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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Papel da flagelina e de lipopolissacarídeos bacterianos na ativação de populações heterogêneas de macrófagos / The role of bacterial flagellin and lipopolysaccharide on the activation of heterogeneous macrophage subpopulations.

Alexandra dos Anjos Cassado 13 September 2007 (has links)
Os macrófagos (MO) são populações heterogêneas de células residentes em diversos tecidos, onde iniciam a resposta imune através do reconhecimento de padrões moleculares de patógenos. Para avaliar a modulação funcional dessas populações, MO peritoneais (PM) e alveolares (AM), com perfil M1 e M2, foram ativados in vivo por flagelina (FliCi) e lipopolissacarídeos bacterianos (LPS). Esse trabalho mostra que o microambiente parece influenciar a resposta diferencial das populações de MO, uma vez que a expressão de MHCII, CD80, CD86 e CD40 e produção de NO por PM são mais intensamente modulados por FliCi, enquanto os AM são mais sensíveis ao LPS. Porém, dentro da população de PM, encontramos duas subpopulações distintas, nomeadas F4/80hi e F4/80lo. A população F4/80hi parece adquirir um perfil M1 após estimulo com FliCi, com alta expressão de iNOS, enquanto a população F4/80sup>lo apresenta um perfil M2, com maior expressão basal de mTGF-ß, indicando que a heterogeneidade dos MO também pode estar expressa no mesmo microambiente. / Macrophages (MO) are a heterogeneous cell population that resides in distinct tissues, where they trigger the immune response through the recognition of pathogen-associated molecular patterns. To evaluate the functional modulation of these populations, peritoneal (PM) and alveolar (AM) MO, from M1 and M2 profile, were in vivo activated by flagellin (FliCi) and bacterial lipopolysaccharide (LPS). In this study we show that microenvironment seems to influence the differential responses of MO populations, since MHCII, CD80, CD86 e CD40 expression and NO production by PM are more intensely modulated by FliCi whereas AM are more sensitive to LPS. However, we found two distinct subpopulations within PM, named F4/80hi e F4/80lo. cells show a M1 profile after FliCi stimulation, with high iNOS expression of mTGF-ß, indicating that the MO heterogeneity can also be finding in the same microenvironment. NOS expression, and F4/80lo population presents a M2 profile, with higher basal expression of mTGF-ß, indicating that the MO heterogeneity can also be finding in the same microenvironment
22

Avaliação do potencial imunogênico e vacinal das flagelinas de Leptospira interrogans sorovar Copenhageni / Evaluation of the immunogenic potential of flagellins Leptospira like adjuvant for development of a subunit vaccine against leptospirosis

Denize Monaris 06 May 2015 (has links)
A leptospirose é uma zoonose de importância global causada por leptospiras patogênicas, que colonizam os túbulos renais de animais selvagens e domésticos. Vacinas comerciais estão sendo usadas, porém promovem proteção apenas contra os sorovares presentes na preparação e falham em induzir imunidade de longa duração. A porção carboxi-terminal da proteina immunoglobulin like A (LigAC) é capaz de induzir imunoproteção contra a leptospirose. No entanto, a imunização com a LigAC não confere imunidade esterilizante. Flagelinas têm sido consideradas adjuvante promissor para o desenvolvimento de vacinas. As leptospiras possuem dois flagelos periplasmáticos que são constituídos por duas classes de proteínas (FlaA e FlaB). Somente as proteínas FlaB apresentam homologia com as regiões importantes que ativam as respostas dependentes ao receptor Toll-like 5 (TLR-5). Neste estudo, avaliou-se a capacidade de indução da atividade do TLR5 das cinco flagelinas de L. interrogans sorovar Copenhageni (FlaB1, FlaB2, FlaB3, FlaB4 e FlaB5) e o potencial vacinal destas flagelinas na imunidade protetora de LigAC contra o desafio letal em hamsters. As flagelinas recombinantes foram expressas em E. coli e purificadas por cromatografia de afinidade com níquel. Os hamsters foram imunizados por via subcutânea com as flagelinas purificadas e LigAC. Dados experimentais demonstram que todas as flagelinas foram capazes de ativar o receptor TLR5 e a secreção de citocinas em macrógafos estimulados de maneira similar. Nos ensaios de desafio, a maioria dos animais imunizados com as flagelinas e LigAC sobreviveram ao desafio letal entretanto, não foram protegidos contra a colonização renal. Os animais do grupo controle vacinados com PBS morreram com sintomas de leptospirose e hamsters imunizados com a vacina comercial sobreviveram após o desafio / Leptospirosis is a zoonosis of global importance caused by pathogenic leptospires that colonize the renal tubules of wild and domestic animals. Commercial vaccines are being used, but only to promote protection against the serovar in the preparation; they have failed to induce short-term immunity. The C-terminal portion of immunoglobulin-like protein A (LigAC) is able to induce immunoprotection against leptospirosis. However, immunization with LigAC did not confer sterilizing immunity. Flagellins have been considered a promising adjuvant for vaccine development. Leptospires have two periplasmic flagella that are formed by two classes of proteins (FlaA and FlaB); only FlaB proteins show homology with important regions that elicit TLR5-dependent responses. In the present study, we have evaluated their ability to induce the TLR5 activity and the protective activity of five L. interrogans sorovar Copenhageni flagellins (FlaB1, FlaB2, FlaB3, FlaB4 and FlaB5) in the protective immunity of LigAC against lethal challenge in hamsters. The recombinant flagellins expressed in E.coli were purified by nickel affinity chromatography. Hamsters were immunized subcutaneously with purified flagellins with LigAC. Experimental data showed that all flagellins activated both the TLR-5 receptor and the secretion of cytokines in stimulated macrofages, similarly. In challenge assays, the majority of hamsters immunized with the flagellins and LigAC survived the lethal challenge. However, they were not protected against kidney colonization. The control animals vaccinated with PBS died with symptoms of leptospirosis and hamsters vaccinated with commercial vaccine survived after challenge
23

Synthesis of Flagellin 22 As a Probe for Plant Signaling and Molecular Trafficking Towards Improved Crops

Offei, Edward 01 August 2021 (has links)
Plant signaling involves the transport of information within and between plant cells from receptors to effectors. Plants are affected by biotic and abiotic stress conditions like insect attack and extreme temperatures, respectively, which cause disease, the induction of senescence and the reduction of crop yield. To improve plant traits for feed, fiber, and energy applications, it is critical to understand the short- and long-range signaling mechanisms plants use to control growth, biomass composition, senescence and responses to environmental stresses. It is known that many plant signaling molecules have profound effects on plants, through mechanisms that remain largely obscure. A key gap in knowledge is the understanding of the mechanisms that govern the movement and fate of signaling molecules. This study seeks to synthesize signaling probes based on flagellin 22 (flg22), a 22-amino acid peptide that induces defense gene expression to trigger both local and systemic immune responses in plants. Solid-phase synthesis of fluorescently-tagged derivatives of flg22 was initiated, and studies on the uptake of labeled probes was conducted using a fiber-optic fluorescence microscope that was adapted for use in plants. Fluorescence microscopy showed uptake and internalization of TAMRA-flg22 in cells of Arabidopsis thaliana Columbia (wild-type strain), which was not observed in the fls2 strain in which FLS2, the receptor for flg22, had been knocked out.
24

Rough leucine auxotrophic strains of <i>Brucella</i> expressing <i>Salmonella</i> flagellin C conjugated gonadotropins, an immunocontraceptive brucellosis vaccine for feral swine population control

Waldrop, S. Grant January 2020 (has links)
Brucellosis, caused by Gram-negative bacteria of the genus <i>Brucella</i>, is a zoonotic disease with global impacts on human, livestock, and wildlife health. Around 500,000 cases of human brucellosis are reported by the World Health Organization annually. Even though brucellosis has been eradicated from domestic livestock in the United States of America, the causative bacterial pathogen is still present in elk, bison, and feral swine. With the growth of free-range farming, domestic livestock and wildlife populations come into close contact, spreading the disease. Feral swine interactions are of particular concern. They carry a number of zoonotic diseases including brucellosis. As there is no commercial vaccination protocol to prevent brucellosis in wildlife and swine, interactions with these populations are especially dangerous for public health. Feral swine population is increasing nationwide even with the current population control practices. There is an urgent need for efficient control of feral swine and preventing the spread of brucellosis. To aid in the prevention of the spread of feral swine across the USA, immunocontraceptives have been employed. Over the years several candidates have been tested, but the search for the perfect vaccine is still ongoing. The monumental task includes reversibly preventing one of life’s most basic necessities, reproduction, through an oral route with no effect on non-target species. One way that science is tackling both of these threats at once is through dual-purpose vaccines. Dual-purpose vaccines produce an immune response that targets two different pathogens, or in this case a pathogen and reproductive hormones. In the effort to produce this vaccine, more knowledge was needed in regards to <i>B. neotomae</i>. This dissertation showed that it has the ability to survive in a variety of cells from different species, in a similar manner to known virulent <i>Brucella</i> species. This is of concern when using <i>B. neotomae</i> as a vaccine, but it has also been shown that attenuated <i>B. neotomae</i> can provide protection against virulent <i>B. suis, B. abortus</i>, and <i>B. melitensis</i> challenge. This is a major finding in the effort towards a universal brucellosis vaccine. After genetic manipulation, cell culture assays, and mouse trials, several leucine auxotrophic <i>B. neotomae</i> and <i>B. abortus</i> strains show promise in the effort towards a dual-purpose vaccine. Strains of <i>B. neotomae</i> <i>ΔwboA ΔleuB</i> pNS4-trcD-fliC-Gonadotropins were discontinued in this effort towards a brucellosis immunocontraceptive dual-purpose vaccine due to lethality issues in mice. These stability and lethality issues are still under investigation. Instead, a proven stable strain of <i>B. abortus</i> RB51 (a USDA approved cattle vaccine) was used to investigate its effects on fertility in mice when expressing fliC-Gonadotropins. Strains <i>B. abortus</i> RB51 ΔleuB pNS4-trcD-fliC-porcineFSHβ (RB51LFSHβ) and <i>B. abortus</i> RB51 ΔleuB pNS4-trcD-fliC-GnRH (RB51LGnRH) confer reduced fertility characteristics in both male and female purpose bred mice. Strain RB51 ΔleuB has also been shown to protect against virulent <i>B. abortus</i> challenge in the literature. These findings warrant further investigation to determine the efficacy of these vaccine strains in swine as an oral vaccine. Ultimately, their ability to prevent brucellosis, while causing immunocontraception needs to be determined in feral swine. / Ph.D. / While brucellosis has been eradicated from domestic livestock in the United States, the causative agent is still present in wildlife like elk, bison, and feral swine. The interactions between these infected wildlife populations with domestic livestock and human populations pose a great health risk. Many tools are employed to mitigate these interactions including vaccination programs and population management. In particular, the feral swine population has proven difficult to control. It has quadrupled in the past ten years and continues to expand nationwide, making their population control an important national objective. Furthermore, feral swine are known carriers of zoonotic diseases, including hemorraghic colitis, leptospirosis, trichinosis, swine influenza, and brucellosis. Many cases of these diseases in humans have been traced back to interactions with feral swine. The current population control practices have failed to minimize the $1.5 billion of damage they cause to the agricultural industry per year. Thus, there is a need to effectively control the feral swine population and prevent the spread of zoonotic diseases like brucellosis. Rough leucine auxotrophic strains of <i>Brucella</i> expressing gonadotropin releasing hormone (GnRH) or porcine follicle stimulating hormone beta subunit (FSH) conjugated to <i>Salmonella</i> fliC show promise. They have been shown to provide protection from virulent Brucella strain challenge and reduce fertility characteristics in mice. Their effectiveness as an immunocontraceptive for feral swine management, while reducing the spread of brucellosis needs to be tested in swine. These vaccine strains [<i>B. abortus</i> RB51 ΔleuB pNS4-trcD-fliC-porcineFSHβ (RB51LFSHβ), <i>B. abortus</i> RB51 ΔleuB pNS4-trcD-fliC-GnRH (RB51LGnRH) and <i>B. neotomae ΔwboA ΔleuB</i> pNS4-trcD-fliC-GnRH (BNWLGnRH)] could pave the way for effective novel immunocontraceptive tools to be used in wildlife management.
25

The Role of Arabidopsis Class-II TGA Transcription Factors in PAMP-mediated Defense Responses / Rolle der Arabidopsis Klasse-II TGA Transkriptionsfaktoren in PAMP-vermittelten Abwehrreaktionen

Rindermann, Katja 28 April 2010 (has links)
No description available.
26

Adordagem vacinal bivalente baseada na fusão genética de seqüência derivada da proteína circunsporozoíta (CS) de Plasmodium yoelii com a flagelina FliCd de Salmonella enterica / Bivalent vaccines approaches based in genetic fusion of sequence derived of the circumsporozoíta (CS) protein de Plasmodium yoelii with FliCd flagellin of Salmonella enterica.

Braga, Catarina Joelma Magalhães 16 August 2007 (has links)
A busca de adjuvantes que estimulem de forma eficiente à resposta imune celular representa uma importante contribuição para a pesquisa de vacinas. O principal objetivo deste trabalho foi a avaliação do efeito imunoestimulador de flagelinas expressas por linhagens de Salmonella sp., particularmente na ativação de respostas mediadas por células T CD8+, ao antígeno modelo ovalbumina. Em uma segunda etapa, foram investigados os efeitos adjuvantes da flagelina FliCd frente a um epítopo T CD8+, específico da proteína CS de P. yoelli. Animais foram imunizados com linhagens atenuadas de S. Dublin que expressam flagelinas geneticamente fusionadas ao epítopo CS ou com flagelina purificada co-administrada ou geneticamente fusionada ao antígeno alvo. A ativação de células T CD8+, foi monitorada por ELISPOT após estimulação com peptídeos específicos. Os resultados obtidos demonstram que a FliCd é capaz de modular o sistema imune, atuando particularmente na ativação de respostas mediadas por células T CD8+, sugerindo seu potencial para a composição de vacinas terapêuticas. / The search for adjuvants stimulating efficient cellular immune responses represents an important contribution in vaccine research. In the present work, we evaluated immunostimulatory effect of flagellins expressed by Salmonella sp. strains, particularly on activation of CD8+, T cells using ovalbumin as a model antigen. Secondly, we explored the adjuvant effect of the FliCd flagellin using an epitope from the CS protein of P. yoelli. Mice were immunized with S. Dublin strains that express flagellin genetically fused to CS epitope or purified flagellin co-administrated or genetically fused to the target antigen. The CD8+, T cells activation was monitored by ELISPOT after stimulation with specific peptides. Our results show that FliCd flagellin modulates the immune system, increasing CD8+, T cell activation, unveiling its potencial use in therapeutic vaccine approaches.
27

Efeitos da associação da sílica SBA-15 a antígenos de Salmonella na imunização oral de camundongos selecionados para alta e baixa produção de anticorpos. / Effect of SBA-15 silica in association with Salmonella antigens in oral immunization of mice selected for high and low antibody production.

Bordenalli, Marcela Aparecida 11 August 2016 (has links)
A sílica mesoporosa SBA-15 é uma forte candidata para uso como adjuvante por apresentar propriedades vantajosas, como a capacidade de integração com moléculas, baixa toxicidade, boa estabilidade química, térmica e hidrotérmica. Seu potencial adjuvante foi demonstrado em trabalhos onde a SBA-15 associada a antígenos de naturezas distintas foi capaz de induzir uma alta produção de anticorpos específicos quando administrados por via parenteral. Além disso, a SBA-15 diminuiu a toxicidade da toxina diftérica na imunização de cavalos. Os efeitos da SBA-15 na produção de anticorpos com imunizações exclusivamente administradas pela via oral não havia sido testada. Assim, verificou-se a produção de anticorpos em camundongos heterogênicos selecionados para alta (HIII) e baixa (LIII) produção de anticorpos e em animais de fundo genético conhecido (BALB/c), após imunização oral com dois antígenos de naturezas distintas: LPS (antígeno T-independente) e flagelina (antígeno Tdependente), associados a sílica SBA-15. Os camundongos foram inoculados com duas doses de LPS ou flagelina de Salmonella typhimurium, associados ou não a SBA-15, pela via oral ou por via subcutânea. Foram pesquisados anticorpos séricos IgM, IgG e IgA, S-IgA no lavado intestinal e citocinas no soro. Células do linfonodo mesentérico foram coletadas após a imunização oral para caracterização fenotípica. Houve IgM anti-flagelina detectável em BALB/c no período de 37 dias no grupos Fla+SBA-15. Os animais de ambas as linhagens produziram IgG anti-LPS e anti-flagelina em todos os períodos avaliados. Foi encontrada uma pequena diferença significativa em BALB/c, entre os grupos Fla+SBA-15 e Fla após reforço por via oral. Não foi possível detectar IgA sérica nem secretória nos lavados intestinais. Não houve níveis detectáveis de citocinas nos soros do período avaliado. Foram encontrados linfócitos B1, T CD4+ e T CD8+, células dendríticas e moléculas coestimulatórias CD80 e CD86. Houve diferença estatística nas células dendríticas de HIII entre os grupos LPS+SBA-15 e LPS. / Ordered mesoporous sílica SBA-15 is a vaccine adjuvant candidate due to its advantageous properties such as the ability to associate with molecules, low toxicity, and also good chemical, thermal and hydrothermal stability. It has been demonstrated that the association of SBA-15 with several antigens, including toxins, induce high production of specific antibodies when injected parenterally.Since the oral route is natural for most infections, oral vaccination would be suitable for immunization against several diseases. Thus, we verified the antibody production of the non-isogenic mice selected for high (HIII) and low (LIII)antibody response after oral immunization with two antigens with distinct nature: LPS (T-independent antigen) and flagellin (Tdependent antigen), associated with silica SBA-15 Three mice per groupwere orally inoculated (gavage) with twodoses of LPS (75&#956;g) or Salmonella typhimurium flagellin (50&#956;g) adsorbed/encapsulated or not to SBA-15 at a 1:10 ratio on days 0 and 30. Blood sampleswere collectedon days 7 and 37andIgG serum levels were determined by ELISA.There was an increasing in antibody levels in HIII animalsi mmunized with both antigens associated with silica when compared to those immunized with antigen alone. We observed highest antibody levels in two of three HIII mice immunized with both antigens, although, due to the small sample, no significant differences were found between groups treated with silica or not. No significant difference was observed in LIII animals. The oral adjuvant effect of silica is encouraging by these preliminary results but must be confirmed by further experiments with a larger number of animals.
28

O papel da flagelina e do sistema de secreção de Escherichia coli enteroinvasora na resposta imune inata dos macrófagos / The role of flagellin and secretion system of enteroinvasive Escherichia coli in the immune response innate macrophages

Ferreira, Lucas Gonçalves 11 December 2012 (has links)
Escherichia coli enteroinvasora (EIEC) é um dos agentes etiológicos da disenteria bacilar. Seu processo fisiopatológico é desencadeado pela expressão de fatores de virulência, que proporcionam sua invasão e sobrevivência nas células do hospedeiro, ativando o sistema imune inato e adaptativo da mucosa intestinal. Trabalhos recentes têm salientado a importância do sistema de secreção e da flagelina bacteriana como agonista de receptores da imuninade inata dos macrófagos, em especial alguns dos receptores do tipo NLR. Uma vez que esta espécie de E. coli também é capaz de expressar flagelina e fazer a montagem completa do flagelo e do sistema de secreção do tipo III, a nossa proposta foi avaliar o papel da flagelina e do sistema de secreção de EIEC na resposta imune dos macrófagos murinos. Para isso, utilizamos três cepas de EIEC: a cepa selvagem; a cepa mutante no gene responsável pela síntese da flagelina; e a cepa sem o plasmídio de virulência plnv, deficiente no sistema de secreção, para a infecção de macrófagos peritoniais de camundongos C57BI/6, caspase-1-/-, IPAF-/- e ASC-/-. Neste estudo foi possível observar que o escape bacteriano e a morte dos macrófagos infectados por EIEC, assim como a ativação da caspase-1 e posterior secreção de IL-1&#946; é independente da flagelina bacteriana, mas dependente do sistema de secreção, além disso, a ativação da caspase-1 de macrófagos infectados por EIEC é dependente do receptor IPAF e parcialmente da proteína adaptadora ASC. Assim, no nosso modelo, a ativação da caspase-1 dos macrófagos infectados por EIEC parece estar envolvida com o processamento e secreção de IL-1&#946; e, possivelmente na secreção de IL-18, mas não na morte celular. No modelo de infecção in vivo, o sistema de secreção bacteriano foi importante para a sobrevivência bacteriana no hospedeiro, assim como para a indução de uma resposta inflamatória no local da infecção. Ainda, a caspase-1 parece ter um papel importante para o controle da infecção in vivo por EIEC, podendo assim contribuir para uma resposta imune protetora do hospedeiro. / Enteroinvasive Escherichia coli (EIEC) is one of the etiologic agents responsible for bacillary dysentery. The pathophysiological process induced by this bacteria is triggered by the expression of virulence factors that provide the invasion and survival in host cells, resulting in activation of innate and adaptive immune system present on intestinal mucosa. Recent studies have emphasized the importance of the secretion system and bacterial flagellin as agonist of innate immune receptors present in macrophage, especially NLR (Nod like receptors). Then, our proposal was evaluate the role of flagellin (f1iC) and secretion system of EIEC in the induction of immune response of murine macrophages using the EIEC strains wild type (WT), mutant flagellin gene (f1iC), and a strain deficient in secretion system (DSS) for infection of peritoneal macrophages of C57Bl/6, caspase-1-/-, IPAF-/- and ASC-/-- mice. In this study we observed that the bacterial escape and death of infected macrophages with EIEC, the caspase-1 activation and subsequent IL-1&#946; secretion is independent of bacterial flagellin, but dependent of secretion system, moreover, the caspase-1 activation in infected macrophages is IPAF-dependent and partially dependent of the adapter protein ASC. Thus, in our model, the caspase-1 activation in EIEC infected macrophages seems to be involved with the processing and secretion of IL-1&#946; and possibly with the secretion of IL-18, but not involved with cell death. In the infection model in vivo, bacterial secretion system was important for bacterial survival in the host, as well as for the inflammatory response induction at the infection site. In addition, caspase-1 seems to have an important role to the control of in vivo infection by EIEC and can contribute to a protective immune response of the host.
29

Inserção de epitopo heterólogo em diferentes regiões de flagelina bacteriana: influência na função flagelar e imunogenicidade / Heterologous epitope insertion in different regions of bacterial flagellin: influence on flagellar function and immunogenicity

Azevedo, Fátima da Piedade de Melo 22 May 1997 (has links)
Uma das estratégias mais promissoras para a biotecnologia de vacinas é o desenvolvimento de linhagens precisamente atenuadas, e que possam ser usadas como carregadoras de antígenos heterólogos. Mutantes de <i}>Salmonella Typhimurium têm sido extensivamente utilizados com essa fmalidade. A flagelina, monômero constituinte do filamento flagelar, vem sendo empregada como carregadora de antígenos heterólogos, inseridos na região central, hipervariável (região IV). Inserções nessa região são freqüentemente funcionais, e levam à exposição do epitopo na superfície do filamento. O presente trabalho explora o potencial de outras regiões da molécula para a inserção de epitopos. Nós inserimos a mesma seqüência usada anteriomente (epitopo da proteína M de S. pyogenes, Tipo 5) em regiões com diferentes níveis de homologia (III e VI), e em região totalmente conservada (VIII). Também foram feitas inserções duplas em regiões que se mostraram toleráveis (III e IV; IV e VI). Todas as proteínas híbridas foram sintetizadas pela Salmonella, como demonstrado em imunoblots, usando anticorpo contra a flagelina e contra o peptídeo. Todas as regiões, exceto a VIII, aceitaram a inserção sem perda de motilidade, apesar de, em alguns casos, ela ter sido extremamente reduzida. A imunogenicidade foi avaliada pela imunização de camundongos com bactérias vivas, inativadas ou, quando possível, flagelina purificada. Os resultados foram similares aos descritos na literatura para inserções envolvendo a região IV, obtendo-se um elevado título de anticorpos contra flagelina. Um baixo nível de anticorpo contra o peptídeo também foi detectado para todas as novas linhagens testadas. Nossos resultados com imunização de bactérias vivas sugerem uma resposta levemente melhor ao peptídeo quando duas cópias estão presentes, mas os dados não são conclusivos. / One of the most promising strategies for the biotechnology of vaccines is the development of precisely attenuated strains, which could be used as carriers of heterologous antigens. Mutants of Salmonella Typhimurium have been extensively explored to this effect, since the infection ofmice by S. Typhimurium mimics the infection of humans by S. Typhi, and the genetics of the species is extremely well known, making it easy the obtention of defined mutants with reduced pathogenicity. Mutants with auxotrofy in genes of the aromatic pathway are particularly attractive, since they need PABA and DHB to grow, and these compounds are unavailable in mammalian tissues. Flagellin, the monomer which constitutes the flagellar filament, has been used as a carrier for heterologous epitopes, inserted in a central, hypervariable region (region IV). Insertions in this region are often functional, and lead to exposition of the epitope at the filament\' s surface. The present work explored the potential of the other regions ofthe molecule for the insertion of epitopes. We inserted the same reporter sequence (MS epitope from S. pyogenes M protein) in regions with different levels of homology (III and VI), and totally conserved (VIII). We also made double insertions in regions shown to be permissive (III and IV; IV and VI). All hybrid proteins were synthesized by Salmonella, as demonstrated by immunoblots using antibody against flagellin and against the synthetic peptide. All regions, except the highly conserved region VIII, accepted the insertions without loss of motility, albeit, in some cases, motility was seriously reduced. Immunogenicity of the hydrids was evaluated by immunization with live bacteria, killed bacteria, and purified flagellin (when possible). Results obtained with the new constructs were similar to the ones published for insertions involving region IV, in the sense that antibody titers to the carrier protein were very high. A low level of antibody to the inserted peptide was also detected in all groups of animals. Our results with live immunization suggest a slightly better response to the peptide when two copies are present, but the data are not conclusive.
30

Papel dos inflamassomas na ativação de células dendríticas e na modulação da resposta imune adaptativa. / Role of inflammasome activation in the maturation of dendritic cells and in the development of adaptive imune response.

Thaís Boccia da Costa 07 August 2014 (has links)
O reconhecimento da flagelina pelos NLRs Naip5 e NLRC4 leva à formação do complexo multiproteico denominado inflamassoma que culmina na ativação da caspase-1, com consequente clivagem da forma inativa das citocinas pró-inflamatórias IL-1b e IL-18 e morte da célula infectada. Neste trabalho pudemos observar que in vitro, a maturação de BMDCs com a estimulação com flagelina citosólica, inserida em vesículas lipídicas que permitem a transfecção da flagelina para o citosol, foi independente da ativação de NLRC4, caspase-1 e TLR5, mas somente de MyD88. Já a ativação de linfócitos T por estas BMDCs ativadas por flagelina citosólica é dependente de caspase-1 e MyD88. A neutralização da citocina IL-1a, levou à inibição da ativação de linfócitos T, indicando a contribuição desta para a montagem de resposta imune. A neutralização de IL-1a também levou a uma redução na produção de IL-12, que seria a citocina responsável pela polarização dos linfócitos para Th1. A imunização com flagelina leva ao desenvolvimento de imunidade protetora contra o desafio com S. typhimurium, igualmente dependente de caspase-1 e MyD88. Podemos dizer que a flagelina induz resposta imune tanto in vivo quanto in vitro e que, em ambos os casos, há a participação das moléculas caspase-1 e MyD88. / TLR5 activates inflammatory genes through MyD88 pathway whereas NLRC4 and NAIP5 assemble multiprotein complexes called inflammasomes, leading to caspase-1 activation and secretion of proinflammatory cytokines IL-1 and IL-18. Cytosolic flagellin (FLA-BSDot) induced upregulation of costimulatory molecules independent on TLR5, NLRC4 and Caspase-1, but dependent on MyD88. In addition, FLA-BSDot-stimulated OVA-pulsed BMDCs induced proliferation and production of IFN by OT-II splenocytes, dependent on caspase-1 and MyD88. FLA-BSDot stimulation leads to the secretion of IL-1 and IL-1. Neutralization of IL-1 inhibited BMDCs maturation in response to FLA-BSDot and led to decreased IFN production by OT-II splenocytes. Searching for the effector mechanism by which IL-1 induces Th1 polarization in response to FLA-BSDot, we observed a significant reduction in IL-12 production when IL-1 was neutralized. Also, we could see that adaptive immune responses induced by flagellin in vivo was protective against S.typhimurium lethal challenge, showing again a role for caspase-1 and MyD88. From these data we can infer that caspase-1 and MyD88 are both involved in the adaptive response induced by flagelin both in vitro and in vivo.

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