Development of a colloidal gold immunochromatographic assay for detection of Escherichia coli F5 fimbriae.

To develop a colloidal gold immunochromatographic assay for detection of enterotoxigenic Escherichia coli F_5 fimbriae,colloidal gold particles,were prepared through deoxidization of trisodium citrate,labeled to purified anti-F5 fimbriae monoclonal antibody,and the gold probe was dispensed on the glass fiber.Purified rabbit anti-F5 fimbriae polyclonal antibody and sheep anti-mouse IgG were blotted on a nitrocellulose membrane as test line and control line,respectively.The colloidal gold immunochromatographic strip was assembled with the different accessory in regular sequence.Its sensitivity,specificity,stability and reproducibility were then evaluated.Meanwhile,the simulated samples and clinical samples were tested preliminary.The assay detection limit was 38.2μg/mL.It was confirmed by experiment that the colloidal gold immunochromatographic strip of F5 fimbriae had good sensitivity(no response to F_4,F_6,F 41 and F 18ab) and stability.The strip stored at 4℃ for 120 days could still detect the samples well.The results of detection of F_5 fimbriae using inter-and intra-batches were identical,with clear test line,and good reproducibility.14 clinical samples were examined by the colloidal gold strips,the results were identical with that of indirect Sandwich ELISA,plate agglutination test and PCR.