Monoclonal antibodies defining immunogenic regions of pili from Bacteroides nodosus strains 198 (A1), 265 (H1) and 336 (F1).

A total of 17 monoclonal antibodies (MoAb) were used to analyse the antigenic structure of pilus protein from three serogroups of Bacteroides nodosus. The four MoAb which agglutinated pili were serogroup (and subgroup) specific, and the agglutinating epitope was present on the pili monomer and dependent on the intra-chain disulfide bond. Non-agglutinating MoAb identified two further non-linear and serogroup-restricted epitopes on strain 198 (A1) pili and two linear epitopes on 336 (F1) and 265 (H1) pili. Three MoAb cross-reacted with pili from six of the eight major serogroups and recognized an epitope in the N-terminal region of the molecule. This panel of MoAb has therefore identified at least four epitopes on pilus protein and will facilitate serotopic analyses of the immunogenicity of each epitope in sheep during vaccination against footrot.