Antigenic cartography of immune responses to Recombinant DBLα tags from Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1).
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PROVIDER: PRJEB32811 | ENA |
REPOSITORIES: ENA
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Project description:Naturally acquired clinical immunity to Plasmodium falciparum is partly mediated by antibodies directed at parasite-derived antigens expressed on the surface of red blood cells which mediate disease and are extremely diverse. Unlike children, adults recognize a broad range of variant surface antigens (VSAs) and are protected from severe disease. Though crucial to the design and feasibility of an effective malaria vaccine, it is not yet known whether immunity arises through cumulative exposure to each of many antigenic types, cross-reactivity between antigenic types, or some other mechanism. In this study, we measured plasma antibody responses of 36 children with symptomatic malaria to a diverse panel of 36 recombinant proteins comprising part of the DBL? domain (the 'DBL?-tag') of PfEMP1, a major class of VSAs. We found that although plasma antibody responses were highly specific to individual antigens, serological profiles of responses across antigens fell into one of just two distinct types. One type was found almost exclusively in children that succumbed to severe disease (19 out of 20) while the other occurred in all children with mild disease (16 out of 16). Moreover, children with severe malaria had serological profiles that were narrower in antigen specificity and shorter-lived than those in children with mild malaria. Borrowing a novel technique used in influenza-antigenic cartography-we mapped these dichotomous serological profiles to amino acid sequence variation within a small sub-region of the PfEMP1 DBL? domain. By applying our methodology on a larger scale, it should be possible to identify epitopes responsible for eliciting the protective version of serological profiles to PfEMP1 thereby accelerating development of a broadly effective anti-disease malaria vaccine.
| S-EPMC6625739 | biostudies-literature
Project description:The malaria parasite Plasmodium falciparum employs antigenic variation of the virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1) to escape adaptive immune responses during blood infection. Antigenic variation of PfEMP1 occurs through transcriptional switches in the mutually exclusive expression of individual members of the multi-copy var gene family. var genes are located in perinuclear clusters of transcriptionally inactive heterochromatin. Singular var gene activation is linked to locus repositioning into a dedicated zone at the nuclear periphery and deposition of histone 3 lysine 4 di-/trimethylation (H3K4me2/3) and H3K9 acetylation marks in the promoter region. While previous work identified the putative H3K4-specific methyltransferase PfSET10 as an essential enzyme and positive regulator of var gene expression, a recent study reported conflicting data. Here, we used iterative genome editing to engineer a conditional PfSET10 knockout line tailored to study the function of PfSET10 in var gene regulation. We demonstrate that PfSET10 is not required for mutually exclusive var gene expression and switching. We also show that PfSET10 is dispensable not only for asexual parasite proliferation but also for sexual conversion and differentiation of gametocytes. Furthermore, comparative RNA-seq experiments revealed that PfSET10 plays no obvious role in regulating gene expression during asexual parasite development and gametocytogenesis. Interestingly, however, PfSET10 shows different subnuclear localization patterns in asexual and sexual stage parasites and female-specific expression in mature gametocytes. In summary, our work confirms in detail that PfSET10 is not involved in regulating var gene expression and is not required for blood stage parasite viability, at least not when cultured in vitro, thus suggesting PfSET10 may be important for life cycle progression in the mosquito vector or during liver stage development.
2024-06-26 | GSE270631 | GEO
Project description:Plasmodium falciparum variant antigens named erythrocyte membrane protein 1 (PfEMP1) are important targets for developing a protective immunity to malaria caused by P. falciparum. One of the major challenges in P. falciparum proteomics studies is identifying PfEMP1s at the protein level due to antigenic variation. To identify these PfEMP1s using shotgun proteomics, we developed a pipeline that searches high resolution mass spectrometry spectra against a custom protein sequence database. An algorithm, LAX, was developed as part of the pipeline that matches sequences to the most similar PfEMP1 and calculates a weight value used for PfEMP1 protein inference. The pipeline was first validated in the analysis of a laboratory strain with a known PfEMP1, then it was implemented on the analysis of parasite isolates from malaria-infected pregnant women and finally on the analysis of parasite isolates from malaria infected children where there was an increase of PfEMP1s identified in 28 out of 31 isolates.
2019-09-27 | PXD012958 | Pride
Project description:The chicken erythrocyte epigenome
| PRJNA305808 | ENA
Project description:This collection contains microRNA expression profiling data for samples purified from umbilical cord blood, belonging to one of the followiing populations: MEP, MEGA1, MEGA2, ERY1, ERY2, ERY3. MEP: megakaryocyte-erythrocyte precursors (defined by CD34+ CD38+ IL-3Ra- CD45RA- ); MEGA1: megakaryocyte population 1 (defined by CD34+ CD61+ CD41+ CD45- ); MEGA2: megakaryocyte population 2 (defined by CD34- CD61+ CD41+ CD45- ); ERY1: erythrocyte population 1 (defined by CD34+ CD71+ GlyA- ); ERY2: erythrocyte population 2 (defined by CD34- CD71+ GlyA- ); ERY3: erythrocyte population 3 (defined by CD34- CD71+ GlyA+ ). Keywords: microRNA, miRNA, MEP, megakaryocyte, erythrocyte, lineage specification
2008-06-10 | GSE10593 | GEO
Project description:Transcriptional regulation is impacted by multiple layers of genome organization. Here, we identified and mapped out all the transcriptionally active chromosomal domains in the chicken immature erythrocyte genome, including the known β- and α-globin domains, by combining a powerful chromatin fractionation method with next generation DNA and RNA sequencing. Two biological replicates of total RNA were sequenced to characterize genes in chicken erythrocyte cells
2016-07-03 | E-GEOD-75848 | biostudies-arrayexpress
Project description:The pathogenesis of severe malaria is complex and involves several pathways that influence host inflammation and endothelial function. The human malaria parasite Plasmodium falciparum is responsible for the majority of mortality and morbidity caused by malaria infection and differs from other human malaria species in the degree of accumulation of parasite-infected red blood cells in the microvasculature, known as cytoadherence or sequestration. In P. falciparum, cytoadherence is mediated by a protein called PfEMP1 which, due to its exposure to the host immune system, undergoes antigenic variation resulting in the expression of different PfEMP1 variants on the infected erythrocyte membrane. These PfEMP1s contain various combinations of adhesive domains, which allow for the differential engagement of a repertoire of endothelial receptors on the host microvasculature, with specific receptor usage associated with severe disease. Cytoadherence results in perturbation of the micro-circulation as well as direct effects on endothelial cells promoted by receptor-mediated signalling. We used a co-culture model of cytoadherence incubating human brain microvascular endothelial cells with erythrocytes infected with two parasite lines expressing different PfEMP1s; IT4var14 (long-form; ups B) that binds strongly to human brain microvascular endothelial cells mainly via ICAM-1, and IT4var 37 (short-form; ups C) that does not bind brain endothelium but shows high levels of binding to human dermal microvascular endothelial cells via CD36. We determined the transcriptional profile of the endothelial cells following different incubation periods with infected erythrocytes, identifying different transcriptional profiles of pathways involved in the pathology of severe malaria, such as inflammation, apoptosis and barrier integrity, induced by the two PfEMP1 variants.
2023-11-01 | E-MTAB-12730 | biostudies-arrayexpress
Project description:Red pulp macrophages of the spleen mediate daily turnover of billions of senescent erythrocytes. However, the exact molecules and mechanisms involved in sequestration of senescent erythrocytes, their recognition and ultimately their turnover remain unclear and are currently subject to debate. In this study we provide evidence that the splenic environment is of substantial importance in facilitating erythrocyte turnover through induction of haemolysis. Detailed characterization of human spleen and its red pulp macrophages lead to the identification of a population of erythrocytes devoid of haemoglobin without fully disintegrating, so-called erythrocyte ghosts. By in-vivo imaging and transfusion experiments we established that senescent erythrocytes are subject to haemolysis specifically within the spleen. We show that aged erythrocytes are captured by the extracellular matrix within the red pulp of the spleen and that their retention under low shear conditions is key in driving haemolysis. In contrast to senescent erythrocytes, the erythrocyte ghost shells were found to be prone to recognition and breakdown by red pulp macrophages. As such, these data put forward haemolysis as an efficient mechanism for the turnover of senescent erythrocytes which alters our current understanding on how erythrocyte turnover is regulated.
2020-09-03 | GSE121629 | GEO
Project description:Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has developed substantial antigenic variability. As the majority of the population now has pre-existing immunity due to infection or vaccination, the use of experimentally generated animal immune sera can be valuable for measuring antigenic differences between virus variants. Here, we immunized Syrian hamsters by two successive infections with one of nine SARS-CoV-2 variants. Their sera were titrated against 16 SARS-CoV-2 variants, and the resulting titers were visualized using antigenic cartography. The antigenic map shows a condensed cluster containing all pre-Omicron variants (D614G, Alpha, Delta, Beta, Mu, and an engineered B.1+E484K variant) and considerably more diversity among a selected panel of Omicron subvariants (BA.1, BA.2, BA.4/BA.5, the BA.5 descendants BF.7 and BQ.1.18, the BA.2.75 descendant BN.1.3.1, the BA.2-derived recombinants XBB.2 and EG.5.1, and the BA.2.86 descendant JN.1). Some Omicron subvariants were as antigenically distinct from each other as the wildtype is from the Omicron BA.1 variant. Compared to titers measured in human sera, titers in hamster sera are of higher magnitude, show less fold change, and result in a more compact antigenic map topology. The results highlight the potential of sera from hamsters for the continued antigenic characterization of SARS-CoV-2.
| S-EPMC11317614 | biostudies-literature
Project description:The antigenic characterization of IBDV, a virus that causes an immunosuppressive disease in young chickens, has been historically addressed using cross virus neutralization (VN) assay and antigen-capture enzyme-linked immunosorbent (AC-ELISA). However, VN assay has been usually carried out either in specific antibody negative embryonated eggs, for non-cell culture adapted strains, which is tedious, or on chicken embryo fibroblasts (CEF), which requires virus adaptation to cell culture. AC-ELISA has provided crucial information about IBDV antigenicity, but this information is limited to the epitopes included in the tested panel with a lack of information of overall antigenic view. The present work aimed at overcoming those technical limitations and providing an extensive antigenic landscape based on original cross VN assays employing primary chicken B cells, where no previous IBDV adaptation is required. Sixteen serotype 1 IBDV viruses, comprising both reference strains and documented antigenic variants were tested against eleven chicken post-infectious sera. The VN data were analysed by antigenic cartography, a method which enables reliable high-resolution quantitative and visual interpretation of large binding assay datasets. The resulting antigenic cartography revealed i) the existence of several antigenic clusters of IBDV, ii) high antigenic relatedness between some genetically unrelated viruses, iii) a highly variable contribution to global antigenicity of previously identified individual epitopes and iv) broad reactivity of chicken sera raised against antigenic variants. This study provides an overall view of IBDV antigenic diversity. Implementing this approach will be instrumental to follow the evolution of IBDV antigenicity and control the disease.
| S-EPMC10194283 | biostudies-literature