Development of a Colloidal Gold-Based Immunochromatographic Assay for the Rapid Detection of Edwardsiella Ictaluri.

Edwardsiella Ictaluri is known as the etiological agent of enteric septicaemia of channel catfish, causing heavy economic losses in the aquaculture industry. In this study, a colloidal gold-based immunochromatography assay (GICA) was developed for rapid detection of E. ictaluri. Briefly, monoclonal antibody (MAbs) and polyclonal antibody (PAbs) against E. ictaluri were prepared. Sensitivity of MAbs and PAbs to E. ictaluri was analyzed by Dot ELISA. Mouse MAb5D11 against E. ictaluri was conjugated with the 20 nm colloidal gold particles as the detector. Rabbit PAbs of E. ictaluri and goat anti-mouse IgG antibody was sprayed on nitrocellulose membranes as test line (T) and control line (C) respectively. The minimum detectable amount of this method to E. ictaluri was 5 × 106 CFU/mL. Cross reactions wouldn't occur when detecting E. tarda, Aeromonas hydrophila, V. parahaemolyticus and other several common standard strains. The result could be got in only 5 to 10 minutes. It didn't need professional technologies and testing experience. So this assay was very suitable for basic departments of aquatic product companies.