Antigenic Structure of Outer Membrane Protein E ofMoraxella catarrhalis and Construction and Characterization of Mutants

ABSTRACT Outer membrane protein E (OMP E) is a 50-kDa protein ofMoraxella catarrhalis which possesses several characteristics indicating that the protein will be an effective vaccine antigen. To study the antigenic structure of OMP E, eight monoclonal antibodies were developed and characterized. Three of the antibodies recognized epitopes which are present on the bacterial surface. Fusion peptides corresponding to overlapping regions of OMP E were constructed, and immunoblot assays were performed to localize the areas of the molecule bound by the monoclonal antibodies. These studies identified a surface-exposed epitope in the region of amino acids 80 through 180. To further study the protein, two mutants which lack OMP E were constructed. In bactericidal assays, the mutants were more readily killed by normal human serum compared to the isogenic parent strains. These results indicate that OMP E is involved in the expression of serum resistance of M. catarrhalis.

Download Full-text

Conservation of Outer Membrane Protein E among Strains of Moraxella catarrhalis

Infection and Immunity ◽

10.1128/iai.69.6.3576-3580.2001 ◽

2001 ◽

Vol 69 (6) ◽

pp. 3576-3580 ◽

Cited By ~ 18

Author(s):

Timothy F. Murphy ◽

Aimee L. Brauer ◽

Norine Yuskiw ◽

Erin R. McNamara ◽

Charmaine Kirkham

Keyword(s):

Monoclonal Antibodies ◽

Membrane Protein ◽

Respiratory Tract ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Moraxella Catarrhalis ◽

Vaccine Antigen ◽

Effective Vaccine ◽

Human Respiratory Tract ◽

The Stability

ABSTRACT Outer membrane protein E (OMP E) is a 50-kDa protein ofMoraxella catarrhalis which has several features that suggest that the protein may be an effective vaccine antigen. To assess the conservation of OMP E among strains of M. catarrhalis,22 isolates were studied with eight monoclonal antibodies which recognize epitopes on different regions of the protein. Eighteen of 22 strains were reactive with all eight antibodies. The sequences ofompE from 16 strains of M. catarrhalis were determined, including the 4 strains which were nonreactive with selected monoclonal antibodies. Analysis of sequences indicate a high degree of conservation among strains, with sequence differences clustered in limited regions of the gene. To assess the stability ofompE during colonization of the human respiratory tract, the sequences of ompE of isolates collected from patients colonized with the same strain for 3 to 9 months were determined. The sequences remained unchanged. These results indicate that OMP E is highly conserved among strains of M. catarrhalis, and preliminary studies indicate that the gene which encodes OMP E remains stable during colonization of the human respiratory tract.

Download Full-text

Subinhibitory Concentrations of Antimicrobial Agents Reduce the Uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 Cells by Altering the Expression of Virulence-Associated Antigens

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.11.2870 ◽

1998 ◽

Vol 42 (11) ◽

pp. 2870-2876 ◽

Cited By ~ 8

Author(s):

P. Christian Lück ◽

Jürgen W. Schmitt ◽

Arne Hengerer ◽

Jürgen H. Helbig

Keyword(s):

Monoclonal Antibodies ◽

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Legionella Pneumophila ◽

Antimicrobial Agents ◽

Acanthamoeba Castellanii ◽

Host Cells ◽

Uncharacterized Protein ◽

Subinhibitory Concentrations

ABSTRACT We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reducedLegionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionellaantigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected.

Download Full-text

Immunoglobulin G antibodies directed against protein III block killing of serum-resistant Neisseria gonorrhoeae by immune serum.

Journal of Experimental Medicine ◽

10.1084/jem.164.5.1735 ◽

1986 ◽

Vol 164 (5) ◽

pp. 1735-1748 ◽

Cited By ~ 85

Author(s):

P A Rice ◽

H E Vayo ◽

M R Tam ◽

M S Blake

Keyword(s):

Membrane Protein ◽

Neisseria Gonorrhoeae ◽

Human Serum ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Immune Serum ◽

Igg Antibodies ◽

Porin Protein ◽

Blocking Activity ◽

Normal Human

Neisseria gonorrhoeae that resist complement-dependent killing by normal human serum (NHS) are sometimes killed by immune convalescent serum from patients recovering from disseminated gonococcal infection (DGI). In these studies, killing by immune serum was prevented or blocked by IgG isolated from NHS. Purified human IgG antibodies directed against gonococcal protein III, an antigenically conserved outer membrane protein, contained most of the blocking activity in IgG. Antibodies specific for gonococcal porin (protein I), the major outer membrane protein, displayed no blocking function. In separate experiments, immune convalescent DGI serum which did not exhibit bactericidal activity was restored to killing by selective depletion of protein III antibodies by immunoabsorption. These studies indicate that protein III antibodies in normal and immune human serum play a role in serum resistance of N. gonorrhoeae.

Download Full-text