Monoclonal antibody based Dot-ELISA and indirect fluorescence antibody technique for detecting Edwardsiella ictaluri infection in yellow catfish (Pelteobagrus fulvidraco)

Abstract Edwardsiella ictaluri is known as the etiological agent of Red-head disease of yellow catfish ( Pelteobagrus fulvidraco ), and is the cause of heavy economic losses in the aquaculture industry. In this study, a Dot-Enzyme Linked Immunosorbent Assay (Dot-ELISA) and an Indirect Fluorescence Antibody technique (IFAT) for detecting Edwardsiella ictaluri were developed by using a monoclonal antibody, 5D11. For Dot-ELISA, the working dilutions of 5D11 and the secondary antisera (enzyme-labeled goat anti-mouse Ig) were 1:320 dilution and 1:3000 dilution, respectively. For IFAT, the working dilutions of 5D11 and goat- anti -mouse Ig conjugated with fluorescein isothiocyanate were as respectively 1:80 and 1:256. Both of the methods established were highly sensitivity (Minimum detectable concentration, 5 × 10 7  CFU/mL) and had a high degree of accuracy (positive rate was 100% for both artificial infected fish and spontaneous diseased Pelteobagrus fulvidraco ). The two reliable methods developed have high potential for quick and efficient detection of Edwardsiella ictaluri in aquaculture production units.