Molecular Characterization And Expression Analyses Of Interferon Stimulated Gene 56(ISG56) And Interferon Stimulated Gene 15(ISG15) In Epinephelus Lanceolatus

Interferon-stimulated genes(ISGs)form the backbone of the innate immune system and are important for limiting intra-and intercellular viral replication and spread,and ISG network may critical for therapeutic targeting to efficiently fight viral infections.Interferon stimulated gene 56(ISG56),also known as Interferon-induced protein with tetratricopeptide repeats 1(IFIT1),is a member of the interferon stimulated genes,was originally identified as induced upon treatment with virus and interferonregulation.It plays a variety of biological functions in the regulation of antiviral immunity and interferon signaling pathway.In addition to Interferon(IFN),a variety of viruses can up-regulate the expression of the isg56.Interferon stimulated gene 15(ISG15)is also a member of the interferon stimulated gene.However,studies on isg56 and isg15 genes in Epinephelus lanceolatus have not been reported,and their role in innate immunity in Epinephelus lanceolatus has rarely been investigated.In the present study,bioinformatic analysis identified the isg56 gene and isg15 gene in Epinephelus lanceolatus,and the complementary DNA sequences of isg56 gene and isg15 gene were cloned.The complete c DNA of isg56 gene of Epinephelus lanceolatus is 2921 nucleotide(nt),containing an open reading frame is 1314 nucleotide,encoding a protein of 437 amino acids(aa),with a putative molecular weight of 50.6 k Da,and the theoretical isoelectric point is 6.10.The complete c DNA of isg15 gene of Epinephelus lanceolatus is 910 nucleotide(nt),containing an open reading frame is 468 nucleotide,encoding a protein of 156 amino acids(aa),with a putative molecular weight of 17.09 k Da,and the theoretical isoelectric point is 9.33.Sequence analysis and phylogenetic analysis showed that the derived ISG56 and ISG15 proteins were highly homologous with the ISG56 and ISG15 proteins in other teleost fish.Real-time quantitative PCR was used to detect the expression patterns of isg56 gene in the healthy tissues,and in the spleen,kidney,after bacterial infection with iridescent virus.The results showed isg56 gene was highly expressed in various immune-related tissues,such as spleen,intestine,kidney and liver.Upon induced with Spotted Knifejaw iridovirus(SKIV),isg56 gene expression is up-regulated in kidney and spleen at 24 h post-induction and reached the peak at 72 h,indicating the isg56may play an important role in the immune response against SKIV infection.Real-time quantitative PCR was used to detect the expression patterns of isg15 gene in the healthy tissues,and in the spleen,kidney,after bacterial infection with iridescent virus.The results showed isg15 gene was highly expressed in various immune-related tissues,such as liver and kidney.Upon induced with Spotted Knifejaw iridovirus(SKIV),isg15 gene expression is up-regulated in kidney and spleen at 24 h post-induction and reached the peak at 72 h,indicating the isg15 may play an important role in the immune response against SKIV infection.These results would contribute the understanding of the antiviral regulation of fish isg56 gene and isg15 in teleost,and provides theoretical basis for disease resistance molecular breeding of Epinephelus lanceolatus.