Molecular Characterization and Expression Analysis of Novel Interleukin-1 Family Member (nIL-1Fm) Gene in Nile Tilapia (<i>Oreochromis niloticus</i>)

In this study, a novel interleukin-1-family member (nIL-1Fm) was studied from the Nile tilapia (Oreochromis niloticus), a widely cultured fish species in brackish water and freshwater in Thailand and worldwide. The complete sequence of the Nile tilapia nIL-1Fm comprised 2474 bp, encoding 350 amino acids. The genome organization of nIL-1Fm had seven exons and six introns, which were conserved in teleost fish. During tissue distribution analysis, the nIL-1Fm was extremely increased in the head kidney, tailfin and trunk kidney, which had the highest levels, followed by the spleen. Additionally, nIL-1Fm was significantly up-regulated under PAMP stimulation, whereas the stimulation of LPS, PHA and poly I:C could significantly induce nIL-1Fm expression in vitro. Moreover, nIL-1Fm transcription was significantly induced when infected with Streptococcus agalactiae in the spleen, liver and intestine. Taking together, our results indicated that nIL-1Fm can expand our knowledge of the IL-1 cytokine family in fish immune response