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

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 × 107 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.