Development of a Multi-Plex Electrochemiluminescent Assay for the Detection of Serum Antibody Responses to Meningococcal Conjugate Vaccines

Neisseria meningitidis is a gram negative diplococcal bacterium. Worldwide, N. meningitidis is the leading cause of bacterial meningitis and sepsis, with five serogroups (A, B, C, Y, and W-135) responsible for the majority of the disease. Multivalent (A, C, Y, and W-135) polysaccharide and conjugate vaccines have been licensed in the United States and elsewhere and are widely available. We have developed a multi-plexed electrochemiluminescent assay to quantitate serum antibody responses to meningococcal polysaccharides A, C, Y, and W-135 to allow for rapid evaluation of li- censed and investigational vaccines. A 96-well plate containing a carbon electrode arrayed with polysaccharides A, C, Y, and W-135 on separate spots within each well has been developed for simultaneous detection of polysaccharidespecific antibodies in serum samples from vaccinated individuals. The assay conditions were optimized using the anti-meningococcal serogroup A/C reference serum pool, CDC 1992 (NIBSC 99/706), through evaluation of plate types, coating polysaccharide concentrations, and blocking and serum diluent buffers. Comparison of single and multiplex assays demonstrated the sensitivity, specificity, and speed of the multi-plex format for the quantification of serum antibody responses to N. meningitidis polysaccharides A, C, Y and W-135.