RESUMEN
Neisseria are obligate human pathogens causing bacterial meningitis, septicaemia and gonorrhoea. Neisseria require iron for survival and can extract it directly from human transferrin for transport across the outer membrane. The transport system consists of TbpA, an integral outer membrane protein, and TbpB, a co-receptor attached to the cell surface; both proteins are potentially important vaccine and therapeutic targets. Two key questions driving Neisseria research are how human transferrin is specifically targeted, and how the bacteria liberate iron from transferrin at neutral pH. To address these questions, we solved crystal structures of the TbpA-transferrin complex and of the corresponding co-receptor TbpB. We characterized the TbpB-transferrin complex by small-angle X-ray scattering and the TbpA-TbpB-transferrin complex by electron microscopy. Our studies provide a rational basis for the specificity of TbpA for human transferrin, show how TbpA promotes iron release from transferrin, and elucidate how TbpB facilitates this process.
Asunto(s)
Proteínas Bacterianas/química , Hierro/metabolismo , Neisseria/metabolismo , Proteína A de Unión a Transferrina/química , Proteína A de Unión a Transferrina/metabolismo , Proteína B de Unión a Transferrina/química , Proteína B de Unión a Transferrina/metabolismo , Animales , Apoproteínas/química , Apoproteínas/metabolismo , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/ultraestructura , Sitios de Unión , Transporte Biológico , Bovinos , Cristalografía por Rayos X , Humanos , Ratones , Modelos Moleculares , Simulación de Dinámica Molecular , Neisseria/patogenicidad , Conformación Proteica , Dispersión del Ángulo Pequeño , Especificidad de la Especie , Relación Estructura-Actividad , Transferrina/química , Transferrina/metabolismo , Transferrina/ultraestructura , Proteína A de Unión a Transferrina/ultraestructura , Proteína B de Unión a Transferrina/ultraestructura , Difracción de Rayos XRESUMEN
BACKGROUND: The genus Bordetella consists of nine species that include important respiratory pathogens such as the 'classical' species B. bronchiseptica, B. pertussis and B. parapertussis and six more distantly related and less extensively studied species. Here we analyze sequence diversity and gene content of 128 genome sequences from all nine species with focus on the evolution of virulence-associated factors. RESULTS: Both genome-wide sequence-based and gene content-based phylogenetic trees divide the genus into three species clades. The phylogenies are congruent between species suggesting genus-wide co-evolution of sequence diversity and gene content, but less correlated within species, mainly because of strain-specific presence of many different prophages. We compared the genomes with focus on virulence-associated genes and identified multiple clade-specific, species-specific and strain-specific events of gene acquisition and gene loss, including genes encoding O-antigens, protein secretion systems and bacterial toxins. Gene loss was more frequent than gene gain throughout the evolution, and loss of hundreds of genes was associated with the origin of several species, including the recently evolved human-restricted B. pertussis and B. holmesii, B. parapertussis and the avian pathogen B. avium. CONCLUSIONS: Acquisition and loss of multiple genes drive the evolution and speciation in the genus Bordetella, including large scale gene loss associated with the origin of several species. Recent loss and functional inactivation of genes, including those encoding pertussis vaccine components and bacterial toxins, in individual strains emphasize ongoing evolution.
Asunto(s)
Bordetella/clasificación , Bordetella/genética , Evolución Molecular , Genoma Bacteriano , Factores de Virulencia/genética , Animales , Sistemas de Secreción Bacterianos/genética , Infecciones por Bordetella/microbiología , Conjuntos de Datos como Asunto , Genes Bacterianos , Variación Genética , Genómica , Genotipo , Humanos , Tipificación de Secuencias Multilocus , Filogenia , Polimorfismo de Nucleótido SimpleRESUMEN
A major outbreak of whooping cough, or pertussis, occurred in 2012 in the United Kingdom (UK), with nearly 10 000 laboratory-confirmed cases and 14 infant deaths attributed to pertussis. A worldwide resurgence of pertussis has been linked to switch to the use of acellular pertussis vaccines and the evolution of Bordetella pertussis away from vaccine-mediated immunity. We have conducted genomic analyses of multiple strains from the UK outbreak. We show that the UK outbreak was polyclonal in nature, caused by multiple distinct but closely related strains. Importantly, we demonstrate that acellular vaccine antigen-encoding genes are evolving at higher rates than other surface protein-encoding genes. This was true even prior to the introduction of pertussis vaccines but has become more pronounced since the introduction of the current acellular vaccines. The fast evolution of vaccine antigen-encoding genes has serious consequences for the ability of current vaccines to continue to control pertussis.
Asunto(s)
Antígenos Bacterianos/genética , Vacunas Bacterianas/inmunología , Bordetella pertussis/genética , Brotes de Enfermedades , Tos Ferina/microbiología , Bordetella pertussis/inmunología , Evolución Molecular , Genoma Bacteriano , Humanos , Filogenia , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADN , Reino Unido/epidemiología , Tos Ferina/epidemiología , Tos Ferina/prevención & controlRESUMEN
UNLABELLED: Bacterial pathogens Neisseria meningitidis and Brucella abortus pose threats to human and animal health worldwide, causing meningococcal disease and brucellosis, respectively. Mortality from acute N. meningitidis infections remains high despite antibiotics, and brucellosis presents alimentary and health consequences. Superoxide dismutases are master regulators of reactive oxygen and general pathogenicity factors and are therefore therapeutic targets. Cu,Zn superoxide dismutases (SODs) localized to the periplasm promote survival by detoxifying superoxide radicals generated by major host antimicrobial immune responses. We discovered that passive immunization with an antibody directed at N. meningitidis SOD (NmSOD) was protective in a mouse infection model. To define the relevant atomic details and solution assembly states of this important virulence factor, we report high-resolution and X-ray scattering analyses of NmSOD and of SOD from B. abortus (BaSOD). The NmSOD structures revealed an auxiliary tetrahedral Cu-binding site bridging the dimer interface; mutational analyses suggested that this metal site contributes to protein stability, with implications for bacterial defense mechanisms. Biochemical and structural analyses informed us about electrostatic substrate guidance, dimer assembly, and an exposed C-terminal epitope in the NmSOD dimer. In contrast, the monomeric BaSOD structure provided insights for extending immunogenic peptide epitopes derived from the protein. These collective results reveal unique contributions of SOD to pathogenic virulence, refine predictive motifs for distinguishing SOD classes, and suggest general targets for antibacterial immune responses. The identified functional contributions, motifs, and targets distinguishing bacterial and eukaryotic SOD assemblies presented here provide a foundation for efforts to develop SOD-specific inhibitors of or vaccines against these harmful pathogens. IMPORTANCE: By protecting microbes against reactive oxygen insults, SODs aid survival of many bacteria within their hosts. Despite the ubiquity and conservation of these key enzymes, notable species-specific differences relevant to pathogenesis remain undefined. To probe mechanisms that govern the functioning of Neisseria meningitidis and Brucella abortus SODs, we used X-ray structures, enzymology, modeling, and murine infection experiments. We identified virulence determinants common to the two homologs, assembly differences, and a unique metal reservoir within meningococcal SOD that stabilizes the enzyme and may provide a safeguard against copper toxicity. The insights reported here provide a rationale and a basis for SOD-specific drug design and an extension of immunogen design to target two important pathogens that continue to pose global health threats.
Asunto(s)
Complejo Antígeno-Anticuerpo/ultraestructura , Brucella abortus/inmunología , Neisseria meningitidis/inmunología , Superóxido Dismutasa/inmunología , Superóxido Dismutasa/ultraestructura , Animales , Anticuerpos/administración & dosificación , Anticuerpos/inmunología , Sitios de Unión de Anticuerpos , Vacuna contra la Brucelosis/inmunología , Brucella abortus/patogenicidad , Brucelosis/inmunología , Brucelosis/prevención & control , Cristalografía por Rayos X , Modelos Animales de Enfermedad , Inmunización Pasiva/métodos , Meningitis Meningocócica/inmunología , Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/inmunología , Ratones , Neisseria meningitidis/patogenicidad , Superóxido Dismutasa/genética , Factores de Virulencia/inmunologíaRESUMEN
BACKGROUND: Herd protection by meningococcal vaccines is conferred by population-level reduction of meningococcal nasopharyngeal colonization. Given the inverse epidemiological association between colonization by commensal Neisseria lactamica and meningococcal disease, we investigated whether controlled infection of human volunteers with N. lactamica prevents colonization by Neisseria meningitidis. METHODS: In a block-randomized human challenge study, 310 university students were inoculated with 10(4) colony-forming units of N. lactamica or were sham-inoculated, and carriage was monitored for 26 weeks, after which all participants were reinoculated with N. lactamica and resampled 2 weeks later. RESULTS: At baseline, natural N. meningitidis carriage in the control group was 22.4% (36/161), which increased to 33.6% (48/143) by week 26. Two weeks after inoculation of N. lactamica, 33.6% (48/143) of the challenge group became colonized with N. lactamica. In this group, meningococcal carriage reduced from 24.2% (36/149) at inoculation to 14.7% (21/143) 2 weeks after inoculation (-9.5%; P = .006). The inhibition of meningococcal carriage was only observed in carriers of N. lactamica, was due both to displacement of existing meningococci and to inhibition of new acquisition, and persisted over at least 16 weeks. Crossover inoculation of controls with N. lactamica replicated the result. Genome sequencing showed that inhibition affected multiple meningococcal sequence types. CONCLUSIONS: The inhibition of meningococcal carriage by N. lactamica is even more potent than after glycoconjugate meningococcal vaccination. Neisseria lactamica or its components could be a novel bacterial medicine to suppress meningococcal outbreaks. This observation explains the epidemiological observation of natural immunity conferred by carriage of N. lactamica. CLINICAL TRIALS REGISTRATION: NCT02249598.
Asunto(s)
Portador Sano/microbiología , Portador Sano/prevención & control , Infecciones Meningocócicas/microbiología , Infecciones Meningocócicas/prevención & control , Neisseria lactamica/crecimiento & desarrollo , Neisseria meningitidis/aislamiento & purificación , Probióticos/administración & dosificación , Adolescente , Adulto , Antibiosis , Femenino , Humanos , Masculino , Estudios Prospectivos , Resultado del Tratamiento , Adulto JovenRESUMEN
The fimbriae of Bordetella pertussis are required for colonization of the human respiratory tract. Two serologically distinct fimbrial subunits, Fim2 and Fim3, considered important vaccine components for many years, are included in the Sanofi Pasteur 5-component acellular pertussis vaccine, and the World Health Organization recommends the inclusion of strains expressing both fimbrial serotypes in whole-cell pertussis vaccines. Each of the fimbrial major subunit genes, fim2, fim3, and fimX, has a promoter poly(C) tract upstream of its -10 box. Such monotonic DNA elements are susceptible to changes in length via slipped-strand mispairing in vitro and in vivo, which potentially causes on/off switching of genes at every cell division. Here, we have described intra-culture variability in poly(C) tract lengths and the resulting fimbrial phenotypes in 22 recent UK B. pertussis isolates. Owing to the highly plastic nature of fimbrial promoters, we used the same cultures for both genome sequencing and flow cytometry. Individual cultures of B. pertussis contained multiple fimbrial serotypes and multiple different fimbrial promoter poly(C) tract lengths, which supports earlier serological evidence that B. pertussis expresses both serotypes during infection.
Asunto(s)
Bordetella pertussis/genética , Bordetella pertussis/inmunología , Fimbrias Bacterianas/genética , Fimbrias Bacterianas/inmunología , Serogrupo , Bordetella pertussis/aislamiento & purificación , ADN Bacteriano/química , ADN Bacteriano/genética , Citometría de Flujo , Variación Genética , Genoma Bacteriano , Genotipo , Humanos , Regiones Promotoras Genéticas , Análisis de Secuencia de ADN , Reino Unido , Tos Ferina/microbiologíaRESUMEN
Bacterial genetic diversity is often described solely using base-pair changes despite a wide variety of other mutation types likely being major contributors. Tandem duplication/amplifications are thought to be widespread among bacteria but due to their often-intractable size and instability, comprehensive studies of these mutations are rare. We define a methodology to investigate amplifications in bacterial genomes based on read depth of genome sequence data as a proxy for copy number. We demonstrate the approach with Bordetella pertussis, whose insertion sequence element-rich genome provides extensive scope for amplifications to occur. Analysis of data for 2430 B. pertussis isolates identified 272 putative amplifications, of which 94â% were located at 11 hotspot loci. We demonstrate limited phylogenetic connection for the occurrence of amplifications, suggesting unstable and sporadic characteristics. Genome instability was further described in vitro using long-read sequencing via the Nanopore platform, which revealed that clonally derived laboratory cultures produced heterogenous populations rapidly. We extended this research to analyse a population of 1000 isolates of another important pathogen, Mycobacterium tuberculosis. We found 590 amplifications in M. tuberculosis, and like B. pertussis, these occurred primarily at hotspots. Genes amplified in B. pertussis include those involved in motility and respiration, whilst in M. tuberuclosis, functions included intracellular growth and regulation of virulence. Using publicly available short-read data we predicted previously unrecognized, large amplifications in B. pertussis and M. tuberculosis. This reveals the unrecognized and dynamic genetic diversity of B. pertussis and M. tuberculosis, highlighting the need for a more holistic understanding of bacterial genetics.
Asunto(s)
Bordetella pertussis/genética , Variación Genética , Mycobacterium tuberculosis/genética , Bordetella pertussis/clasificación , Genes Bacterianos/genética , Genoma Bacteriano , Inestabilidad Genómica , Mutación , Mycobacterium tuberculosis/clasificación , Filogenia , Virulencia/genética , Tos Ferina/microbiologíaRESUMEN
BACKGROUND: Pharyngeal colonisation by the commensal bacterium Neisseria lactamica inhibits colonisation by Neisseria meningitidis and has an inverse epidemiological association with meningococcal disease. The mechanisms that underpin this relationship are unclear, but could involve the induction of cross-reactive immunity. In this study, we aimed to evaluate whether colonisation with N lactamica induces N lactamica-specific B-cell responses that are cross-reactive with N meningitidis. METHODS: In this randomised, placebo-controlled, human infection trial at University Hospital Southampton Clinical Research Facility (Southampton, UK), healthy adults aged 18-45 years were randomly assigned (2:1) to receive intranasal inoculation with either 105 colony-forming units of N lactamica in 1 mL phosphate-buffered saline (PBS) or 1 mL PBS alone. Participants and researchers conducting participant sampling and immunological assays were masked to allocation. The primary endpoint was the frequency of circulating N lactamica-specific plasma cells and memory B cells after N lactamica inoculation (day 7-28) compared with baseline values (day 0), measured using enzyme-linked immunospot assays. The secondary endpoint was to measure the frequency of N meningitidis-specific B cells. In a second study, we measured the effect of duration of N lactamica colonisation on seroconversion by terminating carriage at either 4 days or 14 days with single-dose oral ciprofloxacin. The studies are now closed to participants. The trials are registered with ClinicalTrials.gov, NCT03633474 and NCT03549325. FINDINGS: Of 50 participants assessed for eligibility between Sept 5, 2018, and March 3, 2019, 31 were randomly assigned (n=20 N lactamica, n=11 PBS). Among the 17 participants who were colonised with N lactamica, the median baselines compared with peak post-colonisation N lactamica-specific plasma-cell frequencies (per 105 peripheral blood mononuclear cells) were 0·0 (IQR 0·0-0·0) versus 5·0 (1·5-10·5) for IgA-secreting plasma cells (p<0·0001), and 0·0 (0·0-0·0) versus 3·0 (1·5-9·5) for IgG-secreting plasma cells (p<0·0001). Median N lactamica-specific IgG memory-B-cell frequencies (percentage of total IgG memory B cells) increased from 0·0024% (0·0000-0·0097) at baseline to 0·0384% (0·0275-0·0649) at day 28 (p<0·0001). The frequency of N meningitidis-specific IgA-secreting and IgG-secreting plasma cells and memory B cells also increased signficantly in participants who were colonised with N lactamica. Upper respiratory tract symptoms were reported in ten (50%) of 20 participants who were inoculated with N lactamica and six (55%) of 11 participants who were inoculated with PBS (p>0·99). Three additional adverse events (two in the N lactamica group and one in the PBS group) and no serious adverse events were reported. In the second study, anti-N lactamica and anti-N meningitidis serum IgG titres increased only in participants who were colonised with N lactamica for 14 days. INTERPRETATION: Natural immunity to N meningitidis after colonisation with N lactamica might be due to cross-reactive adaptive responses. Exploitation of this microbial mechanism with a genetically modified live vector could protect against N meningitidis colonisation and disease. FUNDING: Wellcome Trust, Medical Research Council, and NIHR Southampton Biomedical Research Centre.
Asunto(s)
Neisseria lactamica , Neisseria meningitidis , Adulto , Humanos , Leucocitos Mononucleares , Inmunoglobulina A Secretora , Fosfatos , Solución Salina , Inmunoglobulina GRESUMEN
The tetraspanins are a superfamily of transmembrane proteins with diverse functions and can form extended microdomains within the plasma membrane in conjunction with partner proteins, which probably includes receptors for bacterial adhesins. Neisseria meningitidis, the causative agent of meningococcal disease, attaches to host nasopharyngeal epithelial cells via type IV pili and opacity (Opa) proteins. We examined the role of tetraspanin function in Neisseria meningitidis adherence to epithelial cells. Tetraspanins CD9, CD63, and CD151 were expressed by HEC-1-B and DETROIT 562 cells. Coincubation of cells with antibodies against all three tetraspanin molecules used individually or in combination, with recombinant tetraspanin extracellular domains (EC2), or with small interfering RNAs (siRNAs) significantly reduced adherence of Neisseria meningitidis. In contrast, recombinant CD81, a different tetraspanin, had no effect on meningococcal adherence. Antitetraspanin antibodies reduced the adherence to epithelial cells of Neisseria meningitidis strain derivatives expressing Opa and pili significantly more than isogenic strains lacking these determinants. Adherence to epithelial cells of strains of Staphylococcus aureus, Neisseria lactamica, Escherichia coli, and Streptococcus pneumoniae was also reduced by pretreatment of cells with tetraspanin antibodies and recombinant proteins. These data suggest that tetraspanins are required for optimal function of epithelial adhesion platforms containing specific receptors for Neisseria meningitidis and potentially for multiple species of bacteria.
Asunto(s)
Adhesinas Bacterianas/fisiología , Células Epiteliales/microbiología , Antígenos CD/fisiología , Células Cultivadas , Humanos , Glicoproteínas de Membrana/fisiología , Meningitis Meningocócica/microbiología , Microscopía Fluorescente , Neisseria lactamica/fisiología , Neisseria meningitidis/fisiología , Infecciones por Neisseriaceae/microbiología , Glicoproteínas de Membrana Plaquetaria/fisiología , Infecciones Neumocócicas/microbiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/fisiología , Streptococcus pneumoniae/fisiología , Tetraspanina 24 , Tetraspanina 29 , Tetraspanina 30RESUMEN
BACKGROUND: Natural immunity to Neisseria meningitidis may result from nasopharyngeal carriage of closely related commensals, such as Neisseria lactamica. METHODS: We enrolled 61 students with no current carriage of Neisseria species and inoculated them intranasally with 10,000 colony-forming units of Neisseria lactamica or sham control. Colonization was monitored in oropharyngeal samples over 6 months. We measured specific mucosal and systemic antibody responses to N. lactamica and serum bactericidal antibody (SBA) and opsonophagocytic antibodies to a panel of N. meningitidis serogroup B strains. We also inoculated an additional cohort following vaccination with N. lactamica outer-membrane vesicles (OMV) produced from the same strain. RESULTS: Twenty-six (63.4%) of 41 inoculated individuals became colonized with N. lactamica; 85% remained colonized at 12 weeks. Noncarriers were resistant to rechallenge, and carriers who terminated carriage were relatively resistant to rechallenge. No carriers acquired N. meningitidis carriage over 24 weeks, compared with 3 control subjects (15%). Carriers developed serum IgG and salivary IgA antibodies to the inoculated N. lactamica strain by 4 weeks; noncarriers and control subjects did not. Cross-reactive serum bactericidal antibody responses to N.meningitidis were negligible in carriers, but they developed broad opsonophagocytic antimeningococcal antibodies. OMV vaccinees developed systemic and mucosal anti-N. lactamica antibodies and were relatively resistant to N. lactamica carriage but not to natural acquisition of N. meningitidis. CONCLUSIONS: Carriers of N. lactamica develop mucosal and systemic humoral immunity to N. lactamica together with cross-reacting systemic opsonophagocytic but not bactericidal antibodies to N. meningitidis. Possession of humoral immunity to N. lactamica inhibits acquisition of N. lactamica but not of N. meningitidis. Some individuals are intrinsically resistant to N. lactamica carriage, independent of humoral immunity.
Asunto(s)
Portador Sano/inmunología , Nasofaringe/microbiología , Neisseria lactamica/inmunología , Neisseria meningitidis Serogrupo B/inmunología , Infecciones por Neisseriaceae/inmunología , Adolescente , Adulto , Anticuerpos Antibacterianos/sangre , Vacunas Bacterianas/administración & dosificación , Vacunas Bacterianas/inmunología , Actividad Bactericida de la Sangre , Portador Sano/microbiología , Reacciones Cruzadas , Femenino , Humanos , Inmunidad Mucosa , Masculino , Persona de Mediana Edad , Neisseria lactamica/aislamiento & purificación , Infecciones por Neisseriaceae/microbiología , Proteínas Opsoninas/inmunología , Fagocitosis , Vesículas Secretoras/inmunología , Determinación de Anticuerpos Séricos Bactericidas , Adulto JovenRESUMEN
The human nasopharynx contains a stable microbial ecosystem of commensal and potentially pathogenic bacteria, which can elicit protective primary and secondary immune responses. Experimental intranasal infection of human adults with the commensal Neisseria lactamica produced safe, sustained pharyngeal colonization. This has potential utility as a vehicle for sustained release of antigen to the human mucosa, but commensals in general are thought to be immunologically tolerated. Here, we show that engineered N. lactamica, chromosomally transformed to express a heterologous vaccine antigen, safely induces systemic, antigen-specific immune responses during carriage in humans. When the N. lactamica expressing the meningococcal antigen Neisseria Adhesin A (NadA) was inoculated intranasally into human volunteers, all colonized participants carried the bacteria asymptomatically for at least 28 days, with most (86%) still carrying the bacteria at 90 days. Compared to an otherwise isogenic but phenotypically wild-type strain, colonization with NadA-expressing N. lactamica generated NadA-specific immunoglobulin G (IgG)- and IgA-secreting plasma cells within 14 days of colonization and NadA-specific IgG memory B cells within 28 days of colonization. NadA-specific IgG memory B cells were detected in peripheral blood of colonized participants for at least 90 days. Over the same period, there was seroconversion against NadA and generation of serum bactericidal antibody activity against a NadA-expressing meningococcus. The controlled infection was safe, and there was no transmission to adult bedroom sharers during the 90-day period. Genetically modified N. lactamica could therefore be used to generate beneficial immune responses to heterologous antigens during sustained pharyngeal carriage.
Asunto(s)
Vacunas Meningococicas , Neisseria lactamica , Adulto , Anticuerpos Antibacterianos , Antígenos Heterófilos , Ecosistema , Humanos , Memoria InmunológicaRESUMEN
Bordetella pertussis whole-cell vaccines (wP) caused a spectacular drop of global pertussis incidence, but since the replacement of wP with acellular pertussis vaccines (aP), pertussis has resurged in developed countries within 7 to 12 years of the change from wP to aP. In the mouse infection model, we examined whether addition of further protective antigens into the aP vaccine, such as type 2 and type 3 fimbriae (FIM2/3) with outer membrane lipooligosaccharide (LOS) and/or of the adenylate cyclase toxoid (dACT), which elicits antibodies neutralizing the CyaA toxin, could enhance the capacity of the aP vaccine to prevent colonization of the nasal mucosa by B. pertussis. The addition of the toxoid and of the opsonizing antibody-inducing agglutinogens modestly enhanced the already high capacity of intraperitoneally-administered aP vaccine to elicit sterilizing immunity, protecting mouse lungs from B. pertussis infection. At the same time, irrespective of FIM2/3 with LOS and dACT addition, the aP vaccination ablated the natural capacity of BALB/c mice to clear B. pertussis infection from the nasal cavity. While wP or sham-vaccinated animals cleared the nasal infection with similar kinetics within 7 weeks, administration of the aP vaccine promoted persistent colonization of mouse nasal mucosa by B. pertussis.
RESUMEN
The report describes developments in meningococcal disease vaccines presented at the 16th International Pathogenic Neisseria Conference, Rotterdam, 7-12 September 2008. Great progress has been made by the Meningitis Vaccine Project to provide an affordable and effective serogroup A conjugate vaccine for use in the meningitis belt of Sub-Saharan Africa. The vaccine has been shown to be safe and to produce excellent immune response in phase 2 clinical trials in India and Africa in the target populations and will be rolled out to the worst affected countries from 2009. This vaccine has the potential to make a huge impact on public health in this region. This conference heard that the use of an epidemic strain-specific outer membrane vesicle (OMV) vaccine in New Zealand has been discontinued. Views for and against this decision were presented. Several MenB vaccines have progressed to clinical evaluation. The most advanced are the Novartis five recombinant protein variants and the Wyeth vaccine based on two factor H binding protein variants. Promising results from both vaccines with genetically-detoxified lipooligosaccharide and overexpressed heterologous antigens, OMV's from Neisseria lactamica and recombinant Opa proteins.
Asunto(s)
Meningitis Meningocócica/microbiología , Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/inmunología , Investigación Biomédica/tendencias , Ensayos Clínicos como Asunto , Humanos , Vacunas Meningococicas/efectos adversosRESUMEN
INTRODUCTION: We summarise an ethically approved protocol for the development of an experimental human challenge colonisation model. Globally Bordetella pertussis is one of the leading causes of vaccine-preventable death. Many countries have replaced whole cell vaccines with acellular vaccines over the last 20 years during which pertussis appears to be resurgent in a number of countries in the developed world that boast high immunisation coverage. The acellular vaccine provides relatively short-lived immunity and, in contrast to whole cell vaccines, may be less effective against colonisation and subsequent transmission. To improve vaccine strategies, a greater understanding of human B. pertussis colonisation is required. This article summarises a protocol and does not contain any results. METHODS AND ANALYSIS: A controlled human colonisation model will be developed over two phases. In phase A, a low dose of the inoculum will be given intranasally to healthy participants. This dose will be escalated or de-escalated until colonisation is achieved in approximately 70% (95% CI 47% to 93%) of the exposed volunteers without causing disease. The colonisation period, shedding and exploratory immunology will be assessed during a 17-day inpatient stay and follow-up over 1 year. The dose of inoculum that achieves 70% colonisation will then be confirmed in phase B, comparing healthy participants exposed to B. pertussis with a control group receiving a sham inoculum. ETHICS AND DISSEMINATION: This study has been approved by the ethical committee reference: 17/SC/0006, 24 February 2017. Findings will be published in peer-reviewed open access journals as soon as possible.
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Bordetella pertussis/fisiología , Relación Dosis-Respuesta Inmunológica , Vacuna contra la Tos Ferina/administración & dosificación , Tos Ferina/inmunología , Bordetella pertussis/aislamiento & purificación , Protocolos Clínicos , Humanos , Vacuna contra la Tos Ferina/inmunología , Proyectos de Investigación , Vacunación , Vacunas Acelulares/administración & dosificación , Vacunas Acelulares/inmunología , Tos Ferina/prevención & controlRESUMEN
Neisseria meningitidis, a causative agent of bacterial meningitis, obtains transferrin-bound iron by expressing two outer membrane located transferrin-binding proteins, TbpA and TbpB. TbpA is thought to be an integral outer membrane pore that facilitates iron uptake. Evidence suggests that TbpA is a useful antigen for inclusion in a vaccine effective against meningococcal disease, hence the identification of regions involved in ligand binding is of paramount importance to design strategies to block uptake of iron. The protein shares sequence and functional similarities to the Escherichia coli siderophore receptors FepA and FhuA, whose structures have been determined. These receptors are composed of two domains, a 22-stranded beta-barrel and an N-terminal plug region that sits within the barrel and occludes the transmembrane pore. A three-dimensional TbpA model was constructed using FepA and FhuA structural templates, hydrophobicity analysis and homology modelling. TbpA was found to possess a similar architecture to the siderophore receptors. In addition to providing insights into the highly immunogenic nature of TbpA and allowing the prediction of potentially important ligand-binding epitopes, the model also reveals a narrow channel through its entire length. The relevance of this channel and the spatial arrangement of external loops, to the mechanism of iron translocation employed by TbpA is discussed.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa/química , Modelos Moleculares , Neisseria meningitidis/química , Receptores de Superficie Celular/química , Proteína A de Unión a Transferrina/química , Secuencia de Aminoácidos , Proteínas de la Membrana Bacteriana Externa/metabolismo , Sitios de Unión , Epítopos , Escherichia coli/metabolismo , Hierro , Ligandos , Datos de Secuencia Molecular , Receptores de Superficie Celular/metabolismo , Homología de Secuencia de Aminoácido , Sideróforos/metabolismo , Transferrina/metabolismo , Proteína A de Unión a Transferrina/metabolismoRESUMEN
Bordetella pertussis produces two serologically distinct fimbriae, Fim2 and Fim3. Expression of these antigens is governed by the BvgA/S system and by the length of a poly(C) tract in the promoter of each gene. Fim2 and Fim3 are important antigens for whole cell pertussis vaccines as clinical trials have shown an association of anti-fimbriae antibody-mediated agglutination and protection. The current five component acellular pertussis vaccine contains co-purified Fim2/3 and provided good efficacy in clinical trials with the anti-Fim antibody response correlating with protection when pre and post exposure antibody levels were analysed. The predominant serotype of B. pertussis isolates has changed over time in most countries but it is not understood whether this is vaccine-driven or whether serotype is linked to the prevailing predominant genotype. Recent studies have shown that both Fim2 and Fim3 are expressed during infection and that Fim2 is more immunogenic than Fim3 in the acellular vaccine.
Asunto(s)
Bordetella pertussis/inmunología , Fimbrias Bacterianas/inmunología , Vacuna contra la Tos Ferina/inmunología , Animales , Anticuerpos Antibacterianos/análisis , Anticuerpos Antibacterianos/biosíntesis , Bordetella pertussis/genética , Fimbrias Bacterianas/genética , Humanos , Vacuna contra la Tos Ferina/genética , Vacunas Acelulares/inmunologíaRESUMEN
Bordetella pertussis fimbriae (Fim2 and Fim3) are components of a five-component acellular pertussis vaccine (diphtheria-tetanus-acellular pertussis vaccine [DTaP5]), and antibody responses to fimbriae have been associated with protection. We analyzed the IgG responses to individual Fim2 and Fim3 in sera remaining from a Swedish placebo-controlled efficacy trial that compared a whole-cell vaccine (diphtheria-tetanus-whole-cell pertussis vaccine [DTwP]), a two-component acellular pertussis vaccine (DTaP2), and DTaP5. One month following three doses of the Fim-containing vaccines (DTwP or DTaP5), anti-Fim2 geometric mean IgG concentrations were higher than those for anti-Fim3, with a greater anti-Fim2/anti-Fim3 IgG ratio elicited by DTaP5. We also determined the responses in vaccinated children following an episode of pertussis. Those who received DTaP5 showed a large rise in anti-Fim2 IgG, reflecting the predominant Fim2 serotype at the time. In contrast, those who received DTwP showed an equal rise in anti-Fim2 and anti-Fim3 IgG concentrations, indicating that DTwP may provide a more efficient priming effect for a Fim3 response following contact with B. pertussis. Anti-Fim2 and anti-Fim3 IgG concentrations were also determined in samples from two seroprevalence studies conducted in Sweden in 1997, when no pertussis vaccine was used and Fim2 isolates predominated, and in 2007, when either DTaP2 or DTaP3 without fimbriae was used and Fim3 isolates predominated. Very similar distributions of anti-Fim2 and anti-Fim3 IgG concentrations were obtained in 1997 and 2007, except that anti-Fim3 concentrations in 1997 were lower. This observation, together with the numbers of individuals with both anti-Fim2 and anti-Fim3 IgG concentrations, strongly suggests that B. pertussis expresses both Fim2 and Fim3 during infection.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Formación de Anticuerpos , Antígenos Bacterianos/inmunología , Proteínas Fimbrias/inmunología , Vacuna contra la Tos Ferina/inmunología , Factores de Virulencia de Bordetella/inmunología , Tos Ferina/inmunología , Adolescente , Niño , Preescolar , Femenino , Humanos , Inmunoglobulina G/sangre , Lactante , Recién Nacido , Masculino , Vacuna contra la Tos Ferina/administración & dosificación , Suecia , Vacunas Acelulares/administración & dosificación , Vacunas Acelulares/inmunología , Vacunas de Productos Inactivados/administración & dosificación , Vacunas de Productos Inactivados/inmunologíaRESUMEN
Serogroup B meningococcal (MenB) disease remains a serious public health problem for which a cross-protective vaccine effective against a wide range of MenB isolates has not been available. Novartis Vaccines has developed a vaccine for the prevention of MenB disease that contains four antigenic components: factor H binding protein (fHbp), neisserial adhesin A (NadA), Neisseria heparin binding antigen (NHBA) and outer membrane vesicles from a New Zealand epidemic strain (which provides PorA). This vaccine has been submitted for regulatory review in Europe so it is timely to review the design of the vaccine, results to date in clinical studies and the potential strain coverage provided by the vaccine. It is also critical to discuss the key issues for the long-term success of the vaccine which include strain coverage, potential persistence of protection, potential effects on carriage of MenB strains, potential for escape mutants and cost effectiveness.
Asunto(s)
Meningitis Meningocócica/inmunología , Meningitis Meningocócica/prevención & control , Vacunas Meningococicas/inmunología , Adhesinas Bacterianas/inmunología , Antígenos Bacterianos/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas Bacterianas/inmunología , Protección Cruzada , Humanos , Porinas/inmunología , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
Bordetella pertussis expresses two serologically distinct fimbriae (Fim2 and Fim3) which are included in the Sanofi Pasteur 5-component acellular pertussis vaccine, and antibody responses to these antigens have been shown to be associated with protection. Studies to date have assessed the IgG response to this vaccine using a copurified mixture of Fim2 and Fim3, and the response to the individual antigens has not been characterized. We have purified separate Fim2 and Fim3 from strains that express either Fim2 or Fim3 and have used these antigens in an enzyme-linked immunosorbent assay (ELISA) to quantify IgG responses following immunization with 5-component acellular pertussis vaccine in 15-month-old, 4- to 6-year-old, and 11- to 18-year-old subjects. All individuals showed increases in Fim2 and Fim3 IgG concentrations following immunization, with 3-fold-greater Fim2 than Fim3 IgG concentrations seen in the younger two age groups. Fim2 IgG concentrations were 1.5-fold greater than Fim3 IgG concentrations in the 11- to 18-year-olds. We have also compared Fim2 and Fim3 IgG concentrations in individuals with prolonged cough who were diagnosed as having recent pertussis using a pertussis toxin (Ptx) IgG ELISA with individuals with prolonged cough but without elevated Ptx IgG concentrations. Individuals with evidence of recent pertussis had greater Fim3 IgG concentrations, consistent with the predominant serotype of isolates obtained in the United Kingdom. However, a surprising number of individuals had moderate Fim2 IgG concentrations despite very few isolates of that serotype obtained in the sampling period.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Antígenos Bacterianos/inmunología , Proteínas Fimbrias/inmunología , Vacuna contra la Tos Ferina/administración & dosificación , Vacuna contra la Tos Ferina/inmunología , Factores de Virulencia de Bordetella/inmunología , Adolescente , Antígenos Bacterianos/aislamiento & purificación , Niño , Preescolar , Ensayo de Inmunoadsorción Enzimática , Proteínas Fimbrias/aislamiento & purificación , Humanos , Inmunoglobulina G/sangre , Lactante , Vacunas Acelulares/administración & dosificación , Vacunas Acelulares/inmunología , Factores de Virulencia de Bordetella/aislamiento & purificaciónRESUMEN
We sought to determine whether NMB1966, encoding a putative ABC transporter, has a role in pathogenesis. Compared to its isogenic wild-type parent strain Neisseria meningitidis MC58, the NMB1966 knockout mutant was less adhesive and invasive for human bronchial epithelial cells, had reduced survival in human blood and was attenuated in a systemic mouse model of infection. The transcriptome of the wild-type and the NMB1966 mutant was compared. The data are consistent with a previous functional assignment of NMB1966 being the ABC transporter component of a glutamate transporter operon. Forty-seven percent of all the differentially regulated genes encoded known outer membrane proteins or pathways generating complex surface structures such as adhesins, peptidoglycan and capsule. The data show that NMB1966 has a role in virulence and that remodelling of the outer membrane and surface/structures is associated with attenuation of the NMB1966 mutant.