A recombinase polymerase amplification with lateral flow assay for rapid on-the-spot detection of Aeromonas salmonicida

Aeromonas salmonicida is a common pathogen of salmonid fishes that poses a significant threat to the fresh water and marine culture industry, potentially resulting in huge economic losses. To prevent and control fish diseases caused by A. salmonicida, rapid and effective diagnostic approaches must be developed, and which are important for routine monitoring and clinical care. By combining recombinase polymerase amplification (RPA) technology with a visible lateral flow strip (RPA-LF), we have enhanced both the precision of RPA detection and the convenience of real-time monitoring. In this study, we introduce a robust method for detecting A. salmonicida using RPA-LF. This assay specifically targets the ASA_1441 gene of A. salmonicida, ensuring high specificity, without cross-reactivity with other prevalent fresh water or marine pathogens. The optimal amplification temperature of the RPA assay was 39 ​°C. Its sensitivity extends to as low as 100 ​fg of purified DNA, representing more than 1000-fold higher sensitivity than conventional PCR methods. Furthermore, to enhance the usability of the RPA-LF assay, we developed a rapid sample preparation method using cellulose dipsticks for nucleic acid extraction. This method achieves a limit of detection (LOD) as low as 1.67 ​CFU/μL and completes the entire process within 20 ​min. In conclusion, our findings present a rapid and precise tool for monitoring A. salmonicida infection in aquaculture and marine culture. This advancement offers valuable insights for effective disease prevention and control strategies. •The RPA-LF assay for rapid on-the-spot detection is established to monitor Aeromonas salmonicida.•The method targets the ASA_1441 gene of A. salmonicida which ensures high specificity.•The Limit of Detection (LOD) is as low as 100 ​fg of purified A. salmonicida DNA.•A rapid sample preparation method using cellulose dipsticks for nucleic acid extraction was developed.•The limit of detection for RPA-LF is 1.67 ​CFU/μL with an analysis time of less than 20 ​min.