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In this research, Vibrio vulnificus formalin-killed (FKCs) vaccine and ghost (VVGs) vaccine were successfully developed, and shown to prevent vibriosis of Scophthalmus maximus resulting from V. vulnificus. The antibody titre of FKCs and VVGs vaccine was 1: 2 8 and 1: 2 11 . The RPS of FKCs and VVGs vaccine was 60% and 80%. In order to improve the understanding of vaccine protection mechanism, transcriptome data was used to analyse the immune response of S. maximus infected with V. vulnificus after vaccination with FKCs and VVGs vaccine. In the SmCon and SmIV groups, a series of innate immune-related genes were upregulated (such as, TLR5, Tp12, AP-1 and IL-1β) or downregulated (such as, CASP6 and CASP8), which suggested that the immune protection mechanism induced by inactivated vaccine was similar to that of autoimmune response. In the SmIV and SmGho group, a number of innate and adaptive immune-related genes (such as, STAT1, IFN-γ and MHC Ia) were activated, in which the expression of these genes was higher in SmGho, and VVGs vaccine induced stronger innate and acquired immune responses. In conclusion, the results lay a foundation for further study on the molecular mechanisms of immune protection induced by VVGs vaccine and FKCs vaccine., (© 2022 John Wiley & Sons Ltd.)

Galectin-9 is a β -galactoside-binding lectin which could modulate a variety of biological functions including recognition, aggregation and clearance of pathogen. In this study, one Galectin-9 (named PoGalectin-9) was identified from Japanese flounder Paralichthys olivaceus. PoGalectin-9 belongs to the tandem-repeat type, containing one 127-amino acids CRD domain within N terminal and one 122-amino acids CRD domain within C-terminal. The open reading frame of PoGalectin-9 cDNA was 921 bp encoding 306 amino acids. Sequence similarity comparison confirmed that PoGalectin-9 shared high homology with other Galectin-9. The tissue distribution and expression profiles after bacterial infection were also investigated. PoGalectin-9 was widely distributed in all of the examined tissues of Japanese flounder but was predominantly expressed in the spleen, kidney and intestine. After Edwardsiella tarda challenge, the expression of PoGalectin-9 was up-regulated in spleen and down regulated in kidney. ELISA experiment showed that recombinant PoGalectin-9 (rPoGalectin-9) exhibit binding capacity to lipopolysaccharide (LPS) and peptidoglycan (PGN), which is significantly correlated with the concentration of rPoGalectin-9. Meanwhile, the rPoGalectin-9 protein showed strong agglutinating activities against both Gram-negative bacteria and Gram-positive bacteria. Bacterial binding experiments showed that rPoGalectin-9 could bind all examined bacteria. In conclusion, the present study indicate that PoGalectin- 9 might play important roles during the immune responses of Japanese flounder against bacterial pathogens. • One isoform of Galectin-9 from Japanese Flounder were cloned and characterized, named PoGalectin-9. • PoGalectin-9 was ubiquitously expressed in all tested tissues. • PoGalectin-9 was up-regulated in spleen after challenged with E. tarda. • The recombinant PoGalectin-9 showed high affinity to lipopolysaccharide. • PoGalectin-9 may play important roles during immune responses. [ABSTRACT FROM AUTHOR]