Introduction: Serum Bactericidal Assays (SBAs) are considered as the gold standard to evaluate the immunogenicity of many vaccine formulations against infectious agents, for example Neisseria meningitidis vaccines. SBAs are also used to evaluate vaccine lots before release to the market, because it has been demonstrated that there is a correlation between bactericidal antibody titers and protection. For Laboratory and Clinical Good Practice, it is very important to have a positive control in each assay. To our knowledge, there is no commercial positive control to serve this function, therefore the purpose of this work was to evaluate a monoclonal antibody (mAb) panel against N. meningitidis strains produced at Institute Finlay of Vaccines as a reference material in the established bactericidal assay, with the advantage of high homogeneity and specificity and relative low cost of the mAbs test agents.
Materials and Methods: Specificity of a panel of mAbs was evaluated by a whole cell enzyme linked immunoassay (ELISA). The positive mAbs were then tested for bactericidal effect against target strains: F8238 (serogroup A), CU385/83 y NZ228/98 (serogroup B) and C11 (serogroup C). Determinations were carried out in triplicate and the mean was calculated.
Results: In this study, we positively identified five mAbs out of seven that recognised specific, selected N. meningitidis strains. However, only three mAbs (anti-PsA, anti-P1.15 and anti-P1.4) showed bactericidal activity with their homologous strain, and this was related to the mAbs subclass.
Conclusions: Three monoclonal antibodies presented bactericidal activity and they have the potential to be used as positive controls in bactericidal assays.