Diversas proteínas pneumocócicas têm sido estudadas como candidatos vacinais. Entre elas, PspA e Ply induzem anticorpos essenciais para a proteção contra sepse, enquanto, SP 0148 e SP 2108 induzem IL-17 e protegem camundongos contra a colonização. Esse trabalho teve como objetivo principal desenvolver vacinas pneumocócicas baseadas em proteínas. Primeiramente, foi selecionada uma molécula de PspA com ampla reatividade cruzada. Em seguida, esta PspA foi fusionada com PdT, um pneumolisóide derivado da Ply. Essa proteína de fusão mostrou-se capaz de induzir resposta imunológica humoral e celular e protegeu camundongos contra desafio letal. Vacinas baseadas em BCG, que possui diversas propriedades adjuvantes, foram desenvolvidas expressando as proteínas pneumocócicas rPspA-PdT, SP 0148 e SP 2108. A imunização com o rBCG 0148/rSP 0148 induziu IL-17 e levou a proteção contra colonização. A combinação das três vacinas de rBCG mostrou-se mais eficiente na proteção contra desafio de colonização. Esses resultados sugerem um uso promissor do rBCG como vacina pneumocócica. / Several pneumococcal proteins have been proposed as vaccine candidates. PspA and Ply induce protective antibodies against sepse, while SP 0148 and SP 2108, induce IL-17 and protect mice against pneumococcal colonization. The major aim of this study was to produce pneumococcal vaccines based on proteins. First, we selected one PspA molecule able to induce broad-ranging cross-reactivity. Second, we constructed a hybrid protein containing a PspA fused to PdT, a detoxified form of Ply. The hybrid protein was able to induce humoral and cellular responses and protected mice against lethal challenge. Finally, due the adjuvant properties of BCG, we constructed recombinant BCG strains expressing PspA-PdT, SP 0148 and SP 2108. The immunization with rBCG-0148/rSP 0148 induced IL-17 and IFN-, and pneumococcal colonization in mice. Interestingly, the combination of all rBCG vaccines was more efficient in protecting mice against pneumococcal colonization. These results suggesting a promising use of rBCG as pneumococcal vaccine.

Diversas proteínas pneumocócicas têm sido estudadas como candidatos vacinais. Entre elas, PspA e Ply induzem anticorpos essenciais para a proteção contra sepse, enquanto, SP 0148 e SP 2108 induzem IL-17 e protegem camundongos contra a colonização. Esse trabalho teve como objetivo principal desenvolver vacinas pneumocócicas baseadas em proteínas. Primeiramente, foi selecionada uma molécula de PspA com ampla reatividade cruzada. Em seguida, esta PspA foi fusionada com PdT, um pneumolisóide derivado da Ply. Essa proteína de fusão mostrou-se capaz de induzir resposta imunológica humoral e celular e protegeu camundongos contra desafio letal. Vacinas baseadas em BCG, que possui diversas propriedades adjuvantes, foram desenvolvidas expressando as proteínas pneumocócicas rPspA-PdT, SP 0148 e SP 2108. A imunização com o rBCG 0148/rSP 0148 induziu IL-17 e levou a proteção contra colonização. A combinação das três vacinas de rBCG mostrou-se mais eficiente na proteção contra desafio de colonização. Esses resultados sugerem um uso promissor do rBCG como vacina pneumocócica. / Several pneumococcal proteins have been proposed as vaccine candidates. PspA and Ply induce protective antibodies against sepse, while SP 0148 and SP 2108, induce IL-17 and protect mice against pneumococcal colonization. The major aim of this study was to produce pneumococcal vaccines based on proteins. First, we selected one PspA molecule able to induce broad-ranging cross-reactivity. Second, we constructed a hybrid protein containing a PspA fused to PdT, a detoxified form of Ply. The hybrid protein was able to induce humoral and cellular responses and protected mice against lethal challenge. Finally, due the adjuvant properties of BCG, we constructed recombinant BCG strains expressing PspA-PdT, SP 0148 and SP 2108. The immunization with rBCG-0148/rSP 0148 induced IL-17 and IFN-, and pneumococcal colonization in mice. Interestingly, the combination of all rBCG vaccines was more efficient in protecting mice against pneumococcal colonization. These results suggesting a promising use of rBCG as pneumococcal vaccine.

ANGLICKÝ ABSTRAKT Functional study of the putative nucleotidase encoded by spr1057 gene in Streptococcus pneumoniae, a likely homolog of Escherichia coli protein YjjG. Bacterial cells are constantly exposed to innumerable toxic substances, either in their external environment or by by-products of their own metabolism. For these reasons, the bacterial cells evolved several mechanisms to cope with this challenge. These mechanisms are represented by: blocking the uptake, export by specific transporters as well as specific inactivation of these substance by enzymes. A particular group of these toxic substances are noncanonica nucleotides, which can directly inhibit bacterial cell DNA replication or can result in increased mutation rate. Enzymes recognizing these modified derivatives are known as "house-cleaning" nucleotide phsphateses, which can inactivate the potentially mutagenic nucleotides and prevent their incorporation into DNA and RNA. Some of the "house- cleaning" enzymes belong to a group of haloacid dehalogenase enzymes (haloacid dehalogenase-like hydrolase superfamily), which are found in many bacterial species. This thesis is focused on the function of hypothetical protein Spr1057 of Streptococcus pneumoniae with an unknown function. Sequence comparison revealed that Spr1057 has a significant...

Made available in DSpace on 2014-07-29T15:26:24Z (GMT). No. of bitstreams: 1 tese caritas medicina tropical.pdf: 1784866 bytes, checksum: b85c7ab5508fd90ff809159f179430cc (MD5) Previous issue date: 2009-02-17 / Objectives: (i) to identify risk factors for S. pneumoniae penicillin nonsusceptible isolates (PNSp) in children attending day-care centers (DCCs) in Goiânia, Brazil and to assess the genetic patterns of pneumococcal isolates; (ii) to estimate the coverage for carriage serotypes for the 7-valente (PCV7) pneumococcal conjugate vaccine, and for the investigational 10 (PCV10) and 13-valent (PCV13) vaccines; (iii) to assess the genetic relatedeness between isolates expressing capsular type 14 and those non(sero)- typeable isolates (NTPn); (iv) to investigate if carriage isolates match genetically to any international pneumococcal clone (PMEN network). Methods: A cross-sectional survey of carriage PNSp was conducted among 1.192 children, 2 months to 5 years of age, attending 62 DCCs in Central Brazil. Capsular typing was performed in PNSp isolates (CLSI, 2007) and in a sample of isolates susceptible to penicillin (PSSp) matched to PNSp and DCCs whenever possible. Serotyping was performed by Quellung reactions and confirmed by multibead assay. NTPn isolates and serotype 14 were tested by PCR for capsule genes. Odds ratio for PNSp carriage and respective 95% confidence interval (95%CI) were assessed by logistic regression. Pulsed field gel electrophoresis (PFGE) was applied to assess the genetic similarity between PNSp serotype 14 and NTPn isolates. PCR was performed for the presence of pneumococcal capsule gene locus. For comparison purpose we also evaluated the genetic profile of PNSp serotype 14 invasive strains derived from the current pneumococcal invasive disease surveillance for the same pediatric population. Isolates were epidemiologically related if they shared &#8805;80% similarity on the dendrogram (Dice coefficient). A cluster was defined as three or more related isolates. Results: A total of 686 pneumococci were isolated for a colonization rate of 57.6% and 178 (25.8%) were PNSp. Among the PNSp isolates the usual common types were found: 14 (53%), 23F (10.2%), 6B (6%), 19F (4.8%) and 19A (4.2%). PSSp isolates displayed 30 different serotypes although serotype 14 was the most common. Overall a high prevalence of NTPn (11.1%) was observed with 62.9% PNSp. Serotypes coverage xvi for the PCV7, PCV10 and PCV13 vaccines were 55.2%, 55.9% and 65.1%, respectively. Being less than 24 months of age (OR=1.79; p=0.006), hospitalization in the previous three months (OR=2.19; p=0.025), and recurrent acute otitis media (OR=2.89; p=0.013) were independently associated with PNSp in a multivariate model. Among the 123 PNSp submitted to PFGE (106/carriage and 17/ invasive isolates) a major group of 34 serotype 14 strains (8 invasive and 26 carriage) was identified and found to be genetically related to the global pneumococcal clone Spain 9V-3 (82.7% similarity). All NTPn presented capsule gene locus and 10 (45.4%) of them presented capsule gene locus to type 14. Conclusions: (i) DCC attendees with history of recurrent AOM could significantly contribute to the spread of nasopharyngeal PNSp strains into the community; (ii) epidemiologic and molecular evidences support the findings that pneumococcal nonypeable carriage isolates are genetically similar to carriage and invasive isolates expressing capsular type 14; (iii) carriage and invasive isolates circulating in Goiânia belong to a serotype 14 variant of the Spain 9V -3 clone and play a critical role in the spread of PNSp strains to the entire pediatric community of Goiânia / Objetivo: (i) identificar fatores associados à colonização nasofaríngea por S. pneumoniae não suscetíveis à penicilina em crianças que frequentam creches no município de Goiânia-GO e caracterizar geneticamente as cepas não suscetíveis; (ii) determinar a cobertura das vacinas conjugadas pneumocócicas 7, 10 e 13 valente; (iii) avaliar o relacionamento genético entre cepas do sorotipo 14 e pneumococos não tipáveis (PnNT); (iv) identificar a presença de cepas colonizadoras relacionadas geneticamente aos clones internacionais de S. pneumoniae. Metodologia: Um estudo de prevalência de portador de pneumococo não suscetível à penicilina (SpNP) foi conduzido de agosto a dezembro de 2005, em 1192 crianças de dois a 59 meses de idade, atendidas em 62 creches em Goiânia. Os testes de suscetibilidade antimicrobiana seguiram as recomendações do CLSI de 2007 e a sorotipagem foi realizada pela reação de Quellung e confirmada por ensaio multibead. Isolados PnNT e do sorotipo 14 foram analisados por reação de PCR. Odds ratio para portador de SpNP e respectivos intervalos de 95% de confiança foram estimados por regressão logística. Para avaliar a similaridade genética entre os isolados de portador (sorotipo 14 e PnNT) e isolados invasivos (sorotipo 14) obtidos de crianças de Goiânia utilizou-se amostras de isolados invasivos de um estudo maior de vigilância populacional que vem sendo conduzido desde 2007. Assim, eletroforese em campo pulsado (PFGE) foi utilizada para a tipagem molecular. Definiu-se como linhagem a presença de três ou mais cepas resistentes com similaridade genética &#8805; 80%. Resultados: S. pneumoniae foi isolado de 686 (57,6%) crianças das creches e 178 (25,9%) dessas eram portadoras de SpNS. Sorotipo 14 (53%), 23F (10,2%), 6B (6%), 19F (4,8%) e 19A (4,2%) estavam presentes em 78,2% dos PnNS. Detectou-se alta prevalência (11,1%) de isolados não tipáveis, dos quais 62.9% eram resistentes à penicilina. A cobertura dos sorotipos colonizadores para as vacinas 7-valente, 10- valente e 13-valente foi respectivamente 55,2%, 55,9% e 65,1%. Crianças menores de 24 meses de idade (OR=1,79; p=0,006), hospitalização nos últimos três meses (OR=2,19; p=0,025), e otite média aguda recorrente (OR=2,89; p=0,013) foram fatores xiv independentemente associados com SpNS na análise multivariada. Entre os 123 isolados submetidos à PFGE, 106 eram de nasofaringe de crianças das creches, dos quais 84 expressavam a cápsula tipo 14 e 22 eram isolados PnNT. Todas as cepas invasivas eram sorotipo 14. A maior linhagem agrupou 34 pneumococos do sorotipo 14, com 82,7% de similaridade, os quais foram geneticamente relacionados ao clone Spain 9V-3. Todas as cepas PnNT apresentaram locus para o gene da cápsula para o tipo 14. Houve uma diferença estatisticamente significante entre os valores da CIM para a penicilina entre as três principais linhagens (Krukal-Wallis, p<0,001). Conclusões: (i) crianças com otite média recorrente podem exercer papel importante na disseminação de pneumococos resistentes para a comunidade; (ii) Evidências genéticas apóiam os achados de que cepas de pneumococo não tipáveis assemelham-se ao genótipo das cepas do sorotipo 14; (iii) isolados de portadores e invasivos que circulam em Goiânia pertencem a um sorotipo 14 variante do clone Spain9V-3, responsável pela disseminação da resistência do pneumococo na população pediátrica de Goiânia

Streptococcus pneumoniae is a significant cause of mortality and morbidity in both children and older adults, with infection resulting in invasive disease, pneumonia and otitis media. The inclusion of pneumococcal conjugate vaccines in routine infant immunisation programmes has had a major impact on disease rates. Vaccine-induced protection against pneumococcal infection is thought to be mediated by the generation of persistent serotype-specific functional antibodies and antigen-specific memory B cells, the latter capable of generating a rapid secondary antibody response on re-exposure to antigen. Although many studies have investigated the immunogenicity of pneumococcal vaccines in different age groups by measuring serotype-specific antibodies, there is more limited information about the B cells underlying such an immune response. Important areas to investigate include the identity of the B cell subsets involved in antibody production and the potential link between memory B cells (B_MEM) and persistent antibody production by long-lived plasma cells. In this thesis I have investigated in detail the immune response to pneumococcal vaccines given to children and adults by a variety of different methods. By examining the variability of a B_MEM ELISpot method, it was shown that this assay is robust and reproducible and can be performed on fresh or frozen samples and in different laboratories. Using this technique, in a study of pre-school children, it was demonstrated for the first time that the level of pre-existing serotype 3-specific antibody is negatively correlated with, and may directly impair the B_MEM response to a booster dose of 13-valent pneumococcal conjugate vaccine (PCV-13) containing serotype 3 glycoconjugate. In the same study, it was shown that antibody persistence against most vaccine serotypes can be expected until the age of 3.5 years. A novel antigen-labelling technique was used in a detailed kinetics study of antigen-specific B cell subsets in response to either PCV-13 or 23-valent pneumococcal polysaccharide vaccine in adults. The results of this study revealed distinct B cell subset response patterns that were observed in all study participants indicating that IgM B_MEM seem to play a major role in the immune response to pneumococcal vaccines. In addition, in the same study, genome wide analysis of gene expression was performed and it was shown that vaccination with either a pneumococcal conjugate or polysaccharide vaccine results in a marked difference in numbers of differentially expressed genes 8 days following vaccination. A further tool likely to be of use in investigating B cell responses is the analysis of the antibody repertoire using next-generation sequencing techniques. In order to test the ability of these methods to detect vaccine responses, a large dataset of high-throughput B cell receptor sequences was analysed and revealed convergence of antigen-specific complementary-determining region (CDR)₃ amino acid (AA) sequences following vaccination and identified antigen-specific sequences. It was further demonstrated that for sequences directed against the H. influenzae type b (Hib) polysaccharide, diversity of immunoglobulin gene rearrangements is much greater than previously recognised. Frequencies of Hib-specific CDR₃ AA sequences were linked with anti-Hib avidity indices highlighting the potential of this method as an alternative (functional) measure of vaccine immunogenicity. These data suggest that studying the B cells and antibody repertoire post-vaccination can give novel insights into the biology that underlies the immune responses.

No description available.

L'objectif de cette thèse est de développer des outils de modélisation mathématique afin d'étudier la dynamique de transmission des souches de pneumocoque dans la communauté. La dynamique d'émergence et de diffusion de bactéries résistantes dans la population est difficile à anticiper : les phénomènes se produisent à différentes échelles (bactérie, hôte et population) et les bactéries circulent dans des environnements humains complexes (nombreux antibiotiques et vaccins). Dans ce cadre, la formalisation mathématique et la simulation peuvent contribuer à mieux comprendre et anticiper les phénomènes en jeu. Trois questions principales sont posées dans ce travail. Elles portent sur : l'effet d'une modification de l'exposition antibiotique sur la distribution des résistances du pneumocoque ; les conséquences de l'usage de vaccins conjugués sur les distributions de souches ; et l'étude de la dynamique d'incidence des méningites à pneumocoque. Pour y répondre, 4 modèles mathématiques compartimentaux spécifiques sont construits. Les résultats des simulations renforcent l'idée que l'exposition antibiotique est un facteur environnemental majeur pour la sélection des pneumocoques résistants aux antibiotiques. En particulier, ils mettent en évidence l'importance du choix des molécules antibiotiques utilisées et des doses prescrites sur la distribution des résistances dans la population. Ils suggèrent de plus que les virus hivernaux, la consommation antibiotique et l'épidémicité différenciée en fonction de la résistance pourraient expliquer en partie la dynamique des méningites à pneumocoque dans la population.

L’axe adénosinergique est au cœur de divers processus pathophysiologiques. L’enzyme CD73 joue un rôle pivot dans la génération de l’adénosine en catalysant la déphosphorylation de l’adénosine monophosphate. L’adénosine contribue à un éventail large de processus biologiques et pathologiques, principalement via l’activation de récepteurs transmembranaires. L’adénosine est principalement reconnue pour son activité régulatrice des cellules immunitaires et CD73 pour son rôle dans l’accumulation de l’adénosine dans le microenvironnement tumoral. En effet, en altérant la réponse immunitaire anti-tumorale via l’inhibition des fonctions effectrices de divers types de cellules immunes, CD73 et l’adénosine sont fréquemment associés à la progression tumorale et s’inscrivent comme cibles thérapeutiques intéressantes. Les rôles de CD73 et l’adénosine dans d’autres processus immunitaires physiologiques ne sont pas tous aussi bien compris, notamment concernant les processus d’immunisations. En utilisant un modèle murin d’immunisation contre le pneumocoque, cette thèse démontre un rôle positif, mais non essentiel, de CD73 et de l’adénosine dans la commutation isotypique des lymphocytes B et la génération d’une immunité protectrice contre l’infection au S. pneumoniae. Cette découverte est pertinente au développement de stratégies thérapeutiques afin d’augmenter l’efficacité d’immunisation dépendante des cellules B, plus particulièrement chez les populations à risque en bas âge. Ensuite, alors que la modulation de l’axe adénosinergique, notamment via l’inhibition de CD73, est une avenue thérapeutique étudiée dans divers contextes de tumeurs solides, ce potentiel thérapeutique demeure largement inexploré dans des modèles de néoplasmes sanguins. En utilisant un modèle de souris transgénique de leucémie spontanée, cette thèse démontre un rôle pro-tumorigénique, avec un biais sexuel, de CD73 dans la leucémie lymphoïde chronique des lymphocytes B (LLC), via l’altération de l’immunité anti-tumorale. Enfin, alors que les rôles immunosuppressifs de CD73 et l’adénosine sont bien décrits, leurs activités pro-tumorigéniques qui s’étendent au-delà de l’immunité anti-tumorale sont peu connues. En accord avec la littérature, cette thèse explore plusieurs hypothèses selon lesquelles CD73 module l’activité métabolique mitochondriale des cellules cancéreuses. Les résultats présentés dans cette thèse suggèrent un rôle pro-tumorigénique à l’enzyme CD73, indépendant de la signalisation adénosinergique et de l’inhibition de l’immunité anti-tumorale, qui favorise la flexibilité métabolique et plus particulièrement la respiration mitochondriale des cellules cancéreuses, via la voie de récupération de la biosynthèse du nicotinamide (NAD+). En résumé, cette thèse apporte plusieurs précisions quant aux rôles biologiques de l’enzyme CD73 qui sont pertinents à l’immunisation dépendante des lymphocytes B, à la pathogénèse de la LLC ainsi qu’à la régulation de l’activité métabolique des cellules cancéreuses. Cette thèse offre de nouvelles pistes de réflexion quant au potentiel thérapeutique que renferme l’axe adénosinergique et plus particulièrement CD73, en approfondissant nos connaissances quant à l’éventail de ses fonctions. / The adenosinergic axis is central to a plethora of pathophysiological processes. The enzyme CD73 is key to the generation of adenosine by catalyzing the dephosphorylation of adenosine monophosphate. Adenosine’s contribution to biological and pathological processes is mainly carried through the activation of transmembrane receptors. Adenosine is mostly appreciated for its regulatory activity on a variety of immunes cells whereas CD73 is often referred to the enzyme responsible for adenosine accumulation within tumor microenvironment. Thus, by hindering antitumoral immune responses, CD73 and adenosine are frequently associated with cancer progression and targeting these offers great therapeutic potential in clinic. CD73 and adenosine’s role in other immune physiological processes are not fully understood, notably regarding immunization processes. Using a murine model of pneumococcal immunization, this thesis herein demonstrates a positive, but non-essential, role for CD73 and adenosine in B cells’ isotype class switching required to protective immunity against S. pneumoniae. This finding is particularly relevant to the development of novel strategies aimed at enhancing B cell-dependent immunization in high-risk populations such as young infants. While targeting the adenosinergic axis, particularly CD73, was extensively proven efficient in restoring antitumor immunity in many solid tumor contexts, its therapeutic potential in blood neoplastic malignancies remain largely unexplored. Using a transgenic mouse model of spontaneous leukemia, this thesis identifies a sex-oriented pro-tumorigenic role for CD73 in favoring B cells chronic lymphocytic leukemia (CLL) progression, through the inhibition of antitumor immunity. Finally, while immunosuppression by CD73 and adenosine is well described in cancer, other immune-independent pro-tumorigenic roles of CD73 are poorly understood. In accordance with literature, this thesis explores various hypotheses by which CD73 regulates cancer cells’ mitochondrial metabolic activity. Results presented herein suggest an immune- and adenosine signaling-independent pro-tumorigenic function for CD73 in favoring cancer cells’ metabolic flexibility and more particularly mitochondrial respiration through the nicotinamide (NAD+) salvage biosynthesis pathway. In sum, this thesis brings many insights into CD73’s biological functions relevant to B cells-dependent immunization, in CLL pathogenesis and in cancer cells’ metabolic activity. By expanding our knowledge of the extend of CD73’s biological functions, this thesis further discusses novel potential therapeutic opportunities.