Production and characterization of a new monoclonal antibody against Neisseria meningitidis: Study of the cross-reactivity with different bacterial genera

We have generated a hybridoma cell line which produces an 8C7Br1 clone of t he IgM antibody isotype. It recognizes the 50-, 65-, and 60-kDa antigens an d is reactive with strains of N. meningitidis in the 98% of local Neisseria genera by Dot-ELISA assays. Two percent of the strains of N. meningitidis B do not present reactivity with the 8C7Br1 monoclonal antibody (MAb). The antibody reacted against N. meningitidis of serogroups A, B, C, X, Y, Z, an d different serotypes and subtypes of N. meningitidis B and C by means of D ot-ELISA and Immunoblot. It cross-reacted with Neisseria gonorrhoeae, Neiss eria lactamica, Haemophilus influenzae type b, Escherichia coli, Salmonella typhimurium, Salmonella typhi, Shigella flexneri, Bordetella pertussis, an d Bacillus subtilis. The 8C7Br1 MAb reacted with the 65-kDa protein present in the prototype meningococcal strains B:16:B6(B2a:P1.5.2) and 2996 (B2b:P 1.5.2). In H. influenzae type b, E. coli and B. subtilis, the MAb recognize d the protein of 60, 65, and 70 kDa, respectively. FACS analysis showed tha t 8C7Br1 MAb could recognize the 50-kDa protein on the surface of N. mening itidis homologous (B:4:P1.9) strain. These results, together with the bacte ricidal activity of 8C7Br1, and an experiment of passive protection in mice , demonstrated the potential importance of the cross-reactive protein as a candidate antigen for N. meningitidis B vaccine composition.