Transcriptomic profiling reveals the protection mechanism of bivalent inactivated bacteria vaccine Aeromonas salmonicida and Vibrio scophthalmi in turbot (Scophthalmus maximus)

As a high-efficiency and safe strategy, the inactivated vaccine is widely used in aquaculture against bacterial and viral infections. In previous research, we have successfully developed bivalent inactivated vaccine Aeromonas salmonicida and Vibrio scophthalmi, which provided significant protection against bacterial infection in turbot Scophthalmus maximus. However, less is known about the potential protective mechanisms of this bivalent inactivated vaccine. In this study, we applied RNA-seq technology to analyze the head kidney transcriptome of turbot which was vaccinated with the bivalent inactivated vaccine A. salmonicida and V. scophthalmi after 0, 2, and 4 weeks. A total of 127,627,214, 131,894,590, and 126,840,698 high-quality reads were generated from each group, which were ultimately assembled into 38,504 unigenes. Compared to 0 w, a total of 2157 and 2254 differentially expressed genes (DEGs) were identified after vaccination at 2 and 4 weeks, respectively. Six DEGs were randomly selected for qRT-PCR to confirm the reliability of transcriptome data. In this study, the KEGG analysis showed that numerous DEGs were enriched in 12 immune-related pathways, such as phagosome, intestinal immune network for IgA production, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway and so on. Furthermore, several immune-related genes were identified as remarkably up-regulated including complement components (C3, C5, Bf) and cytokines (CCR9). These results provide an insight into the mechanisms of immune responses to turbot vaccination and support further applications to aquaculture.