Molecular characterization of TLR3 and TRIL in silvery pomfret (Pampus argenteus) and their expression profiles in response to bacterial components.

Toll-like receptors (TLRs) play important roles in the innate system by recognizing pathogen-associated molecular patterns derived from various microbes. In this study, we reported the cloning and identification of paTLR3 and paTLR4 interactor with leucine rich repeats (TRIL) cDNA from silvery pomfret (Pampus argenteus). The full-length paTLR3 and paTRIL cDNA were 2996 and 3163 bp long, respectively. Both of the two proteins contained many LRR domains, one LRR-C terminal domain and one transmembrane region, which fits with the characteristic TLR and its analogue domain architecture. Phylogenetic analyses revealed that paTLR3 and paTRIL shared the closest relationship with Lateolabrax japonicas and Notothenia coriiceps, respectively. The expression levels of paTLR3 and paTRIL varied greatly among the examined tissues with the highest expression both in liver. Following exposure to V. anguillarum flagellin, A. hydrophila lipopolysaccharide (LPS) and L. plantarum lipoteichoic acid (LTA), paTLR3 and paTRIL were all up-regulated. V. anguillarum flagellin induced the highest expression levels of paTLR3 and paTRIL. A. hydrophila flagellin and A. hydrophila LPS induced the highest expression levels of IL-1β and IL-8, respectively. The present results will provide the valuable information for understanding the structure, function and the immune defense process of paTLR3 and paTRIL in silvery pomfret.