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1
Hodgson, Susanne H. "Using the controlled human malaria infection model to investigate immunity to malaria." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:b3c9a2eb-beab-4ef6-bd8d-483390f316b8.
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Controlled human malaria infection (CHMI) studies, where healthy volunteers are infected with Plasmodium falciparum have become a vital tool to accelerate vaccine and drug development. As CHMI trials are carried out in a controlled environment, they allow unprecedented, detailed evaluation of parasite growth dynamics and immunological responses to infection. Though commonly performed in malaria-naïve populations, CHMI trials have rarely been conducted in malaria-endemic regions and to date, have not been used to investigate naturally acquired immunity (NAI) to P. falciparum infection. This thesis describes the first CHMI study in Kenya and the first attempt to use the modern CHMI model to explore the dynamics and mechanisms of NAI. Using samples collected post-CHMI from both UK volunteers and Kenyan subjects with varying prior exposure to P. falciparum, this work reports and compares the findings of key in vitro assays including GIA, ADRB activity and changes in gene expression in order to understand the effect of NAI on these measures.
2
Bruce, Marian Cooke. "Intra-host dynamics of human malaria parasites." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298193.
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Goncalves, B. "The human infectious reservoir of Falciparum malaria." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2017. http://researchonline.lshtm.ac.uk/4646827/.
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Malaria control strategies are often targeted at individuals who suffer most morbidity, not at those driving transmission. This is in part due to our limited understanding, described in Chapter 1, of the human infectious reservoir of falciparum malaria – i.e. individuals responsible for human-to-mosquito transmission of Plasmodium falciparum parasites in endemic areas. This work, whose objectives are listed in Chapter 2, assessed the prevalence of infectiousness in naturally exposed human populations during dry and wet seasons. Exposure to Anopheles mosquitoes, a measure of transmission opportunities, was also quantified; and to determine the value of infectiousness-reducing interventions, the use of primaquine to block transmission from infectious individuals was investigated. Experimental infections of mosquitoes were performed to determine malaria infectivity of randomly selected individuals in two villages in Burkina Faso. Molecular assays were used to quantify parasite, including gametocyte, densities. Less than 10% of the population was infectious to mosquitoes. These results are presented in a manuscript that included data from other study sites (Chapter 3). To assess exposure to malaria vectors, bloodfed mosquitoes were collected indoors in one of the study villages in Burkina Faso. A multiplex PCR assay targeting nine human microsatellites and a gender-specific marker was used to identify the human sources of mosquito blood meals. Although there was substantial variation in the number of mosquito bites each individual received (Chapter 4), on average adults received more mosquito bites than children. This suggests that, despite their lower infectiousness, adults are major contributors to malaria transmission in endemic areas. An efficacy trial of single low dose primaquine was performed in Burkina Faso and pre- and post-treatment infectiousness were quantified by mosquito feeding experiments to assess primaquine’s infectiousness-reducing activity (Chapter 5). Individuals receiving primaquine cleared gametocytes faster than individuals who received artemether-lumefantrine alone. Feeding assays, however, suggest that artemether-lumefantrine blocks most parasite transmission after treatment administration. In Chapter 6, these findings, and how they can inform future control strategies, are discussed.
4
Weber, Grace E. "Memory B Cell Dysfunction in Human Malaria." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512731469728517.
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Kaneko, Akira. "Malaria on islands : human and parasite diversities and implications for malaria control in Vanuatu /." Stockholm, 1999. http://diss.kib.ki.se/1999/19990927kane.
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Nisar, Samia. "Role of ATP2B4 and human malaria : looking for functional genetic variants associated with malaria." Thesis, Aix-Marseille, 2020. http://theses.univ-amu.fr.lama.univ-amu.fr/200911_NISAR_992dobfs271wcdsgy656twqjfn399ockic_TH.pdf.
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GWAS pour le paludisme grave identifié 30 variantes génétiques situées dans régions non codantes, avec seulement quelques associations répliquées dans des populations indépendantes. Dans cette étude, nous avons cherché à identifier les variantes génétiques potentielles situées dans ces loci et à démontrer leur activité fonctionnelle. Nous avons systématiquement étudié l'effet régulateur des SNP en déséquilibre liaison avec les tagSNPs associés au paludisme sévère dans plusieurs populations. L'annotation et priorisation ont conduit à l'identification d'une région régulatrice contenant 5 SNP ATP2B4 en déséquilibre liaison avec le tagSNP. Nous confirmé l'association de rs10900585 et trouvé des associations significatives de paludisme sévère avec nos candidats dans population sénégalaise. Nous montré que cette région avait à la fois une activité promoteur et un activateur et que l'individu et combinaison de SNP avaient un effet en utilisant des dosages de luciférase. En outre, la délétion médiée par CRISPR / Cas9 de cette région a diminué le transcrit ATP2B4 et les niveaux de protéines et a augmenté la concentration intracellulaire de Ca2+ dans les cellules K562. Ensemble, nos données montrent les variantes génétiques associées au paludisme grave modifient l'activité d'un promoteur avec une fonction d'activateur. Nous montré que cet amplificateur contrôle l'expression de l'ATP2B4 qui code l'ATPase 4 (PMCA4) transportant le calcium dans la membrane plasmique, qui est la principale pompe à calcium des globules rouges. La modification de l'activité de cet Epromoter affecte le risque de paludisme sévère probablement par l'effet de la concentration de calcium sur la parasitémieGenome-wide association studies (GWAS) for severe malaria have identified 30 genetic variants mostly located in non-coding regions, with only few associations replicated in independent populations. In this study, we aimed at identifying potential causal genetic variants located in these loci and demonstrate their functional activity. We systematically investigated the regulatory effect of the SNPs in linkage disequilibrium with the tagSNPs associated with severe malaria in several populations. Annotating and prioritizing genetic variants led to the identification of a regulatory region containing 5 ATP2B4 SNPs in linkage disequilibrium with the tagSNP rs10900585. We confirmed the association of rs10900585 and also found significant associations of severe malaria with our candidate SNPs (rs11240734, rs1541252, rs1541253, rs1541254, and rs1541255) in a Senegalese population. Then, we showed that this region had both a promoter and an enhancer activity and that both individual SNPs and the combination of SNPs had an effect using luciferase reporter assays. In addition, CRISPR/Cas9-mediated deletion of this region decreased ATP2B4 transcript and protein levels and increased Ca2+ intracellular concentration in K562 cell line. Taken together, our data show that severe malaria associated genetic variants alters the activity of a promoter with enhancer function. We showed that this enhancer controls the expression of ATP2B4 that encodes plasma membrane calcium-transporting ATPase 4 (PMCA4), which is the major calcium pump on red blood cells. Altering the activity of this Epromoter affects the risk of severe malaria probably through calcium concentration effect on parasitaemia
7
Walker, Alison Dalgity. "Protein variation in the malaria parasite Plasmodium falciparum." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/13171.
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Berthoud, Tamara Katherine. "Human cellular immune responses to candidate malaria vaccines." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445763.
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Buitrago, Amanda Elena Maestre. "Immunity to malaria using the rodent malaria parasite Plasmodium chabaudi AS as a model of the human malaria Plasmodium falciparum." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298916.
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Maestre, Buitrago Amanda Elena. "Immunity to malaria using the rodent malaria parasite Plasmodium chabaudi chabaudi AS as a model of the human malaria Plasmodium falciparum." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/2036/.
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The role of IFN in acquisition of immunity against erythrocyte forms of P.c. chabaudi AS was studied. Inbred NIH mice given the construct 7 days before malaria infection, showed a significant delay in the onset and in the level of the recrudescent parasitaemia in comparison with controls. No differences, however, were observed in the recrudescent parasitaemia between the groups. NIH mice infected with malaria 3 days after or on the same day as the administration of the IFN construct, showed a primary peak of infection similar to controls, but the resolution of this patent parasitaemia occurred 1 or 2 days earlier in the experimental mice when compared with controls. In the same experiment, mice given the construct 10 days before malaria infection had a similar course of infection as controls. Simultaneous inoculation with two S. typhimurium constructs: IFN and TNF, 8 days before malaria infection resulted in a course of parasitaemia similar to that observed in mice given the IFN construct alone. On the other hand, inoculation of 'susceptible' inbred A/J mice with S. typhimurium/IFN 3 or 8 days before malaria infection had no effect on the course of the parasitaemia when compared with controls. The immune mechanisms involved in the better control of the malaria infection of NIH mice given S. typhimurium/ IFN, seem to be independent of nitric oxide (NO) production, since increased levels of the molecule were demonstrable around the peak of the primary parasitaemia in control groups but not in experimental mice. In the latter basal levels of serum NO were observed from the period after the S. typhimurium/ IFN inoculation until up to three days after the peak of the parasitaemia.
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Lee, S. H. "Studies on tissue macrophages and their properties in murine malaria." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372083.
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Hume, Jennifer C. C. "Transmission studies and population structure in human malaria parasites." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409801.
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Yates, Simon N. R. "Human genetic diversity and selection by malaria in Africa." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260867.
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Ng, Shengyong. "Engineering human hepatic tissue for modeling liver-stage malaria." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90150.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2014.Cataloged from PDF version of thesis. Vita.
Includes bibliographical references (pages 132-153).
The Plcsmodium liver stage is an attractive target for the development of antimalarial drugs and vaccines, as it provides an opportunity to interrupt the life cycle of the parasite at a critical early stage. However, targeting the liver stage has been difficult due to a lack of human liver models that robustly recapitulate host-pathogen interactions in a physiologically relevant cell type. Through the application of hepatic tissue engineering concepts and techniques, this thesis sought to develop advanced models of liver-stage malaria that will allow the facile interrogation of potential antimalarial drugs in primary human hepatocytes. In the first part of this work, we established liver-stage Plasmodium infection in an engineered microscale human liver platform based on micropatterned cocultures of primary human hepatocytes and supportive stromal cells, enabling medium-throughput phenotypic screens for potential antimalarial drugs in a more authentic host cell, and demonstrated the utility of this model for malaria vaccine testing. We further hypothesized and showed that recapitulation of a more physiologically relevant oxygen tension that is experienced by hepatocytes in vivo improved infection rates and parasite growth in vitro. Next, we demonstrated the feasibility of establishing liver-stage malaria infections in human induced pluripotent stem cell-derived hepatocyte-like cells (iHLCs), thus enabling the study of host genetic variation on liver-stage malaria infection and antimalarial drug responses. We also applied recently discovered small molecules to induce further hepatic maturation, thus increasing the utility of using iHLCs for antimalarial drug development. Finally, we designed and provided a proof-of-concept for a humanized mouse model of liver-stage malaria that involves the fabrication and ectopic implantation of PEG-cryogel-based engineered human artificial livers, and can be generated in a facile, rapid and scalable fashion for future preclinical antimalarial drug testing in vivo. The results of this research represent a three-pronged approach towards engineering scalable human liver models that recapitulate liver-stage malaria infection which may ultimately facilitate antimalarial drug discovery at various stages of the drug development pipeline.
by Shengyong Ng.
Ph. D.
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Elias, Sean C. "Analysis of b cell responses to blood-stage malaria antigens in humans following immunization with candidate vaccines and controlled human malaria infection." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:7dd65dc8-f831-49a7-8885-34072016eebb.
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The apicomplexan parasite Plasmodium falciparum is the causative agent of the most severe and deadly form of human malaria. The production of an efficacious malaria vaccine is seen as one of the key steps towards the eradication of the disease, however to date only one candidate has progressed to application for licensure. Candidate malaria vaccines target the different stages of the P. falciparum lifecycle through induction of a functional immune response. Vaccines targeting the blood-stage parasite require induction of high titre neutralising antibodies. To achieve this, vaccine regimens have been designed specifically to maximise antibody induction and maintenance in humans. The ultimate test of any candidate vaccine is clinical efficacy and controlled human malaria infection (CHMI) is a powerful tool for measuring this. This model can also be used to study how vaccine induced antigen-specific components of the immune system respond to native antigen exposure in the context of parasitic infection In this Thesis I describe the induction and maintenance of B cell responses, including memory B cells (mBC) and antibody secreting cells (ASC) to the candidate blood-stage malaria antigens MSP1 and AMA1 following vaccination with a variety of regimens and CHMI. These B cell populations along with peripheral blood T follicular helper (Tfh) cells correlate strongly with antibody induction. Within these populations I have identified a number of phenotypically distinct subsets which contribute to a functional response to vaccine and/or parasite antigen. From single cell sorting of ASC at day seven post-boost I have managed to produce the first fully human monoclonal antibodies (hmAbs) specific for AMA1, one of which shows significant growth inhibitory activity (GIA). Despite promise the vaccine candidates MSP1 and AMA1 have been disappointing in terms of human efficacy. In this Thesis I have attempted to provide explanations on a cellular level as to why there is such disparity between pre-clinical and human data and ultimately why these candidates may have failed to provide efficacy. Such work will provide a strong basis for analysing future clinical trials of alternative candidate blood-stage vaccines and allow accurate characterisation of immune correlates and clinical efficacy when it is achieved.
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Gravenor, Michael Brynley. "The population biology of Plasmodium falciparum within the human host." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260744.
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Joice, Regina Carol. "Characterization of Malaria Sexual Stage Development in the Human Host." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10921.
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Due to an increase in malaria control programs in the last decade, the world has witnessed dramatic reductions in the number of infections and deaths caused by the malaria parasite. With malaria eradication on the global health agenda, a shift toward transmission-focused research has led to a renewed focus on a previously neglected stage of malaria: the sexual stage (gametocyte). Malaria's sexual stages are the only stages in the human host that are transmitted to the mosquito vector, and are therefore of critical importance for blocking transmission of this devastating disease. The process through which developing gametocytes sequester outside of the bloodstream during their 8-10 day maturation is not well understood and stands to be exploited as a potential target for therapeutic intervention. In Chapter 1, we discuss the current state of knowledge on the development of these stages in the human host. In Chapter 2, we investigate anatomical enrichment sites for developing gametocytes in the human host using autopsy tissue from cases of fatal malaria. Immunohistochemistry (IHC) and quantitative reverse transcriptase PCR-based assessments identified the bone marrow as a preferential enrichment site of developing gametocytes. Co-localization with host proteins revealed the enrichment of gametocytes inside the extravascular space of the bone marrow, often observed in contact with erythroblastic island structures. In vitro experiments with erythrocyte precursor cells, as well as in vivo co-localization studies demonstrated that gametocytes can develop within the cells of the hematopoietic system of the bone marrow.
In Chapter 3, we present an assay and analysis tool for inferring the presence of young and mature asexual and sexual stages in the peripheral blood of infected patients based on gene expression data. We apply this assay to malaria patient cohorts and in vitro drug perturbation time course experiments, and demonstrate its use in identifying young and mature gametocyte carriers, as well as characterizing the effect of a given perturbation on parasite development. This body of work aims to contribute to the overall knowledge base for malaria’s elusive gametocytes as well as to establish tools for performing future assessments on these transmissible stages.
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Murugan, Rajagopal. "Protective memory B cell response in controlled human malaria infection." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19695.
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Antikörper gegen Circumsporozoite protein (CSP), ein Oberflächenantigen von Plasmodium
falciparum (Pf), können sterile Immunität hervorrufen und dadurch die Entwicklung von
Malaria im Tierversuch verhindern. Im Menschen werden protektive B-Zell
Gedächtnisantworten gegen CSP durch natürliche Malariaerkrankung bzw. Vakzinierung
jedoch nur unzureichend erzeugt. - Für die Entwicklung von Gedächtnis-B-Zellen stellt die
Affinitätsreifung, welche durch somatische Immungobulin Hypermutation sowie der
nachfolgenden Selektion von B-Zellen mit verbesserter Antigenaffinität charakterisiert ist, eine
Schlüsselfunktion in der Generierung von protektiven Immunantworten dar. Wie
Affinitätsreifung gegen CSP im Menschen stattfindet ist jedoch nicht bekannt. In dieser Arbeit
wird die Affinitätsreifung von CSP Gedächtnis B-Zellen auf Einzelzellebene im Menschen
über drei kontrollierte Infektionen mit Pf Sporozoiten unter Chemoprophylaxe untersucht.
Durch Hochdurchsatz-Einzelzell-Sequenzierung der Immunoglobulin (Ig) gene loci und der
Produktion von rekombinanten monoklonalen Antikörpern gewährt diese Arbeit Einsicht in
die Selektion und Affinitätsreifung von humanen Gedächtnis-B-Zell Antworten gegen
komplexe Proteinantigene und identifiziert Keimbahn kodierte Immunglobulin
Charakteristika, die mit hoher CSP-Affinität und Pf-Inhibition einhergehen.
Überraschenderweise zeigen die Daten, dass initiale klonale Selektion von hochaffinen B
Zellen eine weitaus wichtigere Rolle als Affinitätsreifung in dieser Infektion spielt. Diese
Arbeit zeigt fundamentale Eigenschaften von humanen Gedächtnisantworten in einer
komplexen Parasiteninfektion und liefert die Grundlage für ein mögliches Design von
neuartigen Immunogenen um hoch-affine B-Zellen gegen CSP effizienter zu induzieren.Antibodies against the major Plasmodium falciparum (Pf) sporozoite surface protein, circumsporozoite protein (CSP), can mediate sterile immunity thereby preventing malaria disease symptoms as shown by passive transfer in animal models. However, protective anti- CSP memory antibody responses are not efficiently induced by natural Pf exposure or vaccination. Affinity maturation, i.e. the diversification of antigen-activated naïve precursor B cells by a somatic immunoglobulin (Ig) gene mutation process and the subsequent selection of B cells expressing antigen receptors with improved antigen affinity in germinal center reactions is considered key to the formation of protective memory B cell responses. However, how the anti-PfCSP memory B cell response matures in humans is not known. To address this question, the clonal evolution of the human anti-Pf CSP memory B cell response over three successive controlled Pf infections under chemoprophylaxis was assessed at single cell level by high throughput paired full-length Ig gene sequencing and recombinant monoclonal antibody production. The work provides basic insights in the longitudinal development of human memory B cell responses and identified germline-encoded Ig gene features that were associated with high anti-CSP affinity and Pf inhibitory antibody activity. The clonal selection of germline B cells expressing such antibodies, rather than affinity maturation, was associated with high quality anti-PfCSP memory B cell responses. The data provide insights into the evolution of antibody response to a complex protein antigen during infection and a strong rational for the design of novel CSP immunogens to target naïve B cell precursors expressing potent anti-CSP antibodies for the induction of protective memory B cell responses by vaccination.
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Amanfo, Seth Appiah. "Parasite and host factors that drive heterogeneity in human malaria." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31238.
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Malaria affects over half of the world's population and causes half a million deaths annually, especially in Sub-Saharan Africa. Four species of the apicomplexan Plasmodium parasite (P. falciparum, P. ovale, P. malariae and P. vivax) are responsible for malaria in Africa. Both parasite and host factors contribute to heterogeneity in the risk of developing malaria, clinical manifestation of the disease as well as the number of treatments required to clear parasites. The epidemiology of the different species, and the role of exposure to mixed-species Plasmodium co-infections in generating heterogeneity remains poorly studied. Being an obligate intracellular parasite the blood-stage life cycle of the Plasmodium parasite takes place in the erythrocytes of the human host. The surfaces of these erythrocytes are the medically important ABO blood group antigens that have been reported to influence the susceptibility or otherwise of an individual developing severe malaria. In this thesis I have considered the contributions of the species of Plasmodium parasites and the ABO blood group of the host in driving heterogeneity in human malaria. The aims of this thesis were to determine: (i) the seroepidemiology of the different Plasmodium species in two mesoendemic African populations (Zimbabwe and Sudan); (ii) to determine if heterogeneity in clinical presentations of malaria (history of fever, body temperature and parasitaemia) and response to drug treatment is related to exposure to single vs. mixed-Plasmodium species infection; (iii) the spatial and temporal dynamics of malaria prevalence and Plasmodium species distribution in a mesoendemic village in eastern Sudan; (iv) gene expression changes in 3D7 P. falciparum parasites as they infect erythrocytes of different ABO blood group donors. For aims (i to iii) I developed an enzyme-linked immunosorbent assay using antigens derived from Plasmodium merozoite surface protein 1, also known as MSP-119, to detect IgG antibodies to all four malaria parasite species in Zimbabwean and Sudanese populations. In the Zimbabwean study, plasma samples from 100 individuals each (aged 5-18 years) from three villages (Burma Valley, Mutoko and Chiredzi) were screened for exposure to Plasmodium parasites. In Daraweesh, Sudan, plasma samples from 333 individuals (aged 1-74 years) who had experienced a first malaria episode between 1990 and 2000 were recruited into the study. For study aim (iv) I cultured a single clone of 3D7 P. falciparum parasite using erythrocytes of individuals of different ABO blood group types, harvested parasite RNA and sequenced it to determine gene expression changes in the different hosts. I showed that human IgG antibodies to MSP-119 antigens of the four Plasmodium species are species-specific and do not cross-react. In both study populations almost all antibody responses involved P. falciparum, and single-species responses were almost exclusively directed against P. falciparum antigens. Mixed-species responses accounted for more than a third of responses, and were associated with chloroquine treatment failure, with significantly high proportion of individuals with mixed-species infections requiring repeated treatment with chloroquine/sulfadoxine-pyrimethamine for parasite clearance. This finding highlights the need for a sensitive method for detecting mixed-species malaria infections to enable the assessment of the true prevalence and magnitude of the disease burden caused by the non-falciparum species in endemic populations. Drug treatment failures associated with mixed species infections have significant impact on malaria morbidity and mortality. Treatment failure or partial parasite clearance has the potential to allow dormant liver stages of P. vivax and P. ovale to become a source of parasite reservoir for onward transmission. Furthermore, untreated low-grade chronic infections caused by P. malariae have been reported to cause systemic diseases many years after the primary infection. Spatial analysis of malaria epidemiology showed that malaria parasite transmission in Daraweesh was focal, and that infections are not randomly distributed in the village. Two space-time clusters of significantly increased malaria risk were identified (1993- 1999, and 1998-1999) with marked variations between households, but little or no variation in the species of Plasmodium over time. Similarly, multiple significant clusters were identified for the parasite species; three for P. falciparum, two for P. vivax and P. malariae, and one for P. ovale. These clusters had overlapping time frames, with some of the species significantly infecting the same households. This suggests that even in a small geographic area malaria transmission shows heterogeneity, and that such data can provide useful information to guide malaria control efforts. Finally, I demonstrated that 3D7 P. falciparum parasite growth was similar in the erythrocytes of different blood group donors, and provide preliminary data to show that the non-coding RNA gene, PF3D7_1370800, is differentially expressed in blood group A donors relative to blood groups B and O donors. Further research is needed to better understand the role of this gene in malaria pathology. All together, these findings will aid malaria researchers and other stakeholders in making informed choices about tools for diagnosing Plasmodium species, and control programmes targeting eradication of malaria caused by all Plasmodium species, as is the case of incorporating these findings into current malaria research in Sudan.
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Holton, S. J. "Structural and functional studies of Plasmodium falciparum protein kinase 5 and Cks proteins." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270634.
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Wesolowski, Amy. "Quantifying Human Movement Patterns for Public Health." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/329.
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Human travel affects important processes in public health and infectious disease dynamics. Refined spatial and temporal data are needed to accurately model how the dynamics of human travel contribute to epidemiological patterns of disease as well as access to healthcare resources. Here, I address a number of key issues related to modeling human mobility patterns and applications for understanding the spatial spread of infectious diseases and geographic access to public health resources. Using large sources of behavioral data anonymously collected from mobile phones within two African countries, I first analyze the utility of these data to quantify human mobility patterns as well as the usefulness of common modeling frameworks. Then I compare these data to two more common sources of human travel data: the national census and a comprehensive travel survey. Next, I use these data to assess the impact of human travel on the movement of malaria parasites. The final component of my thesis focuses on the utility of this data source to generally understand the role of geographic isolation on travel patterns to better understand the disparity between areas with various levels of access to public resources and the uptake of preventative healthcare such as immunizations and antenatal care.
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Chang, Hsiao-Han. "Genomic variation and evolution of the human malaria parasite Plasmodium falciparum." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10774.
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Malaria is a deadly disease that causes nearly one million deaths each year. Understanding the demographic history of the malaria parasite Plasmodium falciparum and the genetic basis of its adaptations to antimalarial treatments and the human immune system is important for developing methods to control and eradicate malaria. To study the long-term demographic history and recent effective size of the population in order to identify genes under selection more efficiently and predict the effectiveness of selection, in Chapter 2 we sequenced the complete genomes of 25 cultured P. falciparum isolates from Senegal. In addition, in Chapter 3 we estimated temporal allele frequencies in 24 loci among 528 strains from the same population across six years. Based on genetic diversity of the genome sequences, we estimate the long-term effective population size to be approximately 100,000, and a major population expansion of the parasite population approximately 20,000-40,000 years ago. Based on temporal changes in allele frequencies, however, the recent effective size is estimated to be less than 100 from 2007-2011. The discrepancy may reflect recent aggressive efforts to control malaria in Senegal or migration between populations.
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Gardner, Jason Paul. "Surface changes to human erythrocytes on infection by Plasmodium falciparum malaria." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:5ecd0f5c-8189-4731-a643-d6cf9463e4e5.
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Of the four Plasmodium species which cause malaria in humans, P. falciparum is responsible for the majority of the morbidity and mortality associated with this disease. The surface expression of parasite-derived proteins in the middle of the asexual cycle coincides with two important modifications of the host erythrocyte. First, a protective immune response is directed against a family of variant antigens, known as P. falciparum Erythrocyte Membrane Protein-1 (PfEMPl). Second, ligands are detected at the surface which mediate the specific cytoadherence of infected erythrocytes to vascular endothelium, such that infected cells are sequestered away from the peripheral circulation in deep vascular beds. The potentially fatal syndrome known as cerebral malaria can ensue when infected cells sequester at high density in the brain. Indirect studies have shown that the antigenic and adhesive phenotypes at the surface are linked to the expression of PfEMPl. However, there is a paucity of biochemical data which relate to PfEMPl, and this problem is addressed in this thesis. This study has confirmed, at the biochemical level, inferences from serology that clonal antigenic variation occurred rapidly. Variation produced a number of novel antigenic and adhesive phenotypes which were associated with unique forms of PfEMPl. Further insights into the mechanism of sequestration were possible because of the finding that single infected erythrocytes had the capacity to bind to at least three putative endothelial cell receptors; CD36, Intercellular Adhesion Molecule-1 (ICAM1), and Thrombospondin (TSP). It was demonstrated for the first time that PfEMPl was responsible for cytoadherence to CD36 and ICAM1, but was probably not involved in adhesion to TSP. Extensive analysis with sequence-specific proteases proved that adhesive interactions with each receptor were separable properties of the surface, and facilitated the proposal of a domain model for PfEMPl. Detailed analysis of the antigenic and adhesive phenotypes of a series of clonally-derived parasites demonstrated that infected cells expressing all variant antigenic types could adhere to CD36 whereas adhesion to ICAM1 was seen in a restricted subset. This may be clinically relevant if, as current data suggests, adhesion of infected cells to ICAM1 is important in the development of cerebral malaria. Identification of all ICAM1 binding phenotypes could lead to the design of novel therapeutic strategies for this life-threatening condition.
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Quinn, David John Sc D. Massachusetts Institute of Technology. "Dynamic behavior of healthy and malaria infected human red blood cells." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61586.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 116-125).
Hereditary hematological disorders and foreign organisms often introduce changes to the spectrin molecular network and membrane of human red blood cells (RBCs). These structural changes lead to altered cell shape, deformability, cytoadherence and rheology which may in turn, promote the onset of vaso-occlusive events and crises that may ultimately cause pain, stroke, organ damage and possibly death. Previous work by our group and others has shown that the RBC membrane exhibits reduced deformability as a manifestation of diseases such as malaria, spherocytosis, elliptocytosis and sickle cell anemia. However, much of this previous work has modeled the RBC membrane as a purely elastic material and experiments are typically performed within the quasistatic deformation regime. This work investigates the connection between disease, structure and function in a more physiologically relevant, dynamic context using two in-vitro experimental approaches: (1) dynamic force-displacement characterizations using advanced optical trapping techniques and (2) microfluidic flow experiments. A new set of dynamic optical trapping experiments are developed using an alternate loading configuration and a broader range of deformation rates (up to 100ptm/s) and forcing frequencies (up to 100Hz) than previously reported with optical trapping systems. Results from these experiments provide further support to recent suggestions that traditional constitutive descriptions of the viscoelastic behavior of the RBC membrane are not applicable to this wide range of deformation rates and frequencies. Initial results on RBCs infected with Plasmodium falciparum malaria suggest that the parasite and its related exported proteins act to increase the effective viscosity of the RBC membrane. The role of the temperature-dependent, viscous behavior of the RBC membrane is further explored in microfluidic flow experiments, where the flow behavior of RBCs is quantified in fluidic structures with length scales approaching the smallest relevant dimensions of the microvasculature (approximately 3pm in characteristic diameter). In particular, the role of a parasitic protein, the ring infected erythrocyte surface antigen (RESA), is investigated and determined to have a rate-dependent effect on microvascular flow behavior that has not previously been identified. Results from optical trapping and microfluidic flow experiments are used to inform and validate a collaborative effort aimed at developing a meso-scale, threedimensional model of microvascular flow using dissipative particle dynamics (DPD). This combination of modeling and experiments give new insight into the relative roles of fluid and membrane viscosity in microvascular flow. The results of this work may be used in the development of new constitutive behaviors to describe the deformation of the RBC membrane and to inform the design and optimization of microfluidic tools for blood separation and point-of-care diagnostic platforms. In addition, using the techniques developed here in further investigation of the roles of particular parasitic proteins may yield additional insight into the pathology of P.f. malaria that may, in turn, provide new avenues and approaches for treatment.
by David John Quinn.
Sc.D.
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Claessens, Antoine. "How Plasmodium falciparum malaria parasites bind to human brain endothelial cells." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4897.
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Cerebral malaria is characterised by an accumulation of infected erythrocytes in the microvasculature of the brain. Plasmodium falciparum infected erythrocytes have been shown to bind to a Human Brain Endothelial Cell line (HBEC-5i) in vitro. This provides a model for the investigation of interactions between P. falcuparum and human brain endothelium. Currently neither the parasite adhesion ligands on infected erythrocytes, nor the host endothelial cell receptors necessary for this interaction have been identified. In this work, the identity of the host receptor on brain endothelial cells was addressed by binding assays of selected and unselected parasites on a wide range of malaria-associated host molecules. The identity of the parasite ligand was investigated by microarray analysis of parasites after selection for cytoadherence to HBEC-5i. The hypothesis being tested was that the gene encoding the parasite cytoadherence ligand would show significant upregulation in selected compared to unselected paarasites. The P. falciparum laboratory strains 3D7, HB3 and IT/FCR3 were selected for binding to HBEC-5i using a panning assay. Compared to unselected parasites, HBEC-5i selected parasites showed a distinct phenotype with reduced platelet-mediated clumping. There was no significant increase in binding of parasites to any of the known endothelial cytoadherence receptors for P. falciparum after selection on HBEC-5i. Binding inhibition assays with various antibodies and soluble receptors did not greatly block the adhesion of parasites to HBEC-5i except for heparin. Altogether, the receptor(s) mediating the interation with HBEC-5i remains unknown. In order to carry out transcriptional analysis of selected and unselected paarasites form all three parasite strains, it was necessary to update the existing microarray chip which is based on the 3D7 genome. This is because each parasite train has a unique repertoire of variant surface antigens (VSAs) including var, rif and stevor genes. Therefore, to fully analysis HB3 and IT genomes. Unique oligonnucleotide probes were then designed for each new sequence and the 3D7-based microarray chip was updated. Transcriptional analysis was then carried out on selected and unselected parasites of all strains. Microarray data clearly indicated that the most highly upregulated genes after selection were group A or group A-like var genes (HB3var3, 3D7_PFDOO2Oc, ITvar7 and ITvar19), showing 11 to over 100 fold upregulation in selected parasites. The rif gene adjacent to the upregulated var gene was also highly expressed. To a lesser extent some exported proteins like RESA-1, PfEMP3 or PHIST family members also showed increased transcription in HBEC-selected parasites (2-3 fold upregulation). Reverse transcriptase-PCR confirmed the upregulation of group A var genes in selected parasites, suggessted that the group A PfEMP1 variants are major candidate ligands for parasite binding to HBEC-5i. These findings are consistent with previous work showing an association between Group A var genes and cerebral malaria.
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Van, Schalkwyk Donelly Andrew. "The interaction of verapamil with the human malaria parasite : Plasmodium falciparum." Doctoral thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/3303.
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Chan, Shiu-Wan. "Aspects of pyrimethamine resistance in the human malaria parasite Plasmodium falciparum." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/13353.
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Pyrimethamine is a commonly used drug in prophylactic and therapeutic treatment of human malaria caused by the parasite Plasmodium falciparum. It has been postulated that the mode of action of pyrimethamine is by inhibition of the enzyme dihydrofolate reductase (DHFR). This was tested genetically in the first part of the study using a cross between a pyrimethamine sensitive and a pyrimethamine resistant cloned line 3D7 and HB3. The results of restriction-fragment-length-polymorphism (RFLP) analysis on the pattern of pyrimethamine resistance inheritance in the progeny confirm that the mutation causing resistance to pyrimethamine in HB3 is closely linked to the dihydrofolate reductase-thymidylate synthetase (DHFR-TS) gene and may be located within it, as previously inferred from sequencing and biochemical results. Structural alterations to DHRF resulting from point mutation in the DHFR gene has been suggested as one way in which resistance to pyrimethamine might occur. However, it is possible that other mechanisms e.g. over-production of the enzyme DHFR may also be important. The second part of the study investigated this possibility. Quantification of the enzyme level revealed no differences between the parents of the cross, 3D7 and HB3. However, pyrimethamine resistant mutant T9/94 (M1-1) selected in vitro was found to produce twice as much protein as the sensitive parent clone T9/94, suggesting that over-production of the enzyme can increase resistance to pyrimethamine. Over-productionof the protein was also observed in a naturally occurring pyrimethamine resistance clone PR70/CB3. Since a mutant over-producing the enzyme was identified, it was decicded to initiate studies that would ultimately be able to assess the role of transcriptional control in pyrimethamine resistance. As a first step, the 5' flanking regions of the DHFR genes from 3D7 and HB3 were sequenced and their transcriptional start sites mapped. Minor variations in the two sequences were found. The relationship of the sequence variations to the RFLP used in the genetic analysis is discussed.
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Mangano, Valentina D. "Dissecting the complexity of human susceptibility to Plasmodium falciparum malaria : genetic approaches /." Doctoral thesis, Stockholm : Wenner-Gren Institute for Experimental Biology, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8310.
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Nantavisai, Kwannan. "The interaction between malaria parasites and human endothelial cells : single cell studies." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548795.
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Chaikuad, Apirat. "Comparative studies on the drug target proteins from two human malaria parasites." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503880.
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Purine nucleoside phosphorylase (PNP) and lactate dehydrogenase (LDH) from Plasmodium parasites are two potential targets for novel anti-malarial compounds. Whereas these enzymes have been well-characterised from the Plasmodium falciparum parasite, information on these enzymes from the similarly prevalent species, Plasmodium vivax, is very limited. This hinders the development of effective common anti-malarial compounds.
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Lucas, Stuart James. "Genetic manipulation and gene expression in the human malaria parasite Plasmodium falciparum." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405550.
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Kurniawan, Davy Putra. "Characterisation of the apicoplast transcripts in the human malaria parasite Plasmodium falciparum." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607909.
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Yim, Lim Brian Youn Sen. "The RhopH1/Clag gene family in the human malaria parasite Plasmodium falciparum." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1446012/.
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The obligate intracellular parasite Plasmodium falciparum causes the most severe forms of human malaria. Apical rhoptry organelles of invasive merozoites contain proteins that are instrumental to the intraerythrocytic development of the parasite. Our group has determined that the RhopHl protein of the high molecular mass rhoptry complex (RhopH) is encoded by genes of the highly-conserved clag (cytoadherence-linked asexual gene) family. In this study, the characterisation of the RhopH 1/Clag proteins is continued. It was ascertained that the family has five members in P. falciparum 3D7 (clag2, -3.1, -3.2, -£and -9), each of which is transcribed. Specific antibodies were raised to demonstrate that all Clags are expressed at the apical end of merozoites, but in an apparently differential distribution. Both Clag3.1 and Clag9 are found in the basal bulb of the rhoptries as part of the RhopH complex. However, Clag2, -3.2 and -8 appear to remain outside the complex and their distribution is distinctly more apical, potentially in the region of the rhoptry neck. It was determined that RhopH complexes contain only individual Clag members in a mutually exclusive association, thereby suggesting the existence of multiple complexes in which specificity is conferred by RhopH 1/Clag. Those Clag proteins that are part of the RhopH complex are carried into the newly invaded red blood cell where they persist. There is evidence to suggest that Clag3.1 and Clag9 are trafficked across the parasitophorous vacuolar membrane, and that their function is in the developing parasite. Clag9 is the most diverse member of the family and was originally proposed to be involved in the pathogenic process of cytoadhesion from the surface of the infected red blood cell. However, we have now identified it as a rhoptry protein. This may suggest that Clag9 is indirectly involved in cytoadherence within the cycle that follows erythrocyte invasion.
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Denloye, Titilola Ifeoma. "Characterization of a glycerophosphodiester phosphodiesterase in the human malaria parasite Plasmodium falciparum." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77090.
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Active lipid metabolism is a key process required for the intra-erythrocytic development of the malaria parasite, Plasmodium falciparum. Enzymes that hydrolyze host-derived lipids play key roles in parasite growth, virulence, differentiation, cell-signaling and hemozoin formation. Therefore, investigating enzymes involved in lipid degradation could uncover novel drug targets. We have identified in P. falciparum, a glycerophosphodiester phosphodiesterase (PfGDPD), involved in the downstream pathway of phosphatidylcholine degradation. PfGDPD hydrolyzes deacylated phospholipids, glycerophosphodiesters to glycerol-3-phosphate and choline. In this study, we have characterized PfGDPD using bioinformatics, biochemical and genetic approaches. Knockout experiments showed a requirement for PfGDPD for parasite survival. Sequence analysis revealed PfGDPD possesses the unique GDPD insertion domain sharing a cluster of conserved residues present in other GDPD homologues. We generated yellow fluorescent fusion proteins that revealed a complex distribution of PfGDPD within the parasite cytosol, parasitophorous vacuole and food vacuole. To gain insight into the role of PfGDPD, sub-cellular localization was modulated and resulted in a shift in protein distribution, which elicited no growth phenotype. Kinetic analyses suggest PfGDPD activity is Mg₂⁺ dependent and catalytically efficient at the neutral pH environment of the parasitophorous vacuole. Next, our aim was to determine the upstream pathway that provides deacylated glycerophosphodiesters as substrate for PfGDPD. We identified via bioinformatics, a P. falciparum lysophospholipase (PfLPL1) that directly generates the substrate. Knockout clones were generated and genotyped by Southern and PCR analysis. The effects of PfLPL1 knockouts on parasite fitness were studied, and the results showed that PfLPL1was not required for parasite survival and proliferation.Ph. D.
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Elahi, AEM Rubayet. "Proteome-wide Functional Profiling of Serine Hydrolases in the Human Malaria Parasite." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90181.
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The serine hydrolase (SH) enzyme superfamily is one of the largest and most diverse enzyme classes in eukaryotes and prokaryotes. The most virulent human malaria parasite Plasmodium falciparum has over 40 predicted serine hydrolases (SH). Prior investigation on a few of these have suggested their critical role in parasite biology. The majority of the SHs in P. falciparum have not been functionally characterized. Investigation of these uncharacterized SHs will provide new insights into essential features of parasite metabolism and possibly lead to new antimalarial targets. In this study, we have employed activity-based protein profiling (ABPP) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to functionally characterize SHs. In our effort to profile plasmodial SHs using ABPP, we have identified a human erythrocyte SH, acylpeptide hydrolase (APEH) in the developing parasites. This finding is the first report of internalization of host hydrolytic enzyme by the parasite. Treatment of parasites with an APEH specific triazole urea inhibitor, AA74-1, caused growth inhibition in parasites with poor potency in the first replication cycle, however, the potency dramatically increased in the second cycle. We show that this unique growth inhibition profile is due to the inability of AA74-1 to inhibit parasite-internalized APEH in vivo. These findings suggest that internalization of active APEH by the parasite is essential for parasite survival.
Lipases catalyze the hydrolysis of ester bonds of lipid species such as neutral lipids and phospholipids. Although roles of lipases in propagation, as well as virulence in various organisms, have been acknowledged, in P. falciparum lipases remain understudied. We combined LC-MS/MS with the SH-directed ABPP to identify lipases of SH superfamily in P. falciparum. We have identified 16 plasmodial SHs with putative lipase activity. Bioinformatics analysis of our identified lipases is consistent with our findings. We have screened a panel of various classes of SH inhibitors in a competitive ABPP. A plasmodial putative lipase was potently and specifically inhibited by human monoacylglycerol lipase inhibitor. This inhibition profile suggests it as a monoacylglycerol lipase which plays a role in releasing fatty acids from neutral lipid. This finding shows that how inhibitor screening can aid in building hypotheses on biological roles of an enzyme. Altogether, in this dissertation, we have presented a robust strategy of identifying and functionally characterizing SHs in P. falciparum, which opens the door to the discovery of new biological processes.Doctor of Philosophy
Malaria contributed to nearly a half a million deaths in 2017. The vast majority of malaria-related deaths are due to the parasite Plasmodium falciparum. This parasite resides inside human red blood cells (erythrocytes) and grows rapidly during a 48 hour cycle. There are over 40 serine hydrolase (SH) superfamily proteins in the parasite. Biological functions of the majority of SHs in the parasite remains unknown. Study on these SHs will provide new insights into parasite biology, and possibly present new antimalarial drug targets. We used chemical biology techniques to identify and functionally characterize parasite SHs. In one study, we show the parasite intenalized a human erythrocyte SH, acylpeptide hydrolase (APEH). We used an APEH-specific inhibitor to investigate the biological significance of internalized APEH in parasite biology. Treatment of the parasite with the inhibitor resulted in parasite growth inhibition suggesting internalization of APEH is essential for parasite survival. Lipases are enzymes that aid in break down of lipids and have shown to be crucial for growth and pathogenicity in various organisms. Lipases and lipid catabolism remain understudied in the malaria parasite. We used mass spectrometry in our approach to identify 16 lipases in asexual parasites. We have also shown that screening with highly specific inhibitors can help in predicting biological function of a particular enzyme. In summary, in this body of work, we have presented an approach of studying SHs in the malaria parasite, which will provide new insights into parasite biology.
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Mulisa, Delesa Damena. "Dissecting the genetic bases of severe malaria resistance using genome-wide and post genomewide study approaches." Doctoral thesis, Faculty of Health Sciences, 2021. http://hdl.handle.net/11427/33890.
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P. falciparum malaria remains one of the leading public health problems worldwide. The global tally of malaria in 2018 was estimated at 228 million cases and 405, 000 deaths worldwide. African countries disproportionately carry the global burden of malaria accounting for 93% and 94% of cases and deaths, respectively. Even though most infected children recover from P. falciparum malaria, a small subset (~1%) of cases progresses to severe disease and death. Over the last decade, several genome-wide association studies (GWASs) have been conducted in diverse malaria endemic populations to understand the natural host protective immunity against severe malaria that can provide clues for the development of new vaccines and therapeutics. However, beyond identifying association variants, conventional GWAS approaches can't inform the underpinning biological functions. To bridge this gap, we applied various contemporary statistical genetic analytic approaches to malaria GWAS datasets of diverse malaria endemic populations. First, we accessed malaria resistance GWAS datasets of three African populations (N=~11,000) including Kenya, Gambia and Malawi from European Genome Phenome Archive (EGA) through MalariaGEN consortium standard data accession procedures. We explored the challenges of GWAS approaches in the genetically diverse Africa populations and figured out how various advanced statistical genetic methods can be implemented to address these challenges. We investigated single nucleotide polymorphism (SNP) heritability (h2 g) of malaria resistance in the Gambian populations and determined appropriate quality (QC) thresholds to accurately estimate the h2 g in our dataset. Second, we estimated h2 g in the three populations and partitioned the h2 g into chromosomes, allele frequencies and annotations using the genetic relationship-matrix restricted maximum likelihood approaches. We further created African specific reference panel from African population datasets obtained from 1000 Genomes Project and African Genome Variation Project dataset and computed linkage disequilibrium (LD). We used LD information obtained from these reference panels to compute cell-type specific and none cell-type specific enrichments for GWAS-summary statistics meta-analyzed across the three populations. Our results showed for the first time that malaria resistance is polygenic trait with h2 g of ~20% and that the causal variants are overrepresented around protein coding regions of the genome. We further showed that the h2 g is disproportionately concentrated on three chromosomes (chr 5, 11 and 20), suggesting cost-effectiveness of targeting these chromosomes in future malaria genomic sequencing studies. Third, we systematically predicted plausible candidate genes and pathways from functional analysis of severe malaria resistance GWAS summary statistics (N = 17,000) meta-analyzed across eleven populations in malaria endemic regions in Africa, Asia and Oceania. We applied positional mapping, expression quantitative trait locus (eQTL), chromatin interaction mapping and gene-based association analyses to identify candidate severe malaria resistance genes. We performed network and pathway analyses to investigate their shared biological functions. We further applied rare variant analysis to raw GWAS datasets of three malaria endemic populations including Kenya, Malawi and Gambia and performed various population genetic structures of the identified genes in the three endemic populations and 20 world-wide ethnics. Our functional mapping analysis identified 57 genes located in the known malaria genomic loci while our gene-based GWAS analysis identified additional 125 genes across the genome. The identified genes were significantly enriched in malaria pathogenic pathways including multiple overlapping pathways in erythrocyte-related functions, blood coagulations, ion channels, adhesion molecules, membrane signaling elements and neuronal systems. Furthermore, our population genetic analysis revealed that the minor allele frequencies (MAF) of the SNPs residing in the identified genes are generally higher in the three malaria endemic populations compared to global populations. Overall, our results suggest that severe malaria resistance trait is attributed to multiple genes that are enriched in pathways linked to severe malaria pathogenesis. This highlights the possibility of harnessing new malaria therapeutics that can simultaneously target multiple malaria protective host molecular pathways. In conclusions, this project showed that malaria resistance trait is mainly a polygenic trait which is influenced by genes and pathways linked to blood stage lifecycle of P. falciparum. These findings constitute the foundations for future experimental studies that can potentially lead to translational medicine including development of new vaccines and therapeutics. However, ‘-omics' studies including those implemented in this study, are limited to single datatype analysis and lack adequate power to explain the complexity of molecular processes and usually lead to identification of correlations than causations. Thus, beyond singe locus analysis, the future direction of malaria resistance requires a paradigm shift from single-omics to multi-stage and multi-dimensional integrative multi-omics studies that combines multiple data types from the human host, the parasite, and the environment. The current biotechnological and statistical advances may eventually lead to the feasibility of systems biology studies and revolutionize malaria research.
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Abimbola, Taiwo. "Malaria, Labor Supply, and Schooling in Sub-Saharan Africa." Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/588.
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The purpose of this study is to evaluate the causal effects of malaria and poor health in general on economic outcome in Sub-Saharan Africa. This study uses panel data from the Living Standard Measurement Survey (LSMS) for Tanzania from 1991 to 2004. Three main hypotheses are tested. First, the study evaluates the effect of malaria and other chronic illnesses on labor supply using the number of hours worked per week as a measure of outcome. Second, it determines the impact of poor health on human capital accumulation by measuring the number of weekly school hours lost to illness. The third objective deals with the question of whether changes in preconditioning factors such as income levels and healthcare accessibility have improved the disease environment in Sub-Saharan Africa over time.
The study uses several identification strategies in the empirical estimation process. The first estimation strategy applies the standard Ordinary Least Squares (OLS) and Fixed Effects (FE) estimators to the schooling and labor supply models. In addition to OLS and FE, the preferred methods of estimating the causal effects of malaria on schooling and labor supply outcomes are Two Stage Least Squares (2SLS) and Limited Information Maximum Likelihood (LIML). Findings in this study suggest that malaria significantly increases school absenteeism. In particular, 2SLS and LIML estimates of the number of school hours lost to malaria suggests that children sick with malaria are absent from school for approximately 24 hours a week. However, the results show the effect of malaria on work hours is inconclusive. Furthermore, difference in difference estimates of the disease environment show slight improvements in the disease environment resulting from changes in income levels. The study finds no statistically significant improvements in the disease environment due to increases in the number of health facilities over time.
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Cenni, Bruno. "Pharmacological aspects of malaria chemotherapy : interactions of the antimalarial drug halofantrine with human blood cells, serum proteins and Plasmodium falciparum parasitised red blood cells /." [S.l. : s.n.], 1994. http://www.gbv.de/dms/bs/toc/159397723.pdf.
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Meaden, Cora S. J. "Genetic determinants of gametocyte sex ratio in the human malaria parasite Plasmodium falciparum." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4700/.
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The aim of this study was to investigate the genetic basis of variation in gametocyte sex ratio in the human malaria parasite, Plasmodium falciparum. The gametocyte sex ratio was measured in progeny clones from the 3D7 x HB3 experimental genetic cross and found to be remarkably stable across replicates of different parasite clones. Significant differences in the sex ratio were observed between the parents of the cross. Progeny clones fell into two classes of sex ratio, one similar to that seen in parent 3D7 and the other like parent HB3, suggesting a single gene of major effect controlling sex ratio. Using a genetic map of the progeny and parental clones, QTL analysis revealed two highly significant loci, the first on chromosome 10 (LOD score = 8.8), and the second on chromosome 14 (LOD = 4.0), linked to gametocyte sex ratio. The locus on chromosome 10, spanning approximately 35kb, contained ten genes. This locus, named PfROS1 (Plasmodium falciparum Ratio of Sex 1), explained 95% of the variation in sex ratio. The second locus on chromosome 14, PfROS2 (Plasmodium falciparum Ratio of Sex 2), explained a small proportion of gametocyte sex ratio variation when combined with PfROS1, the two loci explained 99% of the variation in gametocyte sex ratio observed. As PfROS1 explains such a high percentage of the variation observed in the gametocyte sex ratio it represents a single controlling locus to define the sex ratio of gametocytes produced. This is the first report of a genomic locus influencing gametocyte sex ratio in any Plasmodium species. In addition, changes in the sex ratio of clones 3D7 and HB3, over the course of 16 days of gametocyte culture were investigated. The number of gametocytes, and especially male gametocytes, was observed to fall markedly in the last few days of culture, when the majority of gametocytes were stage V (mature). Fluctuations in temperature during the culture process were found to influence sex ratio, suggesting the loss of males was due to exflagellation of mature gametocytes. Parasite clone and day of culture were also significant explanatory variables in influencing sex ratio.
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Read, Martin. "Investigations into aspects of central metabolism in the human malaria parasite Plasmodium falciparum." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/investigations-into-aspects-of-central-metabolism-in-the-human-malaria-parasite-plasmodium-falciparum(8db40369-5155-4f08-8326-eb262e50babd).html.
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This thesis combines four published research papers and a book chapter investigating aspects of central metabolism in the human malaria parasite Plasmodium falciparum. The publications are preceded by a statement which explores features of the research not fully described in the published texts, incorporates a review of the development over time and the present state of relevant scientific knowledge, and discusses the place of the individual papers and book chapter within malaria research. An assessment of the impact of each publication on its field of study is also included. A general discussion of the combination of papers as representative of the progress of research into the metabolism of malaria parasites concludes the statement section. The first publication is a chapter from a book, which describes detailed methods for the in vitro cultivation of P. falciparum. Such methodology, both robust and reliable, is a prerequisite for any investigation of parasite metabolism. The following publications are all primary research papers. The second publication describes the isolation and characterisation of the gene encoding the glycolytic pathway enzyme enolase from P. falciparum. The inferred amino acid sequence included peptide insertions found only in the enolases of higher plants and other photosynthetic organisms. This raised implications concerning the deep evolutionary history of the malaria parasite and related species. The third is concerned with the elucidation of the molecular basis of resistance to the antimalarial drug sulfadoxine. Resistance was found to result from point mutations within the dihydropteroate synthetase domain of the bifunctional protein hydroxymethylpterin pyrophosphokinase-dihydroptero¬ate synthetase, an enzyme of the parasite folate pathway. Additionally, it was discovered that the presence of exogenous folate has an antagonistic effect on sulfadoxine in some parasites of a defined genotype. This highlighted the importance of folate salvage in parasite metabolism. Fourth is a paper representing the discovery of a novel metabolism in both P. falciparum and the related apicomplexan parasite Toxoplasma gondii. The use of parasite genes in rescuing an Escherichia coli tyrosine auxotroph resulted in a proof of function of the products of these genes as pterin-4a-carbinolaminedehydratases. Pterin recycling, hitherto undetected in apicomplexans, was therefore added to the known metabolic processes of these organisms. The final paper describes an investigation into the subcellular distribution of the folate pathway enzyme serine hydroxymethyltransferase (SHMT) within P. falciparum erythrocytic stage parasites. The use of confocal laser scanning microscopy and immunofluorescent techniques showed that SHMTc, the sole enzymatically active parasite SHMT protein, was found in the cytoplasm but also showed a stage-specific localisation to both the mitochondrion and apicoplast organelles. The otherwise enigmatic, enzymatically inert, SHMTm paralogue revealed a possible function, when in complex, in allowing targeted localisation of SHMTc to the mitochondrion. The spatial distribution of SHMTm also suggested a possible role in the morphogenesis of elongating apicoplasts during schizogony.
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Southworth, Paul. "Quantitative proteomics of the human malaria parasite, Plasmodium falciparum, applied to folate biosynthetic enzymes." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/quantitative-proteomics-of-the-human-malaria-parasite-plasmodium-falciparum-applied-to-folate-biosynthetic-enzymes(3ba6c57f-3f37-443d-92d9-b255722e3f69).html.
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Human malaria caused by Plasmodium falciparum is a major global burden killing between 700,000 and 2.7 million people every year. Africa bears the greatest portion of this burden, with over three quarters of deaths occurring in African children, accounting for 18% of all child deaths in sub-Saharan Africa. Synthesis of tetrahydrofolate through the folate biosynthetic pathway is vital for the survival of P. falciparum parasites and is lacking in the human host. As such, enzymes of this pathway have long presented attractive targets for drug therapy and although increasingly being compromised by resistance, anti-folates such as pyrimethamine and sulfadoxine are still very valuable drugs in many malaria-endemic regions.In this project, further investigation of the enzymes of the folate biosynthetic pathway has been attempted by developing protocols to quantify these proteins and others through proteomic techniques. Two quantification techniques were pursued. The first was quantification using whole, heterologously expressed, stable-isotope labelled forms of P. falciparum proteins for use as heavy standards in mass spectrometry. Great difficulty was experienced in the effort to express and purify P. falciparum enzymes in E. coli expression systems, with only one enzyme successfully expressed and purified in a 13C-labelled form. This one protein was taken forward into quantification experiments. The second quantification technique used a stable-isotope labelled ‘QConcat’ protein, consisting of a number of peptides from 12 P. falciparum proteins of interest, as a heavy standard in mass spectrometry. This was successfully expressed and purified in a 13C-labelled form from an artificial gene using an E. coli expression system. This too was taken forward into quantification experiments.Quantification experiments using the QConcat-based quantification technique were successfully performed on whole P. falciparum extract. Among the proteins quantified were SHMT and DHFR, two proteins of great interest from the folate biosynthetic pathway. Consistent with results from different expression analysis techniques in the literature, the folate enzymes were found to be of lower abundance than housekeeping enzymes and SHMT was found to be more abundant than DHFR.For deep quantitative analysis of the P. falciparum proteome, it was found that fractionation was necessary. Fractionation in this project was performed using a ZOOM™ IEF fractionator (Invitrogen), an OFFGEL™ IEF fractionator (Agilent) and 1D SDS-PAGE. It was found that by using these fractionation techniques, more proteins could be identified within the P. falciparum proteome, with all but one of the enzymes of the folate biosynthetic pathway being identified. Significant advances in the sensitivity of mass spectrometers during this project have also greatly facilitated the investigation of the proteome. In some cases, this meant that proteins which were only previously accessible by prefractionation of the proteome could be seen in whole P. falciparum extract. Unfortunately, QConcat-based quantification using both fractionation and sensitive mass spectrometry could not be successfully achieved in the time available. However, the promising results obtained suggest that, after careful optimisation, such an approach will be valuable.
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Dittrich, Sabine. "Studies on the folate and biopterin pathway in the human malaria parasite Plasmodium falciparum." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491859.
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Crick, Alex James. "Live imaging studies of the interactions of the malaria parasite with the human erythrocyte." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708165.
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Lieber, Matthew Joshua. "Immunological Crosstalk between Human Transforming Growth Factor-β1 and the Malaria Vector Anopheles stephensi." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/42816.
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The emergence of pesticide-resistant mosquitoes and drug-resistant parasites in the last twenty years has made control of malaria more difficult. One novel strategy to better control malaria is the development and release of transgenic mosquitoes whose enhanced immunity prevents transmission of the parasite to the mammalian host. One candidate effector gene is Anopheles stephensi nitric oxide synthase (AsNOS), whose inducible expression and subsequent synthesis of nitric oxide (NO) limits Plasmodium development in A. stephensi.
In mammals, one of the most potent physiological regulators of NOS gene expression and catalytic activity is transforming growth factor-β (TGF-β). Moreover, human TGF-β can activate Drosophila melanogaster Smads, the proteins responsible for TGF-β signal transduction. We have determined that following a bloodmeal, active human TGF-β1 (hTGF-β1) persists in the midgut of A. stephensi for up to 48 hours. My data demonstrate that the midgut epithelium recognizes hTGF-β1 as an immunomodulatory cytokine. Specifically, induction of AsNOS by hTGF-β1 occurs in the midgut within minutes of bloodfeeding. Moreover, hTGF-β1 limits development of the human malaria parasite Plasmodium falciparum in the midgut. In other experiments, provision of the AsNOS catalytic inhibitor L-NAME partially reverses the effect of hTGF-β1 on Plasmodium development. These results suggest that AsNOS is a target of hTGF-β1 signaling and additional effectors that impact parasite development may be regulated by hTGF-β1 as well.
The fact that hTGF-β1 signals mosquito cells to limit malaria parasite development suggests that there is an endogenous TGF-β signaling network in place. An analysis of the A. gambiae genome database revealed the presence of six TGF-β ligands, including gene duplication in the 60A gene, the first evidence of ligand gene duplication outside of chordates. In addition to five receptors, three Smads were identified in the A. gambiae genome predicted to support TGF-β/Activin- and BMP-like signaling. Midgut epithelial cells and an immunocompetent A. stephensi cell line express all three Smads, confirming that a signaling pathway is in place to support signaling by divergent exogenous and endogenous TGF-β superfamily proteins.
The results presented here provide the first evidence of immunological crosstalk between divergent free living hosts of a single parasite. Further, these results imply that the interface between mammals and the mosquitoes that feed on them provide a unique opportunity for circulating molecules in the blood, including TGF-β and other cytokines, to alter the mosquito immune response.Master of Science
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Henriques, G. "Exploring the contribution of new genetic markers of drug resistance in human malaria parasites." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2015. http://researchonline.lshtm.ac.uk/2212899/.
Full textAbstract:
Antimalarial drugs remain as one of the most powerful tools in the fight against malaria with artemisinin derivatives now standing as the cornerstone of anti-malarial drug therapy. Unfortunately, evidence of delayed in vivo parasite clearance after artemisinin treatment is accumulating on the Thai-Cambodian border and in nearby countries. A better understanding of the mechanisms of artemisinin (ART) resistance may contribute to the development and validation of new tools for the surveillance of resistance. One promising approach to identifying candidate genetic markers of ART resistance is genetic analysis of drug-pressured mutants of the rodent malaria parasite Plasmodium chabaudi. This experimental system has identified a number of genetic mutations in parasites artificially selected for resistance to ART derivatives. These mutations encode alterations in a de-ubiquitinating enzyme (UBP-1) and in a 26S proteasome subunit (26SPS), both involved in the ubiquitin-proteasome pathway, responsible for protein turnover through selective degradation. An additional mutation was found to have occurred in a gene encoding the “mu” chain of the AP2 adaptor protein complex, a component of the endocytic machinery. The importance of the above mentioned markers in modulating susceptibility to different drugs in the human malaria parasite remains unclear. In that context, the hypothesis to be tested in this thesis is that the three loci implicated in ART resistance in experimentally selected in P. chabaudi will similarly modify ART response in natural parasite populations of P. falciparum. Increased artemisinin resistance in a P. chabaudi parasite derived from a chloroquine resistant parasite after prolonged and progressive artemisinin selection was phenotypic and genetically characterized. The whole genome sequencing identified a mutation in a gene encoding the mu chain of the AP2 adaptor protein complex. To explore the genetic variability of the ap2-mu gene in P. falciparum and its associations with artemisinin in vitro responses we sequenced field isolates from Brazil, São Tomé and Rwanda. Analysis of P. falciparum field isolates showed a weak association between a Ser160Asn mutation and in vitro dihydroartemisinin responses. To investigate the correlation between polymorphisms in pfubp-1 and pfap2-mu and in vivo parasite susceptibility to ART we genetically characterized samples from an ACT clinical trial carried out in Kenya. Previously work done on the same ACT clinical trial samples described sub-microscopic persistent parasites on day 3 post-treatment samples. These parasites were only detected by qPCR but the children carrying these parasites had a higher transmission potential and were far more likely to go on to classical treatment failure at day 28 or day 42 post-treatment. The molecular work carried out here demonstrates that a Ser160Asn/Thr mutation in the pfap2-mu gene and an E1528D mutation in the pfubp-1 gene might be associated with in vivo responses to artemisinin derivatives. Polymorphisms on the pfubp-1 gene and pfap2-mu genes were further studied using field isolates from an ACT clinical trial in Burkina-Faso which were also tested in vitro for their response to dihydroartemisinin and several other antimalarial drugs. Using these samples, we also investigate the genetic polymorphisms of the pf26S-protSU, another drug resistant candidate gene identified in the studies of P. chabaudi. Data revealed that polymorphisms in pfubp1 and pf26S-protSU, can modulate in vitro responses to lumefantrine. However, this work did not reveal any significant association between polymorphisms in pfubp-1 and pfap2-mu genes and in vitro artemisinin susceptibilities or treatment outcomes. In order to validate the pfap2-mu candidate marker as an important modulator of parasite sensitivity to artemisinins and to improve understanding of the biological mechanisms of resistance to this class of drugs we further performed gene functional characterization using transfection techniques. Transgenic parasites carrying the 160Asn allele of pfap2-mu were significantly less sensitive to dihydroartemisinin using a standard in vitro test. Sensitivity to chloroquine and quinine were also reduced. Localization studies of pfap2-mu were performed by transfection of fluorescent-tagged gene construct into P. falciparum and expression of fluorescent fusion protein in parasites was observed using a confocal microscope. The findings from this study provide the first in vivo evidence that polymorphisms in the pfap2-mu and pfubp-1 genes modulate P. falciparum responses to artemisinins. Additionally, transgenic laboratory lines of P. falciparum carrying the 160Asn mutation in pfap2-mu gene have altered in vitro responses to dihydroartemisinin, quinine and chloroquine. We therefore propose these genes should be evaluated further as potential molecular markers of artemisinin resistance.
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Villegas, Luis Eduardo Martínez. "Genomic study of Anophe les (Nyssorhynchus) aquasalis, Curry 1932. A Neotropical human malaria vector." s.n, 2015. https://www.arca.fiocruz.br/handle/icict/13660.
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Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brasil
A malária humana é uma doença provocada por parasitas do gênero Plasmodium, os quais na natureza requerem de um mosquito anofelíno para completar o seu ciclo de vida e serem transmitidos a um hospedeiro humano. Nas Américas, o Brasil tem a maior incidência de malária, sendo responsável por 41% dos casos. Com o aparecimento do sequenciamento de nova geração e das ferramentas bioinformática relacionados, grandes avanços foram alcançados em relação à montagem de genomas e transcriptomas de anofelinos, assim como na exploração de estratégias de paratransgenesis para interromper a transmissão da malária. No entanto, os vetores neotropicais da malária encontram-se longe dos vetores da África e Ásia no que refere a estes conhecimentos. Este estudo é parte de um esforço contínuo para montar o genoma do Anopheles aquasalis, um vetor neotropical da malária humana, que atualmente posiciona-se como um excelente modelo de transmissão da malária no Brasil. Em paralelo ao sequenciamento do genoma, e para maximizar os dados gerados, optamos por focar em duas tarefas pontuais e viáveis: explorar a diversidade e composição do consórcio bacteriano associado ao anofelino; assim como montar e caracterizar o genoma mitocondrial desta espécie. O sequenciamento metagenômico shotgun ̈e o programa MG-RAST foram utilizados para fazer um ̈screening ̈ das bactérias associadas à pupas de A .aquasalis criadas em laboratório. O consórcio bacteriano predito é composto por 74 gêneros contendo bactérias marinhas e bioluminescentes. No nível taxonômico de família bacteriana, identificamos 14 OTUs compartilhadas entre anofelinos americanos e africanos. Além disso, foram comparadas cinco comunidades bacterianas associadas a duas espécies de anofelinos: A. aquasalis e Anopheles gambiae. Foi identificada uma associação significativa (NPMANOVA p <0,05) entre a composição da comunidade bacteriana e o ambiente aquático laboratório ou condições semi-naturais) nas quais cada hospedeiro anofelino foi criado. Atualmente, o entendimento da filogenia do gênero Anopheles é limitado e as informações sobre o tempo de divergência de dentro da linhagem de mosquitos é escassa. Apresentamos a sequencia de 15,393 pb correspondente ao genoma mitocondrial de A. aquasalis. Quando comparado com outros mitogenomas anofelinos relevantes, observou-se alta similaridade na composição dos genomas assim como características estruturais conservadas. Através de análises Bayesianas, reconstruímos as relações filogenéticas e estimamos a data de divergência entre 22 anofelinos e outras espécies de dípteros. Descobrimos que o mais recente ancestral entre as subfamílias Nyssorhynchus e Anopheles + Cellia existiu ~ 83 milhões anos atrás (MYA). Estimou-se que A. aquasalis divergiu do complexo do Anopheles albitarisis faz ~ 28 MYA, e faz ~ 38 MYA do Anopheles darlingi. A distribuição estreita e o peculiar nicho ecológico do A. aquasalis, além de considerar a sua adaptação a ambientes larvários com água salobra fizeram nos perguntar se a sua história evolutiva deixou uma marca na arquitetura do seu genoma, assim como sobre a estrutura da comunidade bacteria na associada a este anofelino.
Human malaria is a malady caused by Plasmodium parasites, which in nature, require an anopheline mosquito to complete their life cycle and be transmitted to a human host. In the Americas, Brazil has the largest incidence of malaria, accounting for 41% of the cases. With the advent of Next Generati on Sequencing and related bioinformatics’ tools, great leaps forward were attained regarding the assembly of anopheline genomes, transcriptomes; in addition to the exploration of paratransgenesis as means to interrupt malaria transmission. Nonetheless, Neotropical malaria vectors still lag behind those from Africa and Asia on such matters. This study is part of an ongoing effort to assemble the genome of Anopheles aquasalis , a Neotropical human malaria vector currently positioned as a key malaria transmission model in Brazil. In parallel to the genome sequencing study, and to maximize the NGS sequencing data generated, we opted to focus in two punctual a nd feasible tasks: exploring the diversity and composition of this anopheline’s associated b acterial consortium; plus, assemblying and characterizing, the mitochondrial genome of this species. Shotgun metagenomic sequencing and the MG-R AST suite were used to survey the bacteria associated to laboratory reared A. aquasalis pupae. The predicted bacterial consortium is composed of 74 genera and contai ns marine and biolumines cent bacteria. At the bacterial family rank, we identified 14 OTUs shared between African and American anophelines. In addition, we compared five Anopheles associated bacterial communities from two species: A. aquasalis and Anopheles gambiae . We found a significant association (NPMANOVA p < 0.05) between the bacteria l community composition and the aquatic environment (laboratory or semi-natural conditions) in which each Anopheles host was reared. The current understanding of the Anopheles phylogeny is limited and information regarding the time of deep lineage divergences w ithin mosquitoes is scarce. Here we also present the assembled 15,393 bp mitochondrial genome of A. aquasalis . When compared with other relevant anopheline mitogenomes, high com position similarity and conserved features were observed. Through Bayesian analyses, we reconstructed the phylogenetic relationships and estimated the date of divergence between 22 anopheline and other dipteran species. We found that the most r ecent ancestor between Nyssorhynchus and Anopheles + Cellia subfamilies was extant ~83 million y ears ago. It was estimated that A. aquasalis diverged from the Anopheles albitarisis complex ~28 MYA and ~38 MYA from Anopheles darlingi . The narrow distribution and peculiar niche of A. aquasalis , plus considering its adaptation to brackish-water larval environments makes us wonder if its evolutionary history left a mark upon its genome architecture, and also on the bacterial community structure associated to it.
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Birkholtz, Lyn-Marie. "Molecular characterisation of the ornithine decarboxylase gene of the human malaria parasite, plasmidium falciparum." Diss., University of Pretoria, 1998. http://hdl.handle.net/2263/37299.
Full textAbstract:
Malaria is one of the most serious tropical infectious diseases affecting mankind. The
prevention of the disease is hampered by the increasing resistance of the parasite to
existing chemotherapy and -prophylaxis drugs. The need for novel therapeutic targets
and drugs is therefore enormous and the understanding of the biochemistry of the parasite
is imperative. The aim of this study was the identification and molecular characterisation
of the eDNA of one such metabolic target protein, ornithine decarboxylase (ODC), in the
human malaria parasite P. falciparum.
The P. falciparum ODC eDNA was isolated by means of a modified RT-PCR technique,
RACE. No sequence data were available and the primers used were based on consensus
areas identified in the protein sequences from other related organisms. The isolation and
identification of the eDNA with degenerate primers was successful in 3' -RACE, but
necessitated the optimisation of the eDNA synthesis protocol and the use of total RNA as
starting material. The sequence obtained facilitated the application of 5' -RACE with
ODC-specific primers based on the 3' -RACE sequence data. The full-length ODC
eDNA sequence was obtained by overlap-alignment of various segments. A novel
suppression PCR technology was applied during the 5' -RACE in order to create an
uncloned eDNA library of amplified cDNAs representing only the mRNA population. The P. falciparum ODC eDNA contains an open reading frame of ---2847 bp and
translates to a large 939 amino acid protein. The protein contained large internal
insertions and was extended by '""273 N-terminal residues compared to ODCs from other
organisms. Several possible signature motifs were identified for phosphorylation,
glycosylation and transamidation. The P. falciparum ODC protein seems to contain more
hydrophilic and a-helix forming residues. These characteristics should be further
investigated after expression of the recombinant protein.
The isolation of the P. falciparum ODC eDNA facilitates the validation of this protein as
an antimalarial target.Dissertation (MSc)--University of Pretoria, 1998.
gm2014
Biochemistry
unrestricted
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Alghamdi, Sultan Ahmed. "Genetic determinants of selectivity of erythrocyte invasion in the human malaria parasite Plasmodium falciparum." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6605/.
Full textAbstract:
The aim of this study was to investigate the genetic basis of selectivity in invasion of the red blood cells by the human malaria parasite Plasmodium falciparum. Multiple invasions of a single host red blood cell by more than one merozoite, which can be described or assessed in terms of the selectivity index (SI), has been reported to be related to the severity of malaria disease. In this study, selectivity index, defined as the ratio of the number of multiply-infected red cells observed to that expected from random invasion, as modelled by a Poisson distribution was determined for certain clones of P.falciparum. SI was measured under static and shaking culturing conditions for P. falciparum clones 3D7 and HB3 and 18 progeny clones derived from a genetic cross between these two parasite clones. P. falciparum clone 3D7 was found to have a significantly lower SI than HB3 under both static and shaking culture conditions. There was no relationship between SI and days in continuous culture for clone 3D7 under shaking and static conditions; the phenotype therefore appears to be stable over time. The genetic basis of the difference in selectivity index between P. falciparum clones 3D7 and HB3 was investigated in progeny clones from a cross between these two clones, to ascertain the inheritance pattern of the phenotype. Under static conditions, ten progeny clones had a selectivity index lower than either parent, one progeny clone had higher selectivity index than both parent, and six progeny clones had selectivity index intermediate between the parents . Under shaking conditions, fifteen progeny clones were observed to have a selectivity index lower than either parent. These observations suggest the involvement of more than one parasite gene in selectivity index. A Quantitative Trait Locus (QTL) analysis was performed in order to identify genomic regions influencing SI in the progeny clones. The highest LOD score of 5.06 was obtained for a QTL on chromosome 13 for SI measured in parasites cultured under shaking conditions. This QTL denoted, PF_SI_1, extends for approximately 100kb on chromosome 13 and contains 19 open reading frames. This finding indicates the presence of a gene or genes on chromosome 13 that influence the parasite’s selection of erythrocytes for invasion.
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Engels, Sonja [Verfasser], and Michael [Akademischer Betreuer] Lanzer. "The role of human Hsp70 for survival and development of the human malaria parasite Plasmodium falciparum / Sonja Engels ; Betreuer: Michael Lanzer." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1215414862/34.
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Krishnan, Sushma. "Investigating the interaction between rPvDBPII and duffy antigen on human erythrocytes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1427464747.
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