Hag mediates adherence of Moraxella catarrhalis to ciliated human airway cells.
Moraxella catarrhalis is a human pathogen causing otitis media in infants and respiratory infections in adults, particularly patients with chronic obstructive pulmonary disease. The surface protein Hag (also designated MID) has previously been shown to be a key adherence factor for several epithelial cell lines relevant to pathogenesis by M. catarrhalis, including NCIH292 lung cells, middle ear cells, and A549 type II pneumocytes. In this study, we demonstrate that Hag mediates adherence to air-liquid interface cultures of normal human bronchial epithelium (NHBE) exhibiting mucociliary activity. Immunofluorescent staining and laser scanning confocal microscopy experiments demonstrated that the M. catarrhalis wild-type isolates O35E, O12E, TTA37, V1171, and McGHS1 bind principally to ciliated NHBE cells and that their corresponding hag mutant strains no longer associate with cilia. The hag gene product of M. catarrhalis isolate O35E was expressed in the heterologous genetic background of a nonadherent Haemophilus influenzae strain, and quantitative assays revealed that the adherence of these recombinant bacteria to NHBE cultures was increased 27-fold. These experiments conclusively demonstrate that the hag gene product is responsible for the previously unidentified tropism of M. catarrhalis for ciliated NHBE cells.
Balder
Rachel
R
Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia 30602, USA.
Krunkosky
Thomas M
TM
Nguyen
Chi Q
CQ
Feezel
Lacey
L
Lafontaine
Eric R
ER
D018829:Adhesins, Bacterial / Q000235:genetics / Q000502:physiology*; D000328:Adult; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology*; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006193:Haemophilus influenzae / Q000235:genetics / Q000472:pathogenicity; D006801:Humans; D007223:Infant; D018613:Microscopy, Confocal; D001936:Moraxella catarrhalis / Q000472:pathogenicity*; D020545:Respiratory Mucosa / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology*
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C464644:Hag-1 protein, Moraxella catarrhalis; D037521:Virulence Factors