Immunoassay of human Neisseria meningitidis serogroup A antibody

An enzyme immunoassay is described which quantitates antibodies to Neisseria meningitidis serogroup A capsular polysaccharide in human sera. Modifications of a previously developed two-day assay by Carlone et al. were made to permit analysis in one day and to be compatible with automation. The allowable variations in assay conditions and the areas in which stringent control must be maintained for consistent assay performance are described. Antigen-coating parameters, the kinetics of primary and secondary antibody incubation steps, the buffer compositions, including detergents, serum requirements, and the need for blocking steps were examined. Our modified one-day assay showed excellent agreement with the standardized method of Carlone, with a correlation coefficient between the two methods of 0.989. This assay is adaptable within a permissible range of parameters thus facilitating the implementation of the standardized assay. This will maximize the consistency of results from serum analysis for conjugate vaccine trials related to serotype A Neisseria meningitidis.