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Wang F, Coureuil M, Osinski T, Orlova A, Altindal T, Gesbert G, Nassif X, Egelman EH, Craig L. Cryoelectron Microscopy Reconstructions of the Pseudomonas aeruginosa and Neisseria gonorrhoeae Type IV Pili at Sub-nanometer Resolution. Structure 2018; 25:1423-1435.e4. [PMID: 28877506 DOI: 10.1016/j.str.2017.07.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 06/03/2017] [Accepted: 07/25/2017] [Indexed: 01/17/2023]
Abstract
We report here cryoelectron microscopy reconstructions of type IV pili (T4P) from two important human pathogens, Pseudomonas aeruginosa and Neisseria gonorrhoeae, at ∼ 8 and 5 Å resolution, respectively. The two structures reveal distinct arrangements of the pilin globular domains on the pilus surfaces, which impart different helical parameters, but similar packing of the conserved N-terminal α helices, α1, in the filament core. In contrast to the continuous α helix seen in the X-ray crystal structures of the P. aeruginosa and N. gonorrhoeae pilin subunits, α1 in the pilus filaments has a melted segment located between conserved helix-breaking residues Gly14 and Pro22, as seen for the Neisseria meningitidis T4P. Using mutagenesis we show that Pro22 is critical for pilus assembly, as are Thr2 and Glu5, which are positioned to interact in the hydrophobic filament core. These structures provide a framework for understanding T4P assembly, function, and biophysical properties.
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Affiliation(s)
- Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Mathieu Coureuil
- Institut Necker-Enfants Malades, INSERM U1151, 14 Rue Maria Helena Vieira Da Silva, CS 61431, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, 15 Rue de l'École de Médecine, 75006 Paris, France
| | - Tomasz Osinski
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Tuba Altindal
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Gaël Gesbert
- Institut Necker-Enfants Malades, INSERM U1151, 14 Rue Maria Helena Vieira Da Silva, CS 61431, 75014 Paris, France
| | - Xavier Nassif
- Institut Necker-Enfants Malades, INSERM U1151, 14 Rue Maria Helena Vieira Da Silva, CS 61431, 75014 Paris, France
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
| | - Lisa Craig
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
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Ren D, Xie H, Zhang W, Hassan F, Petralia RS, Yu S, Lim DJ, Gu XX. Intranasal immunization of the combined lipooligosaccharide conjugates protects mice from the challenges with three serotypes of Moraxella catarrhalis. PLoS One 2011; 6:e29553. [PMID: 22216312 PMCID: PMC3245267 DOI: 10.1371/journal.pone.0029553] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 11/30/2011] [Indexed: 11/25/2022] Open
Abstract
Background There are no licensed vaccines available against Moraxella catarrhalis, a significant human respiratory pathogen. Lipooligosaccharide (LOS) based conjugate vaccines derived from individual serotype M. catarrhalis only showed partial protection coverage. A vaccine combining LOS conjugates of two or three serotypes might provide a broader protection. Methods Mice were immunized intranasally with the combined conjugates consisting of LOS from serotype A and B or serotype A, B, and C followed by challenge with different M. catarrhalis strains of three serotypes. Mouse lungs, nasal washes, and sera were collected after each challenge for bacterial counts, histological evaluation, cytokine profiles, antibody level and binding activity determinations. Results Intranasal administration of the combined LOS conjugates not only enhanced pulmonary bacterial clearance of all three serotypes of M. catarrhalis strains in vaccinated mice, but also elevated serotype-specific anti-LOS immunoglobulin (Ig)A and IgG titers in nasal wash and serum respectively. Mice vaccinated with the combined LOS conjugates also showed increased interferon (IFN)-γ, interleukin (IL)-12, and IL-4 in the lungs after challenges. Compared to the control group, mice immunized with the combined LOS conjugates also showed reduced lung inflammation after M. catarrhalis infections. The hyperimmune sera induced by the combined conjugates exhibited a broad cross-reactivity toward all three serotypes of M. catarrhalis under transmission electron microscopy. Conclusions The combined vaccine of serotype A and B LOS conjugates provides protection against most M. catarrhalis strains by eliciting humoral and cellular immune responses.
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Affiliation(s)
- Dabin Ren
- Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, United States of America
| | - Hang Xie
- Laboratory of Respiratory Viral Diseases, Office of Vaccines Research and Review, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States of America
| | - Wenhong Zhang
- Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, United States of America
| | - Ferdaus Hassan
- Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, United States of America
| | - Ronald S. Petralia
- Section on Neurotransmitter Receptor Biology, NIDCD, NIH, Bethesda, Maryland, United States of America
| | - Shengqing Yu
- Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, United States of America
| | - David J. Lim
- Section on Pathogenesis of Ear Diseases, House Ear Institute, Los Angeles, California, United States of America
| | - Xin-Xing Gu
- Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, United States of America
- * E-mail:
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Cox AD, St. Michael F, Cairns CM, Lacelle S, Filion AL, Neelamegan D, Wenzel CQ, Horan H, Richards JC. Investigating the potential of conserved inner core oligosaccharide regions of Moraxella catarrhalis lipopolysaccharide as vaccine antigens: accessibility and functional activity of monoclonal antibodies and glycoconjugate derived sera. Glycoconj J 2011; 28:165-82. [DOI: 10.1007/s10719-011-9332-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/22/2011] [Accepted: 03/23/2011] [Indexed: 10/18/2022]
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Galactose residues on the lipooligosaccharide of Moraxella catarrhalis 26404 form the epitope recognized by the bactericidal antiserum from conjugate vaccination. Infect Immun 2008; 76:4251-8. [PMID: 18559429 DOI: 10.1128/iai.01570-07] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipooligosaccharide (LOS) from Moraxella catarrhalis has the potential to elicit bactericidal antibodies against the pathogen. We generated LOS-based conjugate vaccines that elicited bactericidal antibodies in animal models. However, epitopes on the LOS recognized by the functional anti-LOS antibodies remain unidentified. In this study, a mutant strain, D4, which lost the recognition by a bactericidal anti-LOS rabbit serum in Western blotting was generated from a serotype C strain 26404 by random transposon mutagenesis. Sequence analysis revealed there was an insertion of a kanamycin resistance gene in the lgt2 gene of D4, which encodes beta(1-4)-galactosyltransferase. An isogenic lgt2 mutant, 26404lgt2, was constructed. Structural analysis indicated that the mutant strain produced a truncated LOS lacking terminal galactoses from 4- and 6-linked oligosaccharide chains of strain 26404. Further studies showed that the antiserum lost the recognition of both mutant cells and LOSs in Western blotting, an enzyme-linked immunosorbent assay (ELISA), or a flow cytometry assay. The antiserum also lost the ability to kill the mutant strain in a bactericidal assay, whereas it showed a bactericidal titer of 1:80 to strain 26404. In an inhibition ELISA, d-(+)-galactose or 26404lgt2 LOS showed no inhibition. However, the 26404 LOS and a serotype A O35E LOS with terminal galactoses on its 6-linked oligosaccharide chain showed >90% inhibition, while a serotype B 26397 LOS showed >60% inhibition. These studies suggest that the terminal alpha-Gal-(1-->4)-beta-Gal on the 6-linked oligosaccharide chain of 26404 LOS plays a critical role in forming the epitope recognized by the bactericidal antiserum induced by immunization with our conjugate vaccine.
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Gergova RT, Iankov ID, Haralambieva IH, Mitov IG. Bactericidal Monoclonal Antibody Against Moraxella catarrhalis Lipooligosaccharide Cross-Reacts with Haemophilus Spp. Curr Microbiol 2007; 54:85-90. [PMID: 17211546 DOI: 10.1007/s00284-005-0463-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2005] [Accepted: 04/18/2006] [Indexed: 10/23/2022]
Abstract
Monoclonal antibodies (MAbs) against lipooligosaccharide (LOS) determinants after immunization of BALB/c mice with heat inactivated Moraxella catarrhalis serotype A were generated. MAb 219A9 was specific for a common epitope of A, B, and C M. catarrhalis serotypes in ELISA and immunofluorescent test (IFT). In both tests it also cross-reacted with whole bacteria and LPS antigens isolated from non-typeable H. influenzae and H. parainfluenzae strains. IgM antibody clone 219A9 possessed a strong bactericidal effect against the three serotypes in the presence of complement. Our results demonstrate that antibodies directed to a single LOS epitope common for A, B, and C serotype could be highly protective. This suggests that the common determinants are very promising in the development of LOS-based vaccine against M. catarrhalis. The cross-reactions of MAb 219A9 with Haemophilus spp. also show that immunization could result in immune response to epitopes conserved in other important respiratory pathogens.
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Affiliation(s)
- Raina T Gergova
- Department of Microbiology, Medical University, Sofia, Bulgaria.
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O'Connor ET, Piekarowicz A, Swanson KV, Griffiss JM, Stein DC. Biochemical analysis of Lpt3, a protein responsible for phosphoethanolamine addition to lipooligosaccharide of pathogenic Neisseria. J Bacteriol 2006; 188:1039-48. [PMID: 16428408 PMCID: PMC1347319 DOI: 10.1128/jb.188.3.1039-1048.2006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The inner core of neisserial lipooligosaccharide (LOS) contains heptose residues that can be decorated by phosphoethanolamine (PEA). PEA modification of heptose II (HepII) can occur at the 3, 6, or 7 position(s). We used a genomic DNA sequence of lpt3, derived from Neisseria meningitidis MC58, to search the genomic sequence of N. gonorrhoeae FA1090 and identified a homolog of lpt3 in N. gonorrhoeae. A PCR amplicon containing lpt3 was amplified from F62DeltaLgtA, cloned, mutagenized, and inserted into the chromosome of N. gonorrhoeae strain F62DeltaLgtA, producing strain F62DeltaLgtAlpt3::Tn5. LOS isolated from this strain lost the ability to bind monoclonal antibody (MAb) 2-1-L8. Complementation of this mutation by genetic removal of the transposon insertion restored MAb 2-1-L8 binding. Mass spectrometry analysis of LOS isolated from the F62DeltaLgtA indicated that this strain contained two PEA modifications on its LOS. F62DeltaLgtAlpt3::Tn5 lacked a PEA modification on its LOS, a finding consistent with the hypothesis that lpt3 encodes a protein mediating PEA addition onto gonococcal LOS. The DNA encoding lpt3 was cloned into an expression vector and Lpt3 was purified. Purified Lpt3 was able to mediate the addition of PEA to LOS isolated from F62DeltaLgtAlpt3::Tn5.
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Affiliation(s)
- Ellen T O'Connor
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Edwards KJ, Schwingel JM, Datta AK, Campagnari AA. Multiplex PCR assay that identifies the major lipooligosaccharide serotype expressed by Moraxella catarrhalis clinical isolates. J Clin Microbiol 2006; 43:6139-43. [PMID: 16333114 PMCID: PMC1317230 DOI: 10.1128/jcm.43.12.6139-6143.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A heterologous cluster of glycosyltransferase genes was identified in the three Moraxella catarrhalis LOS serotype strains. Multiple PCR primers designed to this region amplified products that differentiate between the serotypes more rapidly and efficiently than previously described serological analyses. This assay will be valuable for clinical and research-based studies.
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Affiliation(s)
- Katie J Edwards
- Department of Microbiology, University at Buffalo, Biomedical Research Bldg. Rm. 143, 3435 Main Street, Buffalo, NY 14214, USA
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Edwards KJ, Allen S, Gibson BW, Campagnari AA. Characterization of a cluster of three glycosyltransferase enzymes essential for Moraxella catarrhalis lipooligosaccharide assembly. J Bacteriol 2005; 187:2939-47. [PMID: 15838019 PMCID: PMC1082826 DOI: 10.1128/jb.187.9.2939-2947.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Moraxella catarrhalis isolates express lipooligosaccharide (LOS) molecules on their surface, which share epitopes similar to that of the Neisseria and Haemophilus species. These common LOS epitopes have been implicated in various steps of pathogenesis for the different organisms. In this study, a cluster of three LOS glycosyltransferase genes (lgt) were identified in M. catarrhalis 7169, a strain that produces a serotype B LOS. Mutants in these glycosyltransferase genes were constructed, and the resulting LOS phenotypes were consistent with varying degrees of truncation compared to wild-type LOS. The LOS structures of each lgt mutant were no longer detected by a monoclonal antibody (MAb 4G5) specific to a highly conserved terminal epitope nor by a monoclonal antibody (MAb 3F7) specific to the serotype B LOS side chain. Mass spectrometry of the LOS glycoforms assembled by two of these lgt mutants indicated that lgt1 encodes an alpha(1-2) glucosyltransferase and the lgt2 encodes a beta(1-4) galactosyltransferase. However, these structural studies could not delineate the function for lgt3. Therefore, M. catarrhalis lgt3 was introduced into a defined beta(1-4) glucosyltransferase Haemophilus ducreyi 35000glu- mutant in trans, and monoclonal antibody analysis confirmed that Lgt3 complemented the LOS defect. These data suggest that lgt3 encodes a glucosyltransferase involved in the addition of a beta(1-4)-linked glucose to the inner core. Furthermore, we conclude that this enzymatic step is essential for the assembly of the complete LOS glycoform expressed by M. catarrhalis 7169.
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Affiliation(s)
- Katie J Edwards
- Department of Microbiology, State University of New York at Buffalo, NY 14214, USA
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Yu S, Gu XX. Synthesis and characterization of lipooligosaccharide-based conjugate vaccines for serotype B Moraxella catarrhalis. Infect Immun 2005; 73:2790-6. [PMID: 15845482 PMCID: PMC1087343 DOI: 10.1128/iai.73.5.2790-2796.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Moraxella catarrhalis is an important cause of otitis media in children and respiratory tract infections in the elderly. Lipooligosaccharide (LOS) is a major surface antigen of the bacterium that elicits bactericidal antibodies. Serological studies show that three major LOS types (A, B, and C) have been identified among clinical isolates. Our previous studies demonstrated that the type A LOS-based conjugates were immunogenic in animals. In this study, LOS from type B strain 26397 was detoxified and conjugated to tetanus toxoid (TT) or a cross-reactive mutant (CRM) of diphtheria toxin to form detoxified LOS (dLOS)-TT and dLOS-CRM, respectively, as vaccine candidates. The molar ratios of dLOS to TT and CRM in the conjugates were 43:1 and 19:1, respectively, while both weight ratios were around 0.9. The antigenicity of the conjugates was similar to that of the LOS, as determined by enzyme-linked immunosorbent assay using a rabbit antiserum to strain 26397. Subcutaneous immunization with each conjugate elicited a 180- to 230-fold rise of serum anti-LOS immunoglobulin G in mice and >2,000-fold rise in rabbits. In addition, both mouse and rabbit antisera showed elevated complement-mediated bactericidal activity against the homologous strain, and a representative rabbit antiserum showed bactericidal activity against nine of twelve clinical isolates studied. The bactericidal activity of the rabbit antiserum can be fully inhibited by the type B LOS but not the A or C LOS. These results indicate that the type B LOS-based conjugates can be used as vaccine components for further investigation.
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Affiliation(s)
- Shengqing Yu
- Vaccine Research Facility, National Institute on Deafness and Other Communication Disorders, Rockville, Maryland 20850, USA
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Braun JM, Beuth J, Blackwell CC, Giersen S, Higgins PG, Tzanakaki G, Unverhau H, Weir DM. Neisseria meningitidis, Neisseria lactamica and Moraxella catarrhalis share cross-reactive carbohydrate antigens. Vaccine 2004; 22:898-908. [PMID: 15040943 DOI: 10.1016/j.vaccine.2003.11.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Carriage of commensal bacteria species is associated with the development of natural immunity to meningococcal disease, with lipo-oligosaccharides (LOS) of meningococci being one of the main virulence factors associated with severity of meningococcal disease. Meningococcal reference strains and isolates from the commensal species Neisseria lactamica and Moraxella catarrhalis were assessed for the presence of cross-reactive glycoconjugate antigens. Binding of human blood group antibodies of the P and Ii system to meningococcal immunotype reference strains were in accordance with the presence of known LOS carbohydrate structures. Binding studies with meningococcal immunotyping antibodies and blood group phenotyping antibodies to N. lactamica strains from different European countries showed, that a greater number of isolates obtained from native Greek and Scottish adults and children bound anti-meningococcal L(3, 7, 9) immunotyping (P < 0.001), pK (P = 0.035) and paragloboside (P < 0.001) blood group typing antibodies compared to isolates obtained from children of Russian immigrants in Greece. A greater number of M. catarrhalis strains isolated from children in Scotland bound anti-L(3, 7, 9) antibodies (38.2%) compared to strains isolated from adults (22.2%) (P = 0.017). These findings provide evidence that blood group like glycoconjugate antigens found on the commensal species N. lactamica and M. catarrhalis might be involved in the development of natural immunity to meningococcal endotoxins during childhood, and might be exploited as anti-meningococcal vaccine candidates.
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Affiliation(s)
- Jan M Braun
- Institute for Scientific Evaluation of Naturopathy, University of Cologne, Robert Koch Str. 10, 50931 Cologne, Germany.
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Rosen J, Robobi A, Nyholm PG. Conformation of the branched O-specific polysaccharide of Shigella dysenteriae type 2: molecular mechanics calculations show a compact helical structure exposing an epitope which potentially mimics galabiose. Carbohydr Res 2002; 337:1633-40. [PMID: 12423964 DOI: 10.1016/s0008-6215(02)00089-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Conformational analyses of the branched repeating unit of the O-antigenic polysaccharide of Shigella dysenteriae type 2 have been performed with molecular mechanics MM3. A filtered systematic search on the trisaccharide alpha-D-GalNAc-(1-->3)-[alpha-D-GlcNAc-(1-->4)]-alpha-D-GalNAc forming the branch, shows essentially a single favored conformation. Also, the downstream alpha-D-GalNAc-(1-->4)-alpha-D-Glc linkage is sterically constrained. The alpha-D-Glc-(1-->4)-beta-D-Gal moiety, however, forms a more flexible link region between the branch points, and shows a 90 degrees bend similar to what is known for the galabiose moiety occurring in globo-glycolipids. The calculations indicate that consecutive repeating units in their minimum energy conformation arrange in a helical structure with three repeating units per turn. This helix is very compact and appears to be stabilized by hydrophobic interactions involving the N-acetyl groups at the branch points. Random conformational search suggests the existence of another helical structure with four repeating units per turn. It appears possible that the alpha-D-Glc-(1-->4)-beta-D-Gal moiety, which is exposed on the surface of the helical structures, can evade recognition by the immune system of the host by the mimicry of globo structures.
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Affiliation(s)
- Jimmy Rosen
- Department of Medical Biochemistry, Centre for Structural Biology, Göteborg University, Medicinaregatan 7B, SE-405 30, Göteborg, Sweden
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Hu WG, Chen J, McMichael JC, Gu XX. Functional characteristics of a protective monoclonal antibody against serotype A and C lipooligosaccharides from Moraxella catarrhalis. Infect Immun 2001; 69:1358-63. [PMID: 11179299 PMCID: PMC98028 DOI: 10.1128/iai.69.3.1358-1363.2001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A monoclonal antibody (MAb), designated MAb 8E7 (immunoglobulin G3), specific for Moraxella catarrhalis lipooligosaccharide (LOS) was evaluated for its functional activity in vitro and in a mouse model of colonization. Enzyme-linked immunosorbent assay (ELISA) demonstrated that the MAb 8E7 could be prepared to a high titer against LOS of the homologous strain 035E, and that it had bactericidal activity. MAb 8E7 reacted with M. catarrhalis serotype A and C LOSs but not serotype B LOS, as measured by ELISA and Western blotting. On the basis of published structures of LOSs, this suggests that the epitope recognized by MAb 8E7 is directed to a common sequence of either alpha-GlcNAc-(1-->2)-beta-Glc-(1--> at the branch substituting position 4 of the trisubstituted Glc residue or a terminal tetrasaccharide alpha-Gal-(1-->4)-beta-Gal-(1-->4)-alpha-Glc-(1-->2)-beta-Glc-(1--> at the branch substituting position 6 of the trisubstituted Glc residue. In a whole-cell ELISA, MAb 8E7 reacted with 70% of the 30 wild-type strains and clinical isolates tested. Immuno-electron microscopy demonstrated that MAb 8E7 reacted with a cell surface-exposed epitope of LOS on strain O35E. MAb 8E7 inhibited the adherence of strain O35E to Chang conjunctival epithelial cells by 90%. Passive immunization with MAb 8E7 could significantly enhance the clearance of strain O35E from mouse lungs in an aerosol challenge mouse model. This enhanced bacterial clearance was inhibited when MAb 8E7 was absorbed by M. catarrhalis serotype A LOS, indicating that the M. catarrhalis LOS-directed antibody may play a major role in the enhancement of M. catarrhalis clearance from lungs. These data suggest that MAb 8E7, which recognizes surface-exposed LOS of M. catarrhalis, is a protective antibody against M. catarrhalis.
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Affiliation(s)
- W G Hu
- Laboratory of Immunology, National Institute on Deafness and Other Communication Disorders, Rockville, Maryland 20850, USA
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McMichael JC. Progress toward the development of a vaccine to prevent Moraxella (Branhamella) catarrhalis infections. Microbes Infect 2000; 2:561-8. [PMID: 10865201 DOI: 10.1016/s1286-4579(00)00310-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Moraxella catarrhalis is a major cause of otitis media and respiratory disease. Vaccine development is at the antigen identification stage. This review examines the more promising antigens, including the 200K protein, the hemagglutinins, the lactoferrin-binding proteins, the UspA proteins, the CopB protein, the transferrin-binding proteins, the CD protein, the E protein and lipooligosaccharide conjugates. Clinical testing of some of these antigens should begin soon.
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Affiliation(s)
- J C McMichael
- Wyeth-Lederle Vaccines, 211 Bailey Road, West Henrietta, NY 14586-9728, USA
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Holme T, Rahman M, Jansson PE, Widmalm G. The lipopolysaccharide of moraxella catarrhalis structural relationships and antigenic properties. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 265:524-9. [PMID: 10504382 DOI: 10.1046/j.1432-1327.1999.00731.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Moraxella catarrhalis has recently been shown to be both widespread and pathogenic, in contrast to previous reports. Several factors have been suggested as virulence factors, lipopolysaccharide (LPS) being one. Recent studies have shown the LPS to be without the O-chain, i.e. the polysaccharide part, and to have specific structural features corresponding to each of the three serogroups, A, B and C. The structures resemble in many respects those present in other Gram-negative nonenteric bacteria, with a galabiosyl element as a prominent common denominator. The presence of such common structures suggests that the LPS of these bacteria might be a part of a mechanism of survival for bacteria colonizing the human host.
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Affiliation(s)
- T Holme
- Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden
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