Abstract
The ability of Bordetella pertussis to bind to cell surfaces was determined with a simple, accurate, reproducible assay measuring the adhesion of radiolabelled bacteria to monolayers of HeLa cells. The rate of adhesion was approximately linear with time for at least 1 h. Viable and radioactivity counts of bound bacteria correlated well. Bacteria grown in the avirulent C-mode were markedly less adhesive than virulent X-mode cells. Reductions in the level of attachment after treatment of bacteria with preparations of specific immunoglobulin suggest that adhesion of B. pertussis depends upon specific mechanisms involving filamentous haemagglutinin and the agglutinogens.