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Browsing Protocols 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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    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.