An IRF-3 homolog that is up-regulated by DNA virus and poly I:C in turbot, Scophthalmus maximus

• Published in: Fish & shellfish immunology 2011-12, Vol.31 (6), p.1224-1231
• Main Authors: Hu, Guo-Bin, Xia, Jun, Lou, Hui-Min, Chen, Xiao-Ling, Li, Jing, Liu, Qiu-Ming
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Base Sequence; Cloning, Molecular; DNA Primers - genetics; Flatfishes - genetics; Gene Components; Gene expression; Gene Expression Regulation - immunology; Head Kidney - metabolism; IFN system; Interferon Regulatory Factor-3 - genetics; Interferon Regulatory Factor-3 - metabolism; IRF-3; Iridovirus; Iridovirus - immunology; Kidney - metabolism; Marine; Molecular Sequence Data; Phylogeny; Poly I-C - immunology; Protein Structure, Tertiary; Real-Time Polymerase Chain Reaction; RNA, Messenger - genetics; Scophthalmus maximus; Sequence Analysis, DNA; Sequence Homology; Species Specificity; Spleen - metabolism; TRBIV
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2011.07.011

In this study, we described the structure, mRNA tissue distribution and regulation of an IRF-3 gene from turbot, Scophthalmus maximus ( SmIRF-3). The gene sequence of SmIRF-3 is 6077 bp long, composed of 11 exons and 10 introns similar to known IRF-3 genes of fish, and encodes a peptide of 466 amino acids. The deduced protein sequence shares the highest identity of 56.0–81.2% with fish IRF-3 and possesses a DNA-binding domain (DBD), an IRF association domain (IAD) and a serine-rich domain (SRD) known to be important for the functions of IRF-3 in vertebrates. Phylogenetic analysis grouped SmIRF-3 with other IRF3s of vertebrates. SmIRF-3 transcripts were detectable in limited tissue types of healthy fish, with higher expression observed in head, kidney, spleen and kidney,. The SmIRF-3 was transcriptionally up-regulated by turbot reddish body iridovirus (TRBIV) and polyinosinic:polycytidylic acid (poly I:C) in the head kidney, spleen and gills, with showing a two wave induced expression during a 7-day time course in all cases. The highest inducibility and the likely earliest increase of SmIRF-3 expression were observed in the spleen, and poly I:C was a stronger inducer. In addition, the maximal expression level of SmIRF-3 arose prior to that of the Mx in all the cases. ► The gene sequence of an IRF-3 homolog in turtbot was cloned. ► Turbot IRF-3 transcripts were more abundant in immune-relative organs. ► Turbot IRF-3 was up-regulated by turbot reddish body iridovirus and poly I:C. ► The highest inducibility and the earliest increase were observed in the spleen. ► The maximal level of turbot IRF-3 expression arose prior to that of the Mx.