Molecular characterization and expression analyses of toll like receptor-5 induced by Vibrio parahaemolyticus antigens in Pacific red snapper

• Published in: Fish & shellfish immunology 2017-09, Vol.68, p.180-189
• Main Authors: Reyes-Becerril, Martha, Alamillo, Erika, Rosales-Mendoza, Sergio, Ascencio, Felipe, Esteban, M. Angeles, Angulo, Carlos
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antigens, Bacterial - immunology; Base Sequence; Fish Diseases - immunology; Fish Proteins - chemistry; Fish Proteins - genetics; Fish Proteins - immunology; Gene Expression Profiling; Gene Expression Regulation - immunology; Immunity, Innate - genetics; Inmunostimulants; Interleukins; Live Vibrio parahaemolyticus; Lysate; Organ Specificity; Pacific red snapper; Perciformes - classification; Perciformes - genetics; Perciformes - immunology; Phylogeny; Random Allocation; Sequence Alignment - veterinary; TLR5M; Toll-Like Receptor 5 - chemistry; Toll-Like Receptor 5 - genetics; Toll-Like Receptor 5 - immunology; ToxA; Vaccines; Vibrio Infections - immunology; Vibrio parahaemolyticus - physiology
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2017.07.022

Toll-like receptor 5 (TLR5) is a member of TLRs family responsible for the bacterial flagellin recognition in vertebrates. Herein, the TLR5M gene structure of Pacific red snapper (Lutjanus peru) was characterized. The full-length cDNA of LpTLR5M comprises an open reading frame (ORF) of 2715 bp, encoding a polypeptide of 904 amino acids including 9 LRRs (residues 119–562) and one LRR-CT domain (residues 593–646) at the extracellular region, and a TIR domain (residues 710–904) in the cytoplasmic region. The amino acid sequence in L. peru TLR5 showed high identity (66–69%) with TLR5 from Paralichthys olivaceus and Scophthalmus maximus. Quantitative real-time PCR (qPCR) analysis demonstrated the constitutive expression of LpTLR5M mRNA in all the examined tissues, with higher levels in intestine, liver, and head-kidney. Furthermore, expression of LpTLR5M and five cytokine genes was also investigated 24 h and one week post-stimulation in fish intraperitoneally injected with ToxA, live V. parahaemolyticus (Vp) or V. parahaemolyticus Lysate antigens. TLR5M was significantly induced in fish infected with Vp. The pro-inflammatory cytokines IL-6, IL8 and IL-12 were significantly up-regulated in head-kidney in fish stimulated with Vp, while in intestine upregulation was observed following ToxA or Lysate injection. In contrast, IL-17 mRNA was significantly up-regulated in the intestine from fish infected with live Vp at 24 h post-injection. The results indicate that Lysate and Vp antigens can induce an immune response via TLR5M and that cytokines have an important role in the defense mechanisms against V. parahaemolyticus. •TLR5 gene functional architecture from Lutjanus peru was characterized in silico.•TLR5 gene is highly expressed in intestine, liver and head-kidney.•TLR5 and interleukine expressions were induced in head-kidney and intestine following bacterial infection.•Recombinant ToxA injection upregulated IL-17 in head-kidney and IL-8 in intestine.•Lysate administration upregulated IL-10 in head-kidney and IL-12 in intestine.