Monoclonal antibodies against pertussis toxin subunits

By immunizing Balb/c mice with glutaraldehyde- inactivated pertussis toxin (PT), we obtained monoclonal antibodies (MAbs) against the PT subunits S1, S2 and S4. MAbs against subunit S5 were obtained by immunizing with the recombinant S5 subunit. Some of the MAbs against the subunit S1 were able to neutralize pertussis toxin in the Chinese hamster ovary cell assay. Recombinant fragments containing only parts of the S1 subunit were then used to map the epitopes recognized by the anti-S1 MAbs. We show that the non-protective MAb 6G7 recognizes an epitope centered at position 143 and that substitution of arginine 143 with threonine abolishes antibody binding.