Rapid detection of Edwardsiella ictaluri in yellow catfish (Pelteobagrus fulvidraco) by real-time RPA and RPA-LFD

Yellow catfish (Pelteobagrus fulvidraco) is an important freshwater cultured fish in China. Enteric septicemia of catfish (ESC) and red-head disease (RHD), caused by Edwardsiella ictaluri, result in huge economic losses to yellow catfish farming industry. Rapid and handy detection of E. ictaluri is a pressing demand for diagnosis. In this study, we developed rapid, convenient, sensitive and accurate detection methods RPA (recombinase polymerase amplification), real-time RPA (based on real-time fluorescent detection) and RPA-LFD (combining RPA with lateral flow dipsticks (LFD)), targeting the conserved sequence of serC gene in E. ictaluri. The RPA-LFD and real-time RPA methods could achieve detection within 30 min at 38 °C. All the three methods had high analytical sensitivity (102 copies/μl) and were 10 times more sensitive than that in general PCR. They were highly specific for identification of E. ictaluri. 24 samples of yellow catfish from farm were examined through RPA, real-time RPA and RPA-LFD methods, the results showed the consistency with the general PCR detection. In short, RPA, real-time RPA and RPA-LFD methods characterize rapid, simple, sensitive and accurate detection and demonstrate great potential for diagnosis of E. ictaluri disease in fish farms.