Recombinase polymerase amplification combined with lateral flow dipstick for equipment-free detection of Salmonella in shellfish
Salmonella is a major pathogen that causes acute foodborne outbreaks worldwide. Seafood, particularly shellfish, is a proven source of Salmonella spp. infection because many people prefer to eat it raw or lightly cooked. However, traditional identification methods are too time-consuming and complex to detect contamination of bacteria in the food chain in a timely manner, and few studies have aimed to identify Salmonella in shellfish early in the supply chain. We herein developed a method for rapid detection of Salmonella in shellfish based on the method of recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD), which targets the invasion gene A (invA). The RPA-LFD was able to function at 30–45 °C, and at the temperature of 40 °C, it only took 8 min of amplification to reach the test threshold of amplicons. The established method had both a good specificity and a sensitivity of 100 fg DNA per reaction (20 µL). Regarding practical performance, RPA-LFD performed better than real-time PCR. Another advantage of RPA-LFD is that it was capable of being performed without expensive equipments. Thus, RPA-LFD has potential for further development as a detection kit for Salmonella in shellfish and other foods under field conditions.
KeywordsRecombinase polymerase amplification Lateral flow dipstick Nucleic acid test Salmonella Shellfish
Authors would like to acknowledge the Ningbo Academy of Inspection and Quarantine for providing the Salmonella strain, DNAs of other serotypes of Salmonella and non-Salmonella organisms for this study, and their allowing us to finish assays of cultivating strains in the laboratory there. Authors also appreciated the assistance and guidance of the staff there. We thank LetPub (http://www.letpub.com) for their linguistic assistance during the preparation of this manuscript.
This study was funded by Ningbo Innovation Team (2015C110018), Ningbo Science and Technology Research Projects (2017C110003), Zhejiang Provincial Public Welfare Technology Program of China (2017C33133), K.C. Wang Magna Fund in Ningbo University (SS), Scientific Research Foundation of Graduate School of Ningbo University (G16091), the Earmarked Fund for Modern Agro-industry Technology Research System, China (CARS-49) and Zhejiang Xinmiao Talents Program (2015R405013).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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