Browsing by Author "Seydel, Karl"

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    Identifying functional antibody responses that protect against malaria in children, version 1.0
    (Kamuzu University of Health Sciences, 2022-08-03) Rogerson, Stephen; Seydel, Karl
    Type of study: Observational cohort study The Problem: Although antibodies have been shown to be important for the protection against malarial disease, the specific characteristics of these protective antibodies have not been well delineated. Methodology: The study population of interest will be children aged 1-8 years of age drawn from three ongoing COMREC-approved studies. This is a secondary analysis of samples already being collected from three ongoing COMREC-approved studies. Children in the ongoing “Treatment of brain swelling in pediatric cerebral malaria” study (P. 09/16/2024, PI: Taylor) with cerebral malaria will be matched with children with uncomplicated malaria from the study “Characterization of Plasmodium falciparum var/PfEMP1 type and immune response to PfEMP1 in severe and uncomplicated clinical malaria” (P.01/15/1668, PI:Kim) and children with asymptomatic parasitemia from the “Malaria pathogenesis: Progression cohort and extremes, case control study” (P.11/18/2530, PI: Seydel). Children with no evidence of malaria infection in the “Malaria pathogenesis” study will be used as uninfected controls. After obtaining informed consent from their primary caretaker, a brief medical history and demographic information will be collected from all participants. Children with cerebral malaria are having a 10ml blood sample collected. Children in the uncomplicated and asymptomatic cohorts are having 4mls of blood collected. Plasma from this sample, as well as peripheral blood mononuclear cells from these samples will be purposed for this proposed study. No additional blood will be drawn for the purpose of this study. The serum from these studies will first be used in a Luminex assay to determine the strongest candidates that might be leading to protective immunity. Antibody and PBMC responses to these antigens will then be prioritized in the subsequent assays. These assays will involve the functional and biochemical characterization of antibodies in ~50 ways (see Research Strategy below). Comparison groups will be among the three disease severity types as well as between acute and convalescent sera. Data from these assays will be analyzed using elastic net regularized logistic regression and partial least squares discriminant analysis to identify the antibody characteristics associated with disease severity. Broad Objective: To identify the biophysical and functional characteristics of antibodies that protect against clinical malaria in children. Specific Objectives: 1) To use the Luminex bead approach to identify a subset of five P. falciparum expressed proteins that serve as targets of protection against cerebral malaria. To use the Systems Serology approach to identify biophysical and functional characteristics of antibodies against the targets identified in Aim 1, that either protect from cerebral malaria or develop during convalescence from cerebral malaria. 3) To use the Systems Serology approach to identify the biophysical and functional characteristics of antibodies that are present in children with asymptomatic P. falciparum infection and not in children with clinical disease. Expected Findings: We expect to find a subset of PfEMP1 domains, as well as a subset of proteins expressed on the merozoite stage of the parasite, that are most important in the protection of children from severe malaria. We also expect to find a distinct antibody profile that is most effective at controlling the P. falciparum infection. This will be accomplished by comparing the antibody characteristics seen in children with severe disease to those seen in children with milder infection, and (for the second question) comparing antibody responses in children with asymptomatic parasite infection to children with symptomatic malaria. Dissemination: Results will be disseminated to the medical community through peerreviewed publications and presentations at relevant scientific conferences. Results will also be shared with KUHeS at the annual Research Dissemination Conference. Annually, we will also be providing COMREC updates as required in the annual report.
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    Malaria breath biomarkers across the spectrum of malaria disease severity
    (2022-05-12) John, Audrey Odom; Seydel, Karl
    Type of study: Observational cohort study The Problem: The need for rapid, accurate, affordable, and non-invasive diagnostic methods for malaria remains urgent, particularly in peripheral health centers. Methodology: The study population of interest will be children aged 4-8 years drawn from two ongoing COMREC-approved studies at Queen Elizabeth Central Hospital in Blantyre. Fifty children in the ongoing “Treatment of brain swelling in pediatric cerebral malaria” study (P. 09/16/2024, PI: Taylor) with cerebral malaria will be matched with fifty children with asymptomatic parasitemia from the “Malaria pathogenesis: Progression cohort and extremes, case control study” (P.11/18/2530, PI: Seydel). Fifty children with no evidence of malaria infection in the “Malaria pathogenesis” study will be used as uninfected controls. After obtaining informed consent from their primary caretaker, a brief medical history and demographic information will be collected. For children with cerebral malaria (CM), breath will be collected through a mask with two one-way valves – allowing for inspiration through one valve and exhalation through a separate valve. Asymptomatic children and children confirmed to not have malaria by qPCR (controls) will provide exhaled breath gas samples after 5 minutes of sitting or lying quietly. A full breath will be exhaled into a small plastic device attached to an inflatable plastic bag. Once the exhaled breath is collected, the sample will be filter concentrated into a sorbet trap that absorbs nonpolar organic molecules. These samples can then be stored refrigerated and shipped at 4-6°C. A finger prick blood sample will be taken on a filter paper at the same time to be used for PCR quantification of asexual parasites and gametocytes. A nasopharyngeal swab will be taken from the children with CM to test for viral and bacterial respiratory pathogens. Following sample collection, children with CM will receive routine medical care for their malaria, including usual antimalarial therapy as warranted. The asymptomatic children will be tested for malaria with a mRDT and treated with standard anti-malarial therapy (LA) if found to be positive. The children with no evidence of malaria will also be tested by mRDT and treated with LA if found to be positive. The breath samples will be analyzed for VOCs by thermal desorption (TD) mass spectrometry. The mass spectrometry resource facility at Children’s Hospital of Philadelphia (CHOP) has successfully detected VOCs emitted by cultured malaria parasites (1) and in breath of Malawian children (2) and will again be engaged to seek these compounds in the breath from patient specimens. Objectives: To develop a novel non-invasive, rapid, accurate, reusable, and affordable malaria diagnostic method capable of detecting P. falciparum even at sub-mRDT parasitemias. This will be achieved through two specific aims:12-May-2022 Breath malaria biomarkers COMREC submission Version 1.2, 26 Feb 2022 Page 5 of 22 5 a) To collect and analyze breath from fifty children with asymptomatic malaria and fifty children without malaria infection to determine the possible presence of biomarkers able to distinguish these populations b) To collect and analyze breath from fifty children with cerebral malaria and simultaneously evaluate these children for the presence of respiratory pathogens, allowing us to characterize the possible role of respiratory pathogens in altering the malaria breathprint. Expected Findings: We hypothesize that VOCs will be detected in the breath of children with malaria even at the very low levels of parasite infection seen in many asymptomatically infected children. Furthermore, we hypothesize that co-infection with respiratory pathogens will shift the VOC profile – but that an underlying ‘breathprint’ can be identified that is malaria specific. These core VOCs can then be explored as novel biomarkers of malaria infection that could be used to screen for asymptomatic infection serving as the basis for future non-invasive malaria diagnostic devices. It is the hope that, in addition to being non-invasive, these devices could be portable, reusable, affordable, and accurate so that they could be used in rural health facilities and communities to identify the population of children who are asymptomatically infected and thus serving as a transmission reservoir. Dissemination: Results will be disseminated to the medical community through peer- reviewed publications and presentations at relevant scientific conferences. Results will also be shared with KUHeS at the annual Research Dissemination Conference. We will also report our findings and publications to COMREC
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    Molecular mechanisms in pediatric cerebral malaria pathogenesis and Immunity
    (Kamuzu University of Health Sciences, 2021-07-21) Seydel, Karl
    Type of Research Study: Prospective case control study Problem: Malaria, caused by the parasite P. falciparum, remains a significant public health problem in Malawi. Objectives: We plan to 1) determine which subset of parasites are responsible for binding to the microvessels of the brain and gut, and 2) investigate the role of lactate in altering the binding characteristics of parasitized erythrocytes to microvessels. Methodology: We have devised a novel 3D microvessel model that accurately mimics the flow velocity and wall shear stress present in the microvessels of the brain. We are able to create an in vitro model of the human brain microcirculation by forming very small 3D blood microvessels from primary human brain endothelial cells, thus accurately mimicking both the cellular and fluidic environment that a parasitized erythrocyte would encounter in the brain. We will use this 3D human brain microvessel model, as well as characterized parasites from malaria patients to investigate the receptors and milieu contributing to life-threatening cerebral malaria infections. Expected findings and dissemination: We anticipate finding a subset of parasites, those expressing a certain subset of PfEMP1 molecules on their surface, that are most adept at binding to brain endothelial cells. We anticipate that the innovative 3D microvessel model will elucidate parasite binding differences under certain flow-based, shear stresses that have not previously been appreciated, given previous models were unable to mimic physiologic flow and the curvature of a blood vessel wall. We also anticipate being able to use this unique model, in combination with known antibodies and shRNA techniques to determine the role of various proteins on the endothelial cell surface in mediating this binding. Moreover, we will determine if different subsets of parasites will adhere to brain and gut microvessels, which are the predominant organs of parasite accumulation in deadly malaria infections. Finally, we will be able to use this model to evaluate the role of external molecules, such as lactate, on infected erythrocyte binding in a physiologically relevant model system. Results will be disseminated in peer-reviewed journals, international conferences, the University of Malawi College of Medicine Research Dissemination Conference, and will be provided to COMREC and community leaders.