Preliminary Study On The Function Of Largemouth Bass (Micropterus Salmoides) TRIM23 In Viral Host Interaction

With the expansion and intensification of largemouth bass(Micropterus salmoides)farming,ulcerative disease has broken out in more and more areas.Largemouth bass ulcerative syndrome virus(LBUSV)is one of the pathogens causing ulcerative disease in largemouth bass culture.As the virus is often invisible and infectious,there is no effective method to prevent and treat the virus,so it is necessary to study the interaction mechanism between LBUSV and the host.1.Transcriptome analysis of branchial tissue of Largemouth bass infected with LBUSVIn order to explore the gene expression changes of largemouth bass infected with LBUSV,the gill tissues of largemouth bass infected for 3 days were taken as the experimental group,and the gill tissues of largemouth bass not infected with virus were taken as the control group by RNA-Seq sequencing.The differential genes of the two groups were analyzed,and GO and KEGG signaling pathway changes were enriched.Finally,174,015,834 and 182,322,452 clean reads were obtained from the control group and the LBUSV infected group,respectively,with a total of 2,947 differential genes.There were 1,531 up-regulated genes and 1,416 down-regulated genes.The items of GO enrichment with significant differences were immune response related genes,leukocyte activation related genes and cell surface related genes.The most significant KEGG pathways are Ig A producing intestinal immune network,phagosome and calcium signaling pathways.2.Preliminary study on the function of largemouth bass TRIM23 in viral host interactionDifferential gene TRIM23 was selected from transcriptome results.TRIM23,a typical TRIM family protein,has been shown to play a key role in innate immunity.But the role of TRIM23 in fish is still largely unknown.In this study,the TRIM23 gene of largemouth bass was cloned.Sequence analysis showed that the gene encoded 580 amino acids,and the homology with Danio rerio was 73%,and with siniperca chuatsi 94.6%.Phylogenetic tree showed that largemouth bass TRIM23 was the most closely related to Mandarin fish.TRIM23 contains three conserved domains,including the RING domain,B-box1 and B-box2 domains,and the curly helix domain.TRIM23 is localized in the cytoplasm,while TRIM23-δRing is localized in the nucleus,suggesting that deletion of the RING domain changes the expression of this gene.The transcription level of TRIM 23 gene was significantly down-regulated after artificial infection with LBUSV.TRIM23 overexpression significantly enhanced the replication of LBUSV in vitro,and TRIM23-ΔRING significantly reduced the replication of LBUSV in vitro.TRIM23 can significantly inhibit the expressions of ISG15,IFN,IRF3,IRF7 and MX1,but has no significant effect on TNF-α and IL-10.On the contrary,overexpression of TRIM23-ΔRING significantly promoted the expressions of ISG15,IFN,IRF3,IRF7,TNF-α and MX1,but had no significant effect on IL-10.This suggests that TRIM 23 affects viral replication by negatively modulating the IFN response.This study lays a theoretical foundation for the prevention and treatment of largemouth bass ulcer syndrome.