MOLECULAR INSIGHTS INTO INTERFERON REGULATORY FACTOR 9 (IRF9) IN BLACK ROCKFISH Sebastes schlegeli AND ITS TRANSCRIPTIONAL MODULATION UPON PATHOGENIC STIMULI

Interferon regulatory factors (IRFs) play vital roles in IFN-induced signaling pathways as critical transcription factors of type I interferons (IFNs) and IFN-stimulated genes (ISGs). They are involved in antiviral defense, early immune responses to pathogens, lymphocyte development and cell growth regulation in vertebrates.

In this study, full-length cDNA sequence of IRF9 from black rockfish (Sebastes schlegeli; RfIRF9) was identified from a previously constructed cDNA library and characterized at molecular level. To investigate RfIRF9 modulation upon pathogenic stress, black rockfish were subjected to challenge experiments (Streptococcus iniae, LPS and Poly I:C) and mRNA expression was assayed using quantitative real-time PCR (qPCR).

RfIRF9 was comprised with an open reading frame (ORF) of 1293 bp which encoded 431 amino acids (~49 kD). RfIRF9 has revealed its typical domain architecture and entailed with IRF and IRF3 domains. The closest evolutionary relationship to the RfIRF9 ortholog as well as the highest identity (77.4%) and similarity (86.4%) values were exhibited by the Miichthys miiuy counterpart. RfIRF9 was highly expressed in blood tissue under physiological conditions and the challenge experiment results revealed that RfIRF9 can be up-regulated with the pathogenic invasions (Fig 1) suggesting, RfIRF9 can be positively involved in bacterial and viral pathogenic host responses.