Viral diseases are a considerabl e threat to cultures and natural fish populations. It is lead to significant losses in livestock and economic lo sses to the world aquaculture industry. Interferons (IFNs) and IFN-inducible proteins are responsible for the antiviral defense mechanisms of the innate immune response . IFN-induced protein-35 kDa (IFP35) is a cytoplasmic protein, and it can be translocated to the nucleus via stimulation. IFP35 has two tandem C terminus Nmi/IFP35 homology domains (NID) and containing an N-terminal leucine zipper motif. That domains are responsible for the IFP35 stabilization. IFP35 can stimulate apoptosis, and other cytokine-signaling pathways interact with CKIP-1 (casein kinase 2-interacting protein-1) and B-ATF (basic leucine zipper transcription factor, ATF-like).
Rock bream interferon-induced protein-35 (RbIFP35 ) homolog was identified, and its biological functions were characterized. r ock bream complete cDNA of IFP35 got from rockfish cDNA transcriptomic database. RbIFP35 protein characteristic and structural features were analyzed by several bioinformatics tools, such as ExPASy PROSITE, NCBI BLAST, and SignalP online server. The expression level of mRNA in rock bream was analyzed by qPCR technique. Conserved domain parts of the RbIFP35 were determined by using multiple sequence alignment tool, ClustalW . The phylogenetic tree analysis was constructed according to the Neighbor-joining (NJ) method by MEGA 5.0 software. The putative 3D structure of the RbIFP35 was constructed by I-TASSER server. RbIFP35 cellular location was predicted by MultiLoc2 software. To measure the immune response of RbIFP35 on stimulant or pathogens, healthy rock breams were used to experiment. Each group of rock bream was injected with rock bream iridovirus, Edwardsiella tarda , Streptococcus iniae, lipopolysaccharide and polyinosinic : polycytidylic acid. Phosphate buffered saline (PBS) was injected into the control group. For each treatment, various tissues were collected from the challenged rock bream from different time intervals. Then total RNA was extracted from each tissue and did the qPCR assay. RbIFP35 Subcellular localization was performed using the rock bream heart cells with constructed pEGFP-N1/RbIFP35 plasmids.