Made available in DSpace on 2014-07-29T15:04:41Z (GMT). No. of bitstreams: 1 dissertacao lilian.pdf: 281825 bytes, checksum: 488c9e5d58cb1a521b28a8592ee6de50 (MD5) Previous issue date: 2006-02-23 / According 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.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Iron is an essential element that plays a role in the process of respiration, oxygen transport and as a principle cofactor to several enzymes. Iron homeostasis is a finely regulated process since excess levels become toxic to healthy cells via the production of reactive oxygen species. A plethora of genes that control several key points throughout this regulatory process have been identified. Research focusing on changes in expression levels and downstream functional effects of these genes has become increasingly important over the past decade. One area of particular interest has emerged since a link between iron status and host response to Mycobacterium tuberculosis infection was discovered. Although the prevalence of Tuberculosis has decreased across the globe with the exception of Africa and parts of Europe, the mortality rate remains high. Therefore, research that focuses on understanding an individual’s predetermined susceptibility to TB infection at the genetic level could provide health care practitioners with the tools required to identify and educate at-risk individuals prior to TB infection. RT-qPCR was utilised to determine expression profiles for eight iron genes (CP, CYBRD1, FTH, FTL, LTF, HFE, HMOX1, and SCL40A1) normalised to three reference genes (ACTB, GUSB, and RPL37A1). Up-regulation is demonstrated in the TB group for transcript levels recorded for CYBRD1, HFE, HMOX1, and SLC40A1. Several measured serum parameters including conjugated, unconjugated, total bilirubin, and total protein were increased in the TB group while albumin was significantly lower in this group. Correlation analysis demonstrated that a positive correlation exists between transferrin saturation and iron and a negative correlation exists between transferrin and ferritin levels. Individuals categorised with low serum iron levels demonstrated lower CP/GUSB levels and higher HMOX1/GUSB levels. Individuals categorised with low transferrin saturation levels demonstrated higher FTL/GUSB and SLC40A1/GUSB levels and lower CP/GUSB. Results from this study provide further evidence for the relationship between iron status and TB infection rates, although protein studies are required to confirm these results. The data obtained illustrate the important role that these profiles and iron parameters may play in the clinical field when identifying at-risk individuals. Further investigation that focuses on which gene profile and parameter combinations show the most distinctive utility in the clinical setting is warranted. / AFRIKAANSE OPSOMMING: Yster is ‘n noodsaaklike element wat ‘n rol speel in die proses van respirasie en die vervoer van suurstof en ook ‘n belangrike ko-faktor vir verskeie ensieme is. Yster homeostase is op ‘n fyn manier gereguleer omdat oormatige vlakke toksies kan wees vir gesonde selle wanneer reaktiewe suurstofspesies geproduseer word. ‘n Magdom gene wat verskeie sleutelpunte in hierdie proses kontroleer is voorheen identifiseer. Navorsing wat fokus op die veranderinge in geenuitdrukkingsvlakke en die funksionele gevolge daarvan het oor die afgelope dekade toenemend belangrik geword. Een gebied van spesifieke belang het na vore gekom nadat ‘n verband tussen ystervlakke en die manier waarop die immuunstelsel reageer op Mycobacterium tuberculosis infeksie, ontdek is. Alhoewel die voorkoms van Tuberkulose wêreldwyd, behalwe in Afrika en sekere dele van Europa, afgeneem het, bly die sterftesyfer hoog. Daarom kan navorsing wat daarop fokus om ‘n individu se voorafbepaalde vatbaarheid vir TB-infeksie op die genetiese vlak te verstaan dalk aan gesondheidswerkers die regte instrumente verskaf om hoë-risiko individue te identifiseer en op te voed voordat hulle TB ontwikkel. RT-qPKR is gebruik om die geenuitdrukkingsvlakke van agt ystergene, wat met drie verwysings-gene (ACTB, GUSB, en RPL37A1) genormaliseer is, te bepaal. ‘n Toename in die uitdrukkingsvlakke van CYBRD1, HFE, HMOX1, en SLC40A1 is in die TB-groep waargeneem. Die bloedvlakke van verskeie parameters insluitend gekonjugeerde, ongekonjugeerde, totale bilirubin, en totale proteïen was hoër in die TB-groep, terwyl albuminvlakke laer was in hierdie groep. Korrelasie-analise het ‘n positiewe korrelasie tussen transferrin-versadiging en yster getoon, terwyl daar ‘n negatiewe korrelasie tussen transferrin- en ferritinvlakke gevind is. Individue met lae ystervlakke het laer CP/GUSB-vlakke en hoër HMOX1/GUSB-vlakke getoon. Individue met lae transferrin-versadiging het hoër FTL/GUSB- en SLC40A1/GUSB-vlakke en laer CP/GUSB-vlakke getoon. Resultate uit hierdie studie verskaf verdere getuienis dat daar ‘n verwantskap tussen ystervlakke en TB-infeksiekoerse bestaan, alhoewel proteïenstudies nodig is om hierdie resultate te bevestig. Die data dui op die belangrike rol wat hierdie profiele en ystervlakke in die kliniese veld mag speel in die identifisering van hoë-risiko individue. Verdere ondersoek, gefokus op watter geenprofiel en parameterkombinasies die grootste nut in die kliniese omgewing bied, is geregverdig.

Les maladies infectieuses sont l’une des principales causes de mortalité à travers le monde. La réponse immunitaire est l’un des phénotypes les plus complexes qui existent. Elle présente une variabilité au sein et entre les populations. Cette thèse vise à identifier des facteurs génétiques et des mécanismes moléculaires sous-jacents aux différences de susceptibilité aux maladies infectieuses grâce à l’utilisation d’une combinaison d’approches in silico et ex vivo. Nous avons tout d’abord réalisé des analyses de génétique des populations et de génétique évolutive pour évaluer l’impact de la sélection naturelle sur les gènes de l’immunité innée. Nos résultats montrent l’étendue et l’hétérogénéité des pressions sélectives sur ces gènes et suggèrent que l’introgression d’allèles provenant de l’Homme de Néandertal dans certaines de ces séquences ont participé à l’adaptation des populations Européennes et Asiatiques à leurs environnements respectifs. Nous avons ensuite estimé l’implication des miARN dans la réponse des cellules dendritiques à l’infection par Mycobacterium tuberculosis. Nos résultats soulignent les conséquences de l’infection sur les réseaux de régulation de l’expression des gènes par les miARN et montrent que l’expression de 3% des miARN est associée à des facteurs génétiques proximaux. Nous identifions en particulier deux associations qui ne sont observées que dans un contexte infectieux. Le travail présenté ici constitue la plus large étude de génétique évolutive et de génétique des populations axée sur les gènes de l’immunité innée réalisée à ce jour et la première caractérisation de l’architecture génétique de la réponse à l’infection impliquant les miARN. / Infectious diseases remain one of the leading causes of death worldwide. The immune response to pathogens, one of the most complex phenotypes that exist, presents substantial variability among individuals and populations. This thesis aims to identify genetic factors and molecular mechanisms underlying differences in susceptibility to infectious diseases using a combination of in silico and ex vivo approaches. First, we performed population and evolutionary genetics analyses to assess the impact of natural selection on innate immunity genes. Our analyses reveal the widespread and heterogeneous nature of the selective pressures acting on those genes. In addition, we suggest that the introgression of Neanderthal alleles in some of these sequences contributed to the adaptation of European and East Asian populations to local pathogens. Second, we profiled the miRNA response to Mycobacterium tuberculosis infection in human dendritic cells. Our results highlight the impact of infection on miRNA-mediated gene regulatory networks and show that the expression of 3% of miRNAs is associated with proximate genetic variants. More specifically, we identify two infection-specific associations. The work presented here provides the largest evolutionary genetics analysis of innate immunity genes to date and the first attempt to characterize the genetic architecture of the miRNA response to infection. Our work offers new insights into the genetic basis of inter-individual variability in immune responses and provides a set of candidate genetic variants for future functional validation to elucidate novel molecular mechanisms underlying differences in susceptibility to infectious diseases.

Tuberculosis (TB) is an infectious and fatal disease that ranks as the second leading killer worldwide. It is caused by Mycobacterium tuberculosis (Mtb) which is an obligate intracellular parasite that colonizes the alveolar macrophages of the immune system. The major health concern associated with TB is its co-infection with HIV and the development of strains with multi-drug resistance. The elimination of TB has been hindered due to the lack of understanding of the survival strategies used by this pathogen. Thus, research towards discovering new effective antibacterial drugs is necessary and a group of Mtb kinase enzymes were targeted in this study because these enzymes are crucial for metabolism, pathogenesis and, hence, the survival of Mtb. Kinases are a group of structurally distinct and diverse proteins that catalyze the transfer of the phosphate group from high energy donor molecules such as ATP (or GTP) to a substrate. The phosphorylation of proteins modifies the activity of specific proteins which is subsequently used to control complex cellular processes within Mtb. The starting point of this research targeted eight specific Mtb kinases namely; Nucleoside diphosphokinase, Homoserine kinase, Acetate kinase, Glycerol kinase, Thiamine monophosphate kinase, Ribokinase, Aspartokinase and Shikimate kinase. The aim of this project was to subclone the gene sequences for these eight recombinant Mtb kinases and express them in Escherichia coli, to purify the proteins and determine their activity. In the effort to find new lead compounds, the final stage of this study focused on the basic screening of the TB kinases against an extract prepared from Pelargonium sidoides, a medicinal plant, to identify any inhibitory effects. Although this traditional medicinal plant has been broadly researched and extensively used to treat TB, there is still a lack of understanding of this plant’s scientific curative effect. Various molecular and biochemical methods were used to achieve the aims of this project. The putative gene sequence was obtained from the annotated genome of H37Rv, deposited at NCBI as NC_000962.2. The genes encoding the kinases were successfully PCR-amplified from genomic DNA, cloned into an expression vector in-frame with a C- or N-terminal 6-histidine-tag and expressed in E. coli BL21 (DE3). The purification of the protein was complex, but various different methods and techniques were explored to obtain sufficient amounts of protein. The functional characterization of the kinases involved an HPLC enzyme assay that showed that the recombinant kinases were active. These enzymes were then screened against the potential inhibitory compounds in P. sidoides using enzyme assays to generate dose-response curves. This allowed an effective comparison not only of the Mtb kinases’ activity under normal conditions but also the kinases’ activity in the presence of a potential inhibitor. Overall, the inhibition of the enzymes required the presence of higher concentrations of the P. sidoides extract. However, the SK enzyme results presented a significantly higher inhibition and the lowest IC50 value, in comparison to the other kinases, which makes this kinase an attractive potential drug target against TB. In summation, cloning and purification of SK was successful, resulting in a concentration of 2030 μg/ml of purified enzyme and its activity analysis demonstrated enzyme functionality. This activity was reduced to zero in the presence of 1 x 102 mg/ml dilution of P. sidoides plant extract. This research conducted has extended the quality of information available in this field of study. These interesting results, proposing and identifying SK as a suitable potential target can be a starting point to significantly contribute and progress in this field of research, with the eventual goal of developing a drug to combat this fatal disease. / Life Sciences / M. Sc. (Life Sciences)

Tuberculosis (TB) is an infectious and fatal disease that ranks as the second leading killer worldwide. It is caused by Mycobacterium tuberculosis (Mtb) which is an obligate intracellular parasite that colonizes the alveolar macrophages of the immune system. The major health concern associated with TB is its co-infection with HIV and the development of strains with multi-drug resistance. The elimination of TB has been hindered due to the lack of understanding of the survival strategies used by this pathogen. Thus, research towards discovering new effective antibacterial drugs is necessary and a group of Mtb kinase enzymes were targeted in this study because these enzymes are crucial for metabolism, pathogenesis and, hence, the survival of Mtb. Kinases are a group of structurally distinct and diverse proteins that catalyze the transfer of the phosphate group from high energy donor molecules such as ATP (or GTP) to a substrate. The phosphorylation of proteins modifies the activity of specific proteins which is subsequently used to control complex cellular processes within Mtb. The starting point of this research targeted eight specific Mtb kinases namely; Nucleoside diphosphokinase, Homoserine kinase, Acetate kinase, Glycerol kinase, Thiamine monophosphate kinase, Ribokinase, Aspartokinase and Shikimate kinase. The aim of this project was to subclone the gene sequences for these eight recombinant Mtb kinases and express them in Escherichia coli, to purify the proteins and determine their activity. In the effort to find new lead compounds, the final stage of this study focused on the basic screening of the TB kinases against an extract prepared from Pelargonium sidoides, a medicinal plant, to identify any inhibitory effects. Although this traditional medicinal plant has been broadly researched and extensively used to treat TB, there is still a lack of understanding of this plant’s scientific curative effect. Various molecular and biochemical methods were used to achieve the aims of this project. The putative gene sequence was obtained from the annotated genome of H37Rv, deposited at NCBI as NC_000962.2. The genes encoding the kinases were successfully PCR-amplified from genomic DNA, cloned into an expression vector in-frame with a C- or N-terminal 6-histidine-tag and expressed in E. coli BL21 (DE3). The purification of the protein was complex, but various different methods and techniques were explored to obtain sufficient amounts of protein. The functional characterization of the kinases involved an HPLC enzyme assay that showed that the recombinant kinases were active. These enzymes were then screened against the potential inhibitory compounds in P. sidoides using enzyme assays to generate dose-response curves. This allowed an effective comparison not only of the Mtb kinases’ activity under normal conditions but also the kinases’ activity in the presence of a potential inhibitor. Overall, the inhibition of the enzymes required the presence of higher concentrations of the P. sidoides extract. However, the SK enzyme results presented a significantly higher inhibition and the lowest IC50 value, in comparison to the other kinases, which makes this kinase an attractive potential drug target against TB. In summation, cloning and purification of SK was successful, resulting in a concentration of 2030 μg/ml of purified enzyme and its activity analysis demonstrated enzyme functionality. This activity was reduced to zero in the presence of 1 x 102 mg/ml dilution of P. sidoides plant extract. This research conducted has extended the quality of information available in this field of study. These interesting results, proposing and identifying SK as a suitable potential target can be a starting point to significantly contribute and progress in this field of research, with the eventual goal of developing a drug to combat this fatal disease. / Life Sciences / M. Sc. (Life Sciences)