ROLE OF PILI IN HAEMOPHILUS-INFLUENZAE ADHERENCE TO, AND INTERNALIZATION BY, RESPIRATORY CELLS

To determine the role of pill in mediating adherence of type b and non typeable Haemophilus influenzae to several respiratory cell types, pil iated bacteria, nonpiliated phase variants, and nonpiliated mutants po ssessing insertionally inactivated pilin genes were tested. Both pilia ted and nonpiliated strains adhered to HeLa cells, nasal epithelial ce lls, A549 cells (type II pneumocyte-like cells), and two types of trac heal epithelial cells. Nonpiliated organisms adhered better than pilia ted variants to cultured HEp-2 cells, whereas piliated organisms adher ed better than nonpiliated variants to bronchial epithelial cells and to shed buccal epithelial cells. GM1, a pilus receptor analog, inhibit ed pilus- but not nonpilus-mediated adherence. Piliated and nonpiliate d H. influenzae were equally internalized by A549 cells. Thus, pill me diate adherence to some, but not all, cells derived from human respira tory tissues; nonpilus mechanisms contribute to both adherence, and in ternalization, of both piliated and nonpiliated organisms.