Development, Characterization, and Biological Properties of Meningococcal Immunotype L3,7,(8),9-specific Monoclonal Antibodies

In this study, we characterize the properties of nine monoclonal antibodies (MAbs) that recognize meningococcal lipopolysaccharides (LPS). The following three specific MAbs that had not been described previously were elicited in BALB/c mice by using an immunotype L3,7,9 oligosaccharide-tetanus toxoid conjugate in combination with Quil A: 4D1-B3, 3A12-E1, and 4A8-B2. These MAbs reacted with L3,7,9 LPS on immunoblots and in the LPS enzyme-linked immunosorbent assay (ELISA) and recognised strains containing L3, L3,7, L8 (except 3A12-E1), or L9 LPS in the whole-cell ELISA. The six other MAbs have been described in previous studies (K. Saukkonen, M. Leinonen, H. Abdillahi, and J.T. Poolman, Vaccine 7:325-328, 1989; R.J.P.M. Scholten, B. Kuipers, H.A. Valkenburg, J. Danjert, W.D. Zollinger, and J.T. Poolman, J. Med. Microbiol., in press) and were obtained after immunization with outer membrane protein complexes containing LPS: MN15A11, MN15A8-1, MN15A17-1, MN11A11G, MN14F20-11, and MN14F21-11. MN15A11 was specific for L3,7,9 LPS and displayed properties similar to those of 3A12-E1. MN15A17-1, MN14F20-1, and MN11A11G were cross-reactive, and MN14F21-11 was specific for the L1,8 immunotype. Epitope specificities of MAbs reacting with L3,7,(8),9 strains were analyzed. MAbs 4D1-B3, 3A12-E1, and 4A8-B2 recognized phosphoethanolamine group-containing oligosaccharide-specific epitopes. MN15A11 and MN15A17-1 were probably directed against a conformational epitope, although for MN5A11 recognition of an unknown L3,7,9-specific epitope in the 2-keto-3-deoxyoctulosonic acid (KDO)-lipid A region cannot be excluded. MN15A8-1, a strongly cross-reactive MAb, recognized a determinant which included the KDO-lipid A region and the more terminal saccharides.(ABSTRACT TRUNCATED AT 250 WORDS)