Bacterial coloration immunofluorescence strip for ultrasensitive rapid detection of bacterial antibodies and targeted antibody-secreting hybridomas.

The indirect enzyme-linked immunosorbent assay (ELISA) is the gold standard method for monoclonal antibody (McAb) detection and plays a unique role in the preparation of bacterial antibodies. To solve the laborious issues associated with indirect ELISA, a novel bacterial coloration immunofluorescence strip (BCIFS) for antibody detection using colored bacteria instead of a labeled antibody as the antigen and tracer simultaneously and goat anti-mouse IgG as the test line was developed. The affinity range survey of BCIFS indicated that hybridoma cell cultures of E. coli O157:H7 (D3, E7) and Vibrio parahemolyticus (H7, C9) were detected, which complied with the results of indirect ELISA. Compared with the traditional indirect ELISA, the BCIFS sensitivity for E7 cell cultures, ascites, and purified antibodies was at least 4-fold more sensitive, and the BCIFS cross-reactivity for E7 cell cultures was almost consistent with that of indirect ELISA. In addition, the BCIFS isotypes for E. coli O157:H7 cell cultures and Vibrio parahemolyticus were IgG2a and IgG1, respectively, which were identical to the indirect ELISA. Furthermore, the BCIFS method was confirmed by McAb preparation, effective antibody use, and targeted antibody-secreted hybridoma preparation and screening, which showed excellent performance and substitution of the indirect ELISA method. Combined with methylcellulose semisolid medium, BCIFS offers a novel, easy to operate, rapid preparation method for antigen-specific hybridomas. This is the first report using BCIFS instead of indirect ELISA for bacterial antibody detection and application in different samples, which demonstrates a rapid and powerful tool for antibody engineering.