Molecular cloning and functional analysis of type I IFNd of Chinese sea bass (Lateolabrax maculatus) under immune stimulation

Abstract

Chinese sea bass (Lateolabrax maculatus) is an economically important marine cultured species in China. Interferons (IFNs) play an essential role in innate antiviral immunity. The study on IFN immune system helps prevent and control viral diseases of L. maculatus. We have obtained cloning and characterization of the type I IFNd gene from L. maculatus (LmIFNd) in the present study. The full length of cDNA was 1190 bp, including 5’UTR (untranslated region) of 354 bp, 3’UTR of 278 bp, and an open reading frame (ORF) of 558 bp. It encodes 185 amino acids, and the first 20 amino acids are hypothetical signal peptides. The results of amino acid multiple sequence alignment and phylogenetic tree analysis showed that LmIFNd and mandarin fish (Siniperca chuatsi) IFNd were clustered into one branch, and the gene sequence similarity was as high as 88.9%. The expression of LmIFNd was tissue-specific and highly expressed in the head kidney, spleen, and gill. After infection with Rana grylio virus (RGV), and polyinosinic-polycytidylic acid [Poly(I:C)], the expression of LmIFNd in gill, spleen, and head-kidney was up-regulated significantly. Besides, the expression level of LmIFNd has increased significantly under the stimulation of Vibrio harveyi and Streptococcus iniae. The results show that LmIFNd may play a protective role in both viral and bacterial infections.