Submitted by RAFAEL MASSA null (rmassavet@yahoo.com.br) on 2017-01-25T17:36:12Z No. of bitstreams: 1 TESE versão final.pdf: 300203 bytes, checksum: 56039d51bf4b813ec825d1d9f0da7f3e (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido não contém o certificado de aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2017-01-27T13:23:12Z (GMT) / Submitted by RAFAEL MASSA null (rmassavet@yahoo.com.br) on 2017-01-27T16:30:18Z No. of bitstreams: 1 Tese_Rafael_Massa.pdf: 774602 bytes, checksum: 777b45d4c1d3d2fb5b52fd11f14af8ad (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-01-30T16:06:29Z (GMT) No. of bitstreams: 1 massa_r_dr_jabo.pdf: 774602 bytes, checksum: 777b45d4c1d3d2fb5b52fd11f14af8ad (MD5) / Made available in DSpace on 2017-01-30T16:06:29Z (GMT). No. of bitstreams: 1 massa_r_dr_jabo.pdf: 774602 bytes, checksum: 777b45d4c1d3d2fb5b52fd11f14af8ad (MD5) Previous issue date: 2017-01-17 / Com o objetivo de analisar as diferentes formas de interpretação dos resultados em pesquisas epidemiológicas com Leptospira spp., em quatro espécies de hospedeiros, as concordâncias entre os resultados da soroaglutinação microscópica (SAM) contra 24 sorovariedades foram testadas por meio do coeficiente Kappa. Os resultados obtidos com o cálculo clássico da soroprevalência, o método da sorovariedade mais provável (SMP) com 24 e oito antígenos e três variações do SMP foram comparados por meio da intersecção entre os intervalos de confiança de 95%. As concordâncias entre sorovariedades nos resultados da SAM indicam que a maioria das coaglutinações ocorre dentro do esperado pelo acaso e que não é possível atribuí-las apenas a reações cruzadas. O SMP resultou em soroprevalências menores que as obtidas pelo método clássico. Quanto mais antígenos são utilizados na SAM, menores serão a soroprevalências para cada sorovariedade, demonstrando que a bateria de antígenos interfere nos resultados. As diferentes formas de calcular o resultado do SMP mostraram ser coeficientes diferentes, que podem confundir os leitores, caso não sejam bem definidos nos trabalhos. Conclui-se que o método clássico de cálculo da soroprevalência seria o mais indicado, respeitando-se as limitações da SAM na conclusão das pesquisas. / Aiming to analyze the different ways of interpreting the results of epidemiological research with Leptospira spp. in four host species, the agreement between the results in the microscopic agglutination test (MAT) against 24 serovars was tested by the Kappa coefficient. The results with the classic seroprevalence method, the most likely serovar method (SMP) with 24 and eight antigens and three variations of the SMP were compared by the intersection of the 95% confidence intervals. Agreements between serovars in the results of MAT indicate that most co-agglutinations occur randonly, and cross-reactions can not assign as the only cause of them. The SMP resulted in lower seroprevalences than those obtained by the classical method. The more antigens are used in MAT, lower the seroprevalences for each serovar, demonstrating that the antigen battery interferes with the results. The different ways of calculating the result of the SMP proved to be different coefficients, which may confuse readers, if they are not well defined in the research. It was concluded that the classic seroprevalence would be the most appropriate method of calculation, respecting the limitations of the MAT in the research's conclusions.

No description available.

Immunological and ultrastructural changes in mononuclear cells exposed to Mycobacterium avium serovar-specific glycopeptidolipid (GPL) and the chemically derived R-lipid (lipopeptide fragment) were examined.

Contaminated poultry and egg products are major sources of Salmonella enterica serovar Enteritidis (S. enteritidis, SE) infections in humans. Colonization of SE in chicken reproductive tract results in the production of contaminated commercial shell-eggs and fertilized hatchery eggs. The complex pathogen-host interactions during SE colonization of chicken reproductive tract are largely unknown. This study was aimed at determining the pathogenic roles of the type three secretion systems (TTSS-1 and TTSS-2) in SE infection of chicken oviduct epithelial cells (COEC). A series of SE strains carrying mutations in the genes encoding structure or effector proteins of TTSS-1 and TTSS-2 were constructed. The invasiveness and intracellular survival rate of each SE strain as well as the host innate immune responses induced by the infections were evaluated. The results demonstrate that both TTSS-1 and TTSS-2 are required by SE to invade COEC which involve genes encoding effector proteins SipA, SopB, SopE2, and PipB. In addition to their involvement in host cell invasion, sipA and sipB are also necessary for the survival or replication of SE inside COEC. Inactivation of TTSS-2 genes (ssaV and pipB) resulted in an enhanced bacterial proliferation inside COEC. The data from this study also show that SE infection triggers pro-inflammatory responses in COEC and TTSS-1 is involved in the expression of iNOS and IL-8, a CXC chemokine. TTSS-1 and TTSS-2 are not necessary for induction of K203, MIP-1β, and IL-10 or suppression of TGF-β3 in COEC.

Opioids have been shown to modulate immune function in a variety of assays and animal models. In a more limited number of studies, opioids have been shown to sensitize to infection. Heroin, the prototypical opioid drug of abuse, is rapidly metabolized to morphine in the body. Morphine has been used as an analgesic for hundreds of years, and continues to be a drug of choice for treating pain in ICU and trauma patients. The continued use of these opioid compounds in humans warrants further investigation of their effect on immune responses against, and progression of, common bacterial infections. Two infections were investigated in this thesis using murine models, Acinetobacter baumannii and Salmonella typhimurium. A recent increase in the prevalence of A. baumannii infections among healthy, but wounded, military personnel, lead to the hypothesis that analgesic morphine might sensitize to infection with this multiply-drug resistant bacterium. A systemic, intraperitoneal A. baumannii infection model was established in mice that resulted in rapid, disseminated disease where animals became septic as organisms replicated in the blood, lungs, and other organs. This model was used to investigate the role of various parameters of innate immune defenses to Acinetobacter. Neutralization of neutrophils by antibody depletion greatly sensitized to this infection. Infection resulted in a rapid, biphasic induction of both IL-17 and the chemokine, KC/CXCL1, a major chemotactic factor for neutrophils, that continued to rise through 18h after bacterial inoculation. However, depletion of either IL-17 or KC/CXCL1 using monoclonal antibodies failed to sensitize to Acinetobacter infection. Further, IL-17 receptor KO mice were not sensitized to this infection. Collectively, these results suggest that there must be other chemotactic factors for neutrophils that can compensate for the absence of IL-17 and KC. Morphine, delivered by extended release pellet, sensitized two strains of mice to two strains of Acinetobacter, as measured by mortality to a sublethal challenge dose, and this effect was blocked by administration of the opioid-receptor antagonist, naltrexone. . Morphine increased Acinetobacter burdens in the organs and blood of infected mice, and increased the levels of pro-inflammatory cytokines. Evidence for an effect of morphine on neutrophil infiltration was obtained. Morphine decreased the total numbers of cells, as well as the total numbers of neutrophils and macrophages infiltrating into the peritoneal cavity. This inhibition of neutrophil accumulation correlated with suppression of levels of both IL-17 and KC/CXCL1. The evidence supports the conclusion that morphine sensitizes to Acinetobacter infection by suppressing the response of neutrophils, potentially via depression of neutrophil chemotactic factors IL-17 and KC. However, taken together with the data above there are probably additional factors in addition to IL-17 and KC that are sensitizing the animals to infection in the presence of morphine. In addition to these studies, the opioid-receptor dependency of morphine-mediated sensitization to Salmonella enteric serovar Typhimurium was examined. Previous experiments had determined that extended release morphine pellets sensitized mice to a sublethal dose of Salmonella, as determined by survival and bacterial burdens in the organs of infected mice, but naltrexone resulted in only incomplete reversal of the morphine-mediated effects. To further characterize the receptor dependency of the observed phenomenon, mu-opioid receptor knockout (MORKO) mice were used. MORKO mice were found to be completely resistant to the lethal effects of morphine plus infection observed in wild-type (WT) mice. In addition, MORKO mice showed greatly reduced bacterial burdens and pro-inflammatory cytokine levels when treated with morphine and challenged with a sublethal challenge dose of Salmonella, in comparison to WT mice. In summary, the studies presented in this thesis explored basic mechanisms of innate immunity to A. baumannii using a systemic model of infection. The work provides additional evidence that morphine sensitizes to infection, using models of Acinetobacter and Salmonella in mice. An implication of this work is use of caution in the administration of opioids in patients that are susceptible to opportunistic infections. / Microbiology and Immunology

Serovare von Salmonella enterica subspecies enterica sind im allgemeinen pathogen für Mensch und andere Säugetiere. In dieser Arbeit habe ich anhand eines “Multilocus Sequences Typing” Typisierungsschemas die Populationsstruktur einer der am häufigsten auftretenden Serovaren dieser Subspecies, das aus Menschen und Schlachttieren isolierte Serovar Newport charakterisiert. Dieses Schema wurde auch für die Charakterisierung von Isolaten derselben Subspecies aus humanen Dauerträgern und Reptilien verwandt, um zu bestimmen, ob Isolate aus diesen Quellen sich in ihrer Populationstruktur von denjenigen unterscheiden, die aus anderen Quellen isoliert wurden. Multilocus Sequences Typing ist eine weitgehend für die Untersuchung der Evolution und Populationsstruktur von einen breiten Spektrum von Organismen verwendete Technik. 400 - 600 bp lange Fragmente von 7 Haushaltsgenen wurden sequenziert, und jede einzelne Sequenz jedes einzelnen Gens wurde eine Allelnummer zugeordnet. Jede einzelne Allelkombination wurde einem Sequenztyp zugeordnet. Die so gewonnenen Daten wurden weiter analysiert. Drei “Lineages”, Newport-I, Newport-II und Newport-III, wurden innerhalb dieses Serovars identifiziert, die jeweils aus Menschen in Europa, Tieren und Menschen in Nordamerika isoliert wurden. Der Multiresistenz-Phänotyp wurde häufiger in Newport II gefunden, während die meisten Newport III Isolate pan-sensitiv waren. Verglichen mit anderen Serovaren war die Anzahl von “Lineages” innerhalb Newport höher als bei Enteritidis, Kentucky und Typhimurium, aber niedriger als bei Paratyphi B. Das heisst, die Serovare von S. enterica subspecies enterica variieren stark in ihrer Populationsstruktur. Die Sequenztypen in Isolaten aus humanen Dauerträgern waren im allgemeinen am häufigsten in Isolaten von klinischen Patienten und Tieren vorhanden. In der Mehrheit der Serovaren waren die meisten Isolate aus Patienten und Tieren genetisch identisch mit solchen, die aus gesunden Trägern isoliert wurden. Die genetische Variabilität war zwischen Isolaten aus diesen Quellen vergleichbar. Diese Ergebnissen deuten daraufhin, dass Salmonellen aus Dauerträgern sowie Isolate aus Patienten und Tieren derselben Population angehören. Die meisten Serovare aus Reptilienisolaten waren genetisch identisch mit denen von Menschen und warmblütigen Tieren. In den Serovaren Bovismorbificans, Decatur, Miami und Oranienburg hingegen waren die meisten Isolate aus Reptilien genetisch anders als Isolate aus anderen Wirten. Allerdings wurden nur wenige Isolate der Serovaren Bovismorbificans, Decatur und Miami aus Reptilien und nur wenige Isolate der Serovaren Oranienburg aus anderen Quellen getestet; eine grössere Anzahl von Isolaten müsste daher untersucht werden, um festzustellen ob diese genetischen Unterschiede statistich signifikant sind oder nicht. / Serovars of Salmonella enterica subspecies enterica are generally pathogenic to humans and other mammals. In this study, I examined the population structure of one of the most common serovars of this subspecies isolated from humans and food animals, serovar Newport, using a multilocus sequence typing scheme. This scheme was also used to analyze isolates of this subspecies from chronic human carriers and reptiles to determine whether isolates from these sources represent distinct populations than those from other hosts. Multilocus sequence typing has extensively been used to study evolution and population structure of a wide range of organisms. 400-600 bp fragments of 7 housekeeping genes were sequenced and every unique sequence of each gene fragment was given a distinct allele number. Each unique combination of alleles was assigned a distinct sequence type number. The data were used in further analyses. Three lineages, namely Newport-I, Newport-II and Newport-III were identified within serovar Newport which were associated to European humans, animals and humans in North America, respectively. Multidrug resistance phenotypes were most common in Newport-II whereas most isolates in Newport-III were pan-susceptible. When compared to other serovars, the numbers of lineages within Newport were higher than for Enteritidis, Kentucky and Typhimurium but lower than for Paratyphi B. Therefore, serovars of S. enterica subspecies enterica vary greatly in their population structures. The sequence types observed for isolates from chronic human carriers were generally the most common among human-clinical and animal isolates. Most isolates from non-carrier humans plus animals were genetically identical to the carried isolates within most serovars. Genetic diversity was also comparable between isolates from these sources. These results suggest that salmonellae from chronic human carriers belong to the same population as isolates from non-carrier humans and animals. For most serovars, most isolates from reptiles were genetically identical to those from humans or other warm blooded animals. However, in serovars Bovismorbificans, Decatur, Miami and Oranienburg, most reptile isolates were genetically distinct from isolates from other hosts. Only few reptile isolates were tested from Bovismorbificans, Decatur and Miami and only few non-reptile isolates were tested from Oranienburg, and in larger numbers of such isolates would be needed to determine whether these differences are statistically significant.

Einleitung: Die Leptospirose ist eine der weltweit bedeutendsten Zoonosen. Durch den häufig asymptomatischen oder unspezifischen Krankheitsverlauf, wird von einer hohen Dunkelziffer ausgegangen. Menschen können sich über direkten Tierkontakt oder indirekten Kontakt mit dem Urin infizierter Tiere, zum Beispiel über kontaminierte Gewässer oder Erde, anstecken. Die Infektion erfolgt dabei über den Eintritt des Erregers in Schleimhäute oder Hautwunden. Ziel der Untersuchungen: Obwohl die Überlebenszeit von Leptospiren in der Umwelt einen entscheidenden Einfluss auf das Infektionsrisiko des Menschen hat, wurden bisher nur sehr wenige Untersuchungen dazu durchgeführt. Diese konzentrierten sich dabei vor allem auf das Überleben der Erreger in Erde oder Wasser. Daher war es Ziel dieser Arbeit die Umweltstabilität eines häufig in Deutschland gefundenen Leptospirenserovars unter verschiedenen Umweltbedingungen zu untersuchen. Zusätzlich zu diesen Untersuchungen war es Ziel dieser Arbeit, durch die Veröffentlichung eines Übersichtsartikels über die Leptospirose Ärzte in Deutschland für diese häufig unerkannt bleibende Erkrankung zu sensibilisieren. Material und Methoden: Ein jahrelang an Kulturmedium adaptierter Labor- und ein erst vor 3 Jahren isolierter Feldstamm von Leptospira kirschneri Serovar Grippotyphosa wurden auf ihr Überleben in der Umwelt untersucht. Es wurde ihre Widerstandsfähigkeit gegenüber verschiedenen Umwelteinflüssen, wie z.B. Tierurin als umgebendes Medium bei verschiedenen Temperaturen oder auch der Einfluss einer Trocknung, untersucht. Nachdem die Leptospiren den Umwelteinflüssen für unterschiedliche Zeitspannen ausgesetzt waren, wurde versucht sie in EMJH-Medium wieder zu kultivieren. Während einer Inkubationszeit von mindestens 28 Tagen bei 29 °C wurden diese Kulturen wöchentlich unter dem Dunkelfeldmikroskop auf das Vorhandensein motiler Leptospiren untersucht. Zusätzlich wurde durch Kultivierungsversuche in EMJH-Medium das Überleben der Leptospiren in einem Wasserstrom mit einer definierten Fließgeschwindigkeit und ihre Verbreitung in diesem Strom mittels real-time PCR untersucht. Alle Versuche wurden im Dreifachansatz durchgeführt. Statistische Untersuchungen wurden mittels eines zweiseitigen Mann-Whitney-U Tests (Fehler 1. Art α = 0,05) durchgeführt. Ergebnisse: Die beiden untersuchten Stämme von L. grippotyphosa überlebten nicht in unverdünntem Tierurin. In verdünntem Tierurin überlebten die Stämme, je nach Temperatur und Verdünnungsmedium, zwischen 1 - 72 Stunden (Laborstamm) und 4 - 24 Stunden (Feldstamm). Beide Stämme überlebten signifikant länger bei 15 °C als bei 37 °C (p < 0,001, bzw. p = 0,041). Der Laborstamm überlebte signifikant länger in verdünntem Rindereurin (max. 72 h bei 15 °C) als in verdünntem Hundeurin (max. 4 h; p = 0,027). Im Gegensatz dazu, überlebte der Feldstamm signifikant länger in Hundeurin (max. 24 h bei 15 °C) als in Rinderurin (max. 4 h; p = 0,028). Das vollständige Trocknen auf einer festen Oberfläche war bei Temperaturen zwischen 15 °C und 37 °C für beide Stämme letal. Jedoch war, unabhängig von der untersuchten Temperatur, eine halbe Stunde vor der vollständigen Trocknung eine Kultivierung der Leptospira spp. noch möglich. In einem Wasserstrom konnten sich die Leptospiren aufgrund ihrer Eigenbewegung schneller und langsamer als die Durchschnittsgeschwindigkeit (0,01 m / s) des Wassers bewegen, überlebten jedoch die mechanischen Schäden während des Schlauchdurchflusses nicht. Schlussfolgerungen: Das Überleben von Leptospira spp. ist offensichtlich von vielen Faktoren abhängig. Eine schnelle Verdünnung nach der Ausscheidung mit dem Urin scheint dabei essentiell zu sein. Niedrigere Temperaturen sowie eine feuchte Umgebung verbessern ihre Widerstandsfähigkeit gegen schädliche Einflüsse, während Trockenheit oder mechanische Schädigung ihr Überleben nicht ermöglichen. Wegen der großen Bedeutung der leptospiralen Überlebenszeit in der Umwelt für das Infektionsrisiko von Mensch und Tier sind weitere Untersuchungen auf diesem Forschungsgebiet in der Zukunft nötig.:1. Einleitung 2. Literaturübersicht 2.1 Die Geschichte der Leptospirose 2.2 Morphologie und Übertragungswege der Erreger 2.3 Taxonomie 2.4 Haupt- und Nebenwirte 2.5 Die Erkrankung beim Menschen 2.5.1 Vorkommen 2.5.2 Klinik und Therapie 2.6 Die Erkrankung beim Tier 2.6.1 Bei Nutztieren 2.6.2 Bei Haustieren 2.6.3 Bei Wildtieren 2.7 Diagnostik 2.8 Die Umweltstabilität der Erreger 2.8.1 In Erde 2.8.2 In Wasser 2.8.3 In Urin 3. Publikationen 3.1 Publikation Nr. 1 3.2 Publikation Nr. 2 4. Diskussion und Schlussfolgerung 5. Zusammenfassung 6. Summary 7. Literaturverzeichnis 8. Danksagung / Introduction: Leptospirosis is one of the most important zoonosis worldwide. Due to the often asymptomatic or non-specific course of the disease, a high number of unreported cases is assumed. Humans can get infected through direct contact with animals or indirect contact with the urine of infected animals, for example through contaminated water or soil. The infection occurs via entry of the pathogen through mucous membranes or skin wounds. Aims of the study: Although the survival time of Leptospira spp. in the environment has a crucial influence on the human infection risk, very few studies have been carried out so far. These studies focused primarily on the survival of the pathogens in soil or water. It was therefore the aim of this study to investigate the environmental stability of a leptospiral serovar that is frequently found in Germany under different environmental conditions. In addition to these investigations, the aim of this work was to raise the awareness of physicians in Germany for this often undetected and neglected disease by publishing a review article on leptospirosis. Material and Methods: The survival in the environment of both a laboratory strain, which has been adapted to culture medium for years and a field strain, which was isolated only 3 years ago, of Leptospira kirschneri Serovar Grippotyphosa was studied. Their resistance to various environmental influences, such as animal urine as surrounding medium at different temperatures or the influence of drying, were examined. After the leptospires were exposed to these influences for various time periods, an attempt was made to cultivate them in EMJH medium. During an incubation period of at least 28 days at 29 °C, the cultures were examined weekly for the presence of motile leptospires under the darkfield microscope. In addition, the survival of the leptospires in a water stream with a defined velocity and their distribution in this stream were examined by real-time PCR and cultivation experiments in EMJH medium. All experiments were carried out in triplicate. The statistical analysis was done using a two-tailed Mann-Whitney U test (type-1-error α = 0.05). Results: Both examined strains of L. grippotyphosa did not survive in undiluted animal urine. In diluted animal urine, the strains survived between 1-72 hours (laboratory strain) and 4-24 hours (field strain), depending on the temperature and dilution medium. Both strains survived significantly longer at 15 °C than at 37 °C (p < 0.001 or p = 0.041). The laboratory strain survived significantly longer in diluted cattle urine (max. 72 h at 15 °C) than in diluted dog urine (max. 4 h) (p = 0.027) while the field strain survived significantly longer in dog urine (max. 24 h at 15 °C) than in cattle urine (max. 4 h) (p = 0.028). Complete drying on a solid surface at temperatures between 15 °C and 37 °C was lethal for both strains. However, regardless of the temperature examined, Leptospira spp. were still cultivatable half an hour before the time point of complete drying. In a water stream, leptospires were able to move faster or slower than the average velocity of the water (0.01 m / s) due to their intrinsic mobility but were not able to survive the mechanical damage caused by running water in the hose system. Conclusions: Overall, it can be concluded that the survival of Leptospira spp. depends on many factors. Rapid dilution after urine excretion appears to be essential. Lower temperatures and a humid environment improve their survival time, while drought or mechanical damage is lethal to them. Because of the great importance of leptospiral survival in the environment for the infection risk of humans and animals, further studies in this research area will be necessary in the future.:1. Einleitung 2. Literaturübersicht 2.1 Die Geschichte der Leptospirose 2.2 Morphologie und Übertragungswege der Erreger 2.3 Taxonomie 2.4 Haupt- und Nebenwirte 2.5 Die Erkrankung beim Menschen 2.5.1 Vorkommen 2.5.2 Klinik und Therapie 2.6 Die Erkrankung beim Tier 2.6.1 Bei Nutztieren 2.6.2 Bei Haustieren 2.6.3 Bei Wildtieren 2.7 Diagnostik 2.8 Die Umweltstabilität der Erreger 2.8.1 In Erde 2.8.2 In Wasser 2.8.3 In Urin 3. Publikationen 3.1 Publikation Nr. 1 3.2 Publikation Nr. 2 4. Diskussion und Schlussfolgerung 5. Zusammenfassung 6. Summary 7. Literaturverzeichnis 8. Danksagung

La bactérie Salmonella enterica sérovar Typhi (S. Typhi) provoque la fièvre typhoïde chez les humains et constitue un problème de santé publique important. La majorité de nos connaissances sur la pathogenèse de cette bactérie provient du modèle de fièvre entérique chez la souris causée par le sérovar Typhimurium. Peu d’études se sont penchées sur les facteurs de virulence uniques au sérovar Typhi, ni sur la possibilité que les pseudogènes retrouvés dans son génome puissent être fonctionnels. Le fimbria stg, unique au sérovar Typhi, renferme un codon d’arrêt TAA prématuré dans le gène stgC qui code pour le placier responsable de l’assemblage des sous-unités fimbriaires à la surface de la bactérie. Ainsi, le fimbria stg a été classifié dans la liste des pseudogènes non-fonctionnels. Les objectifs de cette étude étaient d’évaluer l’implication du fimbria stg lors de l’interaction avec les cellules humaines, puis de vérifier l’importance du pseudogène stgC lors de la biogenèse fimbriaire. Dans une première partie, la transcription de stg a été évaluée à l’aide d’une fusion lacZ. Malgré des niveaux d’expression observés généralement faibles en milieu riche, la croissance en milieu minimal a favorisé la transcription de l’opéron. La délétion complète de l’opéron fimbriaire stgABCD du génome de S. Typhi a été réalisée par échange allélique, puis a été complémentée sur un plasmide. Il a été démontré que la présence de stg chez S. Typhi, S. Typhimurium et E. coli contribue à une adhérence accrue sur les cellules épithéliales humaines. De plus, ce fimbria semble agir comme une structure anti-phagocytaire lors de l’interaction avec des macrophages humains. Ainsi, l’opéron stg semble fonctionnel, malgré son codon d’arrêt prématuré, puisque des phénotypes ont été observés. La seconde partie de cette étude consistait à vérifier le rôle joué par le pseudogène stgC dans la biogenèse du fimbria. Différentes variantes de l’opéron ont été générées, clonées dans un vecteur inductible à l’arabinose, puis transformées dans la souche afimbriaire d’E. coli ORN172. La translocation de la sous-unité fimbriaire StgD à la surface de la bactérie a été évaluée chez ces différents mutants par immunobuvardage de type Western. Cette expérience a permis de démontrer que le pseudogène stgC est essentiel pour l’exportation de la sous-unité StgD à la surface. L’ajout d’une étiquette de 6-histidines en C-terminal de StgC a permis de confirmer la traduction complète du gène, malgré le codon d’arrêt TAA prématuré. Le séquençage peptidique a révélé l’insertion d’une tyrosine à ce codon. Une fusion traductionnelle avec la protéine verte fluorescente a révélé qu’environ 0.8% de l’ARNm peut être traduit et permet la production complète du placier. Ce projet a permis la caractérisation d’un facteur de virulence unique à S. Typhi et constitue une étape de plus vers la compréhension de ses mécanismes de pathogenèse. Il s’agit de la première démonstration chez les bactéries de la fonctionnalité d’un gène interrompu prématurément par un codon d’arrêt TAA. / Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever in humans and is considered as an important health problem. Most of our knowledge on the pathogenesis of this bacterium comes from an enteric fever model in mice caused by serovar Typhimurium. Few studies have examined the virulence factors unique to serovar Typhi or the possibility that pseudogenes harbored in its genome may be functional. stg fimbriae are found only within the serovar Typhi genome and contain a premature TAA stop codon in the stgC gene encoding the usher responsible for the assembly of fimbrial subunits at the bacterial surface. Thus, the stg fimbria has been classified among the list of non-functional pseudogenes. The objectives of this study were to assess the involvement of stg fimbriae during interaction with human cells, and then to evaluate the importance of the stgC pseudogene in fimbrial biogenesis. First, stg transcription was evaluated using a lacZ fusion. Despite low expression levels generally observed in rich medium, growth in minimal medium promoted transcription of the operon. Complete deletion of the stgABCD fimbrial operon from S. Typhi was performed by allelic exchange and was complemented on a plasmid. It has been shown that the presence of stg in S. Typhi, S. Typhimurium and E. coli contributes to increased adherence to human epithelial cells. In addition, the fimbriae seem to act as an anti-phagocytic structure during the interaction with macrophages. Thus, the stg operon appears to be functional despite its premature codon, as phenotypes were observed. The second part of this study involved testing the role of the stgC pseudogene in fimbrial biogenesis. Different variants of the operon were generated, cloned into an arabinose inducible vector, and then transformed into afimbriated E. coli strain ORN172. Translocation of the StgD subunit to the cell surface of the different mutants was evaluated using Western blot. This experiment demonstrated that stgC is essential for export of the StgD subunit to the cell surface. The addition of a 6-histidine tag at the C-terminal end of StgC confirmed the complete translation of the gene, despite the premature TAA stop codon. Peptide sequencing revealed the insertion of a tyrosine at this codon. A translational fusion with the green fluorescent protein demonstrated that approximately 0.8% of the mRNA can be translated to allow full production of the usher. This project allowed characterization of a virulence factor unique to S. Typhi and is a step closer towards better understanding of its pathogenesis mechanisms. This is the first demonstration in bacteria of the functionality of a gene which is interrupted by a premature TAA stop codon.

Les fimbriae sont des structures protéiques extracellulaires retrouvées chez une vaste diversité de bactéries. Ces structures ont fait l’objet de nombreuses études et sont maintenant reconnus pour leur implication dans l’adhésion et l’invasion aux cellules eucaryotes, mais aussi dans la production de biofilms. Ils sont groupés selon leur voie de sécrétion. Certains utilisent une machinerie spécifique et individuelle, c’est le cas des pili de type IV, tandis que d’autres utilisent la voie de sécrétion générale suivit d’une voie spécifique telle que la voie du chaperon-placier (« Chaperon Usher Pathway ») (fimbriae CUP) ou la voie de nucléation précipitation (« nucleation precipitation pathway ») (Curli). Malgré toutes les connaissances actuelles concernant les fimbriae, très peu d’informations sont disponibles quant aux fimbriae de Salmonella enterica sérovar Typhi (S. Typhi). Ce pathogène unique à l’homme est l’agent étiologique de la fièvre typhoïde. Puisque les fimbriae sont reconnus pour être impliqués dans l’adaptation à l’hôte, nous avons décidé d’étudier davantage l’arsenal fimbriaire de S. Typhi, dans l’espoir d’identifier des facteurs de virulence uniques à S. Typhi et impliqués dans la ségrégation de l’hôte. La souche S. Typhi ISP1820 possède 14 opérons codant pour des systèmes d’adhésion, mais plusieurs contiennent des pseudogènes et leur expression n’a jamais été observée in vitro. Afin d’étudier les systèmes d’adhésion de S. Typhi, nous avons supprimé chaque opéron du génome individuellement et cumulativement à l’aide une technique de mutagénèse par échange allélique. Ainsi, nous avons testé chaque mutant individuel et la souche mutante pour tous les systèmes d’adhésion dans plusieurs essais tels que des infections de cellules épithéliales et de macrophages, de mobilité et de formation de biofilm. Nous avons aussi évalué l’expression des fimbriae lors de différentes conditions de croissance en laboratoire par RT-PCR. Tous les tests réalisés nous ont permis de découvrir que plusieurs opérons fimbriaires de S. Typhi sont opérationnels et utilisés pour différentes fonctions par la bactérie. / Fimbriae are extracellular proteinaceous appendages found in many bacteria. They are widely studied and believe to be implicated in several cellular functions such as adhesion, invasion of eukaryotic cells, and biofilm production. They are classified depending on their pathway of secretion: some, like type IV pili, use self-specific machinery, while others use the general secretory pathway followed by their own assembly pathway such as the Chaperon Usher Pathway (CUP fimbriae) and the nucleation precipitation pathway (curli). Despite everything that is known about these structures, little has been discovered regarding fimbrial systems of Salmonella enterica serovar Typhi (S. Typhi). This pathogen is a human restricted serovar and the etiological agent of typhoid fever. Since fimbriae have been implicated in host adaptation, we have decided to further study S. Typhi fimbrial arsenal in the hope of uncovering virulence factors unique to S. Typhi and implicated in host specificity. The S. Typhi ISP1820 strain carries 14 operons encoding for fimbrial structures, but many are believed pseudogenes or are not expressed in vitro. In order to study these different adhesion systems in S. Typhi, we have deleted each one individually and cumulatively by allelic exchange mutagenesis. Hence, we have tested every individual mutation and the mutant strain deprived of all 14 operons in many different assays including epithelial cell and macrophage infection, mobility, and biofilm formation. We also evaluate expression during growth under laboratory conditions by RT-PCR. These experiments have allowed us to discover that many of S. Typhi fimbriae are functional, expressed, and used by the bacteria in many different processes.

Les fimbriae sont des structures protéiques extracellulaires retrouvées chez une vaste diversité de bactéries. Ces structures ont fait l’objet de nombreuses études et sont maintenant reconnus pour leur implication dans l’adhésion et l’invasion aux cellules eucaryotes, mais aussi dans la production de biofilms. Ils sont groupés selon leur voie de sécrétion. Certains utilisent une machinerie spécifique et individuelle, c’est le cas des pili de type IV, tandis que d’autres utilisent la voie de sécrétion générale suivit d’une voie spécifique telle que la voie du chaperon-placier (« Chaperon Usher Pathway ») (fimbriae CUP) ou la voie de nucléation précipitation (« nucleation precipitation pathway ») (Curli). Malgré toutes les connaissances actuelles concernant les fimbriae, très peu d’informations sont disponibles quant aux fimbriae de Salmonella enterica sérovar Typhi (S. Typhi). Ce pathogène unique à l’homme est l’agent étiologique de la fièvre typhoïde. Puisque les fimbriae sont reconnus pour être impliqués dans l’adaptation à l’hôte, nous avons décidé d’étudier davantage l’arsenal fimbriaire de S. Typhi, dans l’espoir d’identifier des facteurs de virulence uniques à S. Typhi et impliqués dans la ségrégation de l’hôte. La souche S. Typhi ISP1820 possède 14 opérons codant pour des systèmes d’adhésion, mais plusieurs contiennent des pseudogènes et leur expression n’a jamais été observée in vitro. Afin d’étudier les systèmes d’adhésion de S. Typhi, nous avons supprimé chaque opéron du génome individuellement et cumulativement à l’aide une technique de mutagénèse par échange allélique. Ainsi, nous avons testé chaque mutant individuel et la souche mutante pour tous les systèmes d’adhésion dans plusieurs essais tels que des infections de cellules épithéliales et de macrophages, de mobilité et de formation de biofilm. Nous avons aussi évalué l’expression des fimbriae lors de différentes conditions de croissance en laboratoire par RT-PCR. Tous les tests réalisés nous ont permis de découvrir que plusieurs opérons fimbriaires de S. Typhi sont opérationnels et utilisés pour différentes fonctions par la bactérie. / Fimbriae are extracellular proteinaceous appendages found in many bacteria. They are widely studied and believe to be implicated in several cellular functions such as adhesion, invasion of eukaryotic cells, and biofilm production. They are classified depending on their pathway of secretion: some, like type IV pili, use self-specific machinery, while others use the general secretory pathway followed by their own assembly pathway such as the Chaperon Usher Pathway (CUP fimbriae) and the nucleation precipitation pathway (curli). Despite everything that is known about these structures, little has been discovered regarding fimbrial systems of Salmonella enterica serovar Typhi (S. Typhi). This pathogen is a human restricted serovar and the etiological agent of typhoid fever. Since fimbriae have been implicated in host adaptation, we have decided to further study S. Typhi fimbrial arsenal in the hope of uncovering virulence factors unique to S. Typhi and implicated in host specificity. The S. Typhi ISP1820 strain carries 14 operons encoding for fimbrial structures, but many are believed pseudogenes or are not expressed in vitro. In order to study these different adhesion systems in S. Typhi, we have deleted each one individually and cumulatively by allelic exchange mutagenesis. Hence, we have tested every individual mutation and the mutant strain deprived of all 14 operons in many different assays including epithelial cell and macrophage infection, mobility, and biofilm formation. We also evaluate expression during growth under laboratory conditions by RT-PCR. These experiments have allowed us to discover that many of S. Typhi fimbriae are functional, expressed, and used by the bacteria in many different processes.