The gene and virus-induced expression of IRF-5 in grass carp Ctenopharyngodon idella

The interferon regulatory factor 5 (IRF-5) is known to be involved in the innate immune response and in the regulation of DNA damage-induced apoptosis. In the present study, the cDNA and genomic sequences of IRF-5 were identified in grass carp (Ctenopharyngodon idella). The cDNA of grass carp IRF-5 (gcIRF-5) contains an open reading frame (ORF) of 1560 nucleotides, encoding a putative 519 amino acid protein, which showed 34.5–83.9% identity to IRF-5 homologues from mammals, amphibian, avian and fish, and 96.2% and 95.0% identity to zebrafish IRF-5 in the DNA-binding domain (DBD) and IRF association domain (IAD), respectively. The genomic DNA sequence of gcIRF-5 contains 6075 bp consisting of 9 exons and 8 introns. The expression of gcIRF-5 was observed in all organs examined. The analysis of real-time quantitative RT-PCR revealed that grass carp reovirus (GCRV) induced the expression of gcIRF-5 in spleen and head kidney.