A Cation-binding Surface Protein as a Vaccine Antigen to Prevent Moraxella catarrhalis Otitis Media and Infections in Chronic Obstructive Pulmonary Disease.

Moraxella catarrhalis is an exclusively human respiratory tract pathogen that is a common cause of otitis media in children and respiratory tract infections in adults with chronic obstructive pulmonary disease. A vaccine to prevent these infections would have a major impact in reducing the substantial global morbidity and mortality in these populations. Through a genome mining approach, we identified AfeA, an ∼32 kDa substrate binding protein of an ABC transport system as an excellent candidate vaccine antigen. Recombinant AfeA was expressed and purified and binds ferric, ferrous, manganese and zinc ions as demonstrated by thermal shift assays. It is a highly conserved protein that is present in all strains of M. catarrhalis Immunization with recombinant, purified AfeA induces high titer antibodies that recognize the native M. catarrhalis protein. AfeA expresses abundant epitopes on the bacterial surface and induces protective responses in the mouse pulmonary clearance model following aerosol challenge with M. catarrhalis. Finally, AfeA is expressed during human respiratory tract infection of adults with COPD. Based on these observations, AfeA is an excellent vaccine antigen to be included in a vaccine to prevent infections caused by M. catarrhalis.