A Novel RAA Combined Test Strip Method Based on Dual Gene Targets for Pathogenic Vibrio vulnificus in Aquatic Products

Vibrio vulnificus can cause disease in aquatic animals and humans, therefore, rapid and simple field detection of pathogenic V. vulnificus is important for early disease prevention. In this study, a novel recombinase-aided amplification (RAA) combined test strip with double T-lines (RAA-TS-DTL) was developed for the rapid detection of V. vulnificus in aquatic products. Pathogenic V. vulnificus was detected using the virulence vvhA gene and the housekeeping gene gyrB gene as the dual target of the test strip. The RAA-TS-DTL method showed 100% specificity for V. vulnificus, and no cross-reaction was observed with Vibrio spp. or other bacteria (n = 14). Furthermore, sensitive detection of V. vulnificus in oysters was achieved. The LODs of the gyrB and vvhA genes were 6 CFU/mL and 23 CFU/mL, respectively, which was about five times higher than that of the commercial test strip. The method was validated with spiked samples (n = 60) of fish, shrimp and oyster. The consistency between RAA-TS-DTL and the traditional culture method was 97.9%. In addition, the entire process of detection, including preparation of the sample, could be completed within 50 min. Our results indicated that the developed RAA-TS-DTL was a reliable and useful tool for rapid screening or on-site detection of pathogenic V. vulnificus in aquatic products and aquaculture water.