Characterization of IL-17/IL-17R gene family in Sebastes schlegelii and their expression profiles under Aeromonas salmonicida and Edwardsiella piscicida infections

Interleukin 17 (IL-17) is a hallmark inflammatory cytokine that can induce a variety of cells to produce immune-related factors, and plays a critical role in host defend itself against invasion by pathogens, which signals through a distinct receptor subclass- IL-17R. In our study, seven IL-17 and eight IL-17R family members were identified in black rockfish. Subsequently, phylogenetic relationships, gene structures and syntenic analysis were performed to confirm the annotation and homology of these genes during evolution. Except for eight positive selection sites were detected in IL-17RA1, IL-17RC1 and IL-17RD, most of gene sites were underwent purification selection. The mRNA levels of IL-17 and IL-17R genes were higher in immune-related tissues. Additionally, the expressions of IL-17RA1 and IL-17RE1 in spleen were dramatically induced by A. salmonicida treatment, as well as IL-17RA1, IL-17RB, IL-17RC1 and IL-17RE1 in liver, which indicated their important roles in antimicrobial infections. Furthermore, the expression patterns of IL-17 and IL-17R genes in mucosal tissues in response to E. piscicida infection were investigated, of which some members were dramatically induced, particularly for IL-17A/F1 and IL-17A/F3 in skin, IL-17A/F2 in gill, IL-17RB in intestine, IL-17RA1 and IL-17RC1 in skin and gill, suggests their potential essential roles in innate immune response. In summary, this study provides a systemic overview of the IL-17 and IL-17R gene families in black rockfish, which is of great importance to further study the functional characteristics of these genes.