Dissertations / Theses on the topic 'Murine Mycobacterium tuberculosis infection'
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Bouzid, Feriel. "La Canettose, une maladie infectieuse émergente dans la corne de l'Afrique." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0548/document.
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La tuberculose est l’une des maladies infectieuses mortelles les plus fréquentes, causée par des mycobactéries tuberculeuses dont principalement M. tuberculosis. Notre thèse a porté sur Mycobacterium canettii caractérisée par un morphotype lisse et un temps de génération plus court que M. tuberculosis. Notre revue de la littérature a montré que moins d'une centaine de cas d’infection à M. canettii ont été rapportés majoritairement à Djibouti située dans la Corne de l’Afrique. Ensuite, notre étude prospective de la tuberculose pulmonaire à Djibouti a mesuré une prévalence d’infections à M. canettii de 4%. A travers un modèle murin d’infection par gavage, nous avons observé la translocation de M. canettii des intestins vers la circulation lymphatique et sanguine ; suivie par une dissémination principalement vers les poumons et les ganglions lymphatiques. Cette étude a alors démontré que M. canettii peut infecter les individus par voie orale et a révélé que M. canettii peut interagir avec le tissu adipeux brun. Ensuite, à travers des modèles cellulaires d’infection, nous avons montré que les pré-adipocytes bruns pourraient constituer une cible potentielle des mycobactéries tuberculeuses et que M. canettii ne persiste pas dans les adipocytes matures contrairement à M. tuberculosis. En conclusion, nous avons apporté des connaissances nouvelles sur l’infection à M. canettii : sa prévalence, son mode de transmission ainsi que de nouvelles pistes sur de possibles réservoirs environnementaux. L’ensemble de ces données suggèrent que l’infection à M. canettii doit être considérée comme une entité clinique distincte de la tuberculose que nous proposons de nommer « Canettose »Tuberculosis is one of the most frequent deadly infectious diseases worldwide, caused by tuberculous mycobacteria including mainly M. tuberculosis. Our thesis focused on Mycobacterium canettii characterized by a smooth morphotype and a shorter generation time than M. tuberculosis. Our review of the literature showed that less than one hundred cases of M. canettii infection have been reported in Djibouti situated in the Horn of Africa. Then, our prospective microbiological study of pulmonary tuberculosis in Djibouti measured a prevalence of M. canettii lung infections of 4%. Through a mouse model by gavage, we observed the translocation of M. canettii from the intestines to the lymphatic and blood circulation; followed by dissemination mainly to the lungs and lymph nodes. In conclusion, this study demonstrated that M. canettii can follow the digestive tract to infect individuals and revealed also that M. canettii can interact with brown adipose tissue. Then, through cell infection models, we have shown that brown pre-adipocytes may be a potential target for tuberculous mycobacteria and that M. does not persist in mature adipocytes contrary to M. tuberculosis. In conclusion, this work allowed to bring new knowledge about M. canettii infection: its prevalence, its mode of transmission as well as new avenues on possible environmental reservoirs. All of these data suggest that M. canettii infection should be considered as a distinct clinical entity from tuberculosis. We propose to name "Canettosis" the M. canettii infection
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Khor, Siew Yan. "The immunomodulating activity of levamisole and gamma-interferon on experimental murine infections with Mycobacterium microti and Mycobacterium tuberculosis and the influence of gamma-interferon on the bactericidal activity of Isoniazid and Rifampicin." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37744.
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Gurcha, Sudagar Singh. "Mannan biosynthesis in mycobacterium tuberculosis." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324798.
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Barr, D. A. "Characterising HIV-associated Mycobacterium tuberculosis blood stream infection." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3028670/.
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Despite the success of antiretroviral therapy roll-out, one-million people still die with HIV-infection annually. In high-burden settings, tuberculosis remains the most common proximal cause of hospital admission and death in people living with HIV. In post-mortem series, 90% of fatal HIV-associated tuberculosis is 'disseminated'. This is a form of tuberculosis which has been poorly characterised and, despite the high associated-mortality, never been the subject of interventional trials to define optimal treatment strategies. This thesis contends that the mode of severe HIV-associated tuberculosis is blood stream infection. First it is argued with reference to historical literature that blood stream dissemination is part of the natural history of post-primary tuberculosis infection, and that HIV-associated M. tuberculosis blood stream infection (MTBBSI) can be conceived of as a reversion to, and exaggerated form of this natural history. Using data from a large cohort (n=571) of HIV-infected inpatients with CD4 cell count < 350 cells/mm3 and a new TB diagnosis from Khayelitsha Hospital, South Africa (the KDHTB study), the extent and magnitude of MTBBSI is shown to be a major determinant of clinical phenotype and mortality risk. Systematic, quantitative markers of blood stream dissemination, including TB blood culture, urine-lipoarabinomannan (uLAM), and urine GeneXpert MTB/RIF testing (uXpert), can be combined into a 'disseminated TB score. KDHTB patients have high prevalence of abnormal sodium and fluid balance, metabolic acidosis associated with acute kidney injury, hyperlactataemia, infiltrative liver and splenic pathology, and anaemia. Each of these pathophysiologies in turn correlates to disseminated TB score, and to risk of death, suggesting bacterial burden and MTBBSI are central to the pathophysiology of severe HIV-associated tuberculosis. An individual patient data meta-analysis, with 20 independent data sets comprising over 6000 patients, is used to establish the prevalence of TB blood culture positive disease amongst critically unwell HIV-infected inpatients. This shows that MTBBSI is more common than previous estimates suggest, is a strong independent association with mortality risk, and is also associated with specific increased risk of death if empirical treatment is delayed. The development of tools to identify and measure MTBBSI is described, including Xpert-ultra testing of blood, and the use of a novel dye, DMN-trehalose, to perform direct microscopy on patient blood samples. These techniques are used to provide the first description of the pharmacodynamics of MTBBSI, by serially quantifying blood bacilli load over the first 72-hours of standard TB therapy, in 28 patients with high predicted probability of bacteraemia. In this cohort, risk of mortality is related to several summary measures of MTBBSI dynamics in the first 72-hours of therapy, suggesting this approach can be used to define biomarkers of treatment response. In conclusion, MTBBSI is a highly-specific diagnosis responsible for substantial mortality in hospitalised people living with HIV. Interventions with strengthened bacteriocidal activity, focussed on reducing bacterial burden, are warranted for MTBBSI. Tools developed in this thesis, including potential pharmacodynamic biomarkers, should facilitate such trials.
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Mitchell, Joni. "Reinfection dynamics of mycobacterium tuberculosis." Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1474.
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Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2007Reinfection is an important mechanism leading to recurrent tuberculosis. Recently, molecular epidemiological studies have shown that in high incidence settings, recurrent tuberculosis may occur through reinfection. Animal model experiments have shown that a reinfecting mycobacterial strain is specifically targeted to existing granulomas and that these structures are more dynamic than was previously thought. In this study we hypothesised that primary infection with M. tuberculosis may reprogramme human macrophages thereby preventing or facilitating reinfection with a secondary mycobacterial strain. Two antibiotic-resistant M. tuberculosis H37Rv variants were generated by electrotransformation of marked plasmids, designated KanRand HygR . A THP1 human macrophage cell line was infected and reinfected with different combinations of these marked strains as well as a hypervirulent M. tuberculosis Beijing strain. Mycobacterial growth has been assessed by colony forming unit enumeration and confirmed with polymerase chain reaction (PCR) analysis. In vitro growth curves of wild-type and differentially marked M. tuberculosis H37Rv Kan Rand HygR strains were compared in the BACTECTM mycobacterial growth indicator tube (MGITTM) system in parallel with conventional liquid culturing. In vitro liquid culture growth curves of hypervirulent clinical Beijing strain isolates were also compared to M. tuberculosis H37Rv growth curves. Through this it was established that there was no fitness cost as result of plasmid integration and that these strains of varying virulence had similar growth curves. Competitive dynamics within THP1 human macrophage cells were then assessed and have shown that there were no significant differences in growth patterns between primary and secondary infecting strains during THP1 cell reinfection. The findings of this study answered fundamental questions regarding reinfection of mycobacterial strains. It was established here that human macrophages can indeed be reinfected with a second virulent mycobacterial strain.
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Alexi, Nancy. "Interactions of Mycobacterium tuberculosis strain H37Rv with murine peritoneal macrophages." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292725.
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Krüüner, Annika. "Drug-resistant Mycobacterium tuberculosis in Estonia /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-455-0/.
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Hamerman, Jessica Ann. "Macrophage activation during Mycobacterium bovis BCG infection /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8359.
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Millington, Kerry. "Functional antigen-specific T cell responses to Mycobacterium tuberculosis infection." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437349.
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Estorninho, Megan. "Studies on mycobacterium tuberculosis transcriptional regulators involved in intracellular infection." Thesis, University of Surrey, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511105.
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Redford, Paul Stuart. "Regulatory mechanisms inhibiting anti-mycobacterial immunity following Mycobacterium tuberculosis infection." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445023/.
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The work reported in this thesis addresses the regulatory factors that function to limit the initiation of protective immune responses following exposure to the bacterium Mycobacterium tuberculosis (MTb). Control and clearance of intracellular pathogens, such as MTb, is dependent on the cytokine Tumour Necrosis Factor (TNF) and induction of a T-helper 1 (Thl) response, which is characterised by production of IFN-gamma driven by interleukin (IL)-12. In other infection models the presence of the immunosuppressive cytokine IL-10 in the local milieu has been shown to down-regulate Thl responses thus limiting detrimental host induced immune-pathology. To determine a role for IL-10 following murine infection, we examined its function during acute and chronic infections with two strains of H37Rv obtained from either i) National Institute for Medical Research (NIMR) or ii) London School of Hygiene and Tropical Medicine (LSHTM). IL-10 receptor blockade during the chronic phase of MTb infection reduced bacterial burdens in mice infected with H37Rv NIMR, but not mice infected with H37Rv LSHTM. However, despite the lack of effect of IL-10 blockade on the bacterial load during chronic infection with H37Rv LSHTM, immune cells obtained from MTb infected mice produced elevated levels of IFN-gamma when stimulated in vitro in the presence of IL-10 blocking antibodies. In addition, neutralisation of IL-10 before and during acute MTb infection with H37Rv LSHTM resulted in a transient reduction in bacterial burdens and enhanced IFN-gamma production, suggesting that IL-10 plays a role in regulating the early immune response to MTb. Additional regulators that may function together with or in parallel to IL-10 to limit bacterial clearance such as regulatory T cells (Tregs) have been shown to be regulators of autoimmunity, atopy and infectious disease. Using flow cytometric analysis of the Treg specific transcription factor FoxP3, we observed an early increase in the number of lung Tregs following aerosol MTb infection of mice. However, when addressing the effect on bacterial clearance in the absence of Tregs by either i) antibody depletion or ii) adoptive transfer approaches into immuno-deficient mice, a suppressive role for Tregs on bacterial burdens could not be found. Finally this work evaluated the role of plasmacytoid precursor DC (pDC) during MTb infection, which is in contrast their normal function as mediators of the anti viral response. Upon in vitro exposure to viable MTb, plasmacytoid pDC could not be infected and did not produce pro-inflammatory cytokines. Using flow cytometry, we observed no increase in plasmacytoid pDC in either the lung or spleen during the early stages of aerosol or intravenous infection. In addition, antibody depletion of plasmacytoid pDC during the early stages of MTb infection did not affect bacterial load. In summary, the data suggests that plasmacytoid pDC play only a minor role during the early immune response to MTb.
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Yates, T. A. "Mycobacterium tuberculosis infection in Southern Africa : exploring patterns, locating transmission." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1532679/.
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Tuberculosis is a major cause of premature mortality. Communities in Southern Africa are disproportionately affected. A growing body of evidence suggests that recent transmission within households can explain only a limited proportion of tuberculosis disease. However, our understanding of where transmission between households occurs is limited. I undertook a systematic review and meta-analysis of molecular epidemiology studies that described rates of strain discordance in co-prevalent cases of tuberculosis resident in the same household. I also conducted a tuberculin school survey in 6-8 year old children in a rural community in Northern KwaZulu-Natal. These children were all registered in a household surveillance programme operated by the Africa Centre for Population Health. I found that, across a range of both high and low burden countries, co-prevalent cases of tuberculosis in the same household often have different strains of Mycobacterium tuberculosis. These molecular epidemiological data suggest, at least in some settings, that recent transmission within households may explain a modest proportion of tuberculosis disease. I estimated the annual risk of tuberculous infection to be approximately two percent in the community around the Africa Centre. I found weak evidence that exposure to HIV positive adults in the household was associated with Mycobacterium tuberculosis infection in children. I found no strong evidence associating use of specific indoor public spaces with Mycobacterium tuberculosis infection. Transmission between households is likely an important determinant of tuberculosis disease. Further research locating Mycobacterium tuberculosis transmission might enable TB control interventions to be better targeted.
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Moshi, Noell Dominika. "Characterization of CD8 T cell responses in Mycobacterium Tuberculosis infection." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11785.
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The aim of this project was to compare the breadth and magnitude of CFP10 and ESAT6-specific CD8 T cell responses in individuals with latent Mycobacterium tuberculosis (MTB) infection (LTBI) and active TB disease, and further define MTB-specific CD8 T cell phenotypes associated with latent infection and active disease. Ex vivo IFN? Elispots and proliferation assays were used to identify immunodominant ESAT6 and CFP10 15mer peptides targeted by CD8 T cells in LTBI and TB donors. A multiparameter flow cytometry panel was designed and optimized to assess turnover, susceptibility to apoptosis and terminal differentiation/senescence in CD8 T cells from TB and LTBI donors. Bcl-2, Ki67,CD95, CD57, CD127 and IFNγ were thus measured in each group.
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Booty, Matthew Gregory. "Regulation of Effector CD8+ T Cells During Mycobacterium Tuberculosis Infection." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17465317.
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Approximately one-third of the world’s population is currently infected with Mycobacterium tuberculosis (Mtb), the bacillus that causes tuberculosis. Globally, it is the second leading cause of death by a single infectious agent. An effective vaccine is needed to stop this ongoing pandemic, but efforts to design one are hampered by our limited understanding of host immunity to this pathogen.
CD8+ T cells are elicited during tuberculosis and are required for optimum host resistance. They produce cytokines such as IFN-γ and can directly lyse infected cells. During infection, the expansion and differentiation of effector CD8+ T cells is a dynamically regulated process that is influenced by the inflammatory milieu of the infected host. Currently, the signals governing CD8+ T cell responses during tuberculosis are not well characterized.
Utilizing a mouse model of disease, we address the effects of key cytokines on CD8+ T cells, beginning with IL-12, type 1 interferons (IFN), and IL-27. All three of these cytokines are produced by innate immune cells during tuberculosis and have profound effects on host resistance. IL-12 proves most essential for robust CD8+ T cell expansion and IFN-γ production and also drives the terminal differentiation of short-lived effector cells. However, IL-12 is not acting alone, and type 1 IFN and IL-27 each have non-redundant roles supporting expansion in infected lungs. Thus, CD8+ T cells reflect the inflammatory environment of the host, responding in different degrees to each cytokine present.
We next examine the role of IL-21, a cytokine produced by activated CD4+ T cells. In the absence of IL-21 signaling, CD8+ T cell expansion and effector functions are severely compromised. IL-21 is also essential to prevent CD8+ T cell exhaustion at later time points during disease. These observations are the first to describe an essential role for IL-21 in the host immune response to Mtb.
Together, these studies establish IL-12 and IL-21 as essential regulators of CD8+ T cells during tuberculosis, and indicate type 1 IFN and IL-27 support expansion in the lungs. We believe these observations have implications for future immunotherapies and rational vaccine design.Medical Sciences
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Ault, Russell. "Extremes in Timing of Mycobacterium tuberculosis Infection: Implications for Managing Human Susceptibility to Tuberculosis." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1584623051351308.
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Freches, Danielle. "Etude du rôle de l'Interleukine 17A dans la réponse immunitaire contre Mycobacterium tuberculosis dans le modèle murin et applications vaccinales." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209679.
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La tuberculose est une maladie contagieuse causée par une infection avec M. tuberculosis. Son incidence globale élevée, des traitements longs et coûteux, l’apparition de souches résistantes aux antibiotiques disponibles et la co-infection avec le VIH en font un problème de santé publique de premier plan. En effet, l’Organisation Mondiale de la Santé estime qu’un tiers de la population mondiale est infectée de façon latente par M. tuberculosis. La mise au point d’un vaccin efficace serait un des moyens de mieux contrôler cette maladie et pour cela une meilleure compréhension de la réponse immunitaire contre M. tuberculosis est indispensable. Il est cependant clair que la réponse Th1 et l’IFN-γ sont essentiels pour la protection contre M. tuberculosis. Cependant, beaucoup d’aspects de cette immunité restent encore indéterminés dont le rôle de la réponse IL-17A. Dans ce travail, nous avons analysé la susceptibilité de souris génétiquement déficientes pour la sous-unité A du récepteur de l’IL-17A à une infection par M. tuberculosis. Nous montrons que la signalisation induite par l’IL-17A est indispensable pour le contrôle à long terme de l’infection et ce malgré une augmentation de la réponse IFN-γ.Dans la deuxième partie du travail, nous avons analysé l’effet de la neutralisation de l’IL-12 sur la susceptibilité de souris préalablement vaccinées avec le Bacille de Calmette et Guérin (BCG) à une infection par M. tuberculosis. La neutralisation de l’IL-12 a été réalisée en utilisant un auto-vaccin anti-IL-12. Les résultats ont confirmé le rôle essentiel de l’IL-12 dans la protection contre une infection primaire avec M. tuberculosis ;ils ont cependant également permis de démontrer que la neutralisation de l’IL-12 n’exerce qu’un effet très modeste sur la protection conférée par le vaccin BCG. Ainsi, la diminution d’IFN-γ induite par la neutralisation de l’IL-12 semble être compensée par une augmentation de la production de TNF-α, d’IL-6 et plus particulièrement de l’IL-17A.
En conclusion, notre travail indique que la réponse IL-17A est importante pour la protection contre M. tuberculosis que ce soit lors d’une infection primaire ou en cas de réponse mémoire. De plus, nos observations renforcent l’idée de plus en plus communément admise que l’IFN-γ seul n’est pas suffisant pour protéger contre M. tuberculosis/Tuberculosis is a contagious disease caused by infection with M. tuberculosis. Due to its high global incidence, the length and cost of antibiotic treatments, the emergence of antibiotics resistant strains and co-infection with HIV, Tuberculosis remains a major health problem. In addition, World Health Organization estimates that one-third of the world population is latently infected with M. tuberculosis. The development of an efficient vaccine could lead to a better control of this disease, but for that purpose a better understanding of the protective immune response against M. tuberculosis is essential. It is clear that Th1 immunity and IFN-γ play an essential role in protection against M. tuberculosis. However, numerous aspects of this immune response are still poorly understood, such as the role of the IL-17A response.
In this work, we have analyzed the susceptibility to M. tuberculosis infection in mice genetically inactivated in the IL-17 receptor.A subunit. We have shown that IL-17A signalling is required for long-term control of M. tuberculosis infection, even if the IFN-γ response is increased.
In the second part of this work, we have analyzed the effect of IL-12 in resistance against M. tuberculosis infection and in the protection conferred by the BCG vaccine. For that purpose, IL-12 was neutralized using an anti-IL-12 auto-vaccine. Our results confirm the essential role of IL-12 in the protection against a primary M. tuberculosis infection. Nevertheless, these results also demonstrate that IL-12 neutralization only marginally affect the protection conferred by the BCG vaccine. Indeed, the decreased IFN-γ production induced by IL-12 neutralization in BCG-vaccinated mice seems compensated by increased TNF-α, IL-6 and more specifically IL-17A production.
In conclusion, our data indicate that the IL-17A response is important in protection against M. tuberculosis, both in primary infection or in the case of memory responses. Moreover, our results emphasize the emerging idea that a functional IFN-γ response alone is not sufficient to protect against M. tuberculosis.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Johnstone-Robertson, Simon Peter. "Calculating the risk of infection of mycobacterium tuberculosis in endemic settings." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20195.
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Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The annual risk of infection (ARI), a measure of recent transmission, has been described as the most important parameter in tuberculosis (TB) epidemics. Nevertheless, mounting evidence suggests all factors contributing to TB transmission are not yet completely understood. This research was performed to investigate the role various parameters, e.g. overcrowding, period of infectivity, ventilation, and infectivity of source cases, play in TB transmission. An established airborne transmission risk model, the Wells-Riley equation (WRE), was modified to account for scenarios where unknown numbers of infectious individuals may be present. Subsequently, the ARI for three indoor locations conducive to TB transmission were calculated. Two locations (households and minibus taxis) were identified in a social mixing survey conducted within a South African community where TB is endemic as a part of this research. The third location (prison) was identified in an earlier independent study in the same community. The impact various interventions could have in reducing the ARI associated with each location was explored. Poor ventilation, severe overcrowding, extended exposure periods, and high incidence rates contributed to high TB transmission risks in each location. The household-associated ARI was related to the number of resident adults. Current TB control programs will only reduce the ARI if household ventilation levels are improved simultaneously. Similar reductions in the ARI could be achieved by trebling current ventilation levels or by separating child and adult sleeping areas. Neighbouring households can also contribute substantially to the ARI. The minibus taxi-associated ARI for drivers and commuters was considerable but readily reduced by opening windows or keeping the fresh-air fan on. Reducing TB case prevalence through active or passive case-finding would reduce the ARI substantially. The prison-associated ARI was proportional to levels of overcrowding. No single intervention, such as improved ventilation, decreased lock-up time, or improved case-finding, would decrease the ARI substantially, but concurrent implementation of all of them to meet national or international standards would. This research shows TB is not only transmitted in epidemics by highly infectious TB cases, but that any TB case, no matter how infectious, has the potential to infect susceptible people under the right conditions.
AFRIKAANSE OPSOMMING:Die jaarlikse infeksierisiko (ARI) – maatstaf van onlangse siekteoordrag – word as die belangrikste parameter in tuberkulose- (TB-)epidemies bestempel. Nietemin dui toenemende bewyse daarop dat nie álle faktore wat tot TB-oordrag bydra, volledig verstaan word nie. Hierdie navorsing is onderneem om ondersoek in te stel na die rol van verskillende parameters – byvoorbeeld oorbevolking, tydperk van aansteeklikheid, ventilasie en die aansteeklikheid van brongevalle – in TB-verspreiding. Gevestigde model vir die raming van siekteverspreiding deur die lug, die Wells-Riley-vergelyking (WRE), is aangepas vir scenario’s waar onbekende aantal aansteeklike individue moontlik aanwesig is. Daarna is die ARI bereken vir drie ingeslote ruimtes wat TB-oordrag bevorder. Twee van die ruimtes (huishoudings en minibustaxi’s) is ten tyde van die navorsing uitgewys in sosialevermengingsopname in Suid-Afrikaanse gemeenskap waar TB endemies is. Die derde ruimte (gevangenisse) is uitgewys in vroeëre onafhanklike studie in dieselfde gemeenskap. Die navorser het gevolglik bepaal watter moontlike impak verskillende intervensies op die verlaging van die ARI in elke ruimte het. Swak ventilasie, ernstige oorbevolking, verlengde blootstellingstydperke en hoë voorkomsyfers het in elke ruimte tot hoë TB-oordragrisiko bygedra. Die huishoudingsverwante ARI het verband gehou met die aantal volwassenes wat in die huis woon. Huidige TB-beheerprogramme sal slegs die ARI kan verlaag indien huishoudelike ventilasievlakke terselfdertyd verbeter word. Drie keer beter ventilasievlakke of die skeiding van kinders en volwassenes se slaapareas kan soortgelyke verlagings in die ARI teweegbring. Buurhuishoudings kan ook aansienlik tot die ARI bydra. Die minibustaxi-verwante ARI vir bestuurders en pendelaars was beduidend, maar kan betreklik maklik verlaag word deur vensters oop te maak of die varslugwaaier aan te hou. Die vermindering van die voorkoms van TBgevalle deur aktiewe óf passiewe gevalle-opsporing kan die ARI ook beduidend verlaag. Die gevangenisverwante ARI het met vlakke van oorbevolking verband gehou. Geen enkele intervensie soos beter ventilasie, korter toesluittye of beter gevalle-opsporing sal die ARI aansienlik verlaag nie, maar die gelyktydige inwerkingstelling van ál hierdie intervensies in pas met nasionale of internasionale standaarde kan wél. Hierdie navorsing toon dat TB in epidemies nie net deur hoogs aansteeklike TB-gevalle oorgedra word nie, maar dat enige TB-geval, ongeag hoe aansteeklik, die siekte in die regte omstandighede na vatbare mense kan oordra.
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Bilton, Matthew. "Activation of MAIT cells, and their role in Mycobacterium tuberculosis infection." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:f6838397-c300-4d00-bac6-60914bc5a69c.
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Mucosal associated invariant T (MAIT) cells are a population of innate-like lymphocytes, with an emerging role in tuberculosis (TB). They are characterised by the expression of high levels of CD161 and IL-18Rα, possession of a Vα7.2+ T cell receptor (TCR), and restriction by the MHC class I-related protein (MR1). MAIT cells can be activated by MR1 presenting microbe-derived riboflavin metabolites; or, by the cytokines IL-12 and IL-18 in a TCR-independent fashion. How human MAIT cells integrate these signals for their activation in response to Mtb is unclear. Lymphatic TB (LNTB) is a common extra-pulmonary manifestation of TB; however, little is known about the status of MAIT cells in LNTB - or in other granulomatous diseases, such as sarcoidosis. In this study, an in vitro approach was used to probe MAIT cell activation by Mtb, and the roles of IL-12/-18, the TCR, cell-cell contact and the immunological synapse (IS). Following TCR ligation, TNFα expression was rapid and transient, and was enhanced following sustained IL-12/-18 exposure. IFNγ expression occurred following sustained exposure to ng/ml concentrations of IL-12/-18; however, alongside TCR stimulation, pg/ml concentrations were sufficient. Using an artificial bilayer system, CD161 was excluded from the central regions of the MAIT cell IS, whilst the distribution of IL-18Rα remained unaffected. In response to Mtb and BCG, MR1 was necessary for rapid activation and TNFα expression, IL-12/-18 were necessary for robust and sustained IFNy expression, whilst an anti-Mtb effect was indicated in an intracellular infection model. Assessment of patients with TB or sarcoid lymphadenopathy revealed a depletion of MAIT cells in the blood in sarcoidosis, but not LNTB. In both groups, MAIT cells could be detected within a proportion of sampled lymph nodes. Overall, these findings indicate the importance of inflammatory cytokine signals in the induction of high-intensity and sustained MAIT cell effector function, including in response to Mtb. The observation of a numerical deficiency of MAIT cells in sarcoidosis requires further investigation.
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Parihar, Suraj P. "A role of statins against listeria monocytogenes and Mycobacterium tuberculosis infection." Doctoral thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/14393.
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Cholesterol has been shown to play important role in the pathogenesis and persistence of intracellular pathogens. Here, we modulate host cholesterol biosynthesis pathway using pharmacological agent statins, which are reversible inhibitors of HMG†CoA reductase enzyme. The aim of the study was to investigate the role of statins in inducing host protective responses against intracellular pathogens. We report reduced growth of Listeria monocytogenes (LM) and Mycobacterium tuberculosis (Mtb) in murine macrophages. We show prominent immunomodulatory activity induced by statins, mainly increased phagosomal maturation and autophagy resulting in decreased bacterial growth in macrophages. Subsequently, statin†treated mice showed decrease in bacterial loads, accompanied by reduced histopathology in the acute phase of infection during listeriosis and tuberculosis. Furthermore, we found decreased growth of Mtb in peripheral blood mononuclear cells (PBMC) and monocyte†derived macrophages (MDM) isolated from patients with familial hypercholesterolemia (FH) on statin therapy when compared to healthy subjects. Together, our results show that statins induces protection against Mtb in murine macrophages, mice and human mononuclear cells and monocyte†derived macrophages.
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Carpenter, Stephen M. "Memory CD8+ T Cell Function during Mycobacterium Tuberculosis Infection: A Dissertation." eScholarship@UMMS, 2016. http://escholarship.umassmed.edu/gsbs_diss/860.
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T cell vaccines against Mycobacterium tuberculosis (Mtb) and other pathogens are based on the principle that memory T cells rapidly generate effector responses upon challenge, leading to pathogen clearance. Despite eliciting a robust memory CD8+ T cell response to the immunodominant Mtb antigen TB10.4 (EsxH), we find the increased frequency of TB10.4-specific CD8+ T cells conferred by vaccination to be short-lived after Mtb challenge. To compare memory and naïve CD8+ T cell function during their response to Mtb, we track their expansions using TB10.4-specific retrogenic CD8+ T cells. We find that the primary (naïve) response outnumbers the secondary (memory) response during Mtb challenge, an effect moderated by increased TCR affinity. To determine whether the expansion of polyclonal memory T cells is restrained following Mtb challenge, we used TCRb deep sequencing to track TB10.4-specific CD8+ T cells after vaccination and subsequent challenge in intact mice. Successful memory T cells, defined by their clonal expansion after Mtb challenge, express similar CDR3b sequences suggesting TCR selection by antigen. Thus, both TCR-dependent and independent factors affect the fitness of memory CD8+ responses. The impaired expansion of the majority of memory T cell clonotypes may explain why some TB vaccines have not provided better protection.
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Lundwall-Roos, Theresa Anne. "An investigation into the role of collectins in tuberculosis infection." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50269.
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Thesis (MSc)--Stellenbosch University, 2005.ENGLISH ABSTRACT: Please see fulltext for abstract.
AFRIKAANSE OPSOMMING: Tuberkulose (TB) affekteer die hele wêreld, maar dit is veral in ontwikkelende lande 'n groot probleem. In Suid-Afrika, soos in baie ander lande, veroorsaak die immuun-paraliserende uitwerking van HIV -koïnfeksie dat die TB-epidemie voortwoeker. Daar is bewyse dat genetiese faktore in die gasheer die uitkoms van die siekte bepaal, aangesien slegs 10% van die individue wat deur Mycobacterium tuberculosis (M tuberculosis) geïnfekteer word, uiteindelik die aktiewe siekte ontwikkel. Die aangebore immuunsisteem is die liggaam se eerste verdedigingslinie, waarna die verworwe immuunreaksie geïnisieer word. Die bakterium se lotgevalle word moontlik bepaal in hierdie vroeë stadium pas nadat dit ingeasem is. Die kollektien-molekule is veral in die long 'n belangrike deel van die aangebore immuunrespons en sluit die mannose-bindende lektien en die surfaktantproteïene A (SP-A) en D (SP-D) in. Dit is al aangetoon dat hierdie drie kollektien-molekule in die gasheer 'n rol speel in die verdediging teen M tuberculosis. In hierdie ondersoek is veral klem gelê op die surfaktantproteïene, wat voorkom asof dit belangrike en kenmerkende rolle speel in die reaksie teen die ingeasemde bakterieë. SP-A versterk die aanhegting van M tuberculosis aan die alveolêre makrofage en verhoog fagositose, terwyl SP-D die bakterieë agglutineer en so verhoed dat dit deur die makrofage gefagositeer word. Gekontroleerde assosiasiestudies in pasiënte is gedoen deur polimorfismes in hierdie gene, wat geassosieer is met TB in ander bevolkings as ons eie, te bestudeer. 'n Polimorfisme in die amino-terminaal area van die SP-D-geen is positief geassosieer met vatbaarheid vir TB. 'n Familie-gebaseerde studie is ook gedoen om die resultate van die gekontroleerde assosiasiestudie te repliseer. Verskillende resultate is verkry en word moontlik bepaal deur die familiestruktuur wat gebruik is. Die aantal families wat bestudeer is, was relatief min en daarom kan daar nie afgelei word dat die assosiasie wat voorheen waargeneem is vals is nie. 'n Groter studie sal gedoen moet word. Die impak van hierdie polimorfisme is verder ondersoek om te bepaal of dit die totale struktuur van die proteïen beïnvloed. Die effekte van hierdie polimorfisme op die konsentrasie van SP-D in die serum van aktiewe TB-pasiënte is ondersoek en vergelyk met die van kontroles. Ons kon nie vasstel watter rol, indien enige, die polimorfisme in die totale struktuur van die SP-D-molekule speel nie, maar ons het bewys dat die serumkonsentrasie van SP-D beduidend verhoog was in aktiewe TB-pasiënte in vergelyking met kontroles (p < 0.0001). Verder het ons ook gedemonstreer dat die konsentrasie van SP-D beduidend verhoog was in die IT-genotipe van die aktiewe TB pasiënte vergeleke met die kontroles (p < 0.0001). Die IT-genotipe is al voorheen positief geassosieer met vatbaarheid vir TB (T. Roos, ongepubliseerde inligting). Verskeie alleliese variante is geïdentifiseer in die SP-A-gene (SP-A1 en SP-A2) wat saam die volle funksionele SP-A-proteïen vorm. Polimorfismes wat onlangs in die kollageen-agtige area van SP-A 1 en SP-A2 gevind is (Madan et al., 2002) en een nuwe polimorfisme wat in hierdie studie geïdentifiseer is, is ondersoek in 'n Suid-Afrikaanse bevolking. Ons het beduidende positiewe assosiasie tussen 'n polimorfisme in die kollageen-agtige area van die SP-A2 geen en vatbaarheid vir TB (p = 0.007) aangetoon. Ons bevindinge bewys die belangrikheid van die bestudering van mensgenetika, wat die immuunkompetensie rig, om vatbaarheid vir infektiewe siektes te verstaan.
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Restis, Eva Marie. "Development of Drug Loaded Nanoparticles for Treatment of Mycobacterium avium Infection." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/52565.
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Currently, about one third of the world's population is latently infected with Mycobacterium tuberculosis and about 4 million people die from the disease annually worldwide. Although treatment with antimicrobials can be curative, many people fail to complete the prescribed therapeutic regimen which can increase the risk of disease re-emergence, spread of infection to others and development of drug resistance. An improved approach is urgently needed for patient compliance. Development of safe and effective colloidal drug delivery systems may reduce the amount and frequency of antimicrobial therapy needed. The major goal of this research effort is to explore the safety and efficacy of antimicrobial loaded nanoparticles against M. avium. Various in vitro efficacy studies were done with a) amikacin-loaded nanoparticles, b) clarithromycin-loaded nanoparticles, and c) with aerogel nanoparticles loaded with rifampicin, clarithromycin and ethambutol. Clarithromycin (CLA) and amikacin (AMK) loaded nanoparticles showed a significant reduction in viable M. avium compared to free antibiotics and untreated controls. Cytotoxicity assays revealed that all types of drug-laden nanoparticles were non-toxic to J774A.1 mouse macrophage cells at therapeutic doses. In vivo efficacy studies showed that only amikacin-loaded polymeric
nanoparticles improved clearance compared to free amikacin in M. avium infected BALB/c mice. In general, none of the nanoparticle formulations elicited any significant microscopic lesions in the organs of infected mice at tested doses. Each nanoparticle formulation was analyzed physicochemically for size, zeta potential, amount of drug load, minimum inhibitory concentration (MIC) and stability. Both the AMK and CLA polymeric nanoparticles were below 200 nm in size and had a slightly negative overall surface charge, aerogel nanoparticles were somewhat larger in size. The amount of drug load varied between all three nanoparticles and is largely dependent on the chemical structure and interactions between the nanoparticle and drug. The AMK and CLA nanoparticles were relatively stable under varying environmental conditions and time points and had MIC ranges equivalent to the respective free drugs.Ph. D.
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LOPES, Lilian Kelly de Oliveira. "INFECÇÃO PELO Mycobacterium tuberculosis ENTRE OS PROFISSIONAIS DA EQUIPE DE ENFERMAGEM, EM UM HOSPITAL DE DOENÇAS INFECCIOSAS, GOIÂNIA - GO." Universidade Federal de Goiás, 2006. http://repositorio.bc.ufg.br/tede/handle/tde/742.
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Previous issue date: 2006-02-23According to the World Health Organization (WHO), an hundred million of individuals are infected by M. tuberculosis, annually. Health care workers play an important role to control of tuberculosis, but they are also at high risk for this infection. Then, the objectives of the present study were to evaluate the prevalence of M tuberculosis infection in nursing professionals from the Tropical Diseases Hospital in Goiânia City, State of Goiás, to analyze the factors associated to tuberculin skin test (TST) positivity and to determine the TB infection incidence density in susceptible professionals Initially, the prevalence and factors associated to TST were investigated in 128 eligible individuals. Further, susceptible professionals (n=32) were followed up during three years (2001-2004) to detect TST conversion. Of the total individuals investigated, 69.5% (IC 95%: 60.7-77.2) were positive to TST. Two occupational factors were independently associated to skin test positivity: duration of profissional activity longer than 5 years (Adjustd OR = 6.3; 95% CI: 1.5-26.2) and occupational contact with a person with pulmonary TB ≤ 2 years (Adjusted OR = 12.2; 95% CI: 1.2-106.3). Seven profissionals showed tuberculinic conversion during the three years of follow up, and an incidence density of 11.5 new conversions to 100 persons-year was detected. All of them had taken care of patients during the period of the study. Two individuals developed tuberculosis disease. The data of this study ratify the high risk of tuberculosis in nursing team, and highlight the importance of this infection as an occupational disease to nursing professionals of our region.
De acordo com a Organização Mundial de Saúde (OMS), cem milhões de pessoas são infectadas pelo M. tuberculosis, a cada ano. Os profissionais de saúde são importantes para o controle da tuberculose, mas também um grupo de risco elevado para esta infecção. Assim, o presente estudo teve como objetivos avaliar a prevalência da infecção causada pelo M. tuberculosis em profissionais de enfermagem de uma instituição especializada em doenças infecciosas, em Goiânia Go, analisar os fatores associados à positividade à prova tuberculínica nesta população e determinar a densidade de incidência da infecção pelo M. tuberculosis, nos profissionais susceptíveis. Inicialmente, verificou-se a prevalência e os fatores associados à positividade à PT. A seguir, os profissionais suscetíveis à infecção (n=32) foram acompanhados, por três anos (2001-2004), para detecção de conversão tuberculínica. Do total de profissionais investigados, 69,5% (IC 95%: 60,7- 77,2) foram positivos à PT. Dois fatores ocupacionais foram independentemente associados à positividade à PT: tempo de atividade profissional > 5 anos (OR ajustado = 6,3; IC 95%: 1,5-26,2) e último contato laboral com alguém com TB ≤ 2 anos (OR ajustado = 12,2; IC95%: 1,2-106,3). Sete profissionais apresentaram viragem tuberculínica, resultando em uma densidade de incidência de 11,5 novas conversões por 100 pessoas/ano. Todos desenvolviam atividades assistenciais, durante o período do estudo. Duas profissionais desenvolveram tuberculose doença. Os resultados, deste estudo, ratificam o elevado risco de tuberculose nos profissionais de enfermagem, e evidenciam a importância desta infecção como doença ocupacional para equipe de enfermagem de nossa região.
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Augenstreich, Jacques. "Rôle et mécanismes moléculaires d'action des lipides de l'enveloppe de Mycobacterium tuberculosis dans la virulence." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30111/document.
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Mycobacterium tuberculosis est la bactérie responsable de la tuberculose (TB), une infection pulmonaire grave. La TB est un problème majeur de santé publique mondial ; un tiers de la population mondiale est porteur de M. tuberculosis et l'émergence de formes de TB résistantes aux antibiotiques confirme la nécessité de développer de nouvelles approches thérapeutiques. Pour atteindre cet objectif, il est crucial de mieux comprendre les mécanismes infectieux de M. tuberculosis. L'équipe de C. Guilhot s'intéresse aux lipides de l'enveloppe bactérienne impliqués dans la virulence de M. tuberculosis, en particulier lors de l'interaction du bacille avec les macrophages de l'hôte. Un type de lipide en particulier s'est démarqué pour son rôle crucial dans cette interaction : les Dimycocérosates de Phthiocérol (DIM). Malgré leur importance, le mécanisme d'action moléculaire des DIM n'est toujours pas connu. Les objectifs de ma thèse ont été 1) d'étudier le rôle des DIM dans le trafic intracellulaire de M. tuberculosis au sein du macrophage, et 2) de comprendre les mécanismes d'action des DIM dans la virulence. Par une combinaison de méthodes biologiques et biophysiques, nous avons montré que les DIM contribuent à l'induction de la rupture du phagosome et de l'apoptose du macrophage infecté par M. tuberculosis, en collaboration avec un autre facteur majeur de virulence bactérien, ESAT-6. Au niveau moléculaire, nous avons confirmé que les DIM sont transférés dans la membrane du macrophage au contact avec la bactérie, et y induisent une rigidification membranaire locale. Nous avons aussi montré que les DIM dans une membrane sont capables de potentialiser l'activité membranolytique d'ESAT-6 et d'autre(s) facteur(s) encore non identifiés. Les DIM ont un rôle pléiotropique dans l'interaction de M. tuberculosis avec le macrophage. Leur mécanisme d'action impliquerait des modifications des propriétés biophysiques membranaires, modifiant l'activité des effecteurs membranaires bactériens et potentiellement de l'hôte. Ces travaux ouvrent la voie à l'étude du mécanisme d'action d'autres lipides de virulence dont certains pourraient également s'insérer dans la membrane du macrophageMycobacterium tuberculosis is the bacterium responsible for tuberculosis (TB), a severe respiratory disease. TB is a major public health threat; one third of the world's population is latently infected by M. tuberculosis, and the emergence of antibiotic-resistant forms of TB confirms that there is a need to develop new therapeutic approaches to control the spread of TB. However, in order to attain that goal, it is crucial to decipher the infectious mechanisms of M. tuberculosis. Research in the team of C. Guilhot focuses on lipids from the envelope of M. tuberculosis which are involved in virulence, in particular those implicated in the interaction of the bacteria with host macrophages. One of these lipids stands out for its crucial role in this interaction: Phthiocerol Dimycocerosate (DIM). Despite its importance, the molecular mechanism of action of DIM is still unknown. The objectives of my PhD were 1) to study the role of DIM in the intracellular trafficking of M. tuberculosis in macrophages, and 2) to decipher the molecular mechanism of action of DIM. By a combination of biological and biophysical techniques, we showed that DIM contributes to phagosomal rupture and induction of apoptosis in macrophages infected with M. tuberculosis, in collaboration with another major virulence factor: ESAT-6. At the molecular level, we confirmed that DIM is transferred to the membrane of the macrophage on contact with M. tuberculosis and induces a local membrane rigidification around the point of contact with the bacterium. We observed that DIM incorporated in membranes is able to promote the membranolytic activity of ESAT-6, and other yet unidentified bacterial factor(s). DIM has a pleiotropic role in the interaction between M. tuberculosis and macrophages, presumably through alterations of the membrane's biophysical properties that influence the activity of membrane effectors from both the bacteria and the host. Thus, this work paves the way for the study of the mechanisms of action of other virulence lipids, some of which could also be inserted in the macrophage membrane
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Yang, Jason D. "Antigen Specific CD4+ and CD8+ T Cell Recognition During Mycobacterium Tuberculosis Infection." eScholarship@UMMS, 2018. https://escholarship.umassmed.edu/gsbs_diss/968.
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Mycobacterium tuberculosis (Mtb) causes human tuberculosis, and more people die of it than of any other pathogen in the world. Immunodominant antigens elicit the large majority of T cells during an infection, making them logical vaccine candidates. Yet, it is still unknown whether these immunodominant antigen-specific T cells recognize Mtb-infected cells. Two immunodominant antigens, TB10.4 and Ag85b, have been incorporated into vaccine strategies. Surprisingly, mice vaccinated with TB10.4 generate TB10.4-specific memory CD8+ T cells but do not lead to additional protection compared to unvaccinated mice during TB. Ag85b-specific CD4+ T cells are also generated during vaccination, but the literature on whether these cells recognize Mtb-infected cells is also inconsistent.
We demonstrate that TB10.4-specific CD8+ T cells do not recognize Mtb-infected cells. However, under the same conditions, Ag85b-specific CD4+ T cells recognize Mtb-infected macrophages and inhibit bacterial growth. In contrast, polyclonal CD4+ and CD8+ T cells from the lungs of infected mice can specifically recognize Mtb-infected macrophages, suggesting macrophages present antigens other than the immunodominant TB10.4. The antigen location may also be critical for presentation to CD8+ T cells, and live Mtb may inhibit antigen presentation of TB10.4. Finally, we propose that TB10.4 is a decoy antigen as it elicits a robust CD8+ T cell response that poorly recognizes Mtb-infected macrophages, allowing Mtb to evade host immunity.
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Makatsa, Mohau Steven. "Characterization of Mycobacterium tuberculosis-specific Th22 cells in HIV-TB co-infection." Doctoral thesis, Faculty of Health Sciences, 2020. http://hdl.handle.net/11427/32398.
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Tuberculosis (TB) remains the infectious disease causing the greatest global mortality, with an estimated 10 million incident cases of TB and 1.45 million deaths in 2018. Although there is a cure for TB, the success of the treatment is hampered by multidrug resistant TB and HIV infection. There is an urgent need for an effective TB vaccine to prevent ongoing transmission. The development of a new and efficacious TB vaccine will likely be dependent on our understanding of protective immunity to TB. Although it is well established that Th1 cells are crucial in the response against Mycobacterium tuberculosis (Mtb), Th1 cytokines may not be sufficient to control Mtb infection. A major focus of this thesis is the contribution of an understudied Th subset in Mtb immunity, namely Th22 cells, producing the cytokine IL-22. IL-22 functions to preserve mucosal barriers and induce antimicrobial peptides, contributing to protective immunity to a range of extracellular and intracellular bacteria. A recent study in IL-22-deficient mice described a protective role for IL-22 during the development of TB. In humans, soluble IL-22 has been detected at sites of extra-pulmonary tuberculosis (TB), and a polymorphism in the IL-22 promoter has been linked to TB susceptibility. However, much remains to be understood about Th22 cells and their role in protective immunity to Mtb. In this study, we investigated the contribution of Th22 cells to TB immune responses by providing a detailed characterisation of Mycobacterium tuberculosis-specific Th22 cells in latent TB infection (LTBI), TB disease and HIV co-infection, using flow cytometric techniques. In Chapter 2, we optimised detection of IL-22 and determined the factors that contribute to Mtb-specific IL-22 production by CD4+ T cells, as well as characterising some aspects of Th22 cell biology. In Chapter 3, we examined the impact of TB disease and HIV infection on Th22 cells, compared to Th1 and Th17 cells. Finally, in Chapter 4, we explored Mtb-specific cytokine production by CD8+ T cells and CD4+ T cells following Mtb peptide stimulation, and the effect of TB disease and HIV infection. We detected significant IL-22 production from CD4+ T cells in healthy individuals following whole blood stimulation with Mtb whole cell lysate (MtbL). However, IL-22 responses were poorly detectable when peripheral blood mononuclear cells (PBMC) were stimulated with MtbL. Therefore, we sought to investigate conditions that influence IL-22 detection in whole blood and PBMC, and characterise Th22 cells further. We found that PBMC are able to produce IL-22 in response to Mtb but appear to lack the physiological environment for optimal induction of IL-22. We also discovered that TCR blocking inhibited Mtb-specific IL-22 production, suggesting that responses are stimulated through recognition of Mtb antigen by the TCR, rather than through bystander activation. IL-22 is produced by CD4+ T cells that appear to be conventional, rather than MAIT, γδ or iNKT cells. Indeed, analysis of the TCR clonality using vβ repertoire typing revealed similar repertoire usage between IL-22, IFN-γ-producing CD4+ T cells, and total CD4+ T cells. Overall, these data shed more light on the biology of IL-22-producing CD4+ T cells. Next, we examined the effects of HIV infection and TB disease on the magnitude, memory profile and activation phenotype of Mtb-specific Th22 cells, compared them to Th1 and Th17 cells. Blood samples were collected from 72 individuals classified into four groups based on their HIV-1 and TB status, namely HIV-/LTBI, HIV+/LTBI HIV-/active TB and HIV+/active TB. Blood was stimulated with MtbL and analysed for cytokine production using multiparameter flow cytometry. We observed similar frequencies of IL-22 to IFN-γ-producing CD4+ T cells in LTBI. Mtb-specific Th22 cells were reduced to a greater extent than Th1 cells by a combination of HIV infection and TB disease. Th22 cells demonstrated differences in their memory and activation phenotype compared to Th1 and Th17 cells. In the context of active TB, Th1 cells were characterised by a high expression of the activation marker HLA-DR. In contrast, Th22 cells did not demonstrate activation using this marker during TB disease. Similarly, Th1 cells were more differentiated in TB disease irrespective of HIV status, while there was no difference in the memory phenotype of Th22 cells during different disease states. Finally, we characterised Mtb peptide-specific CD4+ and CD8+ T cell responses in LTBI, active TB and HIV infection. CD4+ T cells did not produce detectable IL-22 when blood was stimulated with Mtb peptides, and there was also no IL-22 response from CD8+ T cells. Th1 cytokines IFN-γ and TNF-α were detectable from CD4+ and CD8+ T cells in response to Mtb peptides. Consistent with previous studies, there was a higher proportion of individuals with detectable CD8+ responses during active TB and HIV co-infection compared to HIV-infected LTBI individuals, but no difference is the magnitude of response was observed. Interestingly, HIV infection and TB disease induced similar levels of activation in Mtb-specific CD8+ compared to CD4+ T cells. Moreover, active TB and HIV co-infection impaired memory differentiation of Mtb-specific CD8+ T cells towards a less differentiated profile, compared to LTBI. These results confirm that both CD4+ and CD8+ T cells contribute to TB immune responses. In summary, we confirm that Th22 cells constitutes a substantially portion of CD4+ T cell response to Mtb . IL-22 appears to be produced by conventional CD4+ T cells but may require specific antigen presentation requirements to optimally induce its production. Interestingly, HIV infection during TB disease led to a near absence of Th22 cells in blood. Our results warrant further study of the role of Th22 cells in TB immunity, which may lead to insights that could assist the development of an effective vaccine against TB.
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Kim, Jiae. "Effects of Surfactant Proteins A and D on Infection with Mycobacterium Tuberculosis." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428580276.
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Jones, Shelby-Sara Ann. "The role of Lymphoblastic leukemia 1 (Lyl1) in Mycobacterium tuberculosis (Mtb) infection." Doctoral thesis, Faculty of Health Sciences, 2021. http://hdl.handle.net/11427/33727.
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Lymphoblastic leukemia 1 (Lyl1) is a well-studied transcription factor known to exhibit oncogenic potential during various forms of leukemia. Since its discovery in 1989, many reports have been published describing its relationship with cancer as well as demonstrating its function during hematopoiesis. Lyl1 has been shown to serve a significant role during thymopoiesis by contributing to T-cell development. However, it has been recently reported that irrespective of its significance during T-cell development, mature comparable single positive T-cells are observed in mouse models. The use of murine models has been crucial in identifying potential targets for host-directed therapies (HDT) which has been shown to provide great potential in treating tuberculosis (TB). It is evident that Mycobacterium tuberculosis (Mtb), the causative agent for TB, is capable of developing resistance to various treatments that target the bacterium itself. Therefore, by designing therapies that directly target host factors could assist in circumventing Mtb resistance. By analyzing Mtb-infected bone marrow-derived macrophages (BMDM) that have been subjected to genome-wide transcriptional deep sequencing of total RNA using a single molecule sequencer in conjunction with the cap analysis gene expression (CAGE) technique, various differentially expressed genes were identified, including the oncogenic transcription factor, Lyl1. With the use of murine models, we investigated whether Lyl1 is important for various immunological responses at steady state, the regulation of Lyl1 in response to various immune stimulants including LPS and whether this transcription factor is relevant in bacterial infections including Listeria monocytogenes (Lm) and Mtb. The data in this thesis demonstrate comparable immunological responses, including cellular recruitment by means of flow cytometry and cytokine responses by means of ELISA, between naïve littermate control and Lyl1-deficient mice. Further evaluation of Lyl1 regulation revealed the influence of MAPk and NFκB signaling on Lyl1 expression upon LPS stimulation by significantly downregulating this transcription factor in immune stimulated macrophages. A role for Lyl1 during bacterial infections was observed in Lm-infected mice whereby Lyl1-/- mice succumbed earlier to listeriosis compared to the littermate controls. We further established a functional role for this transcription factor during Mtb infection in vitro and in vivo. The early surrender of Lyl1-deficient mice to Mtb HN878 infection, accompanied by increased bacterial burden during chronic Mtb infection, demonstrated enhanced susceptibility in the absence of Lyl1. We show that Lyl1-deficient host susceptibility is a consequence of enhanced inflammatory responses and increased bacterial growth. This is demonstrated by increased neutrophilic inflammation, pro-inflammatory cytokine and chemokine secretion along with a reduction in anti-inflammatory cytokine release during chronic Mtb infection. Here, we demonstrate the first non-leukemia role for Lyl1 by suggesting a role and requirement for this transcription factor during bacterial infections. Given the significant role during Mtb infection, our studies suggest the use of Lyl1 associated pathways as a potential HDT target for TB.
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Rothchild, Alissa Chen. "Antimicrobial Roles for iNKT Cells and GM-CSF in Mycobacterium Tuberculosis Infection." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11371.
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Despite effective antibiotics, Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, still infects nearly one-third of the world's population. While key immune factors including CD4+ T cells and IFNg production have been identified, there are still many antimicrobial mechanisms yet to be explored. Here we characterized the role of invariant natural killer T (iNKT) cells and GM-CSF during Mtb infection.
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Schuck, Sebastian D. "Mycobacterium tuberculosis-specific T-cell responses in latent infection and active disease." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/15916.
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Adaptive Immunantworten gegen Mycobacterium tuberculosis (M. tuberculosis) sind von entscheidender Bedeutung für die effektive Eindämmung des Erregers sowie den Schutz vor einer erneuten, sekundären Tuberkulose (TB). Obwohl Schlüsselfaktoren wie die Th1 Zytokine IFN-gamma und TNF-alpha bekannt sind, blieben Bemühungen zur Identifizierung eindeutiger immunologischer Parameter, welche ausschlaggebend für den Krankheitsverlauf sind, bislang erfolglos. Ein besseres Verständnis der zugrunde liegenden Immunprozesse sowie die Identifikation projektiver Biomarker für TB sind zentrale Ziele dieser Arbeit. Zur Bearbeitung dieser Fragestellungen wurden adaptive Immunantworten gegen M. tuberculosis in gesunden Probanden mit LTBI und Patienten mit aktiver TB analysiert. Hierfür wurde die Erkennung unterschiedlicher Proteine des Erregers durch die Messung IFN-gamma exprimierender CD4+ CD45RO+ Gedächtnis T Zellen untersucht. Eine Besonderheit war die Einbeziehung sogenannter Latenz-assoziierter Proteine, welche in Zusammenhang mit Dormanz und Reaktivierung des Bakteriums stehen. 7 Tage in vitro Inkubation in Verbindung mit einer zweimaligen Restimulation belegten eine spezifische Erkennung durch CD4+ CD45RO+ T Zellen für die Mehrheit der getesteten Proteine bei Spendern mit LTBI. Der darauf folgende Vergleich zwischen Patienten mit aktiver TB und Personen mit LTBI zeigte signifikant höhere T Zell Antworten für 7 der 35 M. tuberculosis Proteine während LTBI. Bemerkenswerterweise konnten spezifische T Zellen für eines der Protein, nämlich Rv3407, ausschließlich während LTBI gemessen werden und nicht bei Patienten mit aktiver TB. Diskriminanz Analysen zeigten, dass eine Unterscheidung zwischen LTBI und TB Patienten basierend auf T Zell Antwort gegen ausgewählte Latenz-assoziierte Antigene mit einer Genauigkeit von 82% möglich ist. Erneut erwies sich Rv3407 als der mit Abstand bedeutendste Faktor innerhalb der ausgewählten M. tuberculosis Proteine.Adaptive immune responses to Mycobacterium tuberculosis (M. tuberculosis) are crucial for an efficient containment of the pathogen and protection against secondary tuberculosis (TB). Although key mediators like the Th1 cytokines IFN-gamma and TNF-alpha released by M. tuberculosis-specific T cells are known, the immunological correlates determining the outcome of infection remain elusive. A better understanding of the underlying immune processes and the identification of protective biomarkers for TB are central aims of this thesis. To address these topics adaptive immune responses to M. tuberculosis were analyzed in healthy LTBI and patients with active pulmonary TB. The recognition of M. tuberculosis derived antigens was studied by measuring the expression of IFN-gamma in CD4+ CD45RO+ memory T cells. A special hallmark was the inclusion of latency proteins associated with dormancy, reactivation and resuscitation of the pathogen. Seven days in vitro incubation of PBMC and two rounds of restimulation followed by FACS analysis revealed T cell mediated recognition of the majority of tested latency-associated proteins in donors with LTBI. Comparison between active TB and LTBI documented significantly higher T-cell responses against 7 of 35 tested M. tuberculosis latency-associated antigens in LTBI. Notably, T cells specific for one M. tuberculosis antigen, namely Rv3407, were exclusively detected in the subgroup of LTBI. Discrimination analysis revealed that the T-cell response against selected antigens with our novel assay is capable of distinguishing TB patients and LTBI with 82% accuracy using cross-validation. Again Rv3407 was by far the most influential component present in this cluster. Peptide pool stimulation in a similar fashion identified single distinct candidate epitopes within Rv3407 in four LTBI.
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Veenstra, Hannelore F. U. "The investigation of peripheral blood cellular immune responses during infection with Mycobacterium Tuberculosis." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019.1/1180.
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Begg, Douglas, and n/a. "Immune profiles in sheep following experimental infection with Mycobacterium paratuberculosis." University of Otago. Department of Microbiology & Immunology, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070427.142318.
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Johne�s disease in ruminants is caused by the pathogenic bacterium Mycobacterium avium subspecies paratuberculosis. An experimental infection model in sheep was developed as a prelude to the testing of new vaccines and the development of improved diagnostic assays for Johne�s disease. The final challenge model developed used four doses of 10⁹ viable organisms given at two to three day intervals. Gross and microscopic lesions were found in a high proportion of sheep (80%) at ten months post challenge. There was considerable variation in immune responses from animals challenged with different strains of M. paratuberculosis. Sheep challenged with a low passage laboratory culture of strain (W) M. paratuberculosis, produced strong lymphocyte transformation responses and Interferon gamma (IFN-γ) production at two months post challenge. Subsequent necropsy and culture from intestinal tissues showed only a low level of infection (25%). In comparison a primary tissue isolate of M. paratuberculosis (JD3) resulted in higher (60-90%) infection rates in orally challenged animals. The immune profile from these animals showed very little reactivity for the first three months post challenge, after which IFN-γ production could be detected. Antibody production and lymphocyte transformation response could not be measured until at least seven months post challenge. Sheep challenged with the primary tissue isolate instilled directly into the tonsil resulted in equivalent levels of Johne�s disease to those obtained with oral challenge. However, intratonsillar challenge resulted in higher levels of immune reactivity than oral challenge.
The proprietary Johne�s vaccines; NeoparsecTM and GudairTM and an Aqueous vaccine were tested in sheep. The immunological reactions of the sheep to these vaccines showed some variations between the two separate studies, with the NeoparasecTM and GudairTM vaccines evoking high levels of CMI and humoral reactivity within two months of vaccination. Detailed immunological examination of gut associated lymphoid tissues were carried out on subgroups of animals that were either vaccinated or non-vaccinated and went on to develop disease or were immune to experimental challenge. The results showed that the diseased animals examined had multibacillary lesions and strong CMI and humoral responses. There were decreased proportions of CD4⁺, CD8⁺ and CD25⁺ T cells in peripheral blood and gut associated lymphatics of diseased animals compared with the immune or unchallenged subgroups. Profiles from the immune subgroups showed a stronger lymphocyte transformation response than case matched diseased animals. Tissues from immune animals showed increased proportions of B cells above those seen in diseased or unchallenged animals. This study has resulted in the development of a robust experimental sheep model in which Johne�s disease occurs in a high proportion of challenged animals. Critical time points for the establishment of infection or disease have been determined. It can be used in the future to evaluate protective efficacy of vaccines or to critically chart immunological profiles that are associated with infection, disease or protective immunity. Considerable research is needed to develop improved diagnostic tests to identify patterns of immunity during the early stages of infection or while the animal has subclinical disease.
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Hill, Philip Campbell. "Evaluation of a T-cell assay for mycobacterium tuberculosis infection in the Gambia." Thesis, University of Auckland, 2005. http://hdl.handle.net/2292/5539.
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New generation T cell assays offer hope in the diagnosis of Mycobacterium tuberculosis infection and disease. We assessed the ELISPOT assay using cross-sectional and longitudinal studies and a natural gradient of M. tuberculosis exposure by sleeping proximity to a tuberculosis (TB) case in The Gambia. Two antigens, ESAT-6 and CFP-10 (EC), were compared to purified protein derivative (PPD) by ELISPOT and to the PPD skin test in 735 TB contacts. All three tests responded to the exposure gradient, the PPD skin test most dramatically. Inter-test comparison showed that the EC ELISPOT provided improved specificity in the diagnosis of M. tuberculosis infection, but at the cost of some sensitivity. Increasing discordance, particularly between PPD ELISPOT and PPD skin test results, down the exposure gradient to 105 community controls was identified. In 693 children, the EC ELISPOT was slightly less sensitive than the PPD skin test in the diagnosis of M. tuberculosis infection from recent exposure; neither test was confounded by prior BCG vaccination, even in the very young. A fusion protein of EC compared favourably with their respective peptides by ELISPOT assay in 488 TB contacts, a combined test result offered improved sensitivity. Quantitative ELISPOT and PPD-skin test responses were assessed in 1052 TB case contacts, according to an ELISPOT response to EC. Only the ELISPOT count was sensitive to the exposure gradient (p=0.009), revealing a positive dose-response relationship. In the longitudinal assessment, both ELISPOT and PPD skin test conversion occurred over time. PPD skin test reversion occurred in 10% of individuals after 18 months, ELISPOT reversion occurred in 39% at 3 months. In conclusion: the EC ELISPOT offers increased specificity in the diagnosis of M. tuberculosis infection in The Gambia, at the cost of some sensitivity; the PPD skin test appears to be down-regulated in the community; neither test is confounded by prior BCG vaccination; a fusion protein in combination with EC peptides offers optimal ELISPOT sensitivity; the quantitative ELISPOT response in specific-antigen-positive TB case contacts reflects the infectious load of M. tuberculosis; and significant early reversion of the ELISPOT test suggests it is unreliable in M. tuberculosis dormancy.
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Dowall, Stuart David. "Immune responses to BCG immunisation and Mycobacterium tuberculosis infection in non-human primates." Thesis, Open University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504257.
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Mwandumba, Henry Charles. "Modulation of human alveolar microphage function during mycobacterium tuberculosis and HIV co-infection." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443938.
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Thawer, Narjis Khatoon G. "Investigating defects in monocyte responses to Mycobacterium tuberculosis in HIV-TB co-infection." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/5923.
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Athman, Jaffre Joseph. "Membrane vesicle trafficking of immune modulatory stimuli during Mycobacterium tuberculosis infection." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1473274168613373.
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Jacques, Miye K. "Role of Tim3 in Mediating T Cell Exhaustion During Chronic Mycobacterium Tuberculosis Infection." eScholarship@UMMS, 2017. https://escholarship.umassmed.edu/gsbs_diss/912.
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Mycobacterium tuberculosis infection is one of the leading causes of mortality worldwide. One third of the population is estimated to be infected, however only 5-10% of those individuals can transmit the disease. While T cell immunity initially limits mycobacterium growth, it is unclear why T cell immunity fails to sterilize the infection and prevent subsequent recrudescence. One hypothesis is T cell exhaustion is mediating the failure of T cell immunity late during infection. Here we show the development of T cell exhaustion during chronic infection, and that the inhibitory receptor T cell-immunoglobulin and mucin domain containing 3 (TIM3) mediates the development of T cell exhaustion. TIM3 accumulates on the surface of T cells throughout the course of infection and there is a subsequent decrease in effector cytokine production, such as IL-2, TNFα, and IFNγ. Furthermore, antibody blockade of TIM3 restores T cell function and improves bacterial control. Our results show that TIM3 is mediating T cell exhaustion during chronic TB infection and leading to suboptimal bacterial control.
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Jacques, Miye K. "Role of Tim3 in Mediating T Cell Exhaustion During Chronic Mycobacterium Tuberculosis Infection." eScholarship@UMMS, 2007. http://escholarship.umassmed.edu/gsbs_diss/912.
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Mycobacterium tuberculosis infection is one of the leading causes of mortality worldwide. One third of the population is estimated to be infected, however only 5-10% of those individuals can transmit the disease. While T cell immunity initially limits mycobacterium growth, it is unclear why T cell immunity fails to sterilize the infection and prevent subsequent recrudescence. One hypothesis is T cell exhaustion is mediating the failure of T cell immunity late during infection. Here we show the development of T cell exhaustion during chronic infection, and that the inhibitory receptor T cell-immunoglobulin and mucin domain containing 3 (TIM3) mediates the development of T cell exhaustion. TIM3 accumulates on the surface of T cells throughout the course of infection and there is a subsequent decrease in effector cytokine production, such as IL-2, TNFα, and IFNγ. Furthermore, antibody blockade of TIM3 restores T cell function and improves bacterial control. Our results show that TIM3 is mediating T cell exhaustion during chronic TB infection and leading to suboptimal bacterial control.
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Dosanjh, Davinder. "Improving diagnosis of tuberculosis infection by detecting ex-vivo T cell responses to Mycobacterium tuberculosis deleted region antigens." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440145.
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Reuter, Helmuth. "The immunopathogenesis and treatment of tuberculous pericardial effusions in a population with a high prevalence of infection with the human immunodeficiency virus." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019.1/1411.
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Garnett, Benjamin Thomas. "Behavioural aspects of bovine tuberculosis (Mycobacterium bovis) transmission and infection in badgers (Meles meles)." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272050.
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Berry, M. P. R. "Transcriptional profiling of whole blood to survey the host response to Mycobacterium tuberculosis infection." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19192/.
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Introduction: Tuberculosis (TB) is a major cause of morbidity and mortality worldwide. The immune response during TB is complex and incompletely characterized, hindering the development of new diagnostics, treatments and vaccines. Studies performed in different disease settings (intermediate versus high burden) have sometimes yielded divergent results, limiting advances in our understanding of TB. We used microarray based approaches to obtain an unbiased comprehensive survey of the host response to TB in both the UK and South Africa. Methods: Whole blood was collected before treatment. RNA was extracted and used for whole genome expression studies using Illumina HT-12 microarrays. This was complemented by multiplexed cytokine analysis using the MILLIPLEX™ Multi-Analyte Profiling system. Biological data was integrated with comprehensive clinical data including radiology. Data mining was performed using Genespring GX 7.3 and Ingenuity® Pathways Analysis software in combination with a novel Genomic Modular Analysis Framework. A subset of patients was assessed at 2 and 12 months post treatment. Results: We identified a robust blood transcriptional signature for Active TB in both intermediate and high burden settings, independent of ethnicity, age and gender. Transcriptional profiles appeared to reflect radiographic extent of disease. Longitudinal analysis revealed that the signature of Active TB disappears during successful treatment. Analysis of blood leucocyte counts and serum cytokines, along with interrogation of gene expression data using pathway and Modular analysis suggests that this signature reflects changes in cellular composition and altered cytokine gene expression, with a key part of the signature being composed of interferon-inducible transcripts. This included several transcripts from the tripartite motif (TRIM) protein family, which have not previously been implicated in TB pathogenesis. Conclusions: This is the first whole genome expression profiling study in human TB. Our findings have implications for understanding disease pathogenesis, and could yield biomarkers for diagnosis and treatment monitoring.
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Backus, Keriann Marie. "Incorporation of trehalose analogues into Mycobacterium tuberculosis : antigen 85 and probes of bacterial infection." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:882d8560-c0d3-471b-a896-224a6b22a0f0.
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Diagnoses of tuberculosis, 'TB,' currently rely upon non-specific techniques such as X-ray exams and acid-fast microscopy. Improved diagnostics would preferably consider specific bacterial processes to provide real-time readouts of disease burden and response to chemotherapy. This dissertation presents the cell-wall incorporation of trehalose analogues (fluorescent and radioactive) by the mycobacterial antigen 85 enzymes as a novel method to label the causative bacteria of TB, Mycobacterium tuberculosis (Mtb). The trehalose mycolyltransesterase enzymes (antigens 85A, B, and C (Ag85)) serve as essential mediators of cell envelope function and biogenesis in Mtb. We show that the Ag85 enzymes display activities so broad that they allow added non-natural carbohydrate probes to be incorporated into Mtb growing in vitro and within macrophages. Design and synthesis of a library of structurally-diverse analogs of the sugar trehalose (Tre) revealed that Ag85-enzymes catalyze esterification of a wide variety of non-natural Tre structures, even stereoisomers and those appended with charged or bulky groups (Chapter 2). A novel mass-spectrometry based Ag85 enzyme assay was developed and employed to screen the library of compounds against all three isoforms of Ag85 (Chapter 3). This screen revealed that the Ag85 enzymes exhibit preference for dissacharides over monosaccharides and a broad tolerance for most modified trehalose compounds. This activity assay also afforded full kinetic analysis and the discovery of a novel, covalent inhibitor of the Ag85 enzymes. The Ag85 activity assay informed the design of a fluorescent trehalose-based compound (FITC-Tre), which is the first, non-toxic, selective, small molecule probe for mycobacterial infection. FITC-Tre was acylated with mycolyl esters by growing mycobacteria, anchoring the probe in the cell envelope resulting in fluorescent bacteria (Chapter 4). Adding FITC-Tre to Mtb-infected macrophages allowed selective, fluorescent tagging of Mtb in vivo (Chapter 5). Colocalization studies with antibodies against a variety of phagosomal associated components have hinted at the possibility of FITC-Tre as readout of cellular trafficking of bacteria. 18F-trehalose, biotin-trehalose and rhodamine-trehalose are also substrates of Ag85. 18F-trehalose shows promise as Mtb selective PET probe in an infected rabbit model of tuberculosis. Future work with these probes may allow for fluorescent tracking of the Mtb during the macrophage infection process, as well as the ability to label Mtb in infected tissue. The functional differences between the three isoforms of Ag85, A, B and C, are not well understood and may have implications for the survival and persistence of mycobacteria within humans. The differences in substrate specificity and catalytic activity between the Ag85 isoforms (discussed in Chapter 3) has been further investigated (Chapter 6). Mutation of three secondary site amino acids from Ag85C into Ag85B afforded nearly a twenty-fold gain in enzyme activity. Mutation of the equivalent Ag85B residues into Ag85C triggered nearly a twenty-fold loss in activity. Dissection of the roles of these three amino acids helps to explain the previously reported large differences in catalytic activity between Ag85A, B and C. Overexpression of Ag85A, B and C under tetracycline regulation revealed that these enzymes differentially modulate incorporation of mycolates into the cell wall. The Ag85 enzymes are not functionally redundant, and instead serve unique purposes in cell wall biosynthesis. In summary, this research has demonstrated that the broad substrate tolerance of Ag85 enzymes, coupled with their extracellular location, opens the door to probes of mycobacterial infection using many imaging modalities.
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Kreutzfeldt, Kaj Maximiliane. "Characterisation of host determinants that influence host-pathogen interaction during infection with Mycobacterium tuberculosis." Thesis, University of Brighton, 2015. https://research.brighton.ac.uk/en/studentTheses/9c2b2ddd-2ae7-4a8e-934a-a7e1dd28369a.
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Tuberculosis is endemic in the Gambian population, in which the magnitude of mycobacterial antigen-driven interferon-γ (IFN-γ) response in BCG vaccinated neonates has been linked to regions on the genome that encode the RIP2 kinase, the toll-like receptor 4 adapter protein MD-2 and the NF-κB subunit NF-κB2 by genome-wide linkage analysis. The receptor interacting protein (RIP2) is an essential kinase downstream of the nucleotide-binding oligomerization domain-containing protein 1 (NOD1) and NOD2, both intracellular pattern-recognition receptors for peptidoglycan moieties that induce activation of NF-κB. To establish the significance of RIP2 kinase during Mycobacterium tuberculosis infection, RIP2 was depleted in THP-1- derived macrophages using small interfering RNAs. In the absence of RIP2, THP- 1-derived macrophages secreted significantly reduced levels of the proinflammatory cytokine IL-1β upon infection with M. tuberculosis.
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DAIM, Sylvia. "Expression of the Mycobacterium tuberculosis PPE37 protein in Mycobacterium smegmatis induces low TNF-α and IL-6 production in murine macrophages." Kyoto University, 2011. http://hdl.handle.net/2433/142100.
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Ibrahim, Murad. "Evaluation of the bactericidal and sterilizing activity of diaryquinoline R207910 in murine model of tuberculosis." Paris 6, 2008. http://www.theses.fr/2008PA066168.
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Bases rationnelles: la tuberculose est à elle seule responsable d’environ 9 millions de nouveaux cas et de 1 à 2 millions de morts par an. Il existe pourtant un traitement antibiotique standard (recommandé par l’OMS) associant rifampicine, isoniazide, pyrazinamide et ethambutol (ou streptomycine), qui assure la guérison dans près de 95% des cas lorsqu’il est correctement suivi. Son efficacité est limité par sa longueur (au moins 6 mois), sa complexité (4 médicaments) et son inefficacité sur les souches multirésistantes. C’est pour outrepasser ces limites que de nouveaux antituberculeux sont nécessaires. R207910 est le chef de file d’une nouvelle famille d’antituberculeux, les diarylquinolines, au mécanisme d’action original : l’inhibition de l’ATP synthase. Objectif: nous avons évalué l’activité bactéricide et stérilisante de R207910 administré seul ou dans des combinaisons d’antibiotiques. Matériels et méthodes: Nous avons utilisé le modèle murin de tuberculose. Les souris étaient infectées par voie intra-veineuse par M. Tuberculosis H37Rv. Nous avons, selon les expériences, mesuré (a) la bactéricidie, c’est-à-dire la décroissance de la population bactérienne dans les poumons et/ou les rates après des durées variables de traitements et (b) l’activité stérilisante de combinaisons d’antibiotiques en mesurant les taux de rechutes après l’arrêt du traitement. Résultats: nous avons montré que le R207910 à 25 mg/kg est bactéricide après seulement 4 jours de traitement. Après 2 mois de traitement, le R207910 (25 mg/kg 5 jours sur 7, 50 mg/kg 2 jours sur 7, 100 mg/kg 1 jour sur 7) permet une décroissance de 5 log10 UFC de la charge bacillaire, activité qui n’est atteinte par aucun des antituberculeux existants. C’est donc la dose total hebdomadaire qui déterminait l’activité bactéricide et non le rythme d’administration ou la posologie unitaire. Du fait d’un action synergétique entre R207910 et pyrazinamide, deux mois de traitement par les double ou triples combinaisons (R207910+pyrazinamide±isoniazide ou rifampicine ou moxifloxacine) entraînait la négativation des cultures des poumons de 70 à 100% des souris alors que les combinaison contenant le R207910 mais pas le pyrazinamide ne rendaient pas plus de 30% des souris négatives en culture. Lorsque le R207910 était combiné aux antituberculeux de première ligne, il permettait de réduire significativement la durée minimale du traitement guérissant les souris et prévenant les rechutes. En effet, la quadruple combinaison R207910, isoniazide, rifampicine et pyrazinamide avait, en 4 mois, une activité équivalente à celle du traitement de référence par isoniazide rifampicine et pyrazinamide en 6 mois. L’ajout du R207910 aux régimes thérapeutiques administrés une fois par semaine, et comprenant la rifapentine et le pyrazinamide, permettait en 2 mois seulement de rendre négatifs en culture les organes de 9 souris sur 10. Une telle activité n’avait jamais été obtenu avec aucun traitement intermittent et s’avérait même être supérieure à celle du traitement quotidien de référence (isoniazide, rifampicine et pyrazinamide). Conclusion: dans le modèle murin de tuberculose, R207910 est actif dans les deux phases de traitement. Quatre mois de traitement avec certaines combinaisons contenant le R207910 étaient aussi efficaces que 6 mois de traitement standardRationale: tuberculosis is the second-ranked infectious disease leading to mortality after AIDS. There are 9. 2 million people develop new disease yearly, and 1. 7 million died from TB in 2006. The efficacy of TB treatment is limited by its length, complexity (4 drugs for 6 months) and by drug resistant tuberculosis. New drugs that are more active than those available today, and that allow shortening of the treatment duration are being developed. R207910 belongs to a new family of antituberculosis drug, the diarylquinolines, inhibiting ATP synthase. Objectives: we evaluated the bactericidal and sterilizing activity of R207910 alone and included in drug combinations. Materials and Methods: Swiss mice were infected by intravenous route with M. Tuberculosis H37Rv. Treatment efficacy was assessed by colony forming units (CFU) counts in lungs and/or spleens at the end of treatment (bactericidal activity) or after 3 months of follow-up period without treatment (sterilizing activity). Results: R207910 at a dose of 25 mg/kg demonstrated bactericidal activity after 4 days. After 2 months of treatment, R207910 (25 mg/kg 5 days/week, 50 mg/kg 2 days/week, 100 mg/kg 1 day/week) decreased bacillary load by 5 log10 CFU, and was more active than the currently available antituberculous drugs. Thus, R207910 could be given once weekly with a bactericidal activity equivalent to daily treatment given that total weekly dose was the same. Due to the synergism between R207910 and pyrazinamide, 2 months of treatment with double or triple combinations R207910+pyrazinamide±isoniazid or rifampin or moxifloxacin led to lung culture negativity 70 to 100% of mice. On the other hand only 30% of lungs were culture negative among mice treated with regimens containing R207910 but not pyrazinamide. When R207910 was combined with first line antituberculous drugs, the duration of treatment and relapse rate were reduced. The sterilizing activity of four drug combination containing R207910, isoniazid, rifampin and pyrazinamide was equivalent in 4 months to the sterilizing activity of isoniazid, rifampin and pyrazinamide in 6 months (6% vs 17% relapse rate). We also demonstrated that, when R207910 was combined with rifapentine and pyrazinamide, this combination given once weekly rendered 9 of 10 mice culture negative in only 2 month. Such activity was not obtained with any other intermittent regimen and was even superior to standard daily treatment (isoniazid, rifampin and pyrazinamide). Conclusion: in murine tuberculosis, R207910 demonstrated potent activity in both initial and continuation phase of treatment. Four months of treatment of certain combinations containing R207910 are as active as 6 months of standard treatment
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Bastos, Gisele Medeiros. "Papel da proteína HspX do Mycobacterium tuberculosis na regulação de genes relacionados à adaptação morfológica de micobactérias ao período de dormência, utilizando Mycobacterium smegmatis como organismo modelo." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-25042013-152531/.
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A manutenção da infecção latente pelo M. tuberculosis (TBIL) pode ser atribuída à sua capacidade de sobreviver durante anos no organismo humano em um estado não replicativo (dormente). A proteína HspX do M. tuberculosis, induzida sob condições de hipóxia, está fortemente associada com a manutenção da viabilidade do bacilo na TBIL. O presente estudo tem como objetivo, verificar se a superexpressão da proteína HspX altera a expressão de genes envolvidos com a síntese de componentes da parede celular, replicação do DNA e divisão celular de bacilos, assim como, na expressão de genes envolvidos com a resposta imune inata em macrófagos infectados com esses bacilos. O gene hspX foi amplificado pela PCR a partir do DNA do M. tuberculosis H37Rv, clonado no vetor de expressão pFPCA1GFP, e a proteína HspX expressa em M. smegmatis mc2155. As bactérias, nas quais, a presença da proteína recombinante foi confirmada por Western Blot, foram utilizadas, para a análise de expressão gênica tanto em bactérias quanto em macrófagos infectados. O estudo de expressão gênica foi realizado utilizando a RT-qPCR. Quando comparado aos controles, as bactérias que expressavam a proteína HspX apresentaram uma redução na expressão de genes de replicação do DNA e divisão celular, que foi acompanhado por uma tendência a filamentação das células e uma redução no tamanho das colônias. Além disso, nos macrófagos infectados com a bactéria expressando a proteína HspX, houve um aumento tanto da expressão do mRNA quanto da secreção de IL-1b, citocina importante para estabilização do granuloma, e uma redução na expressão de IRGM, gene relacionado com o processo autofágico, importante mecanismo de defesa do hospedeiro contra bactérias intracelulares. Portanto, em conjunto, essas alterações de expressão gênica, em consequência da presença da proteína HspX sugerem uma contribuição, direta ou indireta, dessa proteína para a adaptação morfológica e metabólica da bactéria dormente durante a TBIL, e consequentemente, para a resposta imune inata dos macrófagos infectados favorecendo a viabilidade intracelular dessas bactérias.The maintenance of Mycobacterium tuberculosis infection latent (TBIL) may be attributed to its ability to persist for years in the host in a non-replicative state (dormant). The HspX protein from M. tuberculosis, induced under hypoxic, is strongly associated with maintaining the bacillus viability in TBIL. This study aims to determine if HspX overexpression chances the expression of genes involved in the synthesis of cell wall components, DNA replication and cell division of bacilli, as well as, the expression of genes involved in innate immune response of macrophages infected. The gene hspX was amplified by PCR from DNA of M. tuberculosis H37Rv, and cloned into the expression vector pFPCA1GFP. The HspX was expressed in M. smegmatis mc2155 and the recombinant protein was confirmed by Western blot. The bacterias expressing HspX were used for gene expression analysis both in bacteria and in infected macrophages by RT-PCRq. In bacterias expressing HspX, it was observed a reduction in expression of genes involved in DNA replication and cell division, and with cells more filamentous and smaller colonies, compared with controls. In addition, in macrophages infected with bacillus expressing HspX, there was an increase in both mRNA expression and secretion of IL-1b, an important cytokine for granuloma stability, and a reduction in expression of IRGM, an autophagic gene, important for host defense mechanism against intracellular bacteria. Together, these results suggest a direct or indirect contribution of HspX protein for metabolic and morphological adaptation of dormant bacteria in TBIL, and for the innate immune response in infected macrophages, improving the bacteria intracellular viability.
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Mawa, P. A. "The impact of maternal infection with Mycobacterium tuberculosis on the infant response to BCG immunisation." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2017. http://researchonline.lshtm.ac.uk/3928321/.
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Bacille Calmette Guérin (BCG) immunisation induces variable protection against tuberculosis (TB) in adolescents and adults. More information on how it protects, and when, is needed. The infant response to BCG immunisation in Uganda and the influence of maternal latent Mycobacterium tuberculosis (M.tuberculosis) infection (LTBI) and maternal BCG scar on these responses were examined. Innate responses from 29 mother-infant pairs was measured using a Luminex® assay. Gene expression profiles in unstimulated infant samples collected at 1 (n=42) and 6 (n=51) weeks after birth were also analysed. Frequencies of PPD-specific IFN-γ+CD4+ T cells after 24-hour stimulation of infant samples were assessed by flow cytometry, and the time course of BCG-induced responses measured using Luminex® assay. Immunoglobulin G to PPD and tetanus toxoid was measured in plasma samples. The impact of maternal LTBI and maternal BCG scar on infant responses was investigated. Maternal BCG scar was associated with an increased infant pro-inflammatory response. Interferon and inflammation pathways were down-regulated at 1 week, but up-regulated at 6 weeks in infants of mothers with LTBI. In contrast, these pathways were both up-regulated in infants of mothers with a BCG scar at 1 and 6 weeks. PPD-specific IFN-γ+CD4+ T cells increased at 1 week and decreased at 6 weeks after birth (p=0.031). Maternal LTBI was associated with lower frequencies of IFN-γ+CD4+ T cells (p=0.015) and IFN-γ+, TNF-α+ and IL-2+ CD4+ T cells, combined (p=0.002), at 1 week after BCG. BCG-induced responses peaked around 24 weeks of age, but were not associated with maternal LTBI. Antibody responses dropped rapidly at 1 week and were not associated with maternal LTBI. In conclusion, infant responses peaked around 24 weeks of age, and maternal BCG scar was associated with increased infant proinflammatory responses. There was evidence of a shorter-term influence of maternal LTBI on infant responses.
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Jaeckel, Gilta. "Immunopathogenesis of chronic Mycobacterium marinum infection in adult zebrafish (Danio rerio)." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/20897.
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Tuberculosis (TB) is still a global epidemic disease despite its discovery over 100 years ago. It is caused by Mycobacterium tuberculosis, which invades and replicates within macrophages, key cells of the innate immune system. The hallmark of tuberculosis is the granuloma which is an accumulation of Mycobacterium-infected cells surrounded by immune cells, and the containment of the bacteria is assured as long as the host immune response remains intact. Despite a well-developed immune response in the infected host, reactivation of latent tuberculosis infection (LTBI) may occur through the introduction of other bacterial pathogens, re-infection with M. tuberculosis or due to other immunosuppression, e.g. AIDS or cancer. The zebrafish–M. marinum model provides an ideal system for examining the pathogenesis of tuberculosis and the associated immune response of the host due to its vertebrate-like immune system, and the close phylogenetic relationship of M. marinum to M. tuberculosis. Granuloma formation and immune response to M. marinum have been investigated mainly in zebrafish embryos or larvae, which lack an adaptive immune response, and little work has been performed in adult fish. This complicates the transfer of findings in these models to chronic, latent or re-activated disease stages in humans, where adaptive immunity plays an important part. The aim of the research presented here was to investigate the immune response of the adult zebrafish to M. marinum infection, with the focus on the kidney as one of the major immune organs in fish. The results obtained support further use of the adult zebrafish-M. marinum model for human tuberculosis infections in the future. In the present study, adult zebrafish were infected with low doses of M. marinum (NCIMB 1297 or NCIMB 1298) and the kidney was investigated for histopathological changes in the form of granulomas over a period of two months(Chapter 3). No granulomas were detected in the fish infected with M. marinum NCIMB 1298 while in zebrafish infected with NCIMB 1297, macrophage aggregation and granuloma formation were detected as early as day 11 post-infection. Occurrence and severity of granulomas and the presence of replicating bacteria increased over time, resulting in a high density of non-caseating and caseating granulomas in the head and posterior kidney after two months of infection. Interleukin 1 beta (IL-1β), Interleukin-12 (IL-12), Tumor necrosis factor alpha (TNFα) and Interferon gamma (IFNγ) have been shown to be important cytokines functioning in defence against tuberculosis, especially IFNγ which is considered to play an important part in acute, chronic and latent tuberculosis. Changes in gene expression of these immune genes in adult zebrafish were investigated over the first two weeks of infection with M. marinum NCIMB 1298 and NCIMB 1297. The results obtained in the first week after infection were inconclusive for both strains investigated. In agreement with the results presented in Chapter 3, no specific immune response was detectable in fish infected with M. marinum NCIMB 1298. However, after 14 days, a high-fold change in IL-12 and TNFα expression were detected in fish infected with M. marinum NCIMB 1297, while IL-1β showed no changes compared to the control fish. Furthermore, no IFNγ expression was detectable over the first two weeks of infection. The delay in the expression of IL-12 and the lack of IFNγ expression can be explained by the ability of M. marinum to manipulate the host immune response, as described for M. tuberculosis and other intracellular bacteria. Besides in vivo investigations of the host-pathogen interactions, in vitro primary macrophage cultures from individual zebrafish kidneys were developed to investigate macrophage-specific gene expression to M. marinum infection (Chapter 4). Although the results looked promising, further optimization is required before the results of the in vitro assays can be fully compared to the in vivo results. Our understanding of reactivation in latent tuberculosis infection (LTBI) both in healthy and immune compromised individuals is insufficient and is delaying the development of treatments for the disease. Therefore, the transcriptome profile of long-term infections (26 weeks) with M. marinum NCIMB 1297 in adult zebrafish was investigated to determine whether the gene expression in this model is comparable to LTBI in humans or other vertebrate model organisms (Chapter 5). In addition, transcriptome profiling was investigated in a group of long-term infected zebrafish exposed to stress to induce re-activation of the disease. Expression profiles in the long-term infected fish and the infected plus stressed fish differed from each other and displayed similar gene profiles to those found in the latent or re-activated disease states, respectively, in human and other vertebrate models. Infected fish displayed a profile highlighted by IFNγ, TNFα, NOS2b and IL-8 expression alongside activating and regulatory T cell responses, including involvement of cytotoxic T cells (CTLs). The transcriptome profile of the group of fish that had been infected and then stressed was distinguished by the lack of IFNγ expression and reduction in TNFα and NOS2b expression, as well as a lack of T cell response compared to the infected fish. In conclusion, the results obtained from Chapters 3 and 4 showed that M. marinum NCIMB 1298 is non-pathogenic to zebrafish. Infection with M. marinum NCIMB 1297, on the other hand, resulted in a similar immune response to that described for human and other mammalian vertebrate models (Chapters 3-5). These results support the use of the adult zebrafish-M. marinum model to investigate LTBI and disease reactivation, and will aid our understanding host-pathogen interactions for tuberculosis in the future.