European Journal of Molecular & Clinical Medicine

Toll-like receptors (TLRs), which detect infections in vertebrates, are the most thoroughly understood innate immune receptors. However, bony fish’s TLRs shows distinct features and substantial diversity, which are likely originated from the variation in evolutionary history of fish and the distinct environments that they life in. there are a limited data about the structure of the fish immune system. Our work aimed to identify and clone and sequence the Nile tilapia TLR5 for the first time as a model for freshwater fish species. The full-length sequence of Nile tilapia (Oreochromis niloticus) TLR-5 receptor has been identified, where it consisted of 2661 nucleotides. The consensus cDNA sequence showed 81% identity with the sequence from Takifugu rubripes, 77% identity with the sequence form Japanese flounder, and 75% identity with the sequence from Japanese medaka, which confirmed that the new sequence is considered probably homologous to fish TLR-5. The predicted protein structure encoded by the Nile tilapia TLR-5 mRNA composed of 887 amino acids, beginning with signal peptide as ATG, like other functional fish TLR-5 sequences. Analysis of the deduced amino acid sequence indicated that Nile tilapia TLR-5 has typical structural features and contains the main components of proteins in the TLR family. Our results reveal a complete and functional Nile tilapia TLR-5 that is orthologous to other vertebrate receptors