A toll‐like receptor 3 homologue that is up‐regulated by poly I:C and <scp>DNA</scp> virus in turbot Scophthalmus maximus

• Published in: Journal of Fish Biology
• Main Authors: Hu, G.‐B., Li, X.‐P., Liu, D.‐H., Liu, Q.‐M., Zhang, S.‐C.
• Other Authors: National Basic Research Programme of China, National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities, Programme for New Century Excellent Talents in University of Ministry of Education of China, Shandong Provincial Natural Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Scophthalmus maximus; Turbot
• Online Access: http://dx.doi.org/10.1111/jfb.12559; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjfb.12559; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfb.12559

In this study, the gene and promoter sequences of turbot Scophthalmus maximus (Sm) toll‐like receptor 3 (Tlr3) were cloned and its mRNA tissue distribution and gene expression in response to polyinosinic:polycytidylic acid (poly I:C) and turbot reddish body iridovirus ( TRBIV ) challenges were studied in vivo. The smtlr3 gene spans over 4·4 kb with a structure of five exons–four introns and encodes a peptide of 916 amino acids. The putative protein shares the highest sequence identity of 52·8–78·5% with fish Tlr3 and contains a signal peptide sequence, 13 leucine‐rich repeat ( LRR ) motifs, a transmembrane region and a toll/interleukin‐1 receptor ( TIR ) domain. Phylogenetic analysis grouped it with other teleost Tlr3s. A number of transcription factor binding sites were identified in the 1538 bp 5′ flanking region of smtlr3 , including interferon‐stimulated response element ( ISRE ) and those for interferon regulatory factors ( IRF ) and signal transducer and activator of transcriptions ( STATs ) smtlr3 transcripts were expressed ubiquitously with higher levels in the head kidney, heart and digestion organs. They were up‐regulated by both poly I:C and TRBIV in immune and non‐immune organs, but most strongly in the head kidney. Finally, the smtlr3 exhibited a two‐wave induced expression during a five day time course when exposure of S. maximus to poly I:C. These findings provide insights into the role of SmTlr3 in antiviral response.