Detection of Neisseria gonorrhoeae by dot-enzyme immunoassay using monoclonal antibodies

A highly sensitive and specific dot-enzyme immunoassay for the detection of Neisseria gonorrhoeae was developed using a pool of monoclonal antibodies (MAbs). The MAbs were obtained following immunization of mice with lithium acetate extracted outer membrane (OM) preparations. Western immunoblotting experiments demonstrated that MAbs NG26 and NG38, both IgG2a, reacted with lipopolysaccharides (LPS) and with the major OM protein, P1, respectively, MAb NG28, an IgG3, did not react in Western immunoblotting, MAbs NG28 and NG38 failed to react with OM treated with proteolytic enzymes or with semi-purified preparation of LPS. MAb NG26 reacted with the same LPS preparation. Binding radioimmunoassay with live bacteria showed that all the MAbs adsorbed to cell surface-exposed antigenic determinants. The limit of detection of the dot-enzyme immunoassay was between 1 and 4 x 10(4) cfu per dot. Using a panel of 177 strains of N. gonorrhoeae, MAbs NG28 and NG38 recognized only P1A and P1B strains respectively. MAb NG26 reacted with P1A, P1B and non-typable strains. These MAbs did not react with other Neisseria species or other bacterial species. Using this pool, the dot-enzyme immunoassay had a sensitivity of 93.2% and a specificity of 100%.