Exploration of<i>Moraxella catarrhalis</i>outer membrane proteins, CD and UspA, as new carriers for lipooligosaccharide-based conjugates

Hu, Weigang; Berry, Julie; Chen, Jing; Gu, Xin-Xing

doi:10.1016/j.femsim.2004.02.001

Cited by 16 publications

(10 citation statements)

References 44 publications

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“…Our current bactericidal assay revealed that 50 to 65% of the BALB/c mouse antisera elicited by the conjugates plus Ribi adjuvant showed bactericidal activity against the homologous type B strain. This result is partially consistent with type A dLOS-protein conjugates, where 45% of outbred mouse antisera and up to 100% of BALB/c mouse antisera showed bactericidal activity (21,29). It is not clear if the dif- ference is due to different LOS serotypes, protein carriers, mouse strains, or the assays themselves.…”

Section: Discussionmentioning

confidence: 53%

Synthesis and Characterization of Lipooligosaccharide-Based Conjugate Vaccines for Serotype B Moraxella catarrhalis

2005

Infect Immun

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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.Moraxella catarrhalis is a gram-negative diplococcus, currently the third leading cause of otitis media and sinusitis in children along with Streptococcus pneumoniae and nontypeable Haemophilus influenzae (4,5,15,17). Up to 80% of children below 3 years of age will be diagnosed with at least one episode of acute otitis media, and 15 to 20% of these middle-ear infections are caused by M. catarrhalis (18,43). Sinusitis, however, accounts for 5 to 10% of upper respiratory tract infections in early childhood (53). In addition, M. catarrhalis is a frequent cause of lower respiratory tract infections in the elderly, particularly in those with a compromised immune system or chronic obstructive pulmonary disease, where M. catarrhalis can cause severe infections such as pneumonia that can be life-threatening (44). Presently, treatment of the diseases has largely relied on antimicrobial agents. However, with growing antibiotic resistance observed in clinical isolates (34), attention has been focused on the possibility of vaccination against M. catarrhalis.

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Section: Discussionmentioning

confidence: 53%

Synthesis and Characterization of Lipooligosaccharide-Based Conjugate Vaccines for Serotype B Moraxella catarrhalis

2005

Infect Immun

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“…We showed that antibodies derived in this way were bactericidal and protective against wild-type N. meningitidis strains [10]. Previous studies on LPS based vaccines to combat M. catarrhalis have been carried out in the laboratories of Gu [13][14][15][16][17][18][19]. This elegant research has documented that it is indeed possible to raise bactericidal antibodies to M. catarrhalis following immunisation with LPS-based glycoconjugates.…”

Section: Introductionmentioning

confidence: 88%

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

et al. 2011

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We investigated the conservation and antibody accessibility of inner core epitopes of Moraxella catarrhalis lipopolysaccharide (LPS) in order to assess their potential as vaccine candidates. Two LPS mutants, a single mutant designated lgt2 and a double mutant termed lgt2/lgt4, elaborating truncated inner core structures were generated in order to preclude expression of host-like outer core structures and to create an inner core structure that was shared by all three serotypes A, B and C of M. catarrhalis. Murine monoclonal antibodies (mAbs), designated MC2-1 and MC2-10 were obtained by immunising mice with the lgt2 mutant of M. catarrhalis serotype A strain. We showed that mAb MC2-1 can bind to the core LPS of wild-type (wt) serotype A, B and C organisms and concluded that mAb MC2-1 defines an immunogenic inner core epitope of M. catarrhalis LPS. We were unsuccessful in obtaining mAbs to the lgt2/lgt4 mutant. MAb MC2-10 only recognised the lgt2 mutant and the wt serotype A strain, and exhibited a strong requirement for the terminal N-acetyl-glucosamine residue of the lgt2 mutant core oligosaccharide, suggesting that this residue was immunodominant. Subsequently, we showed that both mAbs MC2-1 and MC2-10 could facilitate bactericidal killing of the lgt2 mutant, however neither mAb could facilitate bactericidal killing of the wt serotype A strain. We then confirmed and extended the candidacy of the inner core LPS by demonstrating that it is possible to elicit functional antibodies against M. catarrhalis wt strains following immunisation of rabbits with glycoconjugates elaborating the conserved inner core LPS antigen. The present study describes three conjugation strategies that either uses amidases produced by Dictyostelium discoideum, targeting the amino functionality created by the amidase activity as the attachment point on the LPS molecule, or a strong base treatment to remove all fatty acids from the LPS, thus creating amino functionalities in the lipid A region to conjugate via maleimide-thiol linker strategies targeting the carboxyl residues of the carrier protein and the free amino functionalities of the derived lipid A region of the carbohydrate resulted in a high loading of carbohydrates per carrier protein from these carbohydrate preparations. Immunisation derived antisera from rabbits recognised fully extended M. catarrhalis LPS and whole cells. Moreover, bactericidal activity was demonstrated to both the immunising carbohydrate antigen and importantly to wt cells, thus further supporting the consideration of inner core LPS as a potential vaccine antigen to combat disease caused by M. catarrhalis.

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“…The CD outer membrane protein of M. catarrhalis has been identified as a potential vaccine against Moraxella infection (9,26) and is a safe and effective carrier for M. catarrhalis detoxified lipooligosaccharide (LOS)-based conjugates (18). Serum immunoglobulin G (IgG) antibodies specific to CD are present in infants with otitis media (25) and in children with otitis media with effusion (11).…”

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confidence: 99%

Moraxella catarrhalisOuter Membrane Protein CD Elicits Antibodies That Inhibit CD Binding to Human Mucin and Enhance Pulmonary Clearance ofM. catarrhalisin a Mouse Model

2007

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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 ϳ70% 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.Moraxella catarrhalis is an important human mucosal pathogen of the respiratory tract (20,29,44). It is the third most common cause of bacterial otitis media in infants and young children (3, 40), following Streptococcus pneumoniae and nontypeable Haemophilus influenzae. Among adults, M. catarrhalis is often associated with bronchitis, laryngitis, and other respiratory diseases (1, 5). Patients with chronic obstructive pulmonary disease (COPD) are particularly vulnerable to exacerbations caused by M. catarrhalis (1,6,35). Interest in the development of a Moraxella vaccine is further stimulated by the increasing prevalence of antibiotic resistance among M. catarrhalis strains (2,8,19).The CD outer membrane protein of M. catarrhalis has been identified as a potential vaccine against Moraxella infection (9, 26) and is a safe and effective carrier for M. catarrhalis detoxified lipooligosaccharide (LOS)-based conjugates (18). Serum immunoglobulin G (IgG) antibodies specific to CD are present in infants with otitis media (25) and in children with otitis media with effusion (11). Analysis of salivary immunoglobulin A (IgA) in children with acute respiratory tract infection indicates that CD may be one of the outer membrane antigens eliciting a mucosal immune response (27). IgA antibodies against CD as well as several other surface components of M. catarrhalis are also detected in the saliva of healthy adults (28). Furthe...

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Exploration ofMoraxella catarrhalisouter membrane proteins, CD and UspA, as new carriers for lipooligosaccharide-based conjugates

Cited by 16 publications

References 44 publications

Synthesis and Characterization of Lipooligosaccharide-Based Conjugate Vaccines for Serotype B Moraxella catarrhalis

Synthesis and Characterization of Lipooligosaccharide-Based Conjugate Vaccines for Serotype B Moraxella catarrhalis

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

Moraxella catarrhalisOuter Membrane Protein CD Elicits Antibodies That Inhibit CD Binding to Human Mucin and Enhance Pulmonary Clearance ofM. catarrhalisin a Mouse Model

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