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1.
PLoS Negl Trop Dis ; 14(1): e0007912, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31905228

RESUMO

BACKGROUND: Typhoid fever remains a significant cause of morbidity and mortality in developing countries especially in children ≤5 years old. Although the widely available unconjugated Vi polysaccharide vaccines are efficacious, they confer limited, short-term protection and are not approved for young children or infants. Vi conjugate vaccines, however, are now licensed in several typhoid endemic countries for use in children >6 months of age. As an alternative to conjugate vaccines, Matrivax has applied its novel 'virtual conjugation' Protein Capsular Matrix Vaccine (PCMV) technology to manufacture Typhax, which is composed of Vi polysaccharide entrapped in a cross-linked CRM197 matrix. METHODOLOGY: A randomized, double-blinded, dose escalating Phase 1 study was performed to compare the safety and immunogenicity of three dose levels of aluminum phosphate adjuvanted Typhax (0.5, 2.5, or 10 µg of Vi antigen) to the FDA licensed vaccine, Typhim Vi, and placebo. Groups of 15 healthy adult subjects aged 18 to 55 years were randomized and received Typhax, Typhim Vi, or placebo at a ratio of 9:3:3. Typhax and placebo were administered in a two-dose regimen (Days 0 and 28) while Typhim Vi was administered as a single-dose on Day 0 with a placebo administered on Day 28. All doses were administered as a 0.5 mL intramuscular (IM) injection in a blinded fashion. The anti-Vi IgG antibody response was determined preimmunization (Day 0) and on Days 14, 28, 42, and 180 by ELISA. Seroconversion was defined as a titer 4-fold or greater above baseline. PRINCIPAL FINDINGS: All Typhax vaccine regimens were well tolerated and adverse events were low in number and primarily characterized as mild in intensity and similar in incidence across the treatment groups. Reactogenicity, primarily pain and tenderness at the injection site, was observed in both the Typhax and Typhim Vi treatment groups; a modest increase in incidence was observed with increasing Typhax doses. Following one dose of Typhax, seroconversion rates at day 28 were 12.5%, 77.8%, 66.7% at the 0.5, 2.5, and 10 µg dose levels, respectively, compared to 55.6% and 0% in the Typhim Vi and placebo groups, respectively. A second dose of Typhax on Day 28 did not elicit a significant increase in GMT or seroconversion at Day 42 or Day 180 at any dose level. CONCLUSIONS: Collectively, the results from this randomized phase 1 clinical trial indicate that Typhax is safe, well tolerated, and immunogenic. After a single dose, Typhax at the 2.5 and 10 µg dose levels elicited comparable anti-Vi IgG titers and seroconversion rates as a single dose of Typhim Vi (25 µg dose). A second dose of Typhax at Day 28 did not elicit a booster response. TRIAL REGISTRATION: ClinicalTrials.gov NCT03926455.


Assuntos
Imunogenicidade da Vacina , Febre Tifoide/prevenção & controle , Vacinas Tíficas-Paratíficas/imunologia , Adulto , Anticorpos Antibacterianos/sangue , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/imunologia , Masculino , Pessoa de Meia-Idade , Polissacarídeos Bacterianos/administração & dosagem , Polissacarídeos Bacterianos/efeitos adversos , Polissacarídeos Bacterianos/imunologia , Salmonella typhi , Soroconversão , Vacinas Tíficas-Paratíficas/administração & dosagem , Vacinas Tíficas-Paratíficas/efeitos adversos , Vacinas Conjugadas/administração & dosagem , Vacinas Conjugadas/efeitos adversos , Vacinas Conjugadas/imunologia
2.
Molecules ; 24(18)2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31546911

RESUMO

Zwitterionic polysaccharides (ZPs) have been shown in recent years to display peculiar immunological properties, thus attracting the interest of the carbohydrate research community. To fully elucidate the mechanisms underlying these properties and exploit the potential of this kind of structures, in depth studies are still required. In this context, the preparation of two cationic, an anionic, as well as two zwitterionic tetrasaccharide analogues of the smallest immunogenic structure of Streptococcus pneumoniae type 14 (SP14) capsular polysaccharide are presented. By exploiting a block strategy, the negative charge has been installed on the non-reducing end of the lactose unit of the tetrasaccharide and the positive charge either on the non-reducing end of the lactosamine moiety or on an external linker. These structures have then been tested by competitive ELISA, showing that the structural variations we made do not modify the affinity of the neutral compound to binding to a specific antibody. However, lower efficacies than the natural SP14 compound were observed. The results obtained, although promising, point to the need to further elongate the polysaccharide structure, which is likely too short to cover the entire epitopes.


Assuntos
Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/imunologia , Streptococcus pneumoniae/imunologia , Animais , Camundongos , Conformação Molecular , Polissacarídeos Bacterianos/análogos & derivados , Polissacarídeos Bacterianos/síntese química , Células RAW 264.7
3.
Infect Immun ; 87(12)2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31548320

RESUMO

Lipopolysaccharides (LPSs) of Gram-negative bacteria comprise lipid A, core, and O-polysaccharide (OPS) components. Studies have demonstrated that LPSs isolated from the pathogenic species Burkholderia pseudomallei and Burkholderia mallei and from less-pathogenic species, such as Burkholderia thailandensis, are potent immune stimulators. The LPS structure of B. pseudomallei, the causative agent of melioidosis, is highly conserved in isolates from Thailand; however, the LPSs isolated from other, related species have not been characterized to enable understanding of their immune recognition and antigenicities. Here, we describe the structural and immunological characteristics of the LPSs isolated from eight Burkholderia species and compare those for B. pseudomallei to those for the other seven species. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), gas chromatography (GC), SDS-PAGE, Toll-like receptor 4 (TLR4) stimulation, and immunoblot analysis were performed on these Burkholderia species. MALDI-TOF profiles demonstrated that Burkholderia lipid A contains predominantly penta-acylated species modified with 4-amino-4-deoxy-arabinose residues at both terminal phosphate groups. The lipid A could be differentiated based on mass differences at m/z 1,511, 1,642, 1,773, and 1,926 and on fatty acid composition. LPSs of all species induced TLR4-dependent NF-κB responses; however, while SDS-PAGE analysis showed similar LPS ladder patterns for B. pseudomallei, B. thailandensis, and B. mallei, these patterns differed from those of other Burkholderia species. Interestingly, immunoblot analysis demonstrated that melioidosis patient sera cross-reacted with OPSs of other Burkholderia species. These findings can be used to better understand the characteristics of LPS in Burkholderia species, and they have implications for serological diagnostics based on the detection of antibodies to OPS.


Assuntos
Burkholderia mallei/imunologia , Burkholderia pseudomallei/imunologia , Burkholderia/imunologia , Lipídeo A/imunologia , Receptor 4 Toll-Like/metabolismo , Amino Açúcares/química , Anticorpos Antibacterianos/imunologia , Reações Cruzadas/imunologia , Humanos , Lipídeo A/química , Melioidose/imunologia , Melioidose/microbiologia , Conformação Molecular , Polissacarídeos Bacterianos/imunologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
4.
Int J Food Microbiol ; 309: 108332, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31494483

RESUMO

Vibrio parahaemolyticus is a major food-borne pathogen. V. parahaemolyticus infections are associated with various serotypes; to date, 71 K-serogroups of V. parahaemolyticus have been determined based on capsular polysaccharide (CPS) diversity. In this study, the capsular polysaccharide gene clusters (CPSgcs) of 55 K-serogroups were identified by whole-genome sequencing and analysis. These CPSgcs exhibit a high level of genetic diversity. A microsphere-based suspension array (MSA) was established for the detection and identification of 55 V. parahaemolyticus K-serogroups based on CPSgc-specific genes. To evaluate our array, a double-blind test with 120 clinical isolates was carried out. In addition, an in silico K-serotyping system was established based on V. parahaemolyticus CPSgc-specific genes. This system was then used to examine 845 publicly available V. parahaemolyticus genomes; the results demonstrated that 813 isolates belong to one of 43 K-serogroups. Taken together, these results demonstrate that the molecular system developed in this study is suitable for rapid serotyping of V. parahaemolyticus isolates from environmental and clinical samples. In addition, the system could be applied to epidemiological investigations of this important food-borne pathogen.


Assuntos
Cápsulas Bacterianas/genética , Doenças Transmitidas por Alimentos/diagnóstico , Polissacarídeos Bacterianos/genética , Sorotipagem/métodos , Vibrio parahaemolyticus/genética , Vibrio parahaemolyticus/imunologia , Cápsulas Bacterianas/imunologia , Método Duplo-Cego , Doenças Transmitidas por Alimentos/microbiologia , Humanos , Família Multigênica/genética , Polissacarídeos Bacterianos/imunologia , Sorogrupo , Vibrioses/diagnóstico , Vibrio parahaemolyticus/classificação
5.
Artigo em Inglês | MEDLINE | ID: mdl-31380292

RESUMO

Aspergillus fumigatus and A. flavus are the fungal pathogens responsible for most cases of invasive aspergillosis (IA). Early detection of the circulating antigen galactomannan (GM) in serum allows the prompt application of effective antifungal therapy, thus improving the survival rate of IA patients. However, the use of monoclonal antibodies (mAbs) for the diagnosis of IA is often associated with false positives due to cross-reaction with bacterial polysaccharides. More specific antibodies are therefore needed. Here we describe the characterization of the Aspergillus-specific mAb AP3 (IgG1κ), including the precise identification of its corresponding antigen. The antibody was generated using A. parasiticus cell wall fragments and was shown to bind several Aspergillus species. Immunofluorescence microscopy revealed that AP3 binds a cell wall antigen, but immunoprecipitation and enzyme-linked immunosorbent assays showed that the antigen is also secreted into the culture medium. The inability of AP3 to bind the A. fumigatus galactofuranose (Galf )-deficient mutant ΔglfA confirmed that Galf residues are part of the epitope. Several lines of evidence strongly indicated that AP3 recognizes the Galf residues of O-linked glycans on Aspergillus proteins. Glycoarray analysis revealed that AP3 recognizes oligo-[ß-D-Galf-1,5] sequences containing four or more residues with longer chains more efficiently. We also showed that AP3 captures GM in serum, suggesting it may be useful as a diagnostic tool for patients with IA.


Assuntos
Anticorpos Antifúngicos/imunologia , Anticorpos Monoclonais/imunologia , Antígenos de Fungos/imunologia , Aspergilose/imunologia , Aspergillus/imunologia , Mananas/imunologia , Animais , Antígenos de Fungos/genética , Aspergillus/genética , Aspergillus flavus/genética , Aspergillus flavus/imunologia , Aspergillus fumigatus/imunologia , Parede Celular/química , Reações Cruzadas , Modelos Animais de Doenças , Epitopos/isolamento & purificação , Feminino , Testes Imunológicos , Mananas/genética , Camundongos , Camundongos Endogâmicos BALB C , Polissacarídeos Bacterianos/imunologia , Proteínas Recombinantes
6.
mSphere ; 4(4)2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391276

RESUMO

Group B Streptococcus (GBS) infections constitute a major cause of invasive disease during the first three months of life and an unmet medical need that could be addressed by maternal vaccination. The GBS capsular polysaccharides (CPSs) have shown promise as vaccine targets in clinical studies. A highly specific serological assay to quantify maternal and neonatal anti-CPS antibody levels will be instrumental for GBS vaccine licensure. Here, we describe the development and comparison of two novel multiplex immunoassays (MIAs) based on the Luminex technology for the quantification of IgG antibodies recognizing the five most frequent GBS capsular variants (Ia, Ib, II, III, and V) out of the ten types identified. The first assay is based on the use of biotinylated CPSs coupled to streptavidin-derivatized magnetic microspheres (Biotin-CPS MIA), while the second is a sandwich assay with plain CPSs coupled to magnetic microspheres coated with polysaccharide-specific mouse monoclonal antibodies (Sandwich MIA). Both assays showed good specificity, linearity, and precision, although the Biotin-CPS MIA presented higher sensitivity and lower complexity than the Sandwich MIA. A panel of human sera representing a wide range of anti-CPS IgG concentrations was tested in parallel by the two assays, which resulted in comparable titers. Our data support the preservation of antigenic epitopes in the biotinylated polysaccharides and the suitability of the Biotin-CPS MIA for the precise determination of GBS anti-CPS IgG concentrations in human sera.IMPORTANCE Group B streptococcal infections can cause death in neonates up to 3 months of age. Intrapartum antibiotic prophylaxis in GBS-colonized mothers has limited early infections but has no impact after the first week of life. The development of a maternal vaccine to address this unmet medical need has been identified as a priority by the World Health Organization, and the GBS CPSs are considered the best antigen targets. However, to date there are no accepted standardized assays to measure immune responses to the investigational vaccines and for establishment of serocorrelates of protection. Here, we describe the performance of two microsphere-based pentaplex immunoassays for the determination of antibodies recognizing the five most frequent GBS serotypes. Our data confirm that an assay based on biotinylated polysaccharides coupled to streptavidin microspheres would be suitable for the intended purpose.


Assuntos
Anticorpos Antibacterianos/sangue , Imunoensaio/métodos , Imunoglobulina G/sangue , Polissacarídeos Bacterianos/imunologia , Streptococcus agalactiae/imunologia , Biotina , Humanos , Microesferas , Estreptavidina
7.
PLoS One ; 14(7): e0218427, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291272

RESUMO

This study aimed to explore the feasibility of pneumococcal surface protein A (PspA) as a carrier protein. Three recombinant pneumococcal surface proteins from three different clades were expressed by the prokaryotic expression system and conjugated to group A meningococcal polysaccharide (GAMP) to generate three polysaccharide-protein conjugates. The conjugates, unconjugated proteins, GAMP, and GAMP-TT vaccine bulk (used as positive control) were immunized into mice, and their immune effects were assessed by the methods of enzyme-linked immunosorbent assay (ELISA), flow cytometry (FCM), and serum bactericidal assay (SBA). The results showed that the polysaccharide-protein conjugates could produce higher levels of anti-GAMP IgG titers (P < 0.05), higher ratios of Th1/Th2 (P < 0.05), and higher levels of serum bactericidal activity (P < 0.05), compared with the unconjugated GAMP. The conjugation of PspAs to GAMP also enhanced the anti-PspA responses compared with unconjugated PspAs except for PspA3. In conclusion, the results indicated that the three PspAs were appropriate carrier proteins, as demonstrated by the characteristics of T-cell dependent responses to the GAMP, and might protect against group A of epidemic cerebrospinal meningitis.


Assuntos
Proteínas de Bactérias/farmacologia , Infecções Meningocócicas/imunologia , Vacinas Meningocócicas/farmacologia , Polissacarídeos Bacterianos/farmacologia , Animais , Anticorpos Antibacterianos/imunologia , Proteínas de Bactérias/imunologia , Feminino , Imunoglobulina G/imunologia , Infecções Meningocócicas/prevenção & controle , Vacinas Meningocócicas/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Neisseria meningitidis/imunologia , Polissacarídeos Bacterianos/imunologia , Dados Preliminares , Vacinas Conjugadas/imunologia , Vacinas Conjugadas/farmacologia
8.
Anal Chim Acta ; 1078: 151-160, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358213

RESUMO

Herein, we report a new signal amplification scheme for quantitative biochemical analysis based on gold nanoparticle (GNPs) catalyzed polymerization of transparent silane solution to milky white and turbid siloxane. Using immunoassay as a proof of concept, GNP labeled immunoprobe was used to bind captured antigen and catalyse the polymerization reaction allowing sensitive biochemical investigation. The polymerization reaction was optimized for standard 96 well polystyrene microtiter plates and we discovered that sodium lactate acts as an enhancer in the polymerization reaction as it reduces detection time to merely 30 min. The sensing strategy was applied to detection and quantification of Salmonella Typhimurium in water and egg samples and the platform showed excellent visibly quantifiable analytical response up to 100 cells mL-1. Furthermore, clinical utility and potential of the method was validated by detecting Vi capsular polysaccharide (Vi antigen) responsible for typhoidal Salmonellosis in human serum in sandwich format with a detection limit of 1 ng mL-1. The method serves as the first report towards nanoparticle triggered polymerization for development of rapid and low cost quantitative biochemical assay.


Assuntos
Ouro/química , Imunoensaio/métodos , Nanopartículas Metálicas/química , Polissacarídeos Bacterianos/sangue , Salmonella typhimurium/isolamento & purificação , Siloxanas/síntese química , Animais , Anticorpos/imunologia , Galinhas , Água Potável/microbiologia , Ovos/microbiologia , Contaminação de Alimentos/análise , Humanos , Limite de Detecção , Tamanho da Partícula , Polimerização , Polissacarídeos Bacterianos/imunologia , Estudo de Prova de Conceito , Salmonella typhimurium/imunologia , Silanos/química , Temperatura
9.
Carbohydr Polym ; 218: 269-278, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31221330

RESUMO

The chemical structure of cell surface polysaccharides isolated from Bifidobacterium bifidum strain PRI1, an important member of the gut microbiota of breast-fed infants, has been elucidated by chemical and NMR spectroscopy analysis. Results demonstrated that the bacterium produces a complex mixture of polysaccharides that could be classified in two main groups: a phospho-glycero-ß-galactofuranan, PGßG, and a mixture composed of four neutral polysaccharides named as (CSGG), composed of ß-(1 → 6)-glucan, ß-(1 → 4)-galactan, ß-(1 → 6)-galactan, ß-galactofuranan and starch. These two fractions exerted different immune responses when assayed on dendritic cells: PGßG enhanced pro-inflammatory immune responses by increasing interferon-γ levels while CSGG induced immunosuppressive regulatory T cells and interleukin-10. These findings demonstrate that bacterial polysaccharides have a distinct role depending on their chemical structure in regulation of the host/bacterium interaction. Our findings suggest that polysaccharides may differentially regulate the host immunity depending on the composition of this complex mixture, either enhancing immunity or inducing immune tolerance.


Assuntos
Bifidobacterium bifidum/química , Galactanos/imunologia , Glucanos/imunologia , Polissacarídeos Bacterianos/imunologia , Animais , Sequência de Carboidratos , Células Dendríticas/imunologia , Galactanos/química , Galactanos/isolamento & purificação , Glucanos/química , Glucanos/isolamento & purificação , Camundongos Endogâmicos C57BL , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/isolamento & purificação , Baço/citologia
10.
Glycoconj J ; 36(5): 429-438, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31230165

RESUMO

Enterococcus faecium (E. faecium) has emerged as one of today's leading causes of health care-associated infections that is difficult to treat with the available antibiotics. These pathogens produce capsular polysaccharides on the cell surface which play a significant role in adhesion, virulence and evasion. Therefore, we aimed at the identification and characterization of bacterial polysaccharide antigens which are central for the development of vaccine-based prophylactic approaches. The crude cell wall-associated polysaccharides from E. faecium, its mutant and complemented strains were purified and analyzed by a primary antibody raised against lipoteichoic acid (LTA) and diheteroglycan (DHG). The resistant E. faecium strains presumably possess novel capsular polysaccharides that allow them to avoid the evasion from opsonic killing. The E. faecium U0317 strain was very well opsonized by anti-U0317 (~95%), an antibody against the whole bacterial cell. The deletion mutant showed a significantly increased susceptibility to opsonophagocytic killing (90-95%) against the penicillin binding protein (anti-PBP-5). By comparison, in a mouse urinary tract and rat endocarditis infection model, respectively, there were no significant differences in virulence. In this study we explored the biological role of the capsule of E. faecium. Our findings showed that the U0317 strain is not only sensitive to anti-LTA but also to antibodies against other enterococcal surface proteins. Our findings demonstrate that polysaccharides capsule mediated-resistance to opsonophagocytosis. We also found that the capsular polysaccharides do not play an important role in bacterial virulence in urinary tract and infective endocarditis in vivo models.


Assuntos
Anticorpos Antibacterianos/farmacologia , Antígenos de Bactérias/isolamento & purificação , Parede Celular/química , Enterococcus faecium/química , Lipopolissacarídeos/isolamento & purificação , Polissacarídeos Bacterianos/isolamento & purificação , Ácidos Teicoicos/isolamento & purificação , Animais , Antibacterianos/farmacologia , Anticorpos Antibacterianos/biossíntese , Antígenos de Bactérias/química , Antígenos de Bactérias/imunologia , Cápsulas Bacterianas/química , Cápsulas Bacterianas/imunologia , Parede Celular/imunologia , Modelos Animais de Doenças , Farmacorresistência Bacteriana , Endocardite Bacteriana/tratamento farmacológico , Endocardite Bacteriana/microbiologia , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/imunologia , Enterococcus faecium/patogenicidade , Feminino , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/imunologia , Lipopolissacarídeos/química , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Opsonizantes/farmacologia , Proteínas de Ligação às Penicilinas/química , Proteínas de Ligação às Penicilinas/imunologia , Proteínas de Ligação às Penicilinas/isolamento & purificação , Proteínas de Ligação às Penicilinas/farmacologia , Fagocitose/efeitos dos fármacos , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/imunologia , Cultura Primária de Células , Ratos , Ratos Wistar , Ácidos Teicoicos/química , Ácidos Teicoicos/imunologia , Ácidos Teicoicos/farmacologia , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/microbiologia
11.
mBio ; 10(3)2019 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-31239373

RESUMO

Bacterial pathogens have evolved strategies that enable them to evade neutrophil-mediated killing. The Gram-negative coccobacillus Kingella kingae is an emerging pediatric pathogen and is increasingly recognized as a common etiological agent of osteoarticular infections and bacteremia in young children. K. kingae produces a polysaccharide capsule and an exopolysaccharide, both of which are important for protection against complement-mediated lysis and are required for full virulence in an infant rat model of infection. In this study, we examined the role of the K. kingae polysaccharide capsule and exopolysaccharide in protection against neutrophil killing. In experiments with primary human neutrophils, we found that the capsule interfered with the neutrophil oxidative burst response and prevented neutrophil binding of K. kingae but had no effect on neutrophil internalization of K. kingae In contrast, the exopolysaccharide resisted the bactericidal effects of antimicrobial peptides and efficiently blocked neutrophil phagocytosis of K. kingae This work demonstrates that the K. kingae polysaccharide capsule and exopolysaccharide promote evasion of neutrophil-mediated killing through distinct yet complementary mechanisms, providing additional support for the K. kingae surface polysaccharides as potential vaccine antigens. In addition, these studies highlight a novel interplay between a bacterial capsule and a bacterial exopolysaccharide and reveal new properties for a bacterial exopolysaccharide, with potential applicability to other bacterial pathogens.IMPORTANCE Kingella kingae is a Gram-negative commensal in the oropharynx and represents a leading cause of joint and bone infections in young children. The mechanisms by which K. kingae evades host innate immunity during pathogenesis of disease remain poorly understood. In this study, we established that the K. kingae polysaccharide capsule and exopolysaccharide function independently to protect K. kingae against reactive oxygen species (ROS) production, neutrophil phagocytosis, and antimicrobial peptides. These results demonstrate the intricacies of K. kingae innate immune evasion and provide valuable information that may facilitate development of a polysaccharide-based vaccine against K. kingae.


Assuntos
Evasão da Resposta Imune , Kingella kingae/química , Kingella kingae/imunologia , Neutrófilos/imunologia , Fagocitose , Polissacarídeos Bacterianos/imunologia , Peptídeos Catiônicos Antimicrobianos/imunologia , Células Cultivadas , Humanos , Kingella kingae/patogenicidade , Infecções por Neisseriaceae/microbiologia , Explosão Respiratória , Virulência
12.
Nat Commun ; 10(1): 2153, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089128

RESUMO

The gut commensal Bacteroides fragilis or its capsular polysaccharide A (PSA) can prevent various peripheral and CNS sterile inflammatory disorders. Fatal herpes simplex encephalitis (HSE) results from immune pathology caused by uncontrolled invasion of the brainstem by inflammatory monocytes and neutrophils. Here we assess the immunomodulatory potential of PSA in HSE by infecting PSA or PBS treated 129S6 mice with HSV1, followed by delayed Acyclovir (ACV) treatment as often occurs in the clinical setting. Only PSA-treated mice survived, with dramatically reduced brainstem inflammation and altered cytokine and chemokine profiles. Importantly, PSA binding by B cells is essential for induction of regulatory CD4+ and CD8+ T cells secreting IL-10 to control innate inflammatory responses, consistent with the lack of PSA mediated protection in Rag-/-, B cell- and IL-10-deficient mice. Our data reveal the translational potential of PSA as an immunomodulatory symbiosis factor to orchestrate robust protective anti-inflammatory responses during viral infections.


Assuntos
Bacteroides fragilis/imunologia , Encefalite por Herpes Simples/imunologia , Microbioma Gastrointestinal/imunologia , Herpesvirus Humano 1/imunologia , Polissacarídeos Bacterianos/imunologia , Aciclovir/uso terapêutico , Animais , Antivirais/uso terapêutico , Linfócitos B/imunologia , Linfócitos B/metabolismo , Bacteroides fragilis/metabolismo , Modelos Animais de Doenças , Encefalite por Herpes Simples/tratamento farmacológico , Encefalite por Herpes Simples/virologia , Feminino , Herpesvirus Humano 1/patogenicidade , Interações entre Hospedeiro e Microrganismos/imunologia , Humanos , Interleucina-10/genética , Interleucina-10/imunologia , Interleucina-10/metabolismo , Masculino , Camundongos , Camundongos Knockout , Polissacarídeos Bacterianos/metabolismo , Simbiose/imunologia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Células Vero
13.
Artigo em Inglês | MEDLINE | ID: mdl-31134159

RESUMO

Vi capsular polysaccharide (Vi) is a major virulence factor of human typhoid-causing pathogen Salmonella enterica serovar Typhi (S. Typhi). It distinguishes S. Typhi from closely related non-typhoidal Salmonella serovars such as S. Typhimurium which do not normally cause systemic infection in humans. Vi not only forms a capsule around S. Typhi but it is also readily released from this pathogen. We have previously reported that Vi targets prohibitin to inhibit cellular responses activated through immune receptors. Here, we show that engagement of membrane prohibitin with Vi prevents Salmonella-induced activation of small Rho-family GTPases, Rac1, and Cdc42, and suppresses actin cytoskeletal rearrangements resulting in reduced invasion and highly subdued inflammatory responses. Cells infected with S. Typhimurium in the presence of Vi show poor activation of NF-kB and MAP-kinase pathways of intracellular signaling. Treatment with Vi brings about redistribution of Rac-1, prohibitin, and ganglioside GM1 in membrane raft domains. Vi-mediated interference with activation of Rho-family GTPases represents a previously unrecognized mechanism by which S. Typhi can limit its invasion and alarming of the host.


Assuntos
Células Epiteliais/metabolismo , Polissacarídeos Bacterianos/metabolismo , Salmonella typhi/metabolismo , Febre Tifoide/imunologia , Fatores de Virulência/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Células Epiteliais/imunologia , Células HeLa , Humanos , Interleucina-8/metabolismo , Polissacarídeos Bacterianos/imunologia , Proteínas Repressoras/metabolismo , Salmonella typhi/imunologia , Virulência , Fatores de Virulência/imunologia , Proteína cdc42 de Ligação ao GTP , Proteínas rac1 de Ligação ao GTP
14.
Microbiol Spectr ; 7(2)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30977464

RESUMO

The polysaccharide capsule of Streptococcus pneumoniae is the dominant surface structure of the organism and plays a critical role in virulence, principally by interfering with host opsonophagocytic clearance mechanisms. The capsule is the target of current pneumococcal vaccines, but there are 98 currently recognised polysaccharide serotypes and protection is strictly serotype-specific. Widespread use of these vaccines is driving changes in serotype prevalence in both carriage and disease. This chapter summarises current knowledge on the role of the capsule and its regulation in pathogenesis, the mechanisms of capsule synthesis, the genetic basis for serotype differences, and provides insights into how so many structurally distinct capsular serotypes have evolved. Such knowledge will inform ongoing refinement of pneumococcal vaccination strategies.


Assuntos
Cápsulas Bacterianas/fisiologia , Polissacarídeos Bacterianos/fisiologia , Streptococcus pneumoniae/fisiologia , Animais , Cápsulas Bacterianas/genética , Cápsulas Bacterianas/imunologia , Cápsulas Bacterianas/metabolismo , Humanos , Vacinas Pneumocócicas/administração & dosagem , Vacinas Pneumocócicas/imunologia , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/imunologia , Streptococcus pneumoniae/imunologia , Streptococcus pneumoniae/metabolismo , Streptococcus pneumoniae/patogenicidade
15.
Int Immunol ; 31(5): 315-333, 2019 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-30951606

RESUMO

Typhoid fever is a life-threatening disease caused by the human-restricted pathogen Salmonella enterica serovar Typhi (S. Typhi). The oral live attenuated Ty21a typhoid vaccine protects against this severe disease by eliciting robust, multifunctional cell-mediated immunity (CMI), shown to be associated with protection in wild-type S. Typhi challenge studies. Ty21a induces S. Typhi-responsive CD8+ and CD4+ T cells but little is known about the response to this vaccine in children. To address this important gap in knowledge, we have used mass cytometry to analyze pediatric and adult pre- and post-Ty21a vaccination CMI in an autologous S. Typhi antigen presentation model. Here, using conventional supervised analytical tools, we show adult T cells are more multifunctional at baseline than those obtained from children. Moreover, pediatric and adult T cells respond similarly to Ty21a vaccination, but adult responders remain more multifunctional. The use of the unsupervised dimensionality reduction tool tSNE (t-distributed Stochastic Neighbor Embedding) allowed us to confirm these findings, as well as to identify increases and decreases in well-defined specific CD4+ and CD8+ T-cell populations that were not possible to uncover using the conventional gating strategies. These findings evidenced age-associated maturation of multifunctional S. Typhi-responsive T-cell populations, including those which we have previously shown to be associated with protection from, and/or delayed onset of, typhoid disease. These findings are likely to play an important role in improving pediatric vaccination strategies against S. Typhi and other enteric pathogens.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Polissacarídeos Bacterianos/imunologia , Salmonella typhi/imunologia , Vacinas Tíficas-Paratíficas/imunologia , Adolescente , Adulto , Idoso , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vacinação , Adulto Jovem
16.
Nutrients ; 11(4)2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30987344

RESUMO

Intestinal bifidobacteria benefit human health by promoting and modulating the gut flora, and boosting therapeutic efficiency for chronic metabolic diseases and cancer. Recently, Bifidobacterium adolescentis strains with high adhesion to intestinal epithelial cells were associated with induction of T-helper 17 (Th17) cells in humans and rodents. Here, two B. adolescentis strains with similar adhesive ability but different aggregation properties were investigated for specific immunoregulatory effects, including the underlying cellular pathway, on macrophage and T-regulatory (Treg)/Th17 axis activation in vitro and in the colon of dextran sodium sulfate (DSS)-colitis mice in vivo. In-vitro, the auto-aggregative B. adolescentis strain IF1-11 induced significantly higher IL-6 and lower IL-10 secretion from immune cells, and it induced abundant Th17 cells. The non-aggregating strain IF1-03 induced significantly higher IL-10, less IL-6 and a high proportion of Treg/Th17 cells compared to total T cells. In vivo, orally administered IF1-03 protected DSS-colitis mice via activation of dendritic cells or macrophages and skewing of Treg/Th17 cells, consistent with Treg cell induction in vitro. IF1-03 exopolysaccharides showed a functional recognition pattern similar to IF1-03 for IL-10 cytokine secretion and Treg cell-differentiation induction, both dependent on the toll-like receptor 2-ERK/p38 MAPK-signaling cascade for macrophage activation. We suggest that B. adolescentis exopolysaccharide-associated enterocyte adhesion/aggregation phenotypes determine strain-specific adaptive immune responses in the gut via the macrophage-regulated Treg/Th17 axis.


Assuntos
Aderência Bacteriana , Bifidobacterium adolescentis/metabolismo , Colite/prevenção & controle , Colo/microbiologia , Microbioma Gastrointestinal , Polissacarídeos Bacterianos/metabolismo , Probióticos/administração & dosagem , Linfócitos T Reguladores/microbiologia , Células Th17/microbiologia , Animais , Bifidobacterium adolescentis/imunologia , Colite/imunologia , Colite/metabolismo , Colite/microbiologia , Colo/imunologia , Colo/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Células Dendríticas/microbiologia , Sulfato de Dextrana , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Interações Hospedeiro-Patógeno , Interleucina-10/metabolismo , Interleucina-6/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Polissacarídeos Bacterianos/imunologia , Células RAW 264.7 , Transdução de Sinais , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Células Th17/imunologia , Células Th17/metabolismo , Receptor 2 Toll-Like/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
17.
J Med Microbiol ; 68(5): 791-802, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30990402

RESUMO

PURPOSE: Staphylococcus epidermidis is an opportunistic pathogen and a leading cause of morbidity and premature mortality in patients with medical device-related infections, which is a concern in hospitalized patients. Developing a strategy to raise opsonic antibodies against polysaccharide intracellular adhesin (PIA) could be promising for the elimination of colonizing and biofilm-forming S. epidermidis. Following the purification of truncated rSesC protein and PIA, for the first time, PIA was conjugated to rSesC as a carrier to increase the immunogenicity of PIA and its efficacy in mice was evaluated. The structure of the conjugate was analysed using the Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (H1- NMR) methods. Afterwards, the immune response was evaluated by measuring the total IgG, IgG2a and IgG2b titres. RESULTS: The immunization of mice with the PIA-rSesC conjugate raised the levels of opsonic antibodies, and the vaccinated mice were protected when challenged intravenously by wild-type S. epidermidis strain 1457. Further studies indicated that the conjugated vaccine was able to eliminate S. epidermidis biofilm formation in in vitro or in vivo assays. CONCLUSION: This study confirms the proposal that the immunization of mice with PIA-rSesC conjugate vaccine could protect against S. epidermidis infection.


Assuntos
Anticorpos Antibacterianos/sangue , Biofilmes/crescimento & desenvolvimento , Polissacarídeos Bacterianos/imunologia , Vacinas Antiestafilocócicas/imunologia , Staphylococcus epidermidis/imunologia , Animais , Biofilmes/efeitos dos fármacos , Feminino , Imunogenicidade da Vacina , Imunoglobulina G/sangue , Camundongos , Camundongos Endogâmicos BALB C , Polissacarídeos Bacterianos/administração & dosagem , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Infecções Estafilocócicas/prevenção & controle , Vacinas Conjugadas/imunologia
18.
Int J Biol Macromol ; 131: 933-940, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30905754

RESUMO

The photosynthetic bacterium, Rhodopseudomonas palustris has been widely used as probiotics in aquaculture, while the molecular basis underlying the probiotic properties of this organism remains largely unknown. In this study, a novel extracellular polysaccharides (RPEPS-30) extracted from the fermentation of Rhodopseudomonas palustris was characterized. Results illustrated that RPEPS-30 was an α-mannan with a molecular weight of 46.82 kDa, which possessed a backbone consisted of 1, 2-linked and 1, 4-linked mannose residues, with side chains composed of 1 → 6 linked and 1 → 2,6 linked mannose residues and substitution at O-6. The in vitro immunomodulatory tests revealed that RPEPS-30 could enhance phagocytic capacity, NO release and mRNA expression of cytokines in macrophages. In addition, RPEPS-30 was shown to promote the growth of resident beneficial gut microbiotasuch as Lactobacillus reuteri, Bacteroides thetaiotaomicron and Akkermansia muciniphila. These findings might help us to partially understand the molecular mechanism concerning the probiotic properties of Rhodopseudomonas palustris, in which the extracellular polysaccharide RPEPS-30 stimulated host immune response and favored the growth of specific benificial micriobiota in the gut.


Assuntos
Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/isolamento & purificação , Rodopseudomonas/química , Animais , Fracionamento Químico/métodos , Imunomodulação , Macrófagos/imunologia , Metilação , Camundongos , Peso Molecular , Monossacarídeos/química , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Polissacarídeos Bacterianos/imunologia , Polissacarídeos Bacterianos/ultraestrutura , Rodopseudomonas/imunologia , Análise Espectral
19.
J Infect Dis ; 220(3): 392-399, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-30891604

RESUMO

BACKGROUND: This study tested the hypothesis that the immunogenicity and safety of the simultaneous administration of enterovirus 71 (EV71) vaccine (dose 1) with recombinant hepatitis B vaccine (HepB) on day 1 and EV71 vaccine (dose 2) with group A meningococcal polysaccharide vaccine (MenA) on day 30 is not inferior to separate administration of each vaccine. METHODS: The study was designed as a randomized, open-label, noninferiority trial. A total of 775 healthy infants aged 6 months were randomly assigned in a ratio of 1:1:1 to receive simultaneous administration of EV71 vaccine (dose 1) and HepB on day 1 and EV71 vaccine (dose 2) and MenA on day 30 (the SI group); administration of doses 1 and 2 of EV71 vaccine on days 1 and 30, respectively (the SE1 group); or administration of HepB and MenA on days 1 and 30, respectively (the SE2 group). RESULTS: According to the per protocol set, antibody responses against EV71, hepatitis B virus (HBV), and group A meningococcal polysaccharide were similar regardless of administration schedule. With the non-inferiority margin setting at 10%, the seroconversion rates of the three pathogens in the SI group (100% [98.25, 100], 44.84% [38.20, 51.63] and 27.83% [21.91, 34.38]) were not inferior to those in SE1 or SE2 group (100% [98.31, 100], 44.35% [37.82, 51.02] and 29.17% [23.20, 35.72], respectively). Frequencies of adverse reactions to each vaccination regimen were comparable (60.62% in the SI group vs 52.33% in the SE1 group and 56.98% in the SE2 group; P = .16). CONCLUSIONS: Simultaneous administration of combined EV71 vaccine with HepB and MenA has noninferior immunogenicity and safety, compared with separate administration of these vaccines. CLINICAL TRIALS REGISTRATION: NCT03274102.


Assuntos
Formação de Anticorpos/imunologia , Vacinas contra Hepatite B/imunologia , Vacinas Meningocócicas/imunologia , Polissacarídeos Bacterianos/imunologia , Vacinas Combinadas/imunologia , Vacinas de Produtos Inativados/efeitos adversos , Vacinas de Produtos Inativados/imunologia , Anticorpos Antivirais/imunologia , Enterovirus/imunologia , Infecções por Enterovirus/imunologia , Feminino , Hepatite B/imunologia , Vírus da Hepatite B/imunologia , Humanos , Lactente , Masculino , Infecções Meningocócicas/imunologia , Neisseria meningitidis/imunologia , Vacinação/efeitos adversos
20.
Microbiol Spectr ; 7(2)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30873933

RESUMO

The surface of the Gram-positive opportunistic pathogen Streptococcus agalactiae, or group B Streptococcus (GBS), harbors several carbohydrate and protein antigens with the potential to be effective vaccines. Capsular polysaccharides of all clinically-relevant GBS serotypes coupled to immunogenic proteins of both GBS and non-GBS origin have undergone extensive testing in animals that led to advanced clinical trials in healthy adult women. In addition, GBS proteins either alone or in combination have been tested in animals; a fusion protein construct has recently advanced to human clinical studies. Given our current understanding of the antigenicity and immunogenicity of the wide array of GBS surface antigens, formulations now exist for the generation of viable vaccines against diseases caused by GBS.


Assuntos
Antígenos de Bactérias/imunologia , Antígenos de Superfície/imunologia , Cápsulas Bacterianas/imunologia , Infecções Estreptocócicas/prevenção & controle , Vacinas Estreptocócicas/imunologia , Streptococcus agalactiae/imunologia , Animais , Cápsulas Bacterianas/classificação , Cápsulas Bacterianas/genética , Feminino , Humanos , Imunogenicidade da Vacina , Polissacarídeos Bacterianos/imunologia , Infecções Estreptocócicas/imunologia , Streptococcus agalactiae/genética , Streptococcus agalactiae/patogenicidade , Vacinas Conjugadas , Fatores de Virulência/imunologia
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