Nucleotide sequence variability in tlr-5 gene in chicken and other species

The Toll-like receptor (TLR) family of cell surface molecules represent a major component of the pattern recognition system, which enables both vertebrates and invertebrates to detect invading microorganisms and mount an anti-microbial response. Chicken Toll Like Receptor 5 (chTLR5) recognizes flagellin and induces the expression of a wide range of immunoregulatory and effector molecules. In this study a 248 bp fragment of chTLR5 was amplified, cloned, sequenced (Accession no. GU370775) and characterized in chickens. The deduced protein showed 98% identity with Gallus gallus; 74% with Taeniopygia guttata, 47% with Bos Taurus and Bos indicus; 46% with Bubalis bubalus and Ornithorhynchus anatinus; 45% with Ovis aries, Capra hircus and Homo sapiens. On phylogenetic analysis, Gallus gallus sequence clustered away from the mammalian sequences but was closest to the egg laying mammal (Ornithorhynchus anaticus), and farthest from the primate group (Homo sapiens, Macaca mulatta, Gorilla gorilla, Pan troglodytes, Pongo pygmaeus, Theropithecus gelada, Cercopithecus mona and Cercocebus agilis). Analysis of the number of synonymous substitutions per synonymous site and nonsynonymous substitutions per nonsynonymous site indicate that the nucleotide sequences coding for the chTLR5 were significantly under purifying selection and not under positive selection.