scholarly journals Mapping of a Protective Epitope of the CopB Outer Membrane Protein of Moraxella catarrhalis

1998 ◽  
Vol 66 (2) ◽  
pp. 540-548 ◽  
Author(s):  
Christoph Aebi ◽  
Leslie D. Cope ◽  
Jo L. Latimer ◽  
Sharon E. Thomas ◽  
Clive A. Slaughter ◽  
...  
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Moraxella Catarrhalis ◽  
Amino Acid Sequences ◽  
Nucleotide Sequence Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Protective Epitope

ABSTRACT A monoclonal antibody (MAb) (MAb 10F3) directed against the CopB outer membrane protein of Moraxella catarrhalis previously was found to enhance pulmonary clearance of M. catarrhalisin an animal model (M. Helminen, I. Maciver, J. L. Latimer, L. D. Cope, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 61:2003–2010, 1993). In the present study, this same MAb was shown to exert complement-dependent bactericidal activity against this pathogen in vitro. Nucleotide sequence analysis of thecopB gene from two MAb 10F3-reactive and two MAb 10F3-unreactive strains of M. catarrhalis revealed that the deduced amino acid sequences of these four CopB proteins were at least 90% identical. Comparison of the amino acid sequences of these proteins allowed localization of possible MAb 10F3 binding sites to five relatively small regions of the CopB protein from M. catarrhalis O35E. When five synthetic peptides representing these regions were tested for their ability to bind MAb 10F3 in a direct enzyme-linked immunosorbent assay system, an oligopeptide containing 26 amino acids was shown to bind this MAb. The actual binding region for MAb 10F3 was localized further through the use of overlapping decapeptides that spanned this 26-mer. A fusion protein containing the same 26-mer readily bound MAb 10F3 and was used to immunize mice. The resultant antiserum contained antibodies that reacted with the CopB protein of the homologous M. catarrhalis strain in Western blot analysis and bound to the surface of both homologous and heterologous strains of M. catarrhalis.

scholarly journals Sequence Polymorphism, Predicted Secondary Structures, and Surface-Exposed Conformational Epitopes of Campylobacter Major Outer Membrane Protein

2000 ◽  
Vol 68 (10) ◽  
pp. 5679-5689 ◽  
Author(s):  
Qijing Zhang ◽  
Jerrel C. Meitzler ◽  
Shouxiong Huang ◽  
Teresa Morishita
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Major Outer Membrane Protein ◽  
Amino Acid Sequences ◽  
Variable Regions ◽  
Conserved Sequences ◽  
Conformational Epitopes

ABSTRACT The major outer membrane protein (MOMP), a putative porin and a multifunction surface protein of Campylobacter jejuni, may play an important role in the adaptation of the organism to various host environments. To begin to dissect the biological functions and antigenic features of this protein, the gene (designatedcmp) encoding MOMP was identified and characterized from 22 strains of C. jejuni and one strain of C. coli. It was shown that the single-copy cmp locus encoded a protein with characteristics of bacterial outer membrane proteins. Prediction from deduced amino acid sequences suggested that each MOMP subunit consisted of 18 β-strands connected by short periplasmic turns and long irregular external loops. Alignment of the amino acid sequences of MOMP from different strains indicated that there were seven localized variable regions dispersed among highly conserved sequences. The variable regions were located in the putative external loop structures, while the predicted β-strands were formed by conserved sequences. The sequence homology of cmp appeared to reflect the phylogenetic proximity of C. jejuni strains, since strains with identical cmp sequences had indistinguishable or closely related macrorestriction fragment patterns. Using recombinant MOMP and antibodies recognizing linear or conformational epitopes of the protein, it was demonstrated that the surface-exposed epitopes of MOMP were predominantly conformational in nature. These findings are instrumental in the design of MOMP-based diagnostic tools and vaccines.

scholarly journals Human Immune Response to Outer Membrane Protein CD of Moraxella catarrhalis in Adults with Chronic Obstructive Pulmonary Disease

2003 ◽  
Vol 71 (3) ◽  
pp. 1288-1294 ◽  
Author(s):  
Timothy F. Murphy ◽  
Charmaine Kirkham ◽  
Dai-Fang Liu ◽  
Sanjay Sethi
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Immune Response ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Pulmonary Disease ◽  
Outer Membrane Protein ◽  
Moraxella Catarrhalis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease

ABSTRACT Moraxella catarrhalis is a common cause of lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). The antibody response to outer membrane protein (OMP) CD, a highly conserved surface protein of M. catarrhalis under consideration as a vaccine antigen, was studied in adults with COPD following 40 episodes of infection or colonization. Following infection or colonization, 9 of 40 patients developed new serum immunoglobulin G (IgG) to OMP CD, as measured by enzyme-linked immunosorbent assay. Adsorption assays revealed that a proportion of the serum IgG was directed toward surface-exposed epitopes on OMP CD in six of the nine patients who developed new IgG to OMP CD. Immunoblot assays with fusion peptide constructs indicated that the new antibodies that developed after infection or colonization recognized conformational epitopes, particularly in the carboxy region of the protein. Three of 28 patients developed new mucosal IgA to OMP CD in sputum supernatants. This study establishes that OMP CD is a target of a systemic and mucosal immune response following infection and colonization in some patients with COPD.

The porin OmpC ofSalmonella typhimuriummediates adherence to macrophages

1999 ◽  
Vol 45 (8) ◽  
pp. 658-669 ◽  
Author(s):  
Robert S Negm ◽  
Thomas G Pistole
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Virulent Strain ◽  
Salmonella Typhi ◽  
Amino Acid Sequences ◽  
Wild Type ◽  
E Coli ◽  
Host Cell Recognition

Macrophages recognize, adhere to, and phagocytose Salmonella typhimurium. The major outer membrane protein OmpC is a candidate ligand for macrophage recognition. To confirm this we used transposon mutagenesis to develop an ompC-deficient mutant in a known virulent strain of S. typhimurium; mutant and wild type were compared in macrophage adherence and association assays. Radiolabeled wild type S. typhimurium bound to macrophages at five-fold higher levels than did the ompC mutant. In association assays, macrophages in monolayers bound and internalized three-fold more wild type than mutant, while macrophages in suspension bound and internalized 40-fold more wild type than mutant. The ompC gene of our test strain of S. typhimurium contains several discrete differences compared with the ompC genes of Salmonella typhi and Escherichia coli. The deduced OmpC amino acid sequence of S. typhimurium shares 77 and 98% identity with OmpC amino acid sequences of E. coli and S. typhi, respectively. Evidence from this study supports a role for the OmpC protein in initial recognition by macrophages and distinguishes regions of this protein that potentially participate in host-cell recognition of bacteria by phagocytic cells.Key words: Salmonella, porin, macrophage, outer membrane protein, DNA sequencing.

scholarly journals Moraxella catarrhalis Outer Membrane Protein CD Elicits Antibodies That Inhibit CD Binding to Human Mucin and Enhance Pulmonary Clearance of M. catarrhalis in a Mouse Model

2007 ◽  
Vol 75 (6) ◽  
pp. 2818-2825 ◽  
Author(s):  
Dai-Fang Liu ◽  
John C. McMichael ◽  
Steven M. Baker
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Moraxella Catarrhalis ◽  
Signal Sequence ◽  
Vaccine Antigen ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Bacterial Clearance ◽  
Vitro Assay

ABSTRACT The outer membrane protein CD of Moraxella catarrhalis is considered to be a potential vaccine antigen against Moraxella infection. We purified the native CD from isolate O35E, administered it to mice, and detected considerable titers of anti-CD antibodies. Anti-CD sera were cross-reactive towards six different M. catarrhalis isolates and promoted bacterial clearance of O35E in a pulmonary challenge model. To circumvent the difficulty of generating large quantities of CD from M. catarrhalis for vaccine use, the CD gene from O35E was cloned into Escherichia coli, and the recombinant CD, expressed without a signal sequence or fusion tags, represented ∼70% of the total E. coli proteins. The recombinant CD formed inclusion bodies that were solubilized with 6 M urea and then purified by ion-exchange chromatography, a procedure that produced soluble CD of high purity and yield. Mice immunized with the purified recombinant CD had significant titers of anti-CD antibodies that were cross-reactive towards 24 different M. catarrhalis isolates. Upon challenge, these mice showed enhanced bacterial clearance of both O35E and a heterologous M. catarrhalis isolate, TTA24. In an in vitro assay, antisera to either the native or the recombinant CD inhibited the binding activity of CD to human tracheobronchial mucin in a serum concentration-dependent manner, and the extent of inhibition appeared to correlate with the corresponding anti-CD antibody titer and whole-cell enzyme-linked immunosorbent assay titer. Our results demonstrate that the recombinant CD is a promising vaccine candidate for preventing Moraxella infection.

scholarly journals The Immunoglobulin D-Binding Protein MID from Moraxella catarrhalis Is Also an Adhesin

2003 ◽  
Vol 71 (6) ◽  
pp. 3302-3309 ◽  
Author(s):  
Arne Forsgren ◽  
Marta Brant ◽  
Mirela Karamehmedovic ◽  
Kristian Riesbeck
Keyword(s):  
Amino Acid ◽  
Epithelial Cells ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Moraxella Catarrhalis ◽  
Binding Protein ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Immunoglobulin D

ABSTRACT The Moraxella catarrhalis immunoglobulin D (IgD)-binding protein (MID) is a 200-kDa outer membrane protein displaying a unique and specific affinity for human IgD. MID is found in the majority of M. catarrhalis strains. In the present paper, we show that MID-expressing M. catarrhalis strains agglutinate human erythrocytes and bind to type II alveolar epithelial cells. In contrast, M. catarrhalis isolates with low MID expression levels and two mutants deficient in MID, but with readily detectable UspA1 expression, do not agglutinate erythrocytes and have a 50% lower adhesive capacity. To examine the adhesive part of MID, the protein was dissected into nine fragments covering the entire molecule. The truncated MID proteins were expressed in Escherichia coli, purified, and used for raising polyclonal antibodies in rabbits. Interestingly, by using recombinant fragments, we show that the hemagglutinating and adhesive part of MID is localized within the 150-amino-acid fragment MID764-913. In addition, antibodies against full-length MID, MID764-913, or a 30-amino-acid consensus sequence (MID775-804) inhibited adhesion to alveolar epithelial cells. Antibodies against UspA1, an outer membrane protein expressed in essentially all M. catarrhalis strains, also inhibited adhesion, suggesting that both MID and UspA1 are needed for optimal attachment to epithelial cells. Taken together, in addition to MID-dependent IgD binding, we have demonstrated that the outer membrane protein MID is a novel adhesin that would be a suitable target for a future vaccine against M. catarrhalis.

scholarly journals Bactericidal and Cross-Protective Activities of a Monoclonal Antibody Directed against Neisseria meningitidis NspA Outer Membrane Protein

1999 ◽  
Vol 67 (9) ◽  
pp. 4955-4959 ◽  
Author(s):  
Nathalie Cadieux ◽  
Martin Plante ◽  
Clément R. Rioux ◽  
Josée Hamel ◽  
Bernard R. Brodeur ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Predicted Amino Acid Sequence ◽  
Meningococcal Infections ◽  
Meningococcal Strain ◽  
Conserved Epitope

ABSTRACT The cross-bactericidal and cross-protective activities of a monoclonal antibody (MAb) named Me-7, which is directed against an antigenically highly conserved epitope on the meningococcal NspA protein, were studied. This MAb efficiently killed in vitro, in the presence of rabbit or human serum, 13 of 14 meningococcal strains tested, including 9 of 9, 2 of 3, and 2 of 2 strains of serotypes B, A, and C, respectively. MAb Me-7 also significantly reduced by more than 75% the levels of bacteremia recorded for mice challenged with 10 of 11 meningococcal strains tested. Analysis of the predicted amino acid sequence of the NspA protein from the meningococcal strain MCH88 (A:4:P1.10), which was not killed by MAb Me-7, indicated the presence of an additional glutamine residue at position 73, compared to the three other NspA sequences. The data presented in this study suggest that antibodies directed against this highly conserved outer membrane protein could protect against meningococcal infections.

scholarly journals Genetic Diversity of the 28-Kilodalton Outer Membrane Protein Gene in Human Isolates of Ehrlichia chaffeensis

1999 ◽  
Vol 37 (4) ◽  
pp. 1137-1143 ◽  
Author(s):  
Xue-Jie Yu ◽  
Jere W. McBride ◽  
David H. Walker
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Dna Sequence ◽  
Outer Membrane Protein ◽  
Signal Sequence ◽  
Outer Membrane Proteins ◽  
Protein A ◽  
Amino Acid Sequences ◽  
Ehrlichia Chaffeensis

The Ehrlichia chaffeensis 28-kDa outer membrane protein (p28) gene was sequenced completely by genomic walking with adapter PCR. The DNA sequence of the p28 gene was nearly identical to the previously reported sequence (N. Ohashi, N. Zhi, Y. Zhang, and Y. Rikihisa, Infect. Immun. 66:132–139, 1998), but analysis of a further 75 bp on the 5′ end of the gene revealed DNA that encoded a 25-amino-acid signal sequence. The leader sequence was removed from the N terminus of a 30-kDa precursor to generate the mature p28 protein. A monoclonal antibody (MAb), 1A9, recognizing four outer membrane proteins of E. chaffeensis (Arkansas strain) including the 25-, 26-, 27-, and 29-kDa proteins (X.-J. Yu, P. Brouqui, J. S. Dumler, and D. Raoult, J. Clin. Microbiol. 31:3284–3288, 1993) reacted with the recombinant p28 protein. This result indicated that the four proteins recognized by MAb 1A9 were encoded by the multiple genes of the 28-kDa protein family. DNA sequence alignment analysis revealed divergence of p28 among all five human isolates of E. chaffeensis. The E. chaffeensis strains could be divided into three genetic groups on the basis of the p28 gene. The first group consisted of the Sapulpa and St. Vincent strains. They had predicted amino acid sequences identical to each other. The second group contained strain 91HE17 and strain Jax, which only showed 0.4% divergence from each other. The third group contained the Arkansas strain only. The amino acid sequences of p28 differed by 11% between the first two groups, by 13.3% between the first and third groups, and by 13.1% between the second and third groups. The presence of antigenic variants of p28 among the strains of E. chaffeensis and the presence of multiple copies of heterogeneous genes suggest a possible mechanism by which E. chaffeensismight evade the host immune defenses. Whether or not immunization with the p28 of one strain of E. chaffeensis would confer cross-protection against other strains needs to be investigated.

scholarly journals Serum Resistance in Haemophilus ducreyiRequires Outer Membrane Protein DsrA

2000 ◽  
Vol 68 (3) ◽  
pp. 1608-1619 ◽  
Author(s):  
Christopher Elkins ◽  
K. John Morrow ◽  
Bonnie Olsen
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Serum Antibody ◽  
Amino Acid Sequences ◽  
Serum Resistance ◽  
Naturally Occurring

ABSTRACT Haemophilus ducreyi is resistant to killing by normal serum antibody and complement. We discovered an H. ducreyiouter membrane protein required for expression of serum resistance and termed it DsrA (for “ducreyi serum resistance A”). ThedsrA locus was cloned, sequenced, and mutagenized. An isogenic mutant (FX517) of parent strain 35000 was constructed and characterized, and it was found to no longer express dsrA. FX517 was at least 10-fold more serum susceptible than 35000. DsrA was expressed by all strains of H. ducreyi tested, except three naturally occurring, avirulent, serum-sensitive strains. FX517 and the three naturally occurring dsrA-nonexpressing strains were complemented in trans with a plasmid expressingdsrA. All four strains were converted to a serum-resistant phenotype, including two that contained truncated lipooligosaccharide (LOS). Therefore, serum resistance in H. ducreyi does not require expression of full-length LOS but does require expression ofdsrA. The dsrA locus from eight additionalH. ducreyi strains was sequenced, and the deduced amino acid sequences were more than 85% identical. The major difference between the DsrA proteins was due to the presence of one, two, or three copies of the heptameric amino acid repeat NTHNINK. These repeats account for the variability in apparent molecular mass of the monomeric form of DsrA (28 to 35 kDa) observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Since DsrA is present in virulent strains, is highly conserved, and is required for serum resistance, we speculate that it may be a virulence factor and a potential vaccine candidate.

scholarly journals Characterization of the Humoral Immune Response to Chlamydia Outer Membrane Protein 2 in Chlamydial Infection

2003 ◽  
Vol 10 (1) ◽  
pp. 103-107 ◽  
Author(s):  
I. Portig ◽  
J. C. Goodall ◽  
R. L. Bailey ◽  
J. S. H. Gaston
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Chlamydial Infection ◽  
Chlamydia Pneumoniae ◽  
Specific Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Recent Infection ◽  
Humoral Immune ◽  
Immunodominant Antigen

ABSTRACT Detection of antibodies to an outer membrane protein 2 (OMP2) by enzyme-linked immunosorbent assay (ELISA) by using either the Chlamydia trachomatis- or the Chlamydia pneumoniae-specific protein was investigated. OMP2 is an immunodominant antigen giving rise to antibody responses in humans infected with different C. trachomatis serovars (A to C and D to K) or with C. pneumoniae, which could be detected by OMP2 ELISA. OMP2 ELISA is not species specific, but antibody titers were usually higher on the homologous protein. The sensitivity of this assay was high but varied according to the “gold standard” applied. Levels of antibody to C. pneumoniae OMP2 as detected by ELISA seem to return to background or near-background values within a shorter period of time compared to antibodies to C. pneumoniae detected by microimmunofluorescence (MIF), making it more likely that positive results in ELISA reflect recent infection. Thus, OMP2 ELISA has distinct advantages over MIF and commercially available ELISAs and might be a useful tool for the serodiagnosis of chlamydial infection.

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