Development of a multiplexed fluorescent immunoassay for the quantitation of antibody responses to four Neisseria meningitidis serogroups.

Neisseria meningitidis is a gram-negative bacterium causing disease world wide with a fatality rate of 5-10%. Five serogroups, A, B, C, Y and W-135 are responsible for virtually all cases of the disease in humans. We have developed a multiplexed assay for the simultaneous quantitation of IgG antibody responses to the four most immunogenic (A, C, Y, and W-135) N. meningitidis serogroups. A simple and less manipulative method was employed for conjugation of the capsular polysaccharide antigens to the microspheres. The multiplex assay compared well with traditional individual ELISAs, but demonstrated greater than 1 log increase in dynamic range and sensitivity. Specificity studies of the multiplex assay showed greater than 95% homologous inhibition and less than 5% heterologous inhibition for all four serogroups. Intra and inter-assay CVs were generally less than 10% and the limit of detection was <600 pg/ml. The multiplexed assay proved to be reproducible as well as specific and sensitive when compared to the standardized ELISAs. Advantages included a greater dynamic range and simultaneous detection of antibody responses to the four serogroups contained in the tetravalent meningococcal polysaccharide vaccine.