First identification of nuclear factor kappa B inhibitor delta (NFKBID) in Platichthys stellatus: Molecular cloning...

In this study, the nuclear factor kappa B inhibitor delta gene (NFKBID) of the starry flounder, Platichthys stellatus, was identified through next-generation sequencing (NGS) and verified by cloning and sequencing. The multiple sequence alignment and phylogenetic analysis revealed high conservation of NFKBID among several fish species. The tissue distribution of NFKBID in healthy P. stellatus was analyzed by quantitative PCR, revealing expression in almost all tissues, with relatively high levels in the gills, skin, and trunk kidney. Furthermore, significant changes in NFKBID expression were observed in starry flounder following infection with Streptococcus parauberis PH0710 and viral hemorrhagic septicemia virus (VHSV). Infection with S. parauberis PH0710 downregulated NFKBID in most tissues except the intestine. In contrast, VHSV infection showed a significant upregulation of expression in most tissues during the early phase. These results suggest that immune-related responses to bacterial and viral infections in starry flounder are associated with changes in NFKBID expression. This study provides fundamental molecular insights into the potential involvement of NFKBID in immune-related processes in teleost fish.