Immuno-electronmicroscopy of fimbriae-like structures on Bordetella pertussis serotype 1.3.

Fimbriae-like filaments were demonstrated on the surface of Bordetella pertussis, serotype 1.3, by negative staining and electronmicroscopy. Immunoelectronmicroscopy with a monoclonal antibody specific for strains possessing agglutinogen 3, and colloidal gold, gave strong labelling of these structures. However, incubation with adsorbed polyclonal anti-agglutinogen 3 serum gave only weak labelling of the distal parts of the filaments and of the bacterial surface. The different binding patterns of the two antisera suggested that the epitopes involved were dissimilar. Thus, agglutinogen 3, as defined by conventional adsorbed sera, appeared to be associated with the fimbriae-like structures but was not necessarily identical to the fimbrial subunit protein. The monoclonal antibody, however was more likely directed against the subunits of the fimbriae-like structures on serotype 1.3 bacteria.