HUMAN-ANTIBODY RESPONSE TO MENINGOCOCCAL TRANSFERRIN-BINDING PROTEINS- EVIDENCE FOR VACCINE POTENTIAL

During iron-limited growth Neisseria meningitidis expresses two transf errin binding proteins, TBP1 and TBP2, with molecular masses of approx imately 98 and 65-90 kDa depending on strain. Mixtures of TBP1 and TBP 2 (TBP1+2) from three meningococcal strains were purified using affini ty chromatography and used to determine anti-TBP antibodies in human s era by ELISA. Sera were obtained from healthy individuals, asymptomati c carriers of N. meningitidis and cases of meningococcal disease. Heal thy individuals had little detectable antibody to TBPs but sera from c arriers and cases exhibited a response demonstrating that TBPs ave exp ressed in vivo during both carriage and disease, The ELISA absorbances produced by each of the individual sera to TBPs from the three mening ococcal strains were compared and very high correlation coefficients w ere obtained indicating that human anti-TBP antibodies in contrast to mouse and rabbit antibodies, are cross-reactive between strains. Antib odies to separately purified TBP1 and TBP2 were also detected in both cases and carriers. The IgG and IgM response to TBP1+2 was greater in cases than carriers but the mean IgA response was the same, This demon stration of an antibody response that is cross-reactive between TBP ty pes greatly strengthens the case for inclusion of TBPs in a meningococ cal vaccine to protect against all serogroups and serotypes.