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Rogier E, Nace D, Dimbu PR, Wakeman B, Beeson JG, Drakeley C, Tetteh K, Plucinski M. Antibody dynamics in children with first or repeat Plasmodium falciparum infections. Front Med (Lausanne) 2022; 9:869028. [PMID: 35928289 PMCID: PMC9343764 DOI: 10.3389/fmed.2022.869028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
Immunoglobulin (Ig) production during and after infection with Plasmodium parasites is one of the greatest adaptive immune defenses the human host has against this parasite. Infection with P. falciparum has been shown to induce different B cell maturation responses dependent upon the age of the patient, number of previous exposures, and severity of the disease. Described here are dynamics of Ig responses to a panel of 32 P. falciparum antigens by patients followed for 42 days and classified individuals as showing characteristics of an apparent first P. falciparum infection (naïve) or a repeat exposure (non-naïve). Six parameters were modeled to characterize the dynamics of IgM, IgG1, IgG3, and IgA for these two exposure groups with differences assessed among Ig isotypes/subclasses and unique antigens. Naïve patients had significantly longer periods of time to reach peak Ig titer (range 4–7 days longer) and lower maximum Ig titers when compared with non-naïve patients. Modeled time to seronegativity was significantly higher in non-naïve patients for IgM and IgA, but not for the two IgG subclasses. IgG1 responses to Rh2030, HSP40, and PfAMA1 were at the highest levels for non-naïve participants and may be used to predict previous or nascent exposure by themselves. The analyses presented here demonstrate the differences in the development of the Ig response to P. falciparum if the infection represents a boosting response or a primary exposure. Consistency in Ig isotype/subclasses estimates and specific data for P. falciparum antigens can better guide interpretation of seroepidemiological data among symptomatic persons.
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Affiliation(s)
- Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- *Correspondence: Eric Rogier,
| | - Doug Nace
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | | | - Brian Wakeman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - James G. Beeson
- Burnet Institute, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
- Department of Medicine, University of Melbourne, Melbourne, VIC, Australia
| | - Chris Drakeley
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kevin Tetteh
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Mateusz Plucinski
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- U.S. President’s Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, GA, United States
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2
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Goo YK. Vivax Malaria and the Potential Role of the Subtelomeric Multigene vir Superfamily. Microorganisms 2022; 10:microorganisms10061083. [PMID: 35744600 PMCID: PMC9228997 DOI: 10.3390/microorganisms10061083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 02/01/2023] Open
Abstract
Vivax malaria, caused by Plasmodium vivax, remains a public health concern in Central and Southeast Asia and South America, with more than two billion people at risk of infection. Compared to Plasmodium falciparum, P. vivax is considered a benign infection. However, in recent decades, incidences of severe vivax malaria have been confirmed. The P. falciparum erythrocyte membrane protein 1 family encoded by var genes is known as a mediator of severe falciparum malaria by cytoadherence property. Correspondingly, the vir multigene superfamily has been identified as the largest multigene family in P. vivax and is implicated in cytoadherence to endothelial cells and immune response activation. In this review, the functions of vir genes are reviewed in the context of their potential roles in severe vivax malaria.
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Affiliation(s)
- Youn-Kyoung Goo
- Department of Parasitology and Tropical Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Korea
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3
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Guillochon E, Fraering J, Joste V, Kamaliddin C, Vianou B, Houzé L, Baudrin LG, Faucher JF, Aubouy A, Houzé S, Cot M, Argy N, Taboureau O, Bertin GI. OUP accepted manuscript. J Infect Dis 2022; 225:2187-2196. [PMID: 35255125 PMCID: PMC9200161 DOI: 10.1093/infdis/jiac086] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/03/2022] [Indexed: 11/24/2022] Open
Abstract
Cerebral malaria (CM) is the severest form of Plasmodium falciparum infection. Children under 5 years old are those most vulnerable to CM, and they consequently have the highest risk of malaria-related death. Parasite-associated factors leading to CM are not yet fully elucidated. We therefore sought to characterize the gene expression profile associated with CM, using RNA sequencing data from 15 CM and 15 uncomplicated malaria isolates from Benin. Cerebral malaria parasites displayed reduced circulation times, possibly related to higher cytoadherence capacity. Consistent with the latter, we detected increased var genes abundance in CM isolates. Differential expression analyses showed that distinct transcriptome profiles are signatures of malaria severity. Genes involved in adhesion, excluding variant surface antigens, were dysregulated, supporting the idea of increased cytoadhesion capacity of CM parasites. Finally, we found dysregulated expression of genes in the entry into host pathway that may reflect greater erythrocyte invasion capacity of CM parasites.
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Affiliation(s)
- E Guillochon
- Université Paris Cité, MERIT, IRD, Paris, France
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - J Fraering
- Université Paris Cité, MERIT, IRD, Paris, France
| | - V Joste
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - C Kamaliddin
- Cumming School of Medicine, The University of Calgary, Calgary, Alberta, Canada
| | - B Vianou
- Université Paris Cité, MERIT, IRD, Paris, France
- Institut de Recherche Clinique du Bénin, Cotonou, Bénin
| | - L Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
| | - L G Baudrin
- Institut Curie Genomics of Excellence Platform, PSL Research University, Research Center, Institut Curie, Paris, France
| | - J F Faucher
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - A Aubouy
- Université de Toulouse, PHARMADEV, IRD, UPS, Toulouse, France
| | - S Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - M Cot
- Université Paris Cité, MERIT, IRD, Paris, France
| | - N Argy
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - O Taboureau
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - G I Bertin
- Correspondence: Gwladys I. Bertin, PhD, Université Paris Cité, MERIT, IRD, 4 avenue de l’Observatoire, 75006 Paris, France ()
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4
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Olsen RW, Suurbaar J, Jensen AR. Affinity Purification of PfEMP1-Specific Antibodies from Human Blood. Methods Mol Biol 2022; 2470:369-379. [PMID: 35881359 DOI: 10.1007/978-1-0716-2189-9_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Acquired immunity against Plasmodium falciparum infections relies heavily on IgG antibodies specific for PfEMP1 proteins expressed on the surface of infected erythrocytes. Purified human antibodies can be used, for example, to study the interactions between specific PfEMP1 proteins and receptors expressed by human endothelial cells, and to identify which IgG antibodies play a functional role in natural acquired immunity.This chapter describe how to affinity purify PfEMP1-specific human antibodies on an affinity column coupled with PfEMP1 protein. We include ELISA-based methods for identification of human plasma samples reactive against PfEMP1, and for testing of affinity purified IgG antibodies prior to their use in more advanced procedures.
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Affiliation(s)
- Rebecca W Olsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Jennifer Suurbaar
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
- West Africa Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Anja Ramstedt Jensen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Lopez-Perez M, Viwami F, Seidu Z, Jensen ATR, Doritchamou J, Ndam NT, Hviid L. PfEMP1-Specific Immunoglobulin G Reactivity Among Beninese Pregnant Women With Sickle Cell Trait. Open Forum Infect Dis 2021; 8:ofab527. [PMID: 34909438 PMCID: PMC8664683 DOI: 10.1093/ofid/ofab527] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/14/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Sickle cell trait (HbAS) protects against severe Plasmodium falciparum malaria but not against placental malaria (PM). In this study, P falciparum erythrocyte membrane protein (PfEMP1)-specific antibodies were measured in HbAA and HbAS Beninese pregnant women as a proxy of exposure to specific PfEMP1 variants. METHODS Plasma samples collected at delivery from 338 HbAA and 63 HbAS women were used to measure immunoglobulin (Ig)G levels to 6 recombinant PfEMP1 proteins and 3 corresponding native proteins expressed on the infected erythrocyte (IE) surface. Immunoglobulin G-mediated inhibition of VAR2CSA+ IEs adhesion to chondroitin sulfate A (CSA) was also tested. RESULTS Levels of PfEMP1-specific IgG were similar in the 2 groups, except for native IT4VAR09 on IEs, where IgG levels were significantly higher in HbAS women. Adjusted odds ratios for women with positive IgG to HB3VAR06 and PFD1235w suggest a lower risk of infection with these virulent variants among HbAS individuals. The percentage of IEs binding to CSA did not differ between HbAA and HbAS women, but it correlated positively with levels of anti-VAR2CSA and parity. Women with PM had lower levels of anti-VAR2CSA-specific IgG and lower IgG-mediated inhibition of IE adhesion to CSA. CONCLUSIONS The findings support similar malaria exposure in HbAA and HbAS women and a lack of HbAS-dependent protection against placental infection among pregnant women.
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Affiliation(s)
- Mary Lopez-Perez
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Firmine Viwami
- UMR 261 MERIT, Université de Paris, Institut de Recherche pour le Développement, Paris, France
- Institut de Recherche Clinique du Benin, Abomey Calavi, Benin
| | - Zakaria Seidu
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
- West Africa Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Anja T R Jensen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Nicaise Tuikue Ndam
- UMR 261 MERIT, Université de Paris, Institut de Recherche pour le Développement, Paris, France
- Institut de Recherche Clinique du Benin, Abomey Calavi, Benin
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lars Hviid
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Centre for Medical Parasitology, Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
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6
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Aitken EH, Damelang T, Ortega-Pajares A, Alemu A, Hasang W, Dini S, Unger HW, Ome-Kaius M, Nielsen MA, Salanti A, Smith J, Kent S, Hogarth PM, Wines BD, Simpson JA, Chung AW, Rogerson SJ. Developing a multivariate prediction model of antibody features associated with protection of malaria-infected pregnant women from placental malaria. eLife 2021; 10:e65776. [PMID: 34181872 PMCID: PMC8241440 DOI: 10.7554/elife.65776] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/16/2021] [Indexed: 12/15/2022] Open
Abstract
Background Plasmodium falciparum causes placental malaria, which results in adverse outcomes for mother and child. P. falciparum-infected erythrocytes that express the parasite protein VAR2CSA on their surface can bind to placental chondroitin sulfate A. It has been hypothesized that naturally acquired antibodies towards VAR2CSA protect against placental infection, but it has proven difficult to identify robust antibody correlates of protection from disease. The objective of this study was to develop a prediction model using antibody features that could identify women protected from placental malaria. Methods We used a systems serology approach with elastic net-regularized logistic regression, partial least squares discriminant analysis, and a case-control study design to identify naturally acquired antibody features mid-pregnancy that were associated with protection from placental malaria at delivery in a cohort of 77 pregnant women from Madang, Papua New Guinea. Results The machine learning techniques selected 6 out of 169 measured antibody features towards VAR2CSA that could predict (with 86% accuracy) whether a woman would subsequently have active placental malaria infection at delivery. Selected features included previously described associations with inhibition of placental binding and/or opsonic phagocytosis of infected erythrocytes, and network analysis indicated that there are not one but multiple pathways to protection from placental malaria. Conclusions We have identified candidate antibody features that could accurately identify malaria-infected women as protected from placental infection. It is likely that there are multiple pathways to protection against placental malaria. Funding This study was supported by the National Health and Medical Research Council (Nos. APP1143946, GNT1145303, APP1092789, APP1140509, and APP1104975).
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Affiliation(s)
- Elizabeth H Aitken
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Timon Damelang
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Amaya Ortega-Pajares
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Agersew Alemu
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Wina Hasang
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Saber Dini
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of MelbourneMelbourneAustralia
| | - Holger W Unger
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
- Department of Obstetrics and Gynaecology, Royal Darwin HospitalDarwinAustralia
- Menzies School of Health ResearchDarwinAustralia
| | - Maria Ome-Kaius
- Walter and Eliza Hall Institute of Medical ResearchParkvilleAustralia
| | - Morten A Nielsen
- Centre for Medical Parasitology, Department of Microbiology and immunology, University of CopenhagenCopenhagenDenmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of Microbiology and immunology, University of CopenhagenCopenhagenDenmark
- Department of Infectious Disease, Copenhagen University HospitalCopenhagenDenmark
| | - Joe Smith
- Seattle Children’s Research InstituteSeattleUnited States
- Department of Pediatrics, University of WashingtonSeattleUnited States
| | - Stephen Kent
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - P Mark Hogarth
- Seattle Children’s Research InstituteSeattleUnited States
- Immune Therapies Group, Centre for Biomedical Research, Burnet InstituteMelbourneAustralia
- Department of Clinical Pathology, University of MelbourneMelbourneAustralia
- Department of Immunology and Pathology, Monash UniversityMelbourneAustralia
| | - Bruce D Wines
- Immune Therapies Group, Centre for Biomedical Research, Burnet InstituteMelbourneAustralia
- Department of Clinical Pathology, University of MelbourneMelbourneAustralia
- Department of Immunology and Pathology, Monash UniversityMelbourneAustralia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of MelbourneMelbourneAustralia
| | - Amy W Chung
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
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7
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Chua CLL, Hasang W, Rogerson SJ, Teo A. Poor Birth Outcomes in Malaria in Pregnancy: Recent Insights Into Mechanisms and Prevention Approaches. Front Immunol 2021; 12:621382. [PMID: 33790894 PMCID: PMC8005559 DOI: 10.3389/fimmu.2021.621382] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 02/23/2021] [Indexed: 12/13/2022] Open
Abstract
Pregnant women in malaria-endemic regions are susceptible to malaria in pregnancy, which has adverse consequences on birth outcomes, including having small for gestational age and preterm babies. These babies are likely to have low birthweights, which predisposes to infant mortality and lifelong morbidities. During malaria in pregnancy, Plasmodium falciparum-infected erythrocytes express a unique variant surface antigen, VAR2CSA, that mediates sequestration in the placenta. This process may initiate a range of host responses that contribute to placental inflammation and dysregulated placental development, which affects placental vasculogenesis, angiogenesis and nutrient transport. Collectively, these result in the impairment of placental functions, affecting fetal development. In this review, we provide an overview of malaria in pregnancy and the different pathological pathways leading to malaria in pregnancy-associated low birthweight. We also discuss current prevention and management strategies for malaria in pregnancy, and some potential therapeutic interventions that may improve birth outcomes. Lastly, we outline some priorities for future research that could bring us one step closer to reducing this health burden.
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Affiliation(s)
| | - Wina Hasang
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Stephen J Rogerson
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Andrew Teo
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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8
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Abstract
Introduction: An effective vaccine against malaria forms a global health priority. Both naturally acquired immunity and sterile protection induced by irradiated sporozoite immunization were described decades ago. Still no vaccine exists that sufficiently protects children in endemic areas. Identifying immunological correlates of vaccine efficacy can inform rational vaccine design and potentially accelerate clinical development.Areas covered: We discuss recent research on immunological correlates of malaria vaccine efficacy, including: insights from state-of-the-art omics platforms and systems vaccinology analyses; functional anti-parasitic assays; pre-immunization predictors of vaccine efficacy; and comparison of correlates of vaccine efficacy against controlled human malaria infections (CHMI) and against naturally acquired infections.Expert Opinion: Effective vaccination may be achievable without necessarily understanding immunological correlates, but the relatively disappointing efficacy of malaria vaccine candidates in target populations is concerning. Hypothesis-generating omics and systems vaccinology analyses, alongside assessment of pre-immunization correlates, have the potential to bring about paradigm-shifts in malaria vaccinology. Functional assays may represent in vivo effector mechanisms, but have scarcely been formally assessed as correlates. Crucially, evidence is still meager that correlates of vaccine efficacy against CHMI correspond with those against naturally acquired infections in target populations. Finally, the diversity of immunological assays and efficacy endpoints across malaria vaccine trials remains a major confounder.
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Affiliation(s)
| | - Matthew B B McCall
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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9
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Tomlinson A, Semblat JP, Gamain B, Chêne A. VAR2CSA-Mediated Host Defense Evasion of Plasmodium falciparum Infected Erythrocytes in Placental Malaria. Front Immunol 2021; 11:624126. [PMID: 33633743 PMCID: PMC7900151 DOI: 10.3389/fimmu.2020.624126] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/23/2020] [Indexed: 12/04/2022] Open
Abstract
Over 30 million women living in P. falciparum endemic areas are at risk of developing malaria during pregnancy every year. Placental malaria is characterized by massive accumulation of infected erythrocytes in the intervillous space of the placenta, accompanied by infiltration of immune cells, particularly monocytes. The consequent local inflammation and the obstruction of the maternofetal exchanges can lead to severe clinical outcomes for both mother and child. Even if protection against the disease can gradually be acquired following successive pregnancies, the malaria parasite has developed a large panel of evasion mechanisms to escape from host defense mechanisms and manipulate the immune system to its advantage. Infected erythrocytes isolated from placentas of women suffering from placental malaria present a unique phenotype and express the pregnancy-specific variant VAR2CSA of the Plasmodium falciparum Erythrocyte Membrane Protein (PfEMP1) family at their surface. The polymorphic VAR2CSA protein is able to mediate the interaction of infected erythrocytes with a variety of host cells including placental syncytiotrophoblasts and leukocytes but also with components of the immune system such as non-specific IgM. This review summarizes the described VAR2CSA-mediated host defense evasion mechanisms employed by the parasite during placental malaria to ensure its survival and persistence.
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Affiliation(s)
- Alice Tomlinson
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Jean-Philippe Semblat
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Benoît Gamain
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Arnaud Chêne
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
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10
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Abstract
Purpose of Review Placental malaria is the primary mechanism through which malaria in pregnancy causes adverse perinatal outcomes. This review summarizes recent work on the significance, pathogenesis, diagnosis, and prevention of placental malaria. Recent Findings Placental malaria, characterized by the accumulation of Plasmodium-infected red blood cells in the placental intervillous space, leads to adverse perinatal outcomes such as stillbirth, low birth weight, preterm birth, and small-for-gestational-age neonates. Placental inflammatory responses may be primary drivers of these complications. Associated factors contributing to adverse outcomes include maternal gravidity, timing of perinatal infection, and parasite burden. Summary Placental malaria is an important cause of adverse birth outcomes in endemic regions. The main strategy to combat this is intermittent preventative treatment in pregnancy; however, increasing drug resistance threatens the efficacy of this approach. There are studies dissecting the inflammatory response to placental malaria, alternative preventative treatments, and in developing a vaccine for placental malaria.
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11
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Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon. PLoS One 2020; 15:e0237671. [PMID: 32797068 PMCID: PMC7428160 DOI: 10.1371/journal.pone.0237671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/30/2020] [Indexed: 12/02/2022] Open
Abstract
In high malaria transmission settings, the use of sulfadoxine-pyrimethamine-based intermittent preventive treatment during pregnancy (IPTp-SP) has resulted in decreased antibody (Ab) levels to VAR2CSA. However, information of Ab levels in areas of low or intermediate malaria transmission after long-term implementation of IPTp-SP is still lacking. The present study sought to evaluate antibody prevalence and levels in women at delivery in Etoudi, a peri-urban area in the capital of Yaoundé, Cameroon, that is a relatively low-malaria transmission area. Peripheral plasma samples from 130 pregnant women were collected at delivery and tested for IgG to the full-length recombinant VAR2CSA (FV2) and its most immunogenic subdomain, DBL5. The study was conducted between 2013 and 2015, approximately ten years after implementation of IPTp-SP in Cameroon. About 8.6% of the women attending the clinic had placental malaria (PM). One, two or 3 doses of SP did not impact significantly on either the percentage of women with Ab to FV2 and DBL5 or Ab levels in Ab-positive women compared to women not taking SP. The prevalence of Ab to FV2 and DBL5 was only 36.9% and 36.1%, respectively. Surprisingly, among women who had PM at delivery, only 61.5% and 57.7% had Ab to FV2 and DBL5, respectively, with only 52.9% and 47.1% in PM-positive paucigravidae and 77.7% of multigravidae having Ab to both antigens. These results suggest that long-term implementation of IPTp-SP in a low-malaria transmission area results in few women having Ab to VAR2CSA.
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12
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Doritchamou JYA, Morrison R, Renn JP, Ribeiro J, Duan J, Fried M, Duffy PE. Placental malaria vaccine candidate antigen VAR2CSA displays atypical domain architecture in some Plasmodium falciparum strains. Commun Biol 2019; 2:457. [PMID: 31840102 PMCID: PMC6897902 DOI: 10.1038/s42003-019-0704-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 11/13/2019] [Indexed: 12/15/2022] Open
Abstract
Two vaccines based on Plasmodium falciparum protein VAR2CSA are currently in clinical evaluation to prevent placental malaria (PM), but a deeper understanding of var2csa variability could impact vaccine design. Here we identified atypical extended or truncated VAR2CSA extracellular structures and confirmed one extended structure in a Malian maternal isolate, using a novel protein fragment assembly method for RNA-seq and DNA-seq data. Extended structures included one or two additional DBL domains downstream of the conventional NTS-DBL1X-6ɛ domain structure, with closest similarity to DBLɛ in var2csa and non-var2csa genes. Overall, 4/82 isolates displayed atypical VAR2CSA structures. The maternal isolate expressing an extended VAR2CSA bound to CSA, but its recombinant VAR2CSA bound less well to CSA than VAR2CSANF54 and showed lower reactivity to naturally acquired parity-dependent antibody. Our protein fragment sequence assembly approach has revealed atypical VAR2CSA domain architectures that impact antigen reactivity and function, and should inform the design of VAR2CSA-based vaccines.
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Affiliation(s)
- Justin Y. A. Doritchamou
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Robert Morrison
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Jonathan P. Renn
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Jose Ribeiro
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Junhui Duan
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Michal Fried
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
| | - Patrick E. Duffy
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD USA
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Antibodies to Cryptic Epitopes in Distant Homologues Underpin a Mechanism of Heterologous Immunity between Plasmodium vivax PvDBP and Plasmodium falciparum VAR2CSA. mBio 2019; 10:mBio.02343-19. [PMID: 31594821 PMCID: PMC6786876 DOI: 10.1128/mbio.02343-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In this work, we describe a molecular mechanism of heterologous immunity between two distant species of Plasmodium. Our results suggest a mechanism that subverts the classic parasite strategy of presenting highly polymorphic epitopes in surface antigens to evade immunity to that parasite. This alternative immune pathway can be exploited to protect pregnant women from falciparum placental malaria by designing vaccines to cryptic epitopes that elicit broadly inhibitory antibodies against variant parasite strains. Many pathogens evolve extensive genetic variation in virulence proteins as a strategy to evade host immunity. This poses a significant challenge for the host to develop broadly neutralizing antibodies. In Plasmodium falciparum, we show that a mechanism to circumvent this challenge is to elicit antibodies to cryptic epitopes that are not under immune pressure. We previously discovered that antibodies to the Plasmodium vivax invasion protein, PvDBP, cross-react with P. falciparum VAR2CSA, a distantly related virulence factor that mediates placental malaria. Here, we describe the molecular mechanism underlying this cross-species immunity. We identified an epitope in subdomain 1 (SD1) within the Duffy binding-like (DBL) domain of PvDBP that gives rise to cross-reactive antibodies to VAR2CSA and show that human antibodies affinity purified against a synthetic SD1 peptide block parasite adhesion to chondroitin sulfate A (CSA) in vitro. The epitope in SD1 is subdominant and highly conserved in PvDBP, and in turn, SD1 antibodies target cryptic epitopes in P. falciparum VAR2CSA. The epitopes in VAR2CSA recognized by vivax-derived SD1 antibodies (of human and mouse origin) are distinct from those recognized by VAR2CSA immune serum. We mapped two peptides in the DBL5ε domain of VAR2CSA that are recognized by SD1 antibodies. Both peptides map to regions outside the immunodominant sites, and antibodies to these peptides are not elicited following immunization with VAR2CSA or natural infection with P. falciparum in pregnancy, consistent with the cryptic nature of these target epitopes.
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