Outer membrane protein E (OMP E) is a 50-kDa protein of Moraxella 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.Moraxella catarrhalis is an important human respiratory tract pathogen (6,8,9,21,22). It is the third most common cause of otitis media, accounting for 15 to 20% of all episodes based on cultures of middle ear fluid obtained by tympanocentesis (13,29). M. catarrhalis also causes lower respiratory tract infections, often called exacerbations, in adults with chronic obstructive pulmonary disease (COPD) (23,25). It is difficult to state precisely the etiology of exacerbations in individual patients; however, one study estimated that approximately 30% are caused by M. catarrhalis (33). Nosocomial outbreaks of respiratory tract infections caused by M. catarrhalis have been recognized since the mid-1980s (18, 20, 26-28). Many of these outbreaks of infections have occurred in respiratory units where the presence of a susceptible population with underlying lung disease contributed to the clusters.In view of the importance of M. catarrhalis as a human pathogen, there is interest in developing a vaccine to prevent these infections. Two populations would benefit most from such a vaccine. Infants would be immunized in an effort to prevent otitis media, with particular emphasis on preventing recurrent otitis media in otitis-prone children. The second population that would benefit from such a vaccine is adults with COPD.Outer membrane protein E (OMP E) is a 50-kDa heatmodifiable outer membrane protein (OMP) which has characteristics that indicate that it may be an effective vaccine antigen (2, 3). The protein is abundantly expressed on the bacterial surface as demonstrated by immunofluorescence assays and flow cytometry with monoclonal antibodies (MAbs) (3). OMP E is highly conserved among strains of M. catarrhalis (2, 3). These two features of OMP E suggest that inducing an immune response to the protein may result in protection from infection.The present study was undertaken to further characterize the antigenic structure of OMP E. MAbs were developed and characterized. The regions of the OMP E molecule bound by the MAbs were identified, and two mutants which are defective in...

Outer membrane protein E (OMP E) is a 50-kDa protein of Moraxella 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 of ompE 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 of ompE 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.Moraxella catarrhalis is a common and important human respiratory tract pathogen. It is the third most common cause of otitis media in children, accounting for approximately 3.5 million episodes of otitis media annually in the United States (6,11,15,20,25). Adults with chronic obstructive pulmonary disease (COPD) experience recurrent lower respiratory tract infections, often called exacerbations. M. catarrhalis is a common cause of these infections (15,18,23,27,30). Exacerbations of COPD lead to substantial morbidity and mortality and increased health care costs worldwide (14,19,22). In view of the impact of M. catarrhalis infections, there is considerable interest in developing a vaccine to prevent infections caused by M. catarrhalis. Infants would be immunized to prevent otitis media, with particular emphasis on preventing otitis media in otitis-prone children who experience recurrent episodes of otitis media. The second population which would benefit from such a vaccine would be adults with COPD.Outer membrane protein E (OMP E) is a 50-kDa heatmodifiable OMP which has characteristics indicating that it may be an effective vaccine antigen (3, 4). The protein is expressed in all strains of M. catarrhalis studied thus far (2, 4, 16). Three independent lines of experiments indicate that OMP E contains epitopes on the bacterial surface; these include adsorption studies with polyclonal antisera raised to whole bacterial cells (16), immunofluorescence microscopy with polyclonal antisera raised to purified OMP E (4), and flow cytometry with monoclonal antibodies (MAbs) (4, 17).An important consideration in evaluating an OMP as a potential vaccine is the extent to which the protein is conserved among strains of the species. An ideal vaccine candidate would be highly conserved among strains so that immunization with the protein from one strain would gene...

To determine whether the nasopharynx of children is colonized by a single or multiple strains of nontypeable Haemophilus influenzae, cultures were obtained from six nasopharyngeal sites in five children. For each child, all isolates yielded identical polymerase chain reaction fingerprints. The results indicate that these children were colonized in the nasopharynx with a single strain of nontypeable Haemophilus influenzae at one time.

No abstract