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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: 28 and 1: 211. 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.

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Aeromonas salmonicida is the pathogen of furunculosis, causing a septicaemic infection that influences both salmonid and non-salmonid fish. Early diagnosis of these contagions is essential for disease surveillance and prevention, so that the rapid and sensitive approach is required. Herein, recombinase polymerase amplification (RPA) assay and RPA with a lateral flow dipstick (RPA-LFD) were produced for testing A. salmonicida. The RPA and RPA-LFD primer sets were devised based on the conserved fragment sequence of vapA gene. Then, RPA and RPA-LFD reaction systems were established, and the reaction temperature and time were optimized. After optimization, the RPA method was capable to test A. salmonicida within 10 min and the RPA-LFD method can detect A. salmonicida in only 5 min. The RPA and RPA-LFD methods exhibited high specificity with no cross-reaction with others strains. To assess sensitivity, a partial vapA gene was cloned, and serial plasmid dilutions were created ranging from 1×106 to 1×10− 1 copies/µL. The detection limit of RPA was 1×102 copies/µL and the detection limit of RPA-LFD was 1 copies/µL. For spiked turbot tissue samples, the sensitivity detecting of A. salmonicida was 1.2×101 CFU/mL and 1.2 CFU/mL by RPA and RPA-LFD, respectively. Therefore, our RPA and RPA-LFD assays exhibited excellent specificity and sensitivity, which provided two simple, fast and dependable methods to conduct large-scale field investigations of A. salmonicida in resource-limited settings.