Made available in DSpace on 2014-07-28T18:10:50Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 98.pdf: 3463846 bytes, checksum: 8603b620b9560561e10f307f624ab539 (MD5) Previous issue date: 2008 / Made available in DSpace on 2014-12-22T16:56:35Z (GMT). No. of bitstreams: 2 98.pdf: 3463846 bytes, checksum: 8603b620b9560561e10f307f624ab539 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Fundação Oswaldo Cruz. Instituto Nacional de Controle de Qualidade em Saúde / Dentre os efeitos induzidos pela toxina pertussis (TP) em mamíferos, ocupa um lugar de destaque o fenômeno conhecido por sensibilização aos efeitos biológicos e letais da histamina, cuja intensidade e constância proporcionaram o estabelecimento de um ensaio in vivo de controle de qualidade para avaliação da segurança de vacinas contra a pertussis (coqueluche) e tríplice bacteriana contra a difteria, tétano e coqueluche (DTP). O ensaio de sensibilização à histamina (ESH) em camundongos NIH fêmeas mostrou-se altamente sensível à toxina pertussis de referência NIBSC 90/518 (TPR) detectando níveis tão baixos quanto 20 ng de TP/dose. Todas as 5 vacinas DTP de um produtor nacional noESH apresentaram níveis de TP ativa que variaram entre 84 a 147 ng/mL, valores inferiores ao valor limite de 1789 ng/mL obtido para a vacina pertussis de referência NIBSC 66/303 (VPR), logo, todas as vacinas foram aprovadas para uso humano. Embora o ESH tenha sido conclusivo quanto à alta especificidade à TP, o elevado número de animais, no mínimo, 40 por ensaio, acarretando alto custo e o sofrimento dos animais são fatores limitantes que dificultam o uso rotineiro como ensaio de controle de qualidade da vacina DTP. O objetivo do nosso estudo foi desenvolver uma metodologia in vitro em preparações de íleo isolado de cobaias Short Hair fêmeas (250 a 300 g) fornecidas pelo CECAL/FIOCRUZ /Rio de Janeiro para avaliação do fenômeno de sensibilização à histamina pela TPR. Todos os experimentos foram aprovados de acordo com as diretrizes estabelecidas pela CEUA/FIOCRUZ. Curvas concentração-efeito à histamina em íleos isolados de cobaias foram analisadas e os parâmetros de concentração efetiva média(CE50), concentração efetiva máxima (CEmax) e de constante de dissociação no equilíbrio do complexo droga-receptor (Kd) para histamina foram determinados [...]. / Among the effects induced by pertussis toxin (PT) in mammalian species, a prominence place is occupied by the phenomenon known as sensitization to the biological and lethal effects of the histamine, whose intensity and constancy promoted the establishment of an in vivo quality control assay to evaluate the safety of the pertussis vaccine (PV) against whooping cough and the triple bacterial vaccine, (DPT) against diphtheria, whooping cough and tetanus. The histamine sensitization assay (HSA) performed with NIH female mice was highly sensitive to reference pertussis toxin NIBSC 90/518 (RPT), detecting levels as low as 20 ng of administered RPT/dose, which caused 50% lethality. All five samples of DPT vaccines from one Brazilian producer presented active PT levels in the range of 84 and 147 ng/ml by the HSA, inferior to the limit value of 1789 ng/mL obtained for reference pertussis vaccine NIBSC 66/303 (RPV), thus all the vaccines were approved for use. Although the HSA has been conclusive in relation to its high specificity for RPT, the large number of mice used (at least 40 per assay) results in high costs and the suffering of the mice are limiting factors that make its routine use as a DPT vaccine quality control assay difficult. The aim of our study was to develop an in vitro methodology in ileum segments from female Short Hair guinea pigs (250-300 g) maintained in the animal facilities of the Oswaldo Cruz Foundation in Rio de Janeiro (FIOCRUZ), Brazil, to evaluate the histamine sensitization phenomenon by RPT. All experiments were approved in accordance with the guidelines of the Committee for Ethics in Animal Use of the FIOCRUZ. Concentration effects curves for histamine in guinea pig ileum were studied and the parameters of mean effective concentration (EC50), maximum effective concentration (ECmax) and dissociation constant of drug-receptor complex (Kd) were determined. No increase in ileum contractile response to histamine was detected in relation to control PBS 4 days after intraperitoneal treatment of guinea pigs with doses and dilutions corresponding to mean histamine sensitization dose (HSD50) obtained in NIH female mice of RPT (40 ng), RPV and of 5 DPT vaccines (0.26 IU). In all the ten assays performed on the experimental group, the data followed normal distribution, the variances were homogeneous and no significant differences occurred between assays. With doses 10 times higher than the HSD50 of RPT (400 ng) and of RPV (2.6 IU), analysis of the data showed the same behavior above. Contrary to the anticipated results, histamine EC50 and Kd values in ileum of guinea pigs treated in vivo with RPT were significantly higher than the control and RPV (p< 0.05) with no alteration in ECmax (p= 0.3672). In vitro 15 min treatment of guinea pig ileum with 30 ng/ml of RPT reduced the ECmax to about half in relation to control (p= 0.0028), with no significant reduction in the mean values of histamine EC50 and Kd (p= 0.09). In contrast, in vitro 15 min treatment of ileum with 40 ng/ml of RPT significantly reduced histamine ECmax (p< 0.0069), EC50 (p= 0.0261) and Kd (p= 0.0479) in relation to control ileum. In vitro 15 min treatment with PBS (390 and 520 µL in 13 mL of Tyrode) did not significantly alter the mean values of histamine EC50 (p=0.4043 and p= 0.1035), ECmax (p= 0.2366 and p= 0.2708) or KD (p= 0.4564 and p= 0.1158) in relation to control without treatment, demonstrating no effect of the control solvent (PBS) on ileum contractile response by histamine. In conclusion, increased histamine sensitization in female guinea pig ileum after in vitro treatment of 30 and 40 ng/ml of RPT was demonstrated.

Resumo não disponível.

Resumo não disponível.

Bordetella pertussis produces many virulent factors including adenylate cyclase toxin (CyaA) This toxin preferentially invades cells of immune system with integrin receptor CD11b/CD18 and weakens the immune system of the host. CyaA affects invaded cells in two ways. First, CyaA creates a cation-selective pores in the membrane of invaded cell and causes colloidal osmotic lysis. Second, CyaA converts cytosolic ATP into signal molecule cAMP, which causes a loss of physiological function of invaded cell and also leads to cellular death. The aim of my thesis was to test a suitability of a new model system composed from synthetic lipids - diphytanoyls, for a characterization of pore-forming properties of adenylate cyclase toxin. In the past, asolectin model system comprising many different lipid was used for characterization but it was found to be too complex for defining the role of individual lipids in CyaA activity. Further the effect of cholesterol for activity of CyaA was studied in a new model system because it was found recently that translocation of adenylate cyclase domain takes place at lipids rafts with high concentration of cholesterol. The last aim of my thesis was to characterize a newly discovered type of channel with the two conductance levels. Key words: Bordetella pertussis, adenylate...

The Bordetellae are aerobic Gram-negative coccobacilli colonizing the upper respiratory tract of mammals and thereby causing diseases with similar symptoms but different host specificity. The bacteria produce a variety of adhesins and toxins that facilitate their ability to promote infection and evade the innate immune system. Among them, the filamentous hemagglutinin (FHA) and the adenylate cyclase toxin (CyaA) are the major virulence factors providing the adherence to the host epithelial cells and the protection against bactericidal activity of phagocytic cells, respectively. Moreover, CyaA along with the Escherichia coli α-hemolysin (HlyA) and the Kingella kingae cytotoxin (RtxA) represent a prominent group of Repeats in ToXin (RTX) cytotoxins/hemolysins that undergo post-translational acylation on conserved lysine residues. Here, different mass spectrometry approaches were employed to analyze the structural features of FHA and to characterize the acylation status of the RTX toxins and their various hybrid molecules. First, the differential 16O/18O labeling revealed that the mature FHA proteins of B. pertussis (Bp-FHA) and the B. bronchiseptica (Bb-FHA) are processed at different sites, after Ala2348 and Lys2479 of the FhaB precursor, respectively. Second, the bottom-up proteomics of the...

No description available.

La toxine de pertussis (PTX) est une A-B protéine considérée comme l’un des principaux facteurs de virulence de Bordetella pertussis, l’agent bactérien responsable de la coqueluche. Aujourd’hui, cette maladie représente encore un réel danger pour les nouveaux-nés et les<p>nourrissons non ou partiellement immunisés. Actuellement, la coqueluche provoque encore la<p>mort d’environ 350.000 individus par an. La toxicité de la PTX est liée à l’activité<p>enzymatique de sa sous-unité A capable d’inhiber les voies de signalisation associées aux<p>protéines Gi. La partie B, quant à elle, permet l’entrée de cette sous-unité A dans le<p>cytoplasme des cellules cibles en se liant spécifiquement à son ou ses récepteurs<p>membranaires toujours inconnus de nos jours.<p><p>Des études réalisées chez la souris et chez l’homme ont montré que les vaccins anticoquelucheux combinés à différents antigènes vaccinaux étaient capables de moduler<p>leurs réponses humorales spécifiques. Par ailleurs, la PTX est couramment qualifiée d’agent<p>immunostimulant. En effet, des modèles murins de vaccination permirent d’identifier des<p>propriétés adjuvantes de la PTX coadministrée avec des antigènes non relevants.<p><p>Le travail développé dans ce manuscrit étudie les effets de la PTX sur 2 types cellulaires<p>primordiaux sollicités lors d’une vaccination :la cellule dendritique (DC) et le lymphocyte T<p>CD4+ naïf.<p><p>Les DC sont les seules cellules présentatrices d’antigènes aptes à initier une réponse immune<p>primaire. Dans un premier temps, nous avons montré que la PTX était capable d’activer des<p>DC générées in vitro à partir de monocytes. En effet, elles acquièrent un phénotype mature<p>caractérisé par une augmentation de l’expression membranaire des molécules costimulatrices<p>et du CMH de classe II, démontrant un effet direct et spécifique de la PTX sur les DC<p>myéloïdes. Parallèlement, ces DC produisent du TNF-a, de l’IL-12p40 et de l’IL-12p70 et<p>activent NF-kappaB, un facteur de transcription essentiel au processus de maturation. Nous<p>avons obtenu des résultats similaires avec une toxine génétiquement modifiée qui est<p>enzymatiquement inactive. A partir de sang total incubé avec la PTX, nous avons par ailleurs<p>observé que les DC circulantes du nouveau-né étaient déficientes dans leur maturation et leur<p>sécrétion d’IL-12p70 comparées aux DC de l’adulte.<p><p>D’autre part, il a été décrit précédemment que la PTX exerçait des effets mitogènes sur les<p>lymphocytes T humains et murins. Cependant, le rôle qu’elle joue sur la population des<p>lymphocytes T CD4 naïfs reste peu connu. A l’issue de notre second travail, nous pouvons<p>dès lors affirmer que la PTX est également capable d’activer des lymphocytes T<p>CD4+CD45RA+ naïfs isolés à partir des cellules mononuclées du sang périphérique, et ce<p>indépendamment de son activité enzymatique. En effet, ces lymphocytes T CD4+ naïfs stimulés par la PTX prolifèrent, synthétisent des quantités non négligeables d'ARN messagers<p>codant pour l’IL-2 et le TNF-a, augmentent l’expression membranaire des molécules CD40L,<p>CD69 et CD25 et expriment la protéine Foxp3. Cette activation s’accompagne de la translocation nucléaire de NF-kappaB et NFAT. Parallèlement à l’adulte, la PTX active les lymphocytes T CD4 néonataux. Néanmoins, ceux-ci prolifèrent moins bien et expriment plus faiblement le CD40L à leur surface.<p><p>Enfin, la PTX induit la sécrétion de taux importants d’IFN-g par des T CD4+CD45RA+ naïfs<p>adultes mis en présence de DC autologues.<p><p>Nous terminerons en proposant l’hypothèse suivante :La PTX pourrait exercer ses propriétés<p>adjuvantes par l’intermédiaire de différents mécanismes comprenant notamment la maturation<p>des DC d’origine myéloïde et l’activation des lymphocytes T CD4+CD45RA+ naïfs. Ces 2 populations cellulaires sont en effet les principaux protagonistes impliqués dans la réponse<p>immune primaire. / Doctorat en sciences pharmaceutiques / info:eu-repo/semantics/nonPublished

Bordetella pertussis is a strictly human pathogen colonizing the upper respiratory tract, causing a respiratory disease known as whooping cough or pertussis. The introduction of whole-cell vaccines and acellular vaccines, resulted in a significant reduction in the incidence of disease and reduce the fatalities associated with infection. However, epidemiological data show a significant increase in the incidence of the disease in recent decades. The increasing incidence is mainly attributed to the transition from the whole- cell vaccine to an acellular vaccine. Based on research from recent years has shown that acellular vaccines have many drawbacks, and it is therefore necessary to change the vaccination strategy. One possible solution to the situation is the development of a new generation of whole-cell vaccines with reduced reactogenicity. The new whole-cell vaccine was prepared by a genetically modified B. pertussis strain. B. pertussis was modified using allelic exchange to develop strain encoding enzymatically inactive pertussis toxin, modified lipid A and lacking dermonecrotic toxin. This combination of genetic modifications in mice led to a decrease in reactogenicity test vaccine in vivo. In case of intranasal infection whole-cell vaccine containing genetically modified strain is providing...

Bordetella pertussis is an important human pathogen that causes an infection disease called whooping cough. This gram-negative bacterium produces an adenylate cyclase toxin (CyaA) that recognizes an integrin receptor CD11b/CD18 present on the surface of myeloid phagocytes and delivers an adenylate cyclase (AC) domain into the cell cytosol. This thesis deals with the endocytic machinery of CyaA and its potential use as a specific marker for endocytosis of the CD11b/CD18 receptor molecule. Detoxified mutant of CyaA, CyaA-AC- , that has the capacity to promote calcium influx as well the potassium efflux, was shown to trigger activation of the integrin receptor CD11b/CD18 followed with endocytic uptake by clathrin-dependent pathway. On the other side, the inactive mutant CyaA-KP-AC- that is unable to provoke integrin activation was endocytosed by clathrin-independent pathway. These results suggest that the various endocytic pathways of the CD11b/CD18 are determined by different conformational states of the receptor molecule.

La protéine CyaA est un facteur de virulence majeur de Bordetella pertussis, impliqué dans la maladie de la coqueluche. Le domaine catalytique AC de CyaA est directement transféré dans la cellule hôte eucaryote, où il est activé comme adénylcyclase par la calmoduline, une protéine ubiquitaire et sensible aux ions calcium. Ainsi, AC transforme l'ATP en AMPc de manière incontrôlée, ce qui conduit à des dérèglements cellulaires. Seule la structure de AC complexé à la calmoduline chargée d'ions calcium avait été résolue par cristallographie aux rayons X. À partir de cette structure, des simulations de dynamique moléculaire de AC libre, et en complexe avec la calmoduline nous ont permis de caractériser l'effet de la calmoduline et des ions calcium sur la plasticité conformationnelle du complexe. Les tendances conformationelles de AC libre ont aussi été étudiées. L'analyse conjointe des influences énergétiques et des liaisons hydrogène a révélé un réseau d'interactions entre AC et la calmoduline, dans lequel trois résidus clés, susceptibles de jouer un rôle allostérique sur l'activité de l'adénylcyclase ont été modifiés par mutagenèse dirigée. Ces tests expérimentaux ont conduits à la mise en évidence d'une région allostérique qui assure la communication de l'information de transition conformationnelle entre le site de fixation de la calmoduline et le site catalytique. Une exploration conformationnelle plus approfondie de AC à l'état non-lié a été entreprise par une méthode innovante de dynamique accélérée par la température (TAMD). Elle nous a conduit à la prédiction de conformations échantillonnées de AC dans son état libre. Ces prédictions pourraient être utilisées à l'avenir pour stabiliser l'état libre et faciliter l'étude expérimentale de sa structure