Acts as a fimbriae subunit, allowing adhesion to host cells. With TolR probably plays a role in maintaining the position of the peptidoglycan cell wall in the periplasm. Acts as a porin with low permeability that allows slow penetration of small solutes; an internal gate slows down solute passage. Monomer and homodimer. Antisera against this protein label the whole length of fimbriae. The extracellular loops are most variable in sequence, and in some bacteria confer sensitivity to phage and/or colicins. No fimbrae seen on bacteria, the outer membrane blebs significantly, bacterial adhesion to human oropharyngeal cells decreases about 65%, significantly reduced ear infections in chinchilla. Immunization of chinchillas with this protein provides partial protection against subsequent infection, suggesting it might be a useful vaccine candidate. Non-typeable Haemophilus influenzae (NTHi) is a primary pathogen in otitis media (inflammation of the middle ear). Belongs to the outer membrane OOP (TC 1.B.6) superfamily. OmpA family.