title: Comparison of the serological responses to Moraxella catarrhalis immunoglobulin D-binding outer membrane protein and the ubiquitous surface proteins A1 and A2.
abstract: Moraxella catarrhalis immunoglobulin D-binding protein (MID) is a complex antigen with unique immunoglobulin D (IgD)-binding, adhesion, and hemagglutination properties. Previous studies have shown that antibodies raised against MID764-913 in rabbits inhibited M. catarrhalis adhesion to human alveolar epithelial cells, and immunization with MID764-913 resulted in an increased pulmonary clearance in a murine model. Strong immune responses against MID have also consistently been shown in humans. Here, the MID-specified IgG responses were compared to those of ubiquitous surface proteins A1 and A2 (UspA1/A2) using a series of recombinant fragments that spanned all three proteins. Sera were obtained from young children, aged 6 months to 1 year (n=8) and 2 to 3 years (n=15), and healthy adults (n=16). Acute- and convalescent-phase sera from chronic obstructive pulmonary disease (COPD) patients with M. catarrhalis infective exacerbations (n=23) were also analyzed. Young children, who are at risk of M. catarrhalis infection, had low levels of anti-MID and anti-UspA1/A2 antibodies. Healthy adults and the majority of COPD patients (16/23) had high levels of antibodies directed against, among others, the adhesive domain of MID and the fibronectin- and C3-binding domains of UspA1/A2. Among eight COPD patients in whom a rise in antibody levels could be detected, these functional domains were also the main regions targeted by the antibodies. In addition, human IgG directed against MID was bactericidal and anti-MID antibodies were additive to antibodies targeting UspA1/A2. Hence, the functional domains in these three antigens may have significant potential in a future vaccine against M. catarrhalis.
authors.affiliation: Medical Microbiology, Department of Laboratory Medicine, Malmö University Hospital, Lund University, SE-205 02, Malmö, Sweden.
authors.forename: Thuan Tong
authors.initials: TT
authors.lastname: Tan
authors.forename: Jens Jørgen
authors.initials: JJ
authors.lastname: Christensen
authors.forename: Morten Hanefeld
authors.initials: MH
authors.lastname: Dziegiel
authors.forename: Arne
authors.initials: A
authors.lastname: Forsgren
authors.forename: Kristian
authors.initials: K
authors.lastname: Riesbeck
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000097:blood / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000097:blood / Q000276:immunology*; D001426:Bacterial Proteins / Q000097:blood / Q000276:immunology*; D002675:Child, Preschool; D006801:Humans; D007072:Immunoglobulin D / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D001936:Moraxella catarrhalis / Q000276:immunology*; D010727:Phosphoric Diester Hydrolases / Q000097:blood / Q000276:immunology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000276:immunology / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D007072:Immunoglobulin D; D007074:Immunoglobulin G; C089675:UspA protein, Moraxella catarrhalis; D010727:Phosphoric Diester Hydrolases; C087921:glpQ protein, Bacteria