scholarly journals Evaluation of a Novel Chimeric B Cell Epitope-Based Vaccine against Mastitis Induced by Either Streptococcus agalactiae or Staphylococcus aureus in Mice

2011 ◽  
Vol 18 (6) ◽  
pp. 893-900 ◽  
Author(s):  
Haiyang Xu ◽  
Changmin Hu ◽  
Rui Gong ◽  
Yingyu Chen ◽  
Ningning Ren ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
B Cell ◽  
Streptococcus Agalactiae ◽  
Histopathological Examination ◽  
Cell Epitope ◽  
Mammary Glands ◽  
Universal Vaccine ◽  
Content Type ◽  
Immunization Group ◽  
B Cell Epitope

ABSTRACTTo construct a universal vaccine against mastitis induced by eitherStreptococcus agalactiaeorStaphylococcus aureus, the B cell epitopes of the surface immunogenic protein (Sip) fromS. agalactiaeand clumping factor A (ClfA) fromS. aureuswere analyzed and predicted.sip-clfA, a novel chimeric B cell epitope-based gene, was obtained by overlap PCR, and then the recombinant Sip-ClfA (rSip-ClfA) was expressed and purified. rSip-ClfA and inactivatedS. agalactiaeandS. aureuswere formulated into different vaccines with mineral oil as the adjuvant and evaluated in mouse models. The rSip-ClfA vaccination induced immunoglobulin G (IgG) titers higher than those seen in groups immunized with inactivated bacteria. Furthermore, the response to rSip-ClfA immunization was characterized as having a dominant IgG1 subtype, whereas both bacterial immunizations produced similar levels of IgG1 and IgG2a. The antiserum capacities for opsonizing adhesion and phagocytosis were significantly greater in the rSip-ClfA immunization group than in the killed-bacterium immunization groups (P< 0.05). The immunized lactating mice were challenged with eitherS. agalactiaeorS. aureusvia the intramammary route. At 24 h postinfection, the numbers of bacteria recovered from the mammary glands in the rSip-ClfA group were >5-fold lower than those in both inactivated-bacterium groups (P< 0.01). Histopathological examination of the mammary glands showed that rSip-ClfA immunization provided better protection of mammary gland tissue integrity against bothS. agalactiaeandS. aureuschallenges. Thus, the recombinant protein rSip-ClfA would be a promising vaccine candidate against mastitis induced by eitherS. agalactiaeorS. aureus.

scholarly journals Convergent Evolution of Neutralizing Antibodies to Staphylococcus aureus γ-Hemolysin C That Recognize an Immunodominant Primary Sequence-Dependent B-Cell Epitope

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
David N. Hernandez ◽  
Kayan Tam ◽  
Bo Shopsin ◽  
Emily E. Radke ◽  
Karen Law ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Phage Display ◽  
B Cell ◽  
Neutralizing Antibodies ◽  
Ex Vivo ◽  
Cell Epitope ◽  
Phage Display Library ◽  
Structural Basis ◽  
Peptide Fragments ◽  
Content Type

ABSTRACT Staphylococcus aureus infection is a major public health threat in part due to the spread of antibiotic resistance and repeated failures to develop a protective vaccine. Infection is associated with production of virulence factors that include exotoxins that attack host barriers and cellular defenses, such as the leukocidin (Luk) family of bicomponent pore-forming toxins. To investigate the structural basis of antibody-mediated functional inactivation of Luk toxins, we generated a panel of murine monoclonal antibodies (MAbs) that neutralize host cell killing by the γ-hemolysin HlgCB. By biopanning these MAbs against a phage-display library of random Luk peptide fragments, we identified a small subregion within the rim domain of HlgC as the epitope for all the MAbs. Within the native holotoxin, this subregion folds into a conserved β-hairpin structure, with exposed key residues, His252 and Tyr253, required for antibody binding. On the basis of the phage-display results and molecular modeling, a 15-amino-acid synthetic peptide representing the minimal epitope on HlgC (HlgC241-255) was designed, and preincubation with this peptide blocked antibody-mediated HIgCB neutralization. Immunization of mice with HlgC241-255 or the homologous LukS246-260 subregion peptide elicited serum antibodies that specifically recognized the native holotoxin subunits. Furthermore, serum IgG from patients who were convalescent for invasive S. aureus infection showed neutralization of HlgCB toxin activity ex vivo, which recognized the immunodominant HlgC241-255 peptide and was dependent on His252 and Tyr253 residues. We have thus validated an efficient, rapid, and scalable experimental workflow for identification of immunodominant and immunogenic leukotoxin-neutralizing B-cell epitopes that can be exploited for new S. aureus-protective vaccines and immunotherapies.

Identification of a conserved linear B-cell epitope in the Staphylococcus aureus GapC protein

2018 ◽  
Vol 118 ◽  
pp. 39-47 ◽  
Author(s):  
Mengyao Wang ◽  
Yuhua Wei ◽  
Wei Yu ◽  
Lizi Wang ◽  
Lu Zhai ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
B Cell ◽  
Cell Epitope ◽  
B Cell Epitope ◽  
Linear B

scholarly journals Defining Species-Specific Immunodominant B Cell Epitopes for Molecular Serology of Chlamydia Species

2015 ◽  
Vol 22 (5) ◽  
pp. 539-552 ◽  
Author(s):  
K. Shamsur Rahman ◽  
Erfan U. Chowdhury ◽  
Anil Poudel ◽  
Anke Ruettger ◽  
Konrad Sachse ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Epitope ◽  
Cross Reactivity ◽  
Microbial Pathogens ◽  
B Cell Epitopes ◽  
Content Type ◽  
Peptide Antigens ◽  
Sequence Identity ◽  
B Cell Epitope ◽  
Species Specific

ABSTRACTUrgently needed species-specific enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies againstChlamydiaspp. have been elusive due to high cross-reactivity of chlamydial antigens. To identifyChlamydiaspecies-specific B cell epitopes for such assays, we ranked the potential epitopes of immunodominant chlamydial proteins that are polymorphic among allChlamydiaspecies. High-scoring peptides were synthesized with N-terminal biotin, followed by a serine-glycine-serine-glycine spacer, immobilized onto streptavidin-coated microtiter plates, and tested with mono-specific mouse hyperimmune sera against eachChlamydiaspecies in chemiluminescent ELISAs. For each of nineChlamydiaspecies, three to nine dominant polymorphic B cell epitope regions were identified on OmpA, CT618, PmpD, IncA, CT529, CT442, IncG, Omp2, TarP, and IncE proteins. Peptides corresponding to 16- to 40-amino-acid species-specific sequences of these epitopes reacted highly and with absolute specificity with homologous, but not heterologous,Chlamydiamonospecies-specific sera. Host-independent reactivity of such epitopes was confirmed by testing of sixC. pecorum-specific peptides from five proteins withC. pecorum-reactive sera from cattle, the natural host ofC. pecorum. The probability of cross-reactivity of peptide antigens from closely related chlamydial species or strains correlated with percent sequence identity and declined to zero at <50% sequence identity. Thus, phylograms of B cell epitope regions predict the specificity of peptide antigens for rational use in the genus-, species-, or serovar-specific molecular serology ofChlamydiaspp. We anticipate that these peptide antigens will improve chlamydial serology by providing easily accessible assays to nonspecialist laboratories. Our approach also lends itself to the identification of relevant epitopes of other microbial pathogens.

scholarly journals Comprehensive Molecular Serology of HumanChlamydia trachomatisInfections by Peptide Enzyme-Linked Immunosorbent Assays

mSphere ◽  
2018 ◽  
Vol 3 (4) ◽  
Author(s):  
K. Shamsur Rahman ◽  
Toni Darville ◽  
Ali N. Russell ◽  
Catherine M. O'Connell ◽  
Harold C. Wiesenfeld ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
B Cell ◽  
Cell Epitope ◽  
High Sensitivity ◽  
Cross Reactivity ◽  
Superior Performance ◽  
Content Type ◽  
Peptide Antigens ◽  
B Cell Epitope ◽  
Immunosorbent Assays

ABSTRACTSensitive species-specific detection of anti-Chlamydia trachomatisantibodies is compromised by cross-reactivity of theC. trachomatisantigens used in standard microimmunofluorescence (MIF) testing and enzyme-linked immunosorbent assays (ELISAs). Previously, we discovered 48 strongly reactiveC. trachomatis-specific B cell epitope peptides from 21 immunodominant proteins. Here we comprehensively evaluated the 11 top-rankedC. trachomatis-specific peptide antigens from 8 proteins for use inC. trachomatisserology. Sera from 125 women with nucleic acid amplification test (NAAT)-confirmed activeC. trachomatisinfection and from 49 healthy women with a low risk ofC. trachomatisinfection were used as anti-C. trachomatisantibody-positive and -negative sera. Results obtained for detection of IgG1, IgG3, and IgA1 antibodies against the 11C. trachomatispeptide antigens were compared to results from 4 commercial anti-C. trachomatisIgG ELISAs. Using composite reference standards (CRS) of all assays for anti-C. trachomatisantibody status, commercial ELISAs detected antibodies in antibody-positive women with sensitivities of 51.5% to 64.8%. In contrast, a combination of the results of all 11 peptides detected IgG (IgG1 and IgG3) antibodies with 91.8% sensitivity, and a labor-saving combination of the 5 optimal peptides still detected antibodies in antibody-positive women with 86.5% sensitivity (all at 98% specificity). The superior performance of the combined peptide ELISAs was confirmed by area under the receiver operating characteristic curve (ROC-AUC), likelihood ratio, and predictive value analyses. The higher sensitivity of the peptide assays results from using multiple B cell epitopes of severalC. trachomatisimmunodominant proteins, including OmpA, compared to exclusively using the OmpA antigens used in commercial ELISAs. Thus, ELISAs with combined use of synthetic peptide antigens forC. trachomatisantibody detection have the advantage of simultaneous high sensitivity and high specificity.IMPORTANCEFor detection of anti-Chlamydia trachomatisantibodies by serological assays, use of classical whole-organism chlamydial antigens results in high cross-reactivity. These antigens bind mainly antibodies against the major outer membrane protein (OmpA) and bind antibodies against other immunodominant non-OmpA proteins to a lesser extent, resulting in poor assay sensitivity. The specificity ofC. trachomatisserology is also compromised by the high prevalence of cross-reactive anti-C. pneumoniaeantibodies in human populations. We previously identified 48 highly specificC. trachomatisB cell epitope peptide antigens of 21 immunodominant proteins. This study validated peptide antigen-based novel ELISAs that provide highly specific and sensitive detection of anti-C. trachomatisantibodies. Compared to four commercial ELISAs that achieved only poor sensitivities (51.5% to 64.8%), the combined signals of 5 to 11 peptides provided high sensitivity (86.5% to 91.8%) at the same 98% specificity. Thus, by using multiple peptide antigens of immunodominant proteins, we created simple ELISAs with specificity and sensitivity superior to standardC. trachomatisserodiagnosis.

B-cell epitope mapping of YscF, a T3SS needle protein of Yersinia spp., with the panel of immune sera from vaccinated models

2020 ◽  
Author(s):  
Zaytsev Sergey ◽  
Motin Vladimir ◽  
Khizhnyakova Mariya ◽  
Feodorova Valentina Anatolievna ◽  
Elena Lyapina ◽  
...  
Keyword(s):  
B Cell ◽  
Epitope Mapping ◽  
Cell Epitope ◽  
B Cell Epitope ◽  
Needle Protein
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