Identification ofinterleukin‐16(IL‐16) andinterleukin‐17D(IL‐17D) genes from Dabry's sturgeon (Acipenser dabryanus)

Abstract

Dabry's sturgeon (Acipenser dabryanus) represents an ancient Actinopterygian lineage that are termed “living fossils”. Many diseases have been found in Dabry's sturgeon. In the present study, genes encoding interleukin (IL)‐16 and IL‐17D in Dabry's sturgeon were identified by RNA‐sequencing. Phylogenetic tree analysis suggested that they clustered together with the corresponding pro‐IL‐16 proteins and IL‐17D proteins from other fish. Sequence analysis revealed that IL‐17D protein was more conserved than pro‐IL‐16. Dabry's sturgeon pro‐IL‐16 contains four putative PDZ domains and do not include signal peptides, while IL‐17D only possesses signal peptides (1–25 aa). The expression patterns of IL‐16 and IL‐17D genes were investigated in Dabry's sturgeon to reveal their functions in disease. The expression level of IL‐16 showed no significant changes in embryos; however, the high expression level of IL‐17D at 0–14 hpf (hours post fertilization) implied the existence of maternal expression in the oocyte and an association with embryonic development. Tissue distribution analysis revealed that IL‐16 and IL‐17D proteins have potential functions in immune and non‐immune tissue compartments. IL‐16 and IL‐17D had different fold changes in primary spleen leukocytes after polyinosinic:polycytidylic acid (poly I:C) and lipopolysaccharide (LPS) administration, which suggested that IL‐16 has a stronger antiviral capability compared with its antibacterial response, and IL‐17D has a stronger antibacterial capability compared with its antiviral response. IL‐16 showed an earlier response to virus compared with IL‐17D, and IL‐17D showed earlier and shorter response to bacteria compared with IL‐16. Our findings suggested the roles of IL‐16 and IL‐17D in Dabry's sturgeon, and provided the theoretical basis for the prevention and control of diseases of Dabry's sturgeon.