Bordetella pertussis is the causative agent of whooping cough. An essential step in the disease process is the attachment of the bacteria to the ciliated epithelium of the respiratory tract, enabling the organism to resist normal host-clearance mechanisms. It is unclear which bacterial cell surface component are responsible for adherence but the fimbriae of B.pertussis are prime candidates for being involved in this process. Pili structure on the cell surface. Belongs to the fimbrial protein family.