Abstract: The aim of this study was to establish a colloidal gold immunochromatographic assay for the rapid detection of Flavobacterium columnaris.Colloidal gold particles with diameter 20 nm were prepared by the sodium citrate reduction method.Purified Flavobacterium columnaris monoclonal antibodies (McAb) labelled with 20 nm colloidal gold particles to form colloidal gold combined pad.Purified polyclonal antibody (PcAb) against Flavobacterium columnaris and goat anti mice IgG were coated on the nitrocellulose membrane to be the test line (T line) and the control line (C line).Gold immunochromatographic strips which prepared to detect Flavobacterium columnaris were obtained.Its sensitivity,specificity and stability were evaluated.The results showed that sensitivity of the strip reached to 1×10³ CFU.The testing time was 3.5 min.Specificity analysis showed no cross-reaction with other aquatic pathogenic bacteria such as Edwardsiella tarda,E.coli,Aeromonas hydrophila,Vibrio anguillarum,Vibrio alginolyticus,Vibrio parahaemolyticus and Vibrio harveyi.The strip showed good stability either.This study successfully established colloidal gold immunochromatographic assay of the rapid detection of Flavobacterium columnaris for the first time.The strip prepared was sensitive,specific,stable and rapid.It could be used for the detection of Flavobacterium columnaris.

Key words: Flavobacterium columnaris; colloidal gold; rapid detection