18 results on '"Jakob S. Jespersen"'
Search Results
2. Impact of U2AF1 mutations on circular RNA expression in myelodysplastic neoplasms
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Eileen Wedge, Ulvi Ahmadov, Thomas B. Hansen, Zongliang Gao, Morten Tulstrup, Christophe Côme, Sridhar Nonavinkere Srivatsan, Tanzir Ahmed, Jakob S. Jespersen, Balthasar C. Schlotmann, Claudia Schöllkopf, Klas Raaschou-Jensen, Niels Ødum, Jørgen Kjems, Rasmus O. Bak, Matthew J. Walter, Kirsten Grønbæk, and Lasse S. Kristensen
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Cancer Research ,Mice ,Splicing Factor U2AF/genetics ,Oncology ,Doxycycline ,Neoplasms ,RNA Splicing ,RNA, Circular/genetics ,Mutation ,Animals ,Hematology ,RNA Splicing Factors/genetics ,Myelodysplastic Syndromes/genetics - Abstract
Mutations in U2AF1 are relatively common in myelodysplastic neoplasms (MDS) and are associated with an inferior prognosis, but the molecular mechanisms underlying this are not fully elucidated. Circular RNAs (circRNAs) have been implicated in cancer, but it is unknown how mutations in splicing factors may impact on circRNA biogenesis. Here, we used RNA-sequencing to investigate the effects of U2AF1 mutations on circRNA expression in K562 cells with a doxycycline-inducible U2AF1 S34 mutation, in a mouse model with a doxycycline-inducible U2AF1 S34 mutation, and in FACS-sorted CD34+ bone marrow cells from MDS patients with either U2AF1 S34 or U2AF1 Q157 mutations. In all contexts, we found an increase in global circRNA levels in the U2AF1-mutated setting, which was independent of expression changes in the cognate linear host genes. In patients, the U2AF1 S34 and U2AF1 Q157 mutations were both associated with an overall increased expression of circRNAs. circRNAs generated by a non-Alu-mediated mechanism generally showed the largest increase in expression levels. Several well-described cancer-associated circRNAs, including circZNF609 and circCSNK1G3, were upregulated in MDS patients with U2AF1 mutations compared to U2AF1-wildtype MDS controls. In conclusion, high circRNA expression is observed in association with U2AF1 mutations in three biological systems, presenting an interesting possibility for biomarker and therapeutic investigation.
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- 2023
3. Cerebral malaria is associated with differential cytoadherence to brain endothelial cells
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Janet Storm, Jakob S Jespersen, Karl B Seydel, Tadge Szestak, Maurice Mbewe, Ngawina V Chisala, Patricia Phula, Christian W Wang, Terrie E Taylor, Christopher A Moxon, Thomas Lavstsen, and Alister G Craig
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cerebral malaria ,cytoadherence ,paediatric patient isolates ,PfEMP1 ,Plasmodium falciparum ,Medicine (General) ,R5-920 ,Genetics ,QH426-470 - Abstract
Abstract Sequestration of Plasmodium falciparum‐infected erythrocytes (IE) within the brain microvasculature is a hallmark of cerebral malaria (CM). Using a microchannel flow adhesion assay with TNF‐activated primary human microvascular endothelial cells, we demonstrate that IE isolated from Malawian paediatric CM cases showed increased binding to brain microvascular endothelial cells compared to IE from uncomplicated malaria (UM) cases. Further, UM isolates showed significantly greater adhesion to dermal than to brain microvascular endothelial cells. The major mediator of parasite adhesion is P. falciparum erythrocyte membrane protein 1, encoded by var genes. Higher levels of var gene transcripts predicted to bind host endothelial protein C receptor (EPCR) and ICAM‐1 were detected in CM isolates. These data provide further evidence for differential tissue binding in severe and uncomplicated malaria syndromes, and give additional support to the hypothesis that CM pathology is based on increased cytoadherence of IE in the brain microvasculature.
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- 2019
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4. Identification of a Major Dimorphic Region in the Functionally Critical N-Terminal ID1 Domain of VAR2CSA.
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Justin Doritchamou, Audrey Sabbagh, Jakob S Jespersen, Emmanuelle Renard, Ali Salanti, Morten A Nielsen, Philippe Deloron, and Nicaise Tuikue Ndam
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Medicine ,Science - Abstract
The VAR2CSA protein of Plasmodium falciparum is transported to and expressed on the infected erythrocyte surface where it plays a key role in placental malaria (PM). It is the current leading candidate for a vaccine to prevent PM. However, the antigenic polymorphism integral to VAR2CSA poses a challenge for vaccine development. Based on detailed analysis of polymorphisms in the sequence of its ligand-binding N-terminal region, currently the main focus for vaccine development, we assessed var2csa from parasite isolates infecting pregnant women. The results reveal for the first time the presence of a major dimorphic region in the functionally critical N-terminal ID1 domain. Parasite isolates expressing VAR2CSA with particular motifs present within this domain are associated with gravidity- and parasite density-related effects. These observations are of particular interest in guiding efforts with respect to optimization of the VAR2CSA-based vaccines currently under development.
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- 2015
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5. Expression of the domain cassette 8 Plasmodium falciparum erythrocyte membrane protein 1 is associated with cerebral malaria in Benin.
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Gwladys I Bertin, Thomas Lavstsen, François Guillonneau, Justin Doritchamou, Christian W Wang, Jakob S Jespersen, Sem Ezimegnon, Nadine Fievet, Maroufou J Alao, Francis Lalya, Achille Massougbodji, Nicaise Tuikue Ndam, Thor G Theander, and Philippe Deloron
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Medicine ,Science - Abstract
BackgroundPlasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is a highly polymorphic adherence receptor expressed on the surface of infected erythrocytes. Based on sequence homology PfEMP-1 variants have been grouped into three major groups A-C, the highly conserved VAR2CSA variants, and semi-conserved types defined by tandem runs of specific domains ("domain cassettes" (DC)). The PfEMP-1 type expressed determines the adherence phenotype, and is associated with clinical outcome of infection.MethodsParasite isolates from Beninese children or women presenting with, respectively, CM or PAM were collected along with samples from patients with uncomplicated malaria (UM). We assessed the transcript level of var genes by RT-qPCR and the expression of PfEMP-1 proteins by LC-MS/MS.ResultsVar genes encoding DC8 and Group A PfEMP-1 were transcribed more often and at higher levels in cerebral malaria vs. uncomplicated malaria patients. LC-MS/MS identified peptides from group A, DC8 PfEMP-1 more frequently in cerebral malaria than in uncomplicated malaria and pregnancy-associated malaria samples.ConclusionThis is the first study to show association between PfEMP-1 subtype and disease outcome by direct analysis of parasites proteome. The results corroborate that group A and specifically the PfEMP-1 types DC8 are universally associated with cerebral malaria. This is a crucial observation for promoting studies on malaria pathogenesis.
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- 2013
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6. Level of Unique T-Cell Clonotypes Are Associated with Clonal Hematopoiesis and Survival in Patients with Lymphoma Intended for Autologous Stem Cell Transplant
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Francesco Favero, Lene Hyldahl Ebbesen, Christian Nielsen, Michael Thorsgaard, Betina Samuelsen Sørensen, Simon Husby, Kirsten Grønbæk, Eva Kannik Hastrup, Tarec Christoffer El-Galaly, Joachim Weisenfeldt, Thomas Stauffer Larsen, Jakob S. Jespersen, Gustav Ørting Jørgensen, Pär Josefsson, John Bæch, Peter de Nully Brown, and German G. R. Gonzalez
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T cell ,Immunology ,Clonal hematopoiesis ,Cell Biology ,Hematology ,Biology ,medicine.disease ,Biochemistry ,Lymphoma ,medicine.anatomical_structure ,medicine ,Cancer research ,In patient ,Stem cell - Abstract
The advent of novel immunotherapy (CAR-T cell therapy, bispecific CD20×CD3 antibodies) have highlighted the importance of T-cells in the treatment of lymphoma. However, overall T-cell characteristics have not been properly examined in patients receiving conventional chemotherapy. Next-generation sequencing (NGS) of the T-cell receptor (TCR) has enabled the possibility of identifying hundred thousands of unique T-cell clones in a single patient sample. Here we analyzed the impact of systemic TCR diversity and T-cell clonotypes in patients with Non-Hodgkin lymphoma (NHL) and Hodgkin-lymphoma (HL) receiving high-dose chemotherapy with stem cell support (HDT/ASCT). Autologous peripheral blood stem cell harvest samples from patients with lymphoma (predominantly B-cell NHL) were collected as part of a national population-based study (Husby et al. - Leukemia 2020). We performed high-throughput RNA-based sequencing of the V, D and J segment of the TCR β-chain to identify unique clonal rearrangements. To ensure supreme quality for TCR repertoire calculations, samples with less than 100.000 aligned reads to the TCR β chain were omitted from further analysis. By using the MiXCR bioinformatic pipeline we analyzed the number of unique clonotypes and TCR repertoire diversity, as calculated by the Simpson index. T-cell clonotype and diversity were for categorical analyses split in two groups by the median, respectively. A total of 96 patients with lymphoma who were intended for HDT/ASCT were included and analyzed for TCR characteristics. In brief, median age was 56 years, 64% were male and major subtypes were diffuse large B-cell lymphoma (37%), follicular lymphoma (24%), Hodgkin lymphoma (16%), and mantle cell lymphoma (14%). Median follow-up time was 6.7 years. Number of unique T-cell clonotypes was not associated with age (Fig. 1A), but low levels were highly associated with inferior survival (Fig. 1B, p=0.008), especially in the first year of follow-up. In contrast, elderly patients had a trend toward lower TCR diversity (Fig. 1C, p=0.08), but this did not impact overall survival (Fig. 1D). Low T-cell clonotype levels was also significantly associated with presence of clonal hematopoiesis (Fig. 1E, p=0.033). No association with clonal hematopoiesis was found with regard to TCR diversity (Fig. 1F). Furthermore, we investigated TCR repertoire in relation to subsequent severe infections (defined as sepsis, pneumonia, or invasive fungal infection). Number of unique T-cell clonotypes did not have an impact (Fig. 1F), but remarkably patients with a high T-cell diversity had significant increased incidence of severe infections in the first 500 days after sampling (Fig. 1G, p=0.029). This implies that patients who have a high T-cell diversity before high-dose chemotherapy, are more capable of mounting an immune response against infectious pathogens. These findings should be validated in larger homogenous cohorts. However, they imply the importance of inherent immune characteristics in patients with lymphoma. Although the immune response is exceedingly complex, we have identified systemic T-cell characteristics that associate with several important clinical variables. Assessment of systemic immunological parameters in patients with aggressive lymphoma may in the future inform on choice of optimal personalized therapy. Figure 1 Figure 1. Disclosures El-Galaly: ROCHE Ltd: Ended employment in the past 24 months; Abbvie: Other: Speakers fee. Larsen: Odense University Hospital, Denmark: Current Employment; Celgene: Consultancy; BMS: Consultancy; Novartis: Consultancy; Gilead: Consultancy.
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- 2021
7. Parasites Causing Cerebral Falciparum Malaria Bind Multiple Endothelial Receptors and Express EPCR and ICAM-1-Binding PfEMP1
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Claire Kamaliddin, Anja T. R. Jensen, Rachida Tahar, Philippe Deloron, Atikatou Mama, Jakob S. Jespersen, Christian W. Wang, Nicaise Tuikue Ndam, Thor G. Theander, Benoit Gamain, Thomas Lavstsen, Azizath Moussiliou, and Jules Alao
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0301 basic medicine ,Transcription, Genetic ,ICAM-1 ,CD36 ,Plasmodium falciparum ,030106 microbiology ,Malaria, Cerebral ,Protozoan Proteins ,Receptors, Cell Surface ,Plasma protein binding ,EPCR ,03 medical and health sciences ,Antigens, CD ,parasitic diseases ,Cell Adhesion ,medicine ,Humans ,Immunology and Allergy ,Malaria, Falciparum ,Receptor ,Endothelial protein C receptor ,biology ,Endothelial Cells ,Endothelial Protein C Receptor ,Infant ,Intercellular Adhesion Molecule-1 ,biology.organism_classification ,medicine.disease ,PfEMP1 ,030104 developmental biology ,Infectious Diseases ,Cerebral Malaria ,Child, Preschool ,Immunology ,biology.protein ,cerebral malaria ,Malaria ,Protein Binding - Abstract
Background. Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates the binding and accumulation of infected erythrocytes (IE) to blood vessels and tissues. Specific interactions have been described between PfEMP1 and human endothelial proteins CD36, intercellular adhesion molecule-1 (ICAM-1), and endothelial protein C receptor (EPCR); however, cytoadhesion patterns typical for pediatric malaria syndromes and the associated PfEMP1 members are still undefined. Methods. In a cohort of 94 hospitalized children with malaria, we characterized the binding properties of IE collected on admission, and var gene transcription using quantitative polymerase chain reaction. Results. IE from patients with cerebral malaria were more likely to bind EPCR and ICAM-1 than IE from children with uncomplicated malaria (P = .007). The level of transcripts encoding CIDR alpha 1.4 and CIDR alpha 1.5 domain subclasses was higher in patients with severe disease (P
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- 2017
8. Antibodies to Intercellular Adhesion Molecule 1-Binding Plasmodium falciparum Erythrocyte Membrane Protein 1-DBLβ Are Biomarkers of Protective Immunity to Malaria in a Cohort of Young Children from Papua New Guinea
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Diana S. Hansen, Andrew V. Oleinikov, Bent O. Petersen, Ivo Mueller, Clara S. Lin, Sofonias K. Tessema, Alyssa E. Barry, Livingstone Tavul, Dominic P. Kwiatkowski, Olga Chesnokov, Anthony N. Hodder, Jakob S. Jespersen, G. L. Abby Harrison, Thomas Lavstsen, Peter Siba, and Digjaya Utama
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0301 basic medicine ,Male ,Protozoan Proteins ,Antibodies, Protozoan ,Group A ,ICAM1 ,0302 clinical medicine ,Malaria, Falciparum ,Phylogeny ,Endothelial protein C receptor ,Diversity ,biology ,Incidence ,Endothelial Protein C Receptor ,Intercellular Adhesion Molecule-1 ,Infectious Diseases ,Cerebral Malaria ,Child, Preschool ,Microbial Immunity and Vaccines ,Female ,Antibody ,Protein Binding ,Immunology ,Antigens, Protozoan ,Microbiology ,Risk Assessment ,Antibodies ,03 medical and health sciences ,EPCR ,var genes ,Papua New Guinea ,Antigen ,SDG 3 - Good Health and Well-being ,Protein Domains ,parasitic diseases ,medicine ,Antigenic variation ,Humans ,DBLβ ,Genetic Variation ,Infant ,Plasmodium falciparum ,medicine.disease ,biology.organism_classification ,Malaria ,PfEMP1 ,030104 developmental biology ,biology.protein ,Parasitology ,Biomarkers ,030215 immunology ,Follow-Up Studies - Abstract
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates parasite sequestration to the cerebral microvasculature via binding of DBLβ domains to intercellular adhesion molecule 1 (ICAM1) and is associated with severe cerebral malaria. In a cohort of 187 young children from Papua New Guinea (PNG), we examined baseline levels of antibody to the ICAM1-binding PfEMP1 domain, DBLβ3PF11_0521, in comparison to four control antigens, including NTS-DBLα and CIDR1 domains from another group A variant and a group B/C variant. Antibody levels for the group A antigens were strongly associated with age and exposure. Antibody responses to DBLβ3PF11_0521 were associated with a 37% reduced risk of high-density clinical malaria in the follow-up period (adjusted incidence risk ratio [aIRR] = 0.63 [95% confidence interval {CI}, 0.45 to 0.88; P = 0.007]) and a 25% reduction in risk of low-density clinical malaria (aIRR = 0.75 [95% CI, 0.55 to 1.01; P = 0.06]), while there was no such association for other variants. Children who experienced severe malaria also had significantly lower levels of antibody to DBLβ3PF11_0521 and the other group A domains than those that experienced nonsevere malaria. Furthermore, a subset of PNG DBLβ sequences had ICAM1-binding motifs, formed a distinct phylogenetic cluster, and were similar to sequences from other areas of endemicity. PfEMP1 variants associated with these DBLβ domains were enriched for DC4 and DC13 head structures implicated in endothelial protein C receptor (EPCR) binding and severe malaria, suggesting conservation of dual binding specificities. These results provide further support for the development of specific classes of PfEMP1 as vaccine candidates and as biomarkers for protective immunity against clinical P. falciparum malaria.
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- 2017
9. The Severity of Plasmodium falciparum Infection Is Associated with Transcript Levels of var Genes Encoding Endothelial Protein C Receptor-Binding P. falciparum Erythrocyte Membrane Protein 1
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Steven B. Mwakalinga, Sixbert I. Mkumbaye, Reginald A. Kavishe, Eric Lyimo, John Lusingu, Christian W. Wang, Jakob S. Jespersen, Daniel T. R. Minja, Thomas Lavstsen, Jacklin F. Mosha, Alphaxard Manjurano, and Thor G. Theander
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0301 basic medicine ,Transcription, Genetic ,030106 microbiology ,Immunology ,Plasmodium falciparum ,Protozoan Proteins ,Parasitemia ,Biology ,Microbiology ,Severity of Illness Index ,Tanzania ,Pathogenesis ,03 medical and health sciences ,Gene expression ,parasitic diseases ,medicine ,Antigenic variation ,Humans ,Protein Interaction Domains and Motifs ,Malaria, Falciparum ,Child ,Endothelial protein C receptor ,Cellular Microbiology: Pathogen-Host Cell Molecular Interactions ,Infant ,medicine.disease ,biology.organism_classification ,Bacterial adhesin ,030104 developmental biology ,Infectious Diseases ,Gene Expression Regulation ,Child, Preschool ,Parasitology ,Malaria ,Biomarkers - Abstract
By attaching infected erythrocytes to the vascular lining, Plasmodium falciparum parasites leave blood circulation and avoid splenic clearance. This sequestration is central to pathogenesis. Severe malaria is associated with parasites expressing an antigenically distinct P. falciparum erythrocyte membrane protein 1 (PfEMP1) subset mediating binding to endothelial receptors. Previous studies indicate that PfEMP1 adhesins with so-called CIDRα1 domains capable of binding endothelial protein C receptor (EPCR) constitute the PfEMP1 subset associated with severe pediatric malaria. To analyze the relative importance of different subtypes of CIDRα1 domains, we compared Pf emp1 transcript levels in children with severe malaria (including 9 fatal and 114 surviving cases), children hospitalized with uncomplicated malaria ( n = 42), children with mild malaria not requiring hospitalization ( n = 10), and children with parasitemia and no ongoing fever ( n = 12). High levels of transcripts encoding EPCR-binding PfEMP1 were found in patients with symptomatic infections, and the abundance of these transcripts increased with disease severity. The compositions of CIDRα1 subtype transcripts varied markedly between patients, and none of the subtypes were dominant. Transcript-level analyses targeting other domain types indicated that subtypes of DBLβ or DBLζ domains might mediate binding phenomena that, in conjunction with EPCR binding, could contribute to pathogenesis. These observations strengthen the rationale for targeting the PfEMP1-EPCR interaction by vaccines and adjunctive therapies. Interventions should target EPCR binding of all CIDRα1 subtypes.
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- 2017
10. Cellulose filtration of blood from malaria patients for improving ex vivo growth of Plasmodium falciparum parasites
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Thor G. Theander, Thomas Lavstsen, Daniel T. R. Minja, Jakob S. Jespersen, Christian W. Wang, Steven B. Mwakalinga, Michael Alifrangis, Sixbert I. Mkumbaye, John Lusingu, and Reginald A. Kavishe
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Male ,0301 basic medicine ,Ex vivo growth ,Genotype ,Plasmodium falciparum ,030231 tropical medicine ,Biology ,Polymerase Chain Reaction ,Tanzania ,Parasite Load ,Microbiology ,03 medical and health sciences ,0302 clinical medicine ,parasitic diseases ,Animals ,Humans ,Parasite hosting ,Malaria, Falciparum ,Merozoite surface protein ,Cellulose ,Genotyping ,Research ,Infant, Newborn ,Infant ,Cellulose column filtration ,DNA, Protozoan ,biology.organism_classification ,Culture Media ,Blood ,030104 developmental biology ,Infectious Diseases ,Parasitology ,Child, Preschool ,Female ,Nested polymerase chain reaction ,Filtration ,RNA, Protozoan ,Ex vivo - Abstract
Background Establishing in vitro Plasmodium falciparum culture lines from patient parasite isolates can offer deeper understanding of geographic variations of drug sensitivity and mechanisms of malaria pathogenesis and immunity. Cellulose column filtration of blood is an inexpensive, rapid and effective method for the removal of host factors, such as leucocytes and platelets, significantly improving the purification of parasite DNA in a blood sample. Methods In this study, the effect of cellulose column filtration of venous blood on the initial in vitro growth of P. falciparum parasite isolates from Tanzanian children admitted to hospital was tested. The parasites were allowed to expand in culture without subcultivation until 5 days after admission or the appearance of dead parasites and parasitaemia was determined daily. To investigate whether the filtration had an effect on clonality, P. falciparum merozoite surface protein 2 genotyping was performed using nested PCR on extracted genomic DNA, and the var gene transcript levels were investigated, using quantitative PCR on extracted RNA, at admission and 4 days of culture. Results The cellulose-filtered parasites grew to higher parasitaemia faster than non-filtered parasites seemingly due to a higher development ratio of ring stage parasites progressing into the late stages. Cellulose filtration had no apparent effect on clonality or var gene expression; however, evident differences were observed after only 4 days of culture in both the number of clones and transcript levels of var genes compared to the time of admission. Conclusions Cellulose column filtration of parasitized blood is a cheap, applicable method for improving cultivation of P. falciparum field isolates for ex vivo based assays; however, when assessing phenotype and genotype of cultured parasites, in general, assumed to represent the in vivo infection, caution is advised. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1714-2) contains supplementary material, which is available to authorized users.
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- 2017
11. DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families
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Anders Gorm Pedersen, Thomas Lavstsen, Kirk W. Deitsch, Michael Lisby, Sarah L. Fordyce, David E. Arnot, Adam F. Sander, Jakob S. Jespersen, Ali Salanti, Richard Carter, Thor G. Theander, and Thomas S. Rask
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FLP-FRT recombination ,Saccharomyces cerevisiae ,Genes, Protozoan ,Plasmodium falciparum ,Protozoan Proteins ,Nucleic acid conformation ,Antigens, Protozoan ,Genome Integrity, Repair and Replication ,Genetic recombination ,03 medical and health sciences ,Genetic ,SDG 3 - Good Health and Well-being ,parasitic diseases ,Antigenic variation ,Genetics ,Ectopic recombination ,Antigens ,Gene ,030304 developmental biology ,Recombination, Genetic ,0303 health sciences ,biology ,030306 microbiology ,DNA ,DNA, Protozoan ,biology.organism_classification ,Subtelomere ,Antigenic Variation ,Recombination ,3. Good health ,Protein Structure, Tertiary ,Genes ,Multigene Family ,Protozoan ,Protein structure ,Nucleic Acid Conformation ,Multigene family ,Tertiary - Abstract
Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens.
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- 2014
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12. Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains
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Daniel T. R. Minja, Louise Turner, Thor G. Theander, Sixbert I. Mkumbaye, Jens E.V. Petersen, Thomas Lavstsen, John Lusingu, Jakob S. Jespersen, Bent O. Petersen, and Christian W. Wang
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0301 basic medicine ,Male ,030231 tropical medicine ,Protein domain ,Plasmodium falciparum ,Protozoan Proteins ,Receptors, Cell Surface ,macromolecular substances ,Biology ,CIDR ,Chromatin, Epigenetics, Genomics & Functional Genomics ,Pathogenesis ,Transcriptome ,03 medical and health sciences ,EPCR ,0302 clinical medicine ,SDG 3 - Good Health and Well-being ,Protein Domains ,Antigens, CD ,Report ,parasitic diseases ,Humans ,Malaria, Falciparum ,var ,Gene ,Endothelial protein C receptor ,severe childhood malaria ,Gene Expression Profiling ,Endothelial Protein C Receptor ,Infant ,biology.organism_classification ,Virology ,Microbiology, Virology & Host Pathogen Interaction ,Severe childhood malaria ,PfEMP1 ,030104 developmental biology ,Cerebral Malaria ,Child, Preschool ,Immunology ,Adjunctive treatment ,Host-Pathogen Interactions ,Molecular Medicine ,Female ,Protein Binding ,Reports - Abstract
Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding human endothelial protein C receptor (EPCR) through the CIDRα1 domain of certain PfEMP1 were recently associated with severe malaria in children. However, it has remained unclear to which extend the EPCR‐binding CIDRα1 domains epitomize PfEMP1 expressed in severe malaria. Here, we characterized the near full‐length transcripts dominating the var transcriptome in children with severe malaria and found that the only common feature of the encoded PfEMP1 was CIDRα1 domains. Such genes were highly and dominantly expressed in both children with severe malarial anaemia and cerebral malaria. These observations support the hypothesis that the CIDRα1‐EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction.
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- 2016
13. Identification of a major dimorphic region in the functionally critical N-terminal ID1 domain of VAR2CSA
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Emmanuelle Renard, Justin Doritchamou, Nicaise Tuikue Ndam, Morten Nielsen, Audrey Sabbagh, Jakob S. Jespersen, Ali Salanti, and Philippe Deloron
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Erythrocytes ,Sequence analysis ,Molecular Sequence Data ,Plasmodium falciparum ,lcsh:Medicine ,Antigens, Protozoan ,Gestational Age ,Sequence alignment ,Antigen ,Pregnancy ,Phylogenetics ,Genetic variation ,parasitic diseases ,medicine ,Humans ,Parasite hosting ,lcsh:Science ,Genetic Association Studies ,Phylogeny ,Genetics ,Vaccines, Synthetic ,Multidisciplinary ,biology ,lcsh:R ,Genetic Variation ,biology.organism_classification ,medicine.disease ,Protein Structure, Tertiary ,embryonic structures ,Female ,lcsh:Q ,Malaria ,Research Article - Abstract
The VAR2CSA protein of Plasmodium falciparum is transported to and expressed on the infected erythrocyte surface where it plays a key role in placental malaria (PM). It is the current leading candidate for a vaccine to prevent PM. However, the antigenic polymorphism integral to VAR2CSA poses a challenge for vaccine development. Based on detailed analysis of polymorphisms in the sequence of its ligand-binding N-terminal region, currently the main focus for vaccine development, we assessed var2csa from parasite isolates infecting pregnant women. The results reveal for the first time the presence of a major dimorphic region in the functionally critical N-terminal ID1 domain. Parasite isolates expressing VAR2CSA with particular motifs present within this domain are associated with gravidity- and parasite density-related effects. These observations are of particular interest in guiding efforts with respect to optimization of the VAR2CSA-based vaccines currently under development.
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- 2015
14. Structural conservation despite huge sequence diversity allows EPCR binding by the PfEMP1 family implicated in severe childhood malaria
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Clinton K Y, Lau, Louise, Turner, Jakob S, Jespersen, Edward D, Lowe, Bent, Petersen, Christian W, Wang, Jens E V, Petersen, John, Lusingu, Thor G, Theander, Thomas, Lavstsen, and Matthew K, Higgins
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Male ,Adolescent ,Protein Conformation ,DNA Mutational Analysis ,Plasmodium falciparum ,Protozoan Proteins ,Antibodies, Protozoan ,Endothelial Protein C Receptor ,Genetic Variation ,Receptors, Cell Surface ,Sequence Analysis, DNA ,Crystallography, X-Ray ,Malaria ,Antigens, CD ,Child, Preschool ,Host-Pathogen Interactions ,Humans ,Female ,Child ,Protein Binding - Abstract
The PfEMP1 family of surface proteins is central for Plasmodium falciparum virulence and must retain the ability to bind to host receptors while also diversifying to aid immune evasion. The interaction between CIDRα1 domains of PfEMP1 and endothelial protein C receptor (EPCR) is associated with severe childhood malaria. We combine crystal structures of CIDRα1:EPCR complexes with analysis of 885 CIDRα1 sequences, showing that the EPCR-binding surfaces of CIDRα1 domains are conserved in shape and bonding potential, despite dramatic sequence diversity. Additionally, these domains mimic features of the natural EPCR ligand and can block this ligand interaction. Using peptides corresponding to the EPCR-binding region, antibodies can be purified from individuals in malaria-endemic regions that block EPCR binding of diverse CIDRα1 variants. This highlights the extent to which such a surface protein family can diversify while maintaining ligand-binding capacity and identifies features that should be mimicked in immunogens to prevent EPCR binding.
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- 2014
15. Severe malaria is associated with parasite binding to endothelial protein C receptor
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Pamela Magistrado, Christian W. Wang, John Lusingu, Matthew K. Higgins, Marion Avril, Sanne S. Berger, Joseph D. Smith, Thor G. Theander, Morten Nielsen, Jakob S. Jespersen, Andrew J. Brazier, Thomas Lavstsen, Louise Turner, Jim Freeth, and Jens E.V. Petersen
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030231 tropical medicine ,Plasmodium falciparum ,Protozoan Proteins ,Inflammation ,Receptors, Cell Surface ,CHO Cells ,Article ,Cell Line ,Pathogenesis ,03 medical and health sciences ,0302 clinical medicine ,Antigens, CD ,Cricetinae ,parasitic diseases ,Cell Adhesion ,medicine ,Animals ,Humans ,Malaria, Falciparum ,Cell adhesion ,Receptor ,Blood Coagulation ,030304 developmental biology ,0303 health sciences ,Endothelial protein C receptor ,Multidisciplinary ,biology ,Microcirculation ,Erythrocyte Membrane ,Brain ,Endothelial Cells ,Endothelial Protein C Receptor ,medicine.disease ,biology.organism_classification ,3. Good health ,Immunology ,medicine.symptom ,Malaria ,Protein C ,medicine.drug - Abstract
Sequestration of Plasmodium falciparum-infected erythrocytes in host blood vessels is a key triggering event in the pathogenesis of severe childhood malaria, which is responsible for about one million deaths every year. Sequestration is mediated by specific interactions between members of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family and receptors on the endothelial lining. Severe childhood malaria is associated with expression of specific PfEMP1 subtypes containing domain cassettes (DCs) 8 and 13 (ref. 3), but the endothelial receptor for parasites expressing these proteins was unknown. Here we identify endothelial protein C receptor (EPCR), which mediates the cytoprotective effects of activated protein C, as the endothelial receptor for DC8 and DC13 PfEMP1. We show that EPCR binding is mediated through the amino-terminal cysteine-rich interdomain region (CIDRα1) of DC8 and group A PfEMP1 subfamilies, and that CIDRα1 interferes with protein C binding to EPCR. This PfEMP1 adhesive property links P. falciparum cytoadhesion to a host receptor involved in anticoagulation and endothelial cytoprotective pathways, and has implications for understanding malaria pathology and the development of new malaria interventions. © 2013 Macmillan Publishers Limited. All rights reserved.
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- 2013
16. Expression of the domain cassette 8 Plasmodium falciparum erythrocyte membrane protein 1 is associated with cerebral malaria in Benin
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Justin Doritchamou, Philippe Deloron, Nadine Fievet, Maroufou J. Alao, Jakob S. Jespersen, Nicaise Tuikue Ndam, Christian W. Wang, Francis Lalya, Thor G. Theander, François Guillonneau, Achille Massougbodji, Gwladys Bertin, Thomas Lavstsen, and Sem Ezimegnon
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Proteomics ,Genes, Protozoan ,Protozoan Proteins ,Gene Expression ,Pathogenesis ,Protozoology ,Group A ,Plasmodium ,Mass Spectrometry ,Pregnancy ,Molecular Cell Biology ,Benin ,Child ,Multidisciplinary ,biology ,Infectious Diseases ,Cerebral Malaria ,Child, Preschool ,Proteome ,Medicine ,Female ,Research Article ,Adult ,Adolescent ,Science ,Plasmodium falciparum ,Malaria, Cerebral ,Microbiology ,parasitic diseases ,medicine ,Parasitic Diseases ,Humans ,RNA, Messenger ,Gene ,Biology ,biology.organism_classification ,medicine.disease ,Malaria ,Protein Structure, Tertiary ,Gene Expression Regulation ,Pregnancy Complications, Parasitic ,Immunology ,Parastic Protozoans ,Parasitology ,Chromatography, Liquid - Abstract
BackgroundPlasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is a highly polymorphic adherence receptor expressed on the surface of infected erythrocytes. Based on sequence homology PfEMP-1 variants have been grouped into three major groups A-C, the highly conserved VAR2CSA variants, and semi-conserved types defined by tandem runs of specific domains ("domain cassettes" (DC)). The PfEMP-1 type expressed determines the adherence phenotype, and is associated with clinical outcome of infection.MethodsParasite isolates from Beninese children or women presenting with, respectively, CM or PAM were collected along with samples from patients with uncomplicated malaria (UM). We assessed the transcript level of var genes by RT-qPCR and the expression of PfEMP-1 proteins by LC-MS/MS.ResultsVar genes encoding DC8 and Group A PfEMP-1 were transcribed more often and at higher levels in cerebral malaria vs. uncomplicated malaria patients. LC-MS/MS identified peptides from group A, DC8 PfEMP-1 more frequently in cerebral malaria than in uncomplicated malaria and pregnancy-associated malaria samples.ConclusionThis is the first study to show association between PfEMP-1 subtype and disease outcome by direct analysis of parasites proteome. The results corroborate that group A and specifically the PfEMP-1 types DC8 are universally associated with cerebral malaria. This is a crucial observation for promoting studies on malaria pathogenesis.
- Published
- 2013
17. Plasmodium falciparum erythrocyte membrane protein 1 domain cassettes 8 and 13 are associated with severe malaria in children
- Author
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M. Thomas P. Gilbert, Thomas Lavstsen, Pamela Magistrado, Louise Turner, Jakob S. Jespersen, Christian W. Wang, John Lusingu, Thor G. Theander, Eske Willerslev, Thomas S. Rask, Vito Baraka, Fredy Saguti, Sanne S. Berger, Andaine Seguin-Orlando, and Andrea Marion Marquard
- Subjects
Genes, Protozoan ,Molecular Sequence Data ,Plasmodium falciparum ,Protozoan Proteins ,Virulence ,macromolecular substances ,Parasitemia ,Biology ,Group A ,Asymptomatic ,Commentaries ,parasitic diseases ,medicine ,Animals ,Humans ,Malaria, Falciparum ,Child ,Gene ,Multidisciplinary ,medicine.disease ,biology.organism_classification ,Virology ,PNAS Plus ,Cerebral Malaria ,Immunology ,medicine.symptom ,Malaria - Abstract
The clinical outcome of Plasmodium falciparum infections ranges from asymptomatic parasitemia to severe malaria syndromes associated with high mortality. The virulence of P. falciparum infections is associated with the type of P. falciparum erythrocyte membrane protein 1 (PfEMP1) expressed on the surface of infected erythrocytes to anchor these to the vascular lining. Although var2csa , the var gene encoding the PfEMP1 associated with placental malaria, was discovered in 2003, the identification of the var /PfEMP1 variants associated with severe malaria in children has remained elusive. To identify var /PfEMP1 variants associated with severe disease outcome, we compared var transcript levels in parasites from 88 children with severe malaria and 40 children admitted to the hospital with uncomplicated malaria. Transcript analysis was performed by RT-quantitative PCR using a set of 42 primer pairs amplifying var subtype-specific loci covering most var /PfEMP1 subtypes. In addition, we characterized the near-full-length sequence of the most prominently expressed var genes in three patients diagnosed with severe anemia and/or cerebral malaria. The combined analysis showed that severe malaria syndromes, including severe anemia and cerebral malaria, are associated with high transcript levels of PfEMP1 domain cassette 8-encoding var genes. Transcript levels of group A var genes, including genes encoding domain cassette 13, were also significantly higher in patients with severe syndromes compared with those with uncomplicated malaria. This study specifies the var /PfEMP1 types expressed in severe malaria in children, and thereby provides unique targets for future efforts to prevent and treat severe malaria infections.
- Published
- 2012
18. Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains
- Author
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Jakob S Jespersen, Christian W Wang, Sixbert I Mkumbaye, Daniel TR Minja, Bent Petersen, Louise Turner, Jens EV Petersen, John PA Lusingu, Thor G Theander, and Thomas Lavstsen
- Subjects
CIDR ,EPCR ,PfEMP1 ,severe childhood malaria ,var ,Medicine (General) ,R5-920 ,Genetics ,QH426-470 - Abstract
Abstract Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding human endothelial protein C receptor (EPCR) through the CIDRα1 domain of certain PfEMP1 were recently associated with severe malaria in children. However, it has remained unclear to which extend the EPCR‐binding CIDRα1 domains epitomize PfEMP1 expressed in severe malaria. Here, we characterized the near full‐length transcripts dominating the var transcriptome in children with severe malaria and found that the only common feature of the encoded PfEMP1 was CIDRα1 domains. Such genes were highly and dominantly expressed in both children with severe malarial anaemia and cerebral malaria. These observations support the hypothesis that the CIDRα1‐EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction.
- Published
- 2016
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