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Gbaguidi MLE, Adamou R, Edslev S, Hansen A, Domingo ND, Dechavanne C, Massougbodji A, Garcia A, Theisen M, Milet J, Donadi EA, Courtin D. IgG and IgM responses to the Plasmodium falciparum asexual stage antigens reflect respectively protection against malaria during pregnancy and infanthood. Malar J 2024; 23:154. [PMID: 38764069 PMCID: PMC11103834 DOI: 10.1186/s12936-024-04970-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 04/29/2024] [Indexed: 05/21/2024] Open
Abstract
BACKGROUND Plasmodium falciparum malaria is a public health issue mostly seen in tropical countries. Until now, there is no effective malaria vaccine against antigens specific to the blood-stage of P. falciparum infection. Because the pathogenesis of malarial disease results from blood-stage infection, it is essential to identify the most promising blood-stage vaccine candidate antigens under natural exposure to malaria infection. METHODS A cohort of 400 pregnant women and their infants was implemented in South Benin. An active and passive protocol of malaria surveillance was established during pregnancy and infancy to precisely ascertain malaria infections during the follow-up. Twenty-eight antibody (Ab) responses specific to seven malaria candidate vaccine antigens were repeatedly quantified during pregnancy (3 time points) and infancy (6 time points) in order to study the Ab kinetics and their protective role. Abs were quantified by ELISA and logistic, linear and cox-proportional hazard model were performed to analyse the associations between Ab responses and protection against malaria in mothers and infants, taking into account socio-economic factors and for infants an environmental risk of exposure. RESULTS The levels of IgM against MSP1, MSP2 and MSP3 showed an early protective response against the onset of symptomatic malaria infections starting from the 18th month of life, whereas no association was found for IgG responses during infancy. In women, some IgG responses tend to be associated with a protection against malaria risk along pregnancy and at delivery, among them IgG3 against GLURP-R0 and IgG2 against MSP1. CONCLUSION The main finding suggests that IgM should be considered in vaccine designs during infanthood. Investigation of the functional role played by IgM in malaria protection needs further attention.
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Affiliation(s)
- Mahugnon L Erasme Gbaguidi
- Division of Clinical Immunology, Department of Medicine, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
- IRD, MERIT, Université Paris Cité, 75006, Paris, France
- Centre d'Etude Et de Recherche Sur Les Pathologies Associées À La Grossesse Et À L'Enfance, Cotonou, Bénin
| | - Rafiou Adamou
- IRD, MERIT, Université Paris Cité, 75006, Paris, France
- Centre d'Etude Et de Recherche Sur Les Pathologies Associées À La Grossesse Et À L'Enfance, Cotonou, Bénin
| | - Sofie Edslev
- Institut de Recherche Clinique du Bénin, Abomey-Calavi, Benin
| | - Anita Hansen
- Institut de Recherche Clinique du Bénin, Abomey-Calavi, Benin
| | - Nadia D Domingo
- Centre d'Etude Et de Recherche Sur Les Pathologies Associées À La Grossesse Et À L'Enfance, Cotonou, Bénin
| | | | | | - André Garcia
- IRD, MERIT, Université Paris Cité, 75006, Paris, France
| | - Michael Theisen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | | | - Eduardo A Donadi
- Division of Clinical Immunology, Department of Medicine, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - David Courtin
- IRD, MERIT, Université Paris Cité, 75006, Paris, France.
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2
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Hviid L, Jensen AR, Deitsch KW. PfEMP1 and var genes - Still of key importance in Plasmodium falciparum malaria pathogenesis and immunity. ADVANCES IN PARASITOLOGY 2024; 125:53-103. [PMID: 39095112 DOI: 10.1016/bs.apar.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The most severe form of malaria, caused by infection with Plasmodium falciparum parasites, continues to be an important cause of human suffering and poverty. The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family of clonally variant antigens, which mediates the adhesion of infected erythrocytes to the vascular endothelium in various tissues and organs, is a central component of the pathogenesis of the disease and a key target of the acquired immune response to malaria. Much new knowledge has accumulated since we published a systematic overview of the PfEMP1 family almost ten years ago. In this chapter, we therefore aim to summarize research progress since 2015 on the structure, function, regulation etc. of this key protein family of arguably the most important human parasite. Recent insights regarding PfEMP1-specific immune responses and PfEMP1-specific vaccination against malaria, as well as an outlook for the coming years are also covered.
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Affiliation(s)
- Lars Hviid
- Centre for translational Medicine and Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
| | - Anja R Jensen
- Centre for translational Medicine and Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, United States
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3
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Zhan Q, He Q, Tiedje KE, Day KP, Pascual M. Hyper-diverse antigenic variation and resilience to transmission-reducing intervention in falciparum malaria. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.02.01.24301818. [PMID: 38370729 PMCID: PMC10871444 DOI: 10.1101/2024.02.01.24301818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Intervention against falciparum malaria in high transmission regions remains challenging, with relaxation of control efforts typically followed by rapid resurgence. Resilience to intervention co-occurs with incomplete immunity, whereby children eventually become protected from severe disease but not infection and a large transmission reservoir results from high asymptomatic prevalence across all ages. Incomplete immunity relates to the vast antigenic variation of the parasite, with the major surface antigen of the blood stage of infection encoded by the multigene family known as var. Recent deep sampling of var sequences from individual isolates in northern Ghana showed that parasite population structure exhibited persistent features of high-transmission regions despite the considerable decrease in prevalence during transient intervention with indoor residual spraying (IRS). We ask whether despite such apparent limited impact, the transmission system had been brought close to a transition in both prevalence and resurgence ability. With a stochastic agent-based model, we investigate the existence of such a transition to pre-elimination with intervention intensity, and of molecular indicators informative of its approach. We show that resurgence ability decreases sharply and nonlinearly across a narrow region of intervention intensities in model simulations, and identify informative molecular indicators based on var gene sequences. Their application to the survey data indicates that the transmission system in northern Ghana was brought close to transition by IRS. These results suggest that sustaining and intensifying intervention would have pushed malaria dynamics to a slow-rebound regime with an increased probability of local parasite extinction.
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Affiliation(s)
- Qi Zhan
- Committee on Genetics, Genomics and Systems Biology, The University of Chicago; Chicago, IL, 60637, USA
| | - Qixin He
- Department of Biological Sciences, Purdue University; West Lafayette, IN, 47907, USA
| | - Kathryn E Tiedje
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne; Melbourne, Australia
| | - Karen P Day
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne; Melbourne, Australia
| | - Mercedes Pascual
- Department of Biology, New York University; New York, NY, 10012, USA
- Department of Environmental Studies, New York University; New York, NY, 10012, USA
- Santa Fe Institute; Santa Fe, NM, 87501, USA
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4
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Edassery A, Meher AK, Gupta V, Rodriguez R. Clinico-epidemiological profiles & outcome of severe malaria in children under-five in the tribal area of Kalahandi, Odisha. Indian J Med Res 2024; 159:17-25. [PMID: 38439122 PMCID: PMC10954103 DOI: 10.4103/ijmr.ijmr_3302_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND OBJECTIVES Severe malaria is a cause of excess mortality and morbidity in children in malaria-endemic areas where indigenous people live. Currently, available reports are all from secondary or tertiary care hospitals across India and some African countries. The objective of this study was to assess the clinical and epidemiological profiles of children under five years in two primary care health centres located in tribal-dominant Thuamul Rampur Block of Kalahandi district, Odisha. The outcome of management of severe malaria in these children was also assessed. METHODS A retrospective review of case records of children under five years of age diagnosed and admitted with severe malaria in two non-governmental primary care facilities between 2017 and 2022, was undertaken. RESULTS There was a declining trend in malaria cases documented in primary care health facilities between January 2017 and June 2022. Of the 4858 cases recorded, 242 (4.9%) had severe malaria, of whom 70.7 per cent (n=171) were children under 5 yr. The median age of the study children was 24 months (16-36). Children aged 1-2 yr had a significantly higher risk of malaria. The majority were tribals (87%), more than half the children presented with neurological manifestations (64.4%), and 49.6 per cent had respiratory manifestations, while 20.5 per cent had severe anaemia (Hb <5 g/dl). Most, 167 (97.7%) severe malaria was due to Plasmodium falciparum. Thirty-two percent of children were severely wasted (WHZ < -3 SD) and 28 per cent were moderately wasted (WHZ <-2 SD). There was no fatality among the 171 children who were managed for severe malaria in the two primary care facilities. INTERPRETATION CONCLUSIONS In high endemic areas severe malaria is predominantly a disease of under-five children and is caused by P. falciparum. Clinical manifestations of severe malaria in children can be varied and life-threatening. Primary health facilities can manage severe malaria successfully, thereby reducing child mortality. Effective collaboration between malaria control and nutrition intervention programmes is essential for appropriate case management.
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Affiliation(s)
- Aquinas Edassery
- Swasthya Swaraj Comprehensive Community Health Programme, Swasthya Swaraj Society, Bhawanipatna, Odisha, India
| | - Ajay Kumar Meher
- Swasthya Swaraj Comprehensive Community Health Programme, Swasthya Swaraj Society, Bhawanipatna, Odisha, India
| | - Vanshika Gupta
- Swasthya Swaraj Comprehensive Community Health Programme, Swasthya Swaraj Society, Bhawanipatna, Odisha, India
| | - Rashmi Rodriguez
- Department of Community Health, St. John’s Medical College, Bengaluru, Karnataka, India
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5
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Walker IS, Rogerson SJ. Pathogenicity and virulence of malaria: Sticky problems and tricky solutions. Virulence 2023; 14:2150456. [PMID: 36419237 PMCID: PMC9815252 DOI: 10.1080/21505594.2022.2150456] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.
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Affiliation(s)
- Isobel S Walker
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
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Tewey MA, Coulibaly D, Lawton JG, Stucke EM, Zhou AE, Berry AA, Bailey JA, Pike A, Dara A, Ouattara A, Lyke KE, Ifeonu O, Laurens MB, Adams M, Takala-Harrison S, Niangaly A, Kouriba B, Koné AK, Rowe JA, Doumbo OK, Patel JJ, Tan JC, Felgner PL, Plowe CV, Thera MA, Travassos MA. Natural immunity to malaria preferentially targets the endothelial protein C receptor-binding regions of PfEMP1s. mSphere 2023; 8:e0045123. [PMID: 37791774 PMCID: PMC10597466 DOI: 10.1128/msphere.00451-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 08/21/2023] [Indexed: 10/05/2023] Open
Abstract
Antibody responses to variant surface antigens (VSAs) produced by the malaria parasite Plasmodium falciparum may contribute to age-related natural immunity to severe malaria. One VSA family, P. falciparum erythrocyte membrane protein-1 (PfEMP1), includes a subset of proteins that binds endothelial protein C receptor (EPCR) in human hosts and potentially disrupts the regulation of inflammatory responses, which may lead to the development of severe malaria. We probed peptide microarrays containing segments spanning five PfEMP1 EPCR-binding domain variants with sera from 10 Malian adults and 10 children to determine the differences between adult and pediatric immune responses. We defined serorecognized peptides and amino acid residues as those that elicited a significantly higher antibody response than malaria-naïve controls. We aimed to identify regions consistently serorecognized among adults but not among children across PfEMP1 variants, potentially indicating regions that drive the development of immunity to severe malaria. Adult sera consistently demonstrated broader and more intense serologic responses to constitutive PfEMP1 peptides than pediatric sera, including peptides in EPCR-binding domains. Both adults and children serorecognized a significantly higher proportion of EPCR-binding peptides than peptides that do not directly participate in receptor binding, indicating a preferential development of serologic responses at functional residues. Over the course of a single malaria transmission season, pediatric serological responses increased between the start and the peak of the season, but waned as the transmission season ended. IMPORTANCE Severe malaria and death related to malaria disproportionately affect sub-Saharan children under 5 years of age, commonly manifesting as cerebral malaria and/or severe malarial anemia. In contrast, adults in malaria-endemic regions tend to experience asymptomatic or mild disease. Our findings indicate that natural immunity to malaria targets specific regions within the EPCR-binding domain, particularly peptides containing EPCR-binding residues. Epitopes containing these residues may be promising targets for vaccines or therapeutics directed against severe malaria. Our approach provides insight into the development of natural immunity to a binding target linked to severe malaria by characterizing an "adult-like" response as recognizing a proportion of epitopes within the PfEMP1 protein, particularly regions that mediate EPCR binding. This "adult-like" response likely requires multiple years of malaria exposure, as increases in pediatric serologic response over a single malaria transmission season do not appear significant.
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Affiliation(s)
- Madison A. Tewey
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Jonathan G. Lawton
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Emily M. Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Albert E. Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrea A. Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Jason A. Bailey
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrew Pike
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Antoine Dara
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Amed Ouattara
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kirsten E. Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Olukemi Ifeonu
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew B. Laurens
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew Adams
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K. Koné
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - J. Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | | | - John C. Tan
- Roche NimbleGen, Inc., Madison, Wisconsin, USA
| | - Philip L. Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, California, USA
| | - Christopher V. Plowe
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Mahamadou A. Thera
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Mark A. Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Barua P, Duffy MF, Manning L, Laman M, Davis TME, Mueller I, Haghiri A, Simpson JA, Beeson JG, Rogerson SJ. Antibody to Plasmodium falciparum Variant Surface Antigens, var Gene Transcription, and ABO Blood Group in Children With Severe or Uncomplicated Malaria. J Infect Dis 2023; 228:1099-1107. [PMID: 37341543 PMCID: PMC10582907 DOI: 10.1093/infdis/jiad217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 06/08/2023] [Accepted: 06/20/2023] [Indexed: 06/22/2023] Open
Abstract
BACKGROUND Antibodies to variant surface antigens (VSAs) such as Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) may vary with malaria severity. The influence of ABO blood group on antibody development is not understood. METHODS Immunoglobulin G antibodies to VSAs in Papua New Guinean children with severe (n = 41) or uncomplicated (n = 30) malaria were measured by flow cytometry using homologous P falciparum isolates. Isolates were incubated with ABO-matched homologous and heterologous acute and convalescent plasma. RNA was used to assess var gene transcription. RESULTS Antibodies to homologous, but not heterologous, isolates were boosted in convalescence. The relationship between antibody and severity varied by blood group. Antibodies to VSAs were similar in severe and uncomplicated malaria at presentation, higher in severe than uncomplicated malaria in convalescence, and higher in children with blood group O than other children. Six var gene transcripts best distinguished severe from uncomplicated malaria, including UpsA and 2 CIDRα1 domains. CONCLUSIONS ABO blood group may influence antibody acquisition to VSAs and susceptibility to severe malaria. Children in Papua New Guinea showed little evidence of acquisition of cross-reactive antibodies following malaria. Var gene transcripts in Papua New Guinean children with severe malaria were similar to those reported from Africa.
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Affiliation(s)
- Priyanka Barua
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne
| | - Michael F Duffy
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, Bio21 Institute, University of Melbourne, Parkville, Victoria
| | | | - Moses Laman
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang
| | | | - Ivo Mueller
- Population Health and Immunity, Walter and Eliza Hall Institute, Parkville, Victoria, Australia
- Department of Parasites and Insect Vector, Institut Pasteur, Paris, France
| | - Ali Haghiri
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
| | - James G Beeson
- Malaria Immunity and Vaccines Laboratory, Burnet Institute, Melbourne
- Central Clinical School and Department of Microbiology, Monash University, Clayton
- Department of Infectious Diseases, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Stephen J Rogerson
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne
- Department of Infectious Diseases, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
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8
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Mbambo G, Dwivedi A, Ifeonu OO, Munro JB, Shrestha B, Bromley RE, Hodges T, Adkins RS, Kouriba B, Diarra I, Niangaly A, Kone AK, Coulibaly D, Traore K, Dolo A, Thera MA, Laurens MB, Doumbo OK, Plowe CV, Berry AA, Travassos M, Lyke KE, Silva JC. Immunogenomic profile at baseline predicts host susceptibility to clinical malaria. Front Immunol 2023; 14:1179314. [PMID: 37465667 PMCID: PMC10351378 DOI: 10.3389/fimmu.2023.1179314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 06/19/2023] [Indexed: 07/20/2023] Open
Abstract
Introduction Host gene and protein expression impact susceptibility to clinical malaria, but the balance of immune cell populations, cytokines and genes that contributes to protection, remains incompletely understood. Little is known about the determinants of host susceptibility to clinical malaria at a time when acquired immunity is developing. Methods We analyzed peripheral blood mononuclear cells (PBMCs) collected from children who differed in susceptibility to clinical malaria, all from a small town in Mali. PBMCs were collected from children aged 4-6 years at the start, peak and end of the malaria season. We characterized the immune cell composition and cytokine secretion for a subset of 20 children per timepoint (10 children with no symptomatic malaria age-matched to 10 children with >2 symptomatic malarial illnesses), and gene expression patterns for six children (three per cohort) per timepoint. Results We observed differences between the two groups of children in the expression of genes related to cell death and inflammation; in particular, inflammatory genes such as CXCL10 and STAT1 and apoptotic genes such as XAF1 were upregulated in susceptible children before the transmission season began. We also noted higher frequency of HLA-DR+ CD4 T cells in protected children during the peak of the malaria season and comparable levels cytokine secretion after stimulation with malaria schizonts across all three time points. Conclusion This study highlights the importance of baseline immune signatures in determining disease outcome. Our data suggests that differences in apoptotic and inflammatory gene expression patterns can serve as predictive markers of susceptibility to clinical malaria.
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Affiliation(s)
- Gillian Mbambo
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Ankit Dwivedi
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Olukemi O. Ifeonu
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - James B. Munro
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Biraj Shrestha
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Robin E. Bromley
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Theresa Hodges
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Ricky S. Adkins
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Bourema Kouriba
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Issa Diarra
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Amadou Niangaly
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoulaye K. Kone
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Drissa Coulibaly
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Karim Traore
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Amagana Dolo
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Mahamadou A. Thera
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Matthew B. Laurens
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, International Centers for Excellence in Research (NIH), University of Science Techniques and Technologies of Bamako, Bamako, Mali
| | - Christopher V. Plowe
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Andrea A. Berry
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Mark Travassos
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Kirsten E. Lyke
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Joana C. Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, United States
- Global Health and Tropical Medicine, Instituto deHigiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM, IHMT, UNL), Lisboa, Portugal
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9
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Travassos MA, Rohlwink UK, Tucker EW. Editorial: Broadening our understanding of the impact of infections on the developing central nervous system - from basic to clinical sciences. Front Neurol 2023; 14:1198518. [PMID: 37234785 PMCID: PMC10206214 DOI: 10.3389/fneur.2023.1198518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 04/06/2023] [Indexed: 05/28/2023] Open
Affiliation(s)
- Mark A. Travassos
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Ursula K. Rohlwink
- Division of Neurosurgery, Department of Surgery and Neuroscience Institute, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Elizabeth W. Tucker
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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10
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Sobota RS, Goron AR, Berry AA, Bailey JA, Coulibaly D, Adams M, Kone AK, Kouriba B, Doumbo OK, Sztein MB, Felgner PL, Plowe CV, Lyke KE, Thera MA, Travassos MA. Serologic and Cytokine Profiles of Children with Concurrent Cerebral Malaria and Severe Malarial Anemia Are Distinct from Other Subtypes of Severe Malaria. Am J Trop Med Hyg 2022; 107:315-319. [PMID: 35895583 PMCID: PMC9393435 DOI: 10.4269/ajtmh.22-0135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/25/2022] [Indexed: 11/07/2022] Open
Abstract
We used a protein microarray featuring Plasmodium falciparum field variants of a merozoite surface antigen to examine malaria exposure in Malian children with different severe malaria syndromes. Unlike children with cerebral malaria alone or severe malarial anemia alone, those with concurrent cerebral malaria and severe malarial anemia had serologic responses demonstrating a broader prior parasite exposure pattern than matched controls with uncomplicated disease. Comparison of levels of malaria-related cytokines revealed that children with the concurrent phenotype had elevated levels of interleukin (IL)-6, IL-8, and IL-10. Our results suggest that the pathophysiology of this severe subtype is unique and merits further investigation.
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Affiliation(s)
- Rafal S. Sobota
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
- Ken and Ruth Davee Department of Neurology, Northwestern University, Chicago, Illinois
| | - Abby R. Goron
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea A. Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jason A. Bailey
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Matthew Adams
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Abdoulaye K. Kone
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Marcelo B. Sztein
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Philip L. Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, California
| | - Christopher V. Plowe
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kirsten E. Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Mahamadou A. Thera
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Mark A. Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
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11
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Identifying Targets of Protective Antibodies against Severe Malaria in Papua, Indonesia, Using Locally Expressed Domains of Plasmodium falciparum Erythrocyte Membrane Protein 1. Infect Immun 2022; 90:e0043521. [PMID: 34871039 PMCID: PMC8853675 DOI: 10.1128/iai.00435-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a diverse family of multidomain proteins expressed on the surface of malaria-infected erythrocytes, is an important target of protective immunity against malaria. Our group recently studied transcription of the var genes encoding PfEMP1 in individuals from Papua, Indonesia, with severe or uncomplicated malaria. We cloned and expressed domains from 32 PfEMP1s, including 22 that were upregulated in severe malaria and 10 that were upregulated in uncomplicated malaria, using a wheat germ cell-free expression system. We used Luminex technology to measure IgG antibodies to these 32 domains and control proteins in 63 individuals (11 children). At presentation to hospital, levels of antibodies to PfEMP1 domains were either higher in uncomplicated malaria or were not significantly different between groups. Using principal component analysis, antibodies to 3 of 32 domains were highly discriminatory between groups. These included two domains upregulated in severe malaria, a DBLβ13 domain and a CIDRα1.6 domain (which has been previously implicated in severe malaria pathogenesis), and a DBLδ domain that was upregulated in uncomplicated malaria. Antibody to control non-PfEMP1 antigens did not differ with disease severity. Antibodies to PfEMP1 domains differ with malaria severity. Lack of antibodies to locally expressed PfEMP1 types, including both domains previously associated with severe malaria and newly identified targets, may in part explain malaria severity in Papuan adults.
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12
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Zhou AE, Shah ZV, Bradwell KR, Munro JB, Berry AA, Serre D, Takala-Harrison S, O'Connor TD, Silva JC, Travassos MA. STRIDE: a command-line HMM-based identifier and sub-classifier of Plasmodium falciparum RIFIN and STEVOR variant surface antigen families. BMC Bioinformatics 2022; 23:15. [PMID: 34991452 PMCID: PMC8733436 DOI: 10.1186/s12859-021-04515-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 12/06/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND RIFINs and STEVORs are variant surface antigens expressed by P. falciparum that play roles in severe malaria pathogenesis and immune evasion. These two highly diverse multigene families feature multiple paralogs, making their classification challenging using traditional bioinformatic methods. RESULTS STRIDE (STevor and RIfin iDEntifier) is an HMM-based, command-line program that automates the identification and classification of RIFIN and STEVOR protein sequences in the malaria parasite Plasmodium falciparum. STRIDE is more sensitive in detecting RIFINs and STEVORs than available PFAM and TIGRFAM tools and reports RIFIN subtypes and the number of sequences with a FHEYDER amino acid motif, which has been associated with severe malaria pathogenesis. CONCLUSIONS STRIDE will be beneficial to malaria research groups analyzing genome sequences and transcripts of clinical field isolates, providing insight into parasite biology and virulence.
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Affiliation(s)
- Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zalak V Shah
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Katie R Bradwell
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James B Munro
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David Serre
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Timothy D O'Connor
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Program in Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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13
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Zhou AE, Jain A, Nakajima R, Shrestha B, Stucke EM, Joshi S, Strauss KA, Hedde PN, Berry AA, Felgner PL, Travassos MA. Protein Microarrays as a Tool to Analyze Antibody Responses to Variant Surface Antigens Expressed on the Surface of Plasmodium falciparum-Infected Erythrocytes. Methods Mol Biol 2022. [PMID: 35881357 DOI: 10.1007/978-1-0716-2189-9_25/cover] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Enzyme-linked immunosorbent assays (ELISAs) remain the gold standard for measuring antibodies, but are time-consuming and use significant amounts of precious sample and reagents. Protein microarrays represent an appealing alternative, particularly for studies focused on large gene families such as those encoding variant surface antigens in the malaria parasite Plasmodium falciparum. Such microarrays represent an ideal high-throughput platform to study antibody responses to hundreds of malaria parasite variant surface antigens at once, providing critical insights into the development of natural immunity to malaria. We describe the essential background and approach to run an assay using a P. falciparum microarray populated with variant surface antigens. This allows the user to define serologic profiles and identify serodominant antigens that represent promising targets for vaccine or therapeutic development.
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Affiliation(s)
- Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aarti Jain
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Rie Nakajima
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Biraj Shrestha
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sudhaunshu Joshi
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathy A Strauss
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Per N Hedde
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Philip L Felgner
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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14
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Zhou AE, Jain A, Nakajima R, Shrestha B, Stucke EM, Joshi S, Strauss KA, Hedde PN, Berry AA, Felgner PL, Travassos MA. Protein Microarrays as a Tool to Analyze Antibody Responses to Variant Surface Antigens Expressed on the Surface of Plasmodium falciparum-Infected Erythrocytes. Methods Mol Biol 2022; 2470:343-358. [PMID: 35881357 DOI: 10.1007/978-1-0716-2189-9_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Enzyme-linked immunosorbent assays (ELISAs) remain the gold standard for measuring antibodies, but are time-consuming and use significant amounts of precious sample and reagents. Protein microarrays represent an appealing alternative, particularly for studies focused on large gene families such as those encoding variant surface antigens in the malaria parasite Plasmodium falciparum. Such microarrays represent an ideal high-throughput platform to study antibody responses to hundreds of malaria parasite variant surface antigens at once, providing critical insights into the development of natural immunity to malaria. We describe the essential background and approach to run an assay using a P. falciparum microarray populated with variant surface antigens. This allows the user to define serologic profiles and identify serodominant antigens that represent promising targets for vaccine or therapeutic development.
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Affiliation(s)
- Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aarti Jain
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Rie Nakajima
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Biraj Shrestha
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sudhaunshu Joshi
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathy A Strauss
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Per N Hedde
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Philip L Felgner
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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15
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Walker IS, Chung AW, Damelang T, Rogerson SJ. Analysis of Antibody Reactivity to Malaria Antigens by Microsphere-Based Multiplex Immunoassay. Methods Mol Biol 2022; 2470:309-325. [PMID: 35881355 DOI: 10.1007/978-1-0716-2189-9_23] [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
Protein multiplex assays enable serological analysis of multiple target proteins simultaneously, using relatively small volumes of patient sample per assay. Here we present a detailed protocol to analyze antibody reactivity to malaria antigens by microsphere-based multiplex assay (xMAP technology). This method involves coupling of recombinant proteins to fluorescently labeled microspheres; simultaneous exposure of all microspheres to plasma or sera, and detection of antigen-specific antibodies with a fluorescent labeled anti-human Fc region antibody. In addition to total IgG, this assay can be adapted to measure multiple properties of the antibody Fc region, including subclass, isotype, and Fc receptor or complement C1q binding.
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Affiliation(s)
- Isobel S Walker
- Department of Medicine, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
| | - Amy W Chung
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Timon Damelang
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Stephen J Rogerson
- Department of Infectious Diseases, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
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16
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Immunoprofiles associated with controlled human malaria infection and naturally acquired immunity identify a shared IgA pre-erythrocytic immunoproteome. NPJ Vaccines 2021; 6:115. [PMID: 34518543 PMCID: PMC8438027 DOI: 10.1038/s41541-021-00363-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/29/2021] [Indexed: 12/12/2022] Open
Abstract
Knowledge of the Plasmodium falciparum antigens that comprise the human liver stage immunoproteome is important for pre-erythrocytic vaccine development, but, compared with the erythrocytic stage immunoproteome, more challenging to classify. Previous studies of P. falciparum antibody responses report IgG and rarely IgA responses. We assessed IgG and IgA antibody responses in adult sera collected during two controlled human malaria infection (CHMI) studies in malaria-naïve volunteers and in 1- to 6-year-old malaria-exposed Malian children on a 251 P. falciparum antigen protein microarray. IgG profiles in the two CHMI groups were equivalent and differed from Malian children. IgA profiles were robust in the CHMI groups and a subset of Malian children. We describe immunoproteome differences in naïve vs. exposed individuals and report pre-erythrocytic proteins recognized by the immune system. IgA responses detected in this study expand the list of pre-erythrocytic antigens for further characterization as potential vaccine candidates.
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17
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Ventimiglia NT, Stucke EM, Coulibaly D, Berry AA, Lyke KE, Laurens MB, Bailey JA, Adams M, Niangaly A, Kone AK, Takala-Harrison S, Kouriba B, Doumbo OK, Felgner PL, Plowe CV, Thera MA, Travassos MA. Malian adults maintain serologic responses to virulent PfEMP1s amid seasonal patterns of fluctuation. Sci Rep 2021; 11:14401. [PMID: 34257318 PMCID: PMC8277812 DOI: 10.1038/s41598-021-92974-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/08/2021] [Indexed: 12/03/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein-1s (PfEMP1s), diverse malaria proteins expressed on the infected erythrocyte surface, play an important role in pathogenesis, mediating adhesion to host vascular endothelium. Antibodies to particular non-CD36-binding PfEMP1s are associated with protection against severe disease. We hypothesized that given lifelong P. falciparum exposure, Malian adults would have broad PfEMP1 serorecognition and high seroreactivity levels during follow-up, particularly to non-CD36-binding PfEMP1s such as those that attach to endothelial protein C receptor (EPCR) and intercellular adhesion molecule-1 (ICAM-1). Using a protein microarray, we determined serologic responses to 166 reference PfEMP1 fragments during a dry and subsequent malaria transmission season in Malian adults. Malian adult sera had PfEMP1 serologic responses throughout the year, with decreased reactivity to a small subset of PfEMP1 fragments during the dry season and increases in reactivity to a different subset of PfEMP1 fragments during the subsequent peak malaria transmission season, especially for intracellular PfEMP1 domains. For some individuals, PfEMP1 serologic responses increased after the dry season, suggesting antigenic switching during asymptomatic infection. Adults were more likely to experience variable serorecognition of CD36-binding PfEMP1s than non-CD36-binding PfEMP1s that bind EPCR or ICAM-1, which remained serorecognized throughout the year. Sustained seroreactivity to non-CD36-binding PfEMP1s throughout adulthood amid seasonal fluctuation patterns may reflect underlying protective severe malaria immunity and merits further investigation.
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Affiliation(s)
| | - Emily M Stucke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Drissa Coulibaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Andrea A Berry
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kirsten E Lyke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Jason A Bailey
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew Adams
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K Kone
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | | | - Bourema Kouriba
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Ogobara K Doumbo
- University of Sciences, Techniques and Technologies, Bamako, Mali
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18
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Parra M, Yang J, Weitner M, Akkoyunlu M. Neonatal mice resist Plasmodium yoelii infection until exposed to para-aminobenzoic acid containing diet after weaning. Sci Rep 2021; 11:90. [PMID: 33420157 PMCID: PMC7794322 DOI: 10.1038/s41598-020-79703-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/04/2020] [Indexed: 12/03/2022] Open
Abstract
We developed a newborn (NB) mouse Plasmodium yoelii NL infection model to study malaria in early age. Surprisingly, the onset of parasitemia in P. yoelii challenged NB mice was delayed compared to adults and coincided with the weaning date when weanlings switched from maternal milk to normal chow diet. Also, compared to adult mice, parasitemia resolved much later (48 days vs 20 days post challenge) and the peak parasitemia was twice as high in weanlings. Concurrently, weanlings’ germinal center reaction was delayed and diminished compared to adult mice. Maternal milk is deficient in para-aminobenzoic acid (PABA), which is required for de novo folate synthesis by Plasmodium. Suggesting a possible role for the protection afforded by PABA-deficient maternal milk, mice fed with a PABA-deficient diet after the weaning continued to control parasitemia. Despite the reduced parasitemia, these mice developed robust T follicular helper (Tfh) responses and were protected from a second P. yoelii challenge. The NB malaria model provides mechanistic insight into the human infant malaria manifestations where a diet solely based on breast-feeding reduces the incidence of severe malaria in infants. NB mice experiments also support further studies to investigate dietary PABA restriction in the management of severe malaria in infants.
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Affiliation(s)
- Marcela Parra
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Jiyeon Yang
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Megan Weitner
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA.,Viral & Rickettsial Diseases Department (NMRC VRDD), Naval Medical Research Center, Silver Spring, MD, USA
| | - Mustafa Akkoyunlu
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA. .,DBPAP, US FDA, CBER, 10903 New Hampshire Ave., Building 52/72, Room, 5214, Silver Spring, MD, 209903, USA.
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19
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Gonzales SJ, Reyes RA, Braddom AE, Batugedara G, Bol S, Bunnik EM. Naturally Acquired Humoral Immunity Against Plasmodium falciparum Malaria. Front Immunol 2020; 11:594653. [PMID: 33193447 PMCID: PMC7658415 DOI: 10.3389/fimmu.2020.594653] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/07/2020] [Indexed: 12/18/2022] Open
Abstract
Malaria remains a significant contributor to the global burden of disease, with around 40% of the world's population at risk of Plasmodium infections. The development of an effective vaccine against the malaria parasite would mark a breakthrough in the fight to eradicate the disease. Over time, natural infection elicits a robust immune response against the blood stage of the parasite, providing protection against malaria. In recent years, we have gained valuable insight into the mechanisms by which IgG acts to prevent pathology and inhibit parasite replication, as well as the potential role of immunoglobulin M (IgM) in these processes. Here, we discuss recent advances in our understanding of the mechanisms, acquisition, and maintenance of naturally acquired immunity, and the relevance of these discoveries for the development of a potential vaccine against the blood stage of Plasmodium falciparum.
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Affiliation(s)
| | | | | | | | | | - Evelien M. Bunnik
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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20
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Nyarko PB, Claessens A. Understanding Host-Pathogen-Vector Interactions with Chronic Asymptomatic Malaria Infections. Trends Parasitol 2020; 37:195-204. [PMID: 33127332 DOI: 10.1016/j.pt.2020.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 01/06/2023]
Abstract
The last malaria parasite standing will display effective adaptations to selective forces. While substantial progress has been made in reducing malaria mortality, eradication will require elimination of all Plasmodium parasites, including those in asymptomatic infections. These typically chronic, low-density infections are difficult to detect, yet can persist for months. We argue that asymptomatic infection is the parasite's best asset for survival but it can be exploited if studied as a new model for host-pathogen-vector interactions. Regular sampling from cohorts of asymptomatic individuals can provide a means to investigate continuous parasite development within its natural host. State-of-the-art techniques can now be applied to such infections. This approach may reveal key molecular drivers of chronic infections - a critical step for malaria eradication.
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Affiliation(s)
- Prince B Nyarko
- Laboratory of Pathogen-Host Interaction (LPHI), CNRS, University of Montpellier, France
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21
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Kassegne K, Komi Koukoura K, Shen HM, Chen SB, Fu HT, Chen YQ, Zhou XN, Chen JH, Cheng Y. Genome-Wide Analysis of the Malaria Parasite Plasmodium falciparum Isolates From Togo Reveals Selective Signals in Immune Selection-Related Antigen Genes. Front Immunol 2020; 11:552698. [PMID: 33193320 PMCID: PMC7645038 DOI: 10.3389/fimmu.2020.552698] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 09/02/2020] [Indexed: 12/19/2022] Open
Abstract
Malaria is a public health concern worldwide, and Togo has proven to be no exception. Effective approaches to provide information on biological insights for disease elimination are therefore a research priority. Local selection on malaria pathogens is due to multiple factors including host immunity. We undertook genome-wide analysis of sequence variation on a sample of 10 Plasmodium falciparum (Pf) clinical isolates from Togo to identify local-specific signals of selection. Paired-end short-read sequences were mapped and aligned onto > 95% of the 3D7 Pf reference genome sequence in high fold coverage. Data on 266 963 single nucleotide polymorphisms were obtained, with average nucleotide diversity π = 1.79 × 10−3. Both principal component and neighbor-joining tree analyses showed that the Togo parasites clustered according to their geographic (Africa) origin. In addition, the average genome-wide diversity of Pf from Togo was much higher than that from other African samples. Tajima’s D value of the Togo isolates was −0.56, suggesting evidence of directional selection and/or recent population expansion. Against this background, within-population analyses identifying loci of balancing and recent positive selections evidenced that host immunity has been the major selective agent. Importantly, 87 and 296 parasite antigen genes with Tajima’s D values > 1 and in the top 1% haplotype scores, respectively, include a significant representation of membrane proteins at the merozoite stage that invaded red blood cells (RBCs) and parasitized RBCs surface proteins that play roles in immunoevasion, adhesion, or rosetting. This is consistent with expectations that elevated signals of selection due to allele-specific acquired immunity are likely to operate on antigenic targets. Collectively, our data suggest a recent expansion of Pf population in Togo and evidence strong host immune selection on membrane/surface antigens reflected in signals of balancing/positive selection of important gene loci. Findings from this study provide a fundamental basis to engage studies for effective malaria control in Togo.
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Affiliation(s)
- Kokouvi Kassegne
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Komi Komi Koukoura
- Laboratoire des Sciences Biomédicales, Alimentaires et Santé Environnementale, Département des Analyses Biomédicales, Ecole Supérieure des Techniques Biologiques et Alimentaires, Université de Lomé, Lomé, Togo
| | - Hai-Mo Shen
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Chinese Centre for Tropical Diseases Research, WHO Collaborating Centre for Tropical Diseases, National Centre for International Research on Tropical Diseases, Ministry of Science and Technology, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China.,National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention-Shenzhen Centre for Disease Control and Prevention Joint Laboratory for Imported Tropical Disease Control, Shanghai, China.,The School of Global Health, Chinese Centre for Tropical Diseases Research, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Shen-Bo Chen
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Chinese Centre for Tropical Diseases Research, WHO Collaborating Centre for Tropical Diseases, National Centre for International Research on Tropical Diseases, Ministry of Science and Technology, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China.,National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention-Shenzhen Centre for Disease Control and Prevention Joint Laboratory for Imported Tropical Disease Control, Shanghai, China.,The School of Global Health, Chinese Centre for Tropical Diseases Research, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Hai-Tian Fu
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Yong-Quan Chen
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, China.,School of Food Science and Technology, State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Chinese Centre for Tropical Diseases Research, WHO Collaborating Centre for Tropical Diseases, National Centre for International Research on Tropical Diseases, Ministry of Science and Technology, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China.,National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention-Shenzhen Centre for Disease Control and Prevention Joint Laboratory for Imported Tropical Disease Control, Shanghai, China.,The School of Global Health, Chinese Centre for Tropical Diseases Research, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jun-Hu Chen
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Chinese Centre for Tropical Diseases Research, WHO Collaborating Centre for Tropical Diseases, National Centre for International Research on Tropical Diseases, Ministry of Science and Technology, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China.,National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention-Shenzhen Centre for Disease Control and Prevention Joint Laboratory for Imported Tropical Disease Control, Shanghai, China.,The School of Global Health, Chinese Centre for Tropical Diseases Research, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Yang Cheng
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, China
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22
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Kanoi BN, Nagaoka H, White MT, Morita M, Palacpac NMQ, Ntege EH, Balikagala B, Yeka A, Egwang TG, Horii T, Tsuboi T, Takashima E. Global Repertoire of Human Antibodies Against Plasmodium falciparum RIFINs, SURFINs, and STEVORs in a Malaria Exposed Population. Front Immunol 2020; 11:893. [PMID: 32477363 PMCID: PMC7235171 DOI: 10.3389/fimmu.2020.00893] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/17/2020] [Indexed: 11/15/2022] Open
Abstract
Clinical immunity to malaria develops after repeated exposure to Plasmodium falciparum parasites. Broadly reactive antibodies against parasite antigens expressed on the surface of infected erythrocytes (variable surface antigens; VSAs) are candidates for anti-malaria therapeutics and vaccines. Among the VSAs, several RIFIN, STEVOR, and SURFIN family members have been demonstrated to be targets of naturally acquired immunity against malaria. For example, RIFIN family members are important ligands for opsonization of P. falciparum infected erythrocytes with specific immunoglobulins (IgG) acquiring broad protective reactivity. However, the global repertoire of human anti-VSAs IgG, its variation in children, and the key protective targets remain poorly understood. Here, we report wheat germ cell-free system-based production and serological profiling of a comprehensive library of A-RIFINs, B-RIFINs, STEVORs, and SURFINs derived from the P. falciparum 3D7 parasite strain. We observed that >98% of assayed proteins (n = 265) were immunogenic in malaria-exposed individuals in Uganda. The overall breadth of immune responses was significantly correlated with age but not with clinical malaria outcome among the study volunteers. However, children with high levels of antibodies to four RIFINs (PF3D7_0201000, PF3D7_1254500, PF3D7_1040600, PF3D7_1041100), STEVOR (PF3D7_0732000), and SURFIN 1.2 (PF3D7_0113600) had prospectively reduced the risk of developing febrile malaria, suggesting that the 5 antigens are important targets of protective immunity. Further studies on the significance of repeated exposure to malaria infection and maintenance of such high-level antibodies would contribute to a better understanding of susceptibility and naturally acquired immunity to malaria.
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Affiliation(s)
- Bernard N Kanoi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Michael T White
- Department of Parasites and Insect Vectors, Pasteur Institute, Paris, France
| | - Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Nirianne M Q Palacpac
- Department of Malaria Vaccine Development, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Edward H Ntege
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine and Hospital, University of the Ryukyus, Okinawa, Japan
| | - Betty Balikagala
- Department of Tropical Medicine and Parasitology, School of Medicine, Juntendo University, Tokyo, Japan
| | - Adoke Yeka
- Makerere University School of Public Health, Kampala, Uganda
| | | | - Toshihiro Horii
- Department of Malaria Vaccine Development, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
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23
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Tessema SK, Nakajima R, Jasinskas A, Monk SL, Lekieffre L, Lin E, Kiniboro B, Proietti C, Siba P, Felgner PL, Doolan DL, Mueller I, Barry AE. Protective Immunity against Severe Malaria in Children Is Associated with a Limited Repertoire of Antibodies to Conserved PfEMP1 Variants. Cell Host Microbe 2020; 26:579-590.e5. [PMID: 31726028 DOI: 10.1016/j.chom.2019.10.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/08/2019] [Accepted: 10/18/2019] [Indexed: 01/31/2023]
Abstract
Extreme diversity of the major Plasmodium falciparum antigen, PfEMP1, poses a barrier to identifying targets of immunity to malaria. Here, we used protein microarrays containing hundreds of variants of the DBLα domain of PfEMP1 to cover the diversity of Papua New Guinean (PNG) parasites. Probing the plasma of a longitudinal cohort of malaria-exposed PNG children showed that group 2 DBLα antibodies were moderately associated with a lower risk of uncomplicated malaria, whereas individual variants were only weakly associated with clinical immunity. In contrast, antibodies to 85 individual group 1 and 2 DBLα variants were associated with a 70%-100% reduction in severe malaria. Of these, 17 variants were strong predictors of severe malaria. Analysis of full-length PfEMP1 sequences from PNG samples shows that these 17 variants are linked to pathogenic CIDR domains. This suggests that whereas immunity to uncomplicated malaria requires a broad repertoire of antibodies, immunity to severe malaria targets a subset of conserved variants. These findings provide insights into antimalarial immunity and potential antibody biomarkers for disease risk.
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Affiliation(s)
- Sofonias K Tessema
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne 3000, VIC, Australia
| | - Rie Nakajima
- Physiology & Biophysics Department, Vaccine R&D Center, University of California, Irvine, Irvine 92697, CA, USA
| | - Algis Jasinskas
- Physiology & Biophysics Department, Vaccine R&D Center, University of California, Irvine, Irvine 92697, CA, USA
| | - Stephanie L Monk
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne 3000, VIC, Australia
| | - Lea Lekieffre
- Infectious Diseases Programme, QIMR Berghofer Medical Research Institute, Brisbane 4006, QLD, Australia
| | - Enmoore Lin
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Goroka 441, EHG, Papua New Guinea
| | - Benson Kiniboro
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Goroka 441, EHG, Papua New Guinea
| | - Carla Proietti
- Infectious Diseases Programme, QIMR Berghofer Medical Research Institute, Brisbane 4006, QLD, Australia; Australian Institute of Tropical Health and Medicine, James Cook University, Cairns 4878, QLD, Australia
| | - Peter Siba
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Goroka 441, EHG, Papua New Guinea
| | - Philip L Felgner
- Physiology & Biophysics Department, Vaccine R&D Center, University of California, Irvine, Irvine 92697, CA, USA
| | - Denise L Doolan
- Infectious Diseases Programme, QIMR Berghofer Medical Research Institute, Brisbane 4006, QLD, Australia; Australian Institute of Tropical Health and Medicine, James Cook University, Cairns 4878, QLD, Australia
| | - Ivo Mueller
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne 3000, VIC, Australia; Department of Parasites and Insect Vectors, Institut Pasteur, Paris 75015, France
| | - Alyssa E Barry
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne 3000, VIC, Australia.
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24
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Müller-Sienerth N, Shilts J, Kadir KA, Yman V, Homann MV, Asghar M, Ngasala B, Singh B, Färnert A, Wright GJ. A panel of recombinant proteins from human-infective Plasmodium species for serological surveillance. Malar J 2020; 19:31. [PMID: 31952523 PMCID: PMC6969409 DOI: 10.1186/s12936-020-3111-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/08/2020] [Indexed: 12/20/2022] Open
Abstract
Background Malaria remains a global health problem and accurate surveillance of Plasmodium parasites that are responsible for this disease is required to guide the most effective distribution of control measures. Serological surveillance will be particularly important in areas of low or periodic transmission because patient antibody responses can provide a measure of historical exposure. While methods for detecting host antibody responses to Plasmodium falciparum and Plasmodium vivax are well established, development of serological assays for Plasmodium knowlesi, Plasmodium ovale and Plasmodium malariae have been inhibited by a lack of immunodiagnostic candidates due to the limited availability of genomic information. Methods Using the recently completed genome sequences from P. malariae, P. ovale and P. knowlesi, a set of 33 candidate cell surface and secreted blood-stage antigens was selected and expressed in a recombinant form using a mammalian expression system. These proteins were added to an existing panel of antigens from P. falciparum and P. vivax and the immunoreactivity of IgG, IgM and IgA immunoglobulins from individuals diagnosed with infections to each of the five different Plasmodium species was evaluated by ELISA. Logistic regression modelling was used to quantify the ability of the responses to determine prior exposure to the different Plasmodium species. Results Using sera from European travellers with diagnosed Plasmodium infections, antigens showing species-specific immunoreactivity were identified to select a panel of 22 proteins from five Plasmodium species for serological profiling. The immunoreactivity to the antigens in the panel of sera taken from travellers and individuals living in malaria-endemic regions with diagnosed infections showed moderate power to predict infections by each species, including P. ovale, P. malariae and P. knowlesi. Using a larger set of patient samples and logistic regression modelling it was shown that exposure to P. knowlesi could be accurately detected (AUC = 91%) using an antigen panel consisting of the P. knowlesi orthologues of MSP10, P12 and P38. Conclusions Using the recent availability of genome sequences to all human-infective Plasmodium spp. parasites and a method of expressing Plasmodium proteins in a secreted functional form, an antigen panel has been compiled that will be useful to determine exposure to these parasites.
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Affiliation(s)
| | - Jarrod Shilts
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, UK
| | - Khamisah Abdul Kadir
- Malaria Research Centre, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
| | - Victor Yman
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Manijeh Vafa Homann
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Muhammad Asghar
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania.,Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden
| | - Balbir Singh
- Malaria Research Centre, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
| | - Anna Färnert
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.,Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, UK.
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25
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Rambhatla JS, Turner L, Manning L, Laman M, Davis TME, Beeson JG, Mueller I, Warrel J, Theander TG, Lavstsen T, Rogerson SJ. Acquisition of Antibodies Against Endothelial Protein C Receptor-Binding Domains of Plasmodium falciparum Erythrocyte Membrane Protein 1 in Children with Severe Malaria. J Infect Dis 2019; 219:808-818. [PMID: 30365003 DOI: 10.1093/infdis/jiy564] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 09/18/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates parasite sequestration in postcapillary venules in P. falciparum malaria. PfEMP1 types can be classified based on their cysteine-rich interdomain region (CIDR) domains. Antibodies to different PfEMP1 types develop gradually after repeated infections as children age, and antibodies to specific CIDR types may confer protection. METHODS Levels of immunoglobulin G to 35 recombinant CIDR domains were measured by means of Luminex assay in acute-stage (baseline) and convalescent-stage plasma samples from Papua New Guinean children with severe or uncomplicated malaria and in healthy age-matched community controls. RESULTS At baseline, antibody levels were similar across the 3 groups. After infection, children with severe malaria had higher antibody levels than those with uncomplicated malaria against the endothelial protein C receptor (EPCR) binding CIDRα1 domains, and this difference was largely confined to older children. Antibodies to EPCR-binding domains increased from presentation to follow-up in severe malaria, but not in uncomplicated malaria. CONCLUSIONS The acquisition of antibodies against EPCR-binding CIDRα1 domains of PfEMP1 after a severe malaria episode suggest that EPCR-binding PfEMP1 may have a role in the pathogenesis of severe malaria in Papua New Guinea.
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Affiliation(s)
- Janavi S Rambhatla
- Department of Medicine, The Peter Doherty Institute for Infection and Immunity, Parkville
| | - Louise Turner
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Laurens Manning
- School of Medicine and Pharmacology, University of Western Australia, Harry Perkins Research Institute, Fiona Stanley Hospital, Murdoch
| | - Moses Laman
- Papua New Guinea Institute of Medical Research, Madang
| | - Timothy M E Davis
- School of Medicine and Pharmacology, University of Western Australia, Harry Perkins Research Institute, Fiona Stanley Hospital, Murdoch
| | - James G Beeson
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Ivo Mueller
- Department of Medical Biology, University of Melbourne, Parkville.,Walter and Eliza Hall Institute of Medical Research, Parkville.,Parasite and Insect Vectors Department, Institut Pasteur, Paris, France
| | | | - Thor G Theander
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Stephen J Rogerson
- Department of Medicine, The Peter Doherty Institute for Infection and Immunity, Parkville
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26
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Stucke EM, Niangaly A, Berry AA, Bailey JA, Coulibaly D, Ouattara A, Lyke KE, Laurens MB, Dara A, Adams M, Pablo J, Jasinskas A, Nakajima R, Zhou AE, Agrawal S, Friedman-Klabanoff DJ, Takala-Harrison S, Kouriba B, Kone AK, Rowe JA, Doumbo OK, Felgner PL, Thera MA, Plowe CV, Travassos MA. Serologic responses to the PfEMP1 DBL-CIDR head structure may be a better indicator of malaria exposure than those to the DBL-α tag. Malar J 2019; 18:273. [PMID: 31409360 PMCID: PMC6692945 DOI: 10.1186/s12936-019-2905-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/05/2019] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP1) antigens play a critical role in host immune evasion. Serologic responses to these antigens have been associated with protection from clinical malaria, suggesting that antibodies to PfEMP1 antigens may contribute to natural immunity. The first N-terminal constitutive domain in a PfEMP1 is the Duffy binding-like alpha (DBL-α) domain, which contains a 300 to 400 base pair region unique to each particular protein (the DBL-α "tag"). This DBL-α tag has been used as a marker of PfEMP1 diversity and serologic responses in malaria-exposed populations. In this study, using sera from a malaria-endemic region, responses to DBL-α tags were compared to responses to the corresponding entire DBL-α domain (or "parent" domain) coupled with the succeeding cysteine-rich interdomain region (CIDR). METHODS A protein microarray populated with DBL-α tags, the parent DBL-CIDR head structures, and downstream PfEMP1 protein fragments was probed with sera from Malian children (aged 1 to 6 years) and adults from the control arms of apical membrane antigen 1 (AMA1) vaccine clinical trials before and during a malaria transmission season. Serological responses to the DBL-α tag and the DBL-CIDR head structure were measured and compared in children and adults, and throughout the season. RESULTS Malian serologic responses to a PfEMP1's DBL-α tag region did not correlate with seasonal malaria exposure, or with responses to the parent DBL-CIDR head structure in either children or adults. Parent DBL-CIDR head structures were better indicators of malaria exposure. CONCLUSIONS Larger PfEMP1 domains may be better indicators of malaria exposure than short, variable PfEMP1 fragments such as DBL-α tags. PfEMP1 head structures that include conserved sequences appear particularly well suited for study as serologic predictors of malaria exposure.
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Affiliation(s)
- Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Drissa Coulibaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Amed Ouattara
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kirsten E Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew B Laurens
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Antoine Dara
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Matthew Adams
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jozelyn Pablo
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Algis Jasinskas
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Rie Nakajima
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sonia Agrawal
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - DeAnna J Friedman-Klabanoff
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoulaye K Kone
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - J Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Ogobara K Doumbo
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Philip L Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Mahamadou A Thera
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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27
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Kobayashi T, Jain A, Liang L, Obiero JM, Hamapumbu H, Stevenson JC, Thuma PE, Lupiya J, Chaponda M, Mulenga M, Mamini E, Mharakurwa S, Gwanzura L, Munyati S, Mutambu S, Felgner P, Davies DH, Moss WJ. Distinct Antibody Signatures Associated with Different Malaria Transmission Intensities in Zambia and Zimbabwe. mSphere 2019; 4:e00061-19. [PMID: 30918058 PMCID: PMC6437277 DOI: 10.1128/mspheredirect.00061-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/30/2022] Open
Abstract
Antibodies to Plasmodium falciparum are specific biomarkers that can be used to monitor parasite exposure over broader time frames than microscopy, rapid diagnostic tests, or molecular assays. Consequently, seroprevalence surveys can assist with monitoring the impact of malaria control interventions, particularly in the final stages of elimination, when parasite incidence is low. The protein array format to measure antibodies to diverse P. falciparum antigens requires only small sample volumes and is high throughput, permitting the monitoring of malaria transmission on large spatial and temporal scales. We expanded the use of a protein microarray to assess malaria transmission in settings beyond those with a low malaria incidence. Antibody responses in children and adults were profiled, using a P. falciparum protein microarray, through community-based surveys in three areas in Zambia and Zimbabwe at different stages of malaria control and elimination. These three epidemiological settings had distinct serological profiles reflective of their malaria transmission histories. While there was little correlation between transmission intensity and antibody signals (magnitude or breadth) in adults, there was a clear correlation in children younger than 5 years of age. Antibodies in adults appeared to be durable even in the absence of significant recent transmission, whereas antibodies in children provided a more accurate picture of recent levels of transmission intensity. Seroprevalence studies in children could provide a valuable marker of progress toward malaria elimination.IMPORTANCE As malaria approaches elimination in many areas of the world, monitoring the effect of control measures becomes more important but challenging. Low-level infections may go undetected by conventional tests that depend on parasitemia, particularly in immune individuals, who typically show no symptoms of malaria. In contrast, antibodies persist after parasitemia and may provide a more accurate picture of recent exposure. Only a few parasite antigens-mainly vaccine candidates-have been evaluated in seroepidemiological studies. We examined antibody responses to 500 different malaria proteins in blood samples collected through community-based surveillance from areas with low, medium, and high malaria transmission intensities. The breadth of the antibody responses in adults was broad in all three settings and was a poor correlate of recent exposure. In contrast, children represented a better sentinel population for monitoring recent malaria transmission. These data will help inform the use of multiplex serology for malaria surveillance.
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Affiliation(s)
- Tamaki Kobayashi
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Aarti Jain
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Li Liang
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Joshua M Obiero
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | | | - Jennifer C Stevenson
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Macha Research Trust, Choma, Zambia
| | - Philip E Thuma
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Macha Research Trust, Choma, Zambia
| | - James Lupiya
- Tropical Diseases Research Centre, Ndola, Zambia
| | | | | | - Edmore Mamini
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | | | | | - Shungu Munyati
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Susan Mutambu
- National Institute of Health Research, Harare, Zimbabwe
| | - Philip Felgner
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - D Huw Davies
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - William J Moss
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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28
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Abstract
Plasmodium falciparum malaria remains a globally leading infectious disease problem. Despite decades of intense investigation, an efficacious and practical vaccine offering durable protection to people living in areas with transmission of malaria parasites remains an elusive goal. Plasmodium falciparum malaria remains a globally leading infectious disease problem. Despite decades of intense investigation, an efficacious and practical vaccine offering durable protection to people living in areas with transmission of malaria parasites remains an elusive goal. Our fragmentary understanding of the mechanisms of protective immunity to the disease is a major obstacle, and the almost complete focus on a very small subset of P. falciparum proteins as vaccine candidates has left most parasite antigens essentially unexplored as targets of acquired immunity. However, with the protein microarray technology, it is now possible to interrogate the entire parasite proteome for new vaccine candidates and for markers of parasite exposure. Recent mSphere papers describe the results of such research.
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29
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Antibodies to Peptides in Semiconserved Domains of RIFINs and STEVORs Correlate with Malaria Exposure. mSphere 2019; 4:4/2/e00097-19. [PMID: 30894432 PMCID: PMC6429043 DOI: 10.1128/msphere.00097-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs. The repetitive interspersed family (RIFIN) and the subtelomeric variable open reading frame (STEVOR) family represent two of three major Plasmodium falciparum variant surface antigen families involved in malaria pathogenesis and immune evasion and are potential targets in the development of natural immunity. Protein and peptide microarrays populated with RIFINs and STEVORs associated with severe malaria vulnerability in Malian children were probed with adult and pediatric sera to identify epitopes that reflect malaria exposure. Adult sera recognized and reacted with greater intensity to all STEVOR proteins than pediatric sera did. Serorecognition of and seroreactivity to peptides within the semiconserved domain of STEVORs increased with age and seasonal malaria exposure, while serorecognition and seroreactivity increased for the semiconserved and second hypervariable domains of RIFINs only with age. Serologic responses to RIFIN and STEVOR peptides within the semiconserved domains may play a role in natural immunity to severe malaria. IMPORTANCE Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs.
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Chan JA, Boyle MJ, Moore KA, Reiling L, Lin Z, Hasang W, Avril M, Manning L, Mueller I, Laman M, Davis T, Smith JD, Rogerson SJ, Simpson JA, Fowkes FJI, Beeson JG. Antibody Targets on the Surface of Plasmodium falciparum-Infected Erythrocytes That Are Associated With Immunity to Severe Malaria in Young Children. J Infect Dis 2019; 219:819-828. [PMID: 30365004 PMCID: PMC6376912 DOI: 10.1093/infdis/jiy580] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/15/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Sequestration of Plasmodium falciparum-infected erythrocytes (IEs) in the microvasculature contributes to pathogenesis of severe malaria in children. This mechanism is mediated by antigens expressed on the IE surface. However, knowledge of specific targets and functions of antibodies to IE surface antigens that protect against severe malaria is limited. METHODS Antibodies to IE surface antigens were examined in a case-control study of young children in Papua New Guinea presenting with severe or uncomplicated malaria (n = 448), using isolates with a virulent phenotype associated with severe malaria, and functional opsonic phagocytosis assays. We used genetically modified isolates and recombinant P. falciparum erythrocyte membrane protein 1 (PfEMP1) domains to quantify PfEMP1 as a target of antibodies associated with disease severity. RESULTS Antibodies to the IE surface and recombinant PfEMP1 domains were significantly higher in uncomplicated vs severe malaria and were boosted following infection. The use of genetically modified P. falciparum revealed that PfEMP1 was a major target of antibodies and that PfEMP1-specific antibodies were associated with reduced odds of severe malaria. Furthermore, antibodies promoting the opsonic phagocytosis of IEs by monocytes were lower in those with severe malaria. CONCLUSIONS Findings suggest that PfEMP1 is a dominant target of antibodies associated with reduced risk of severe malaria, and function in part by promoting opsonic phagocytosis.
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Affiliation(s)
- Jo-Anne Chan
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Kerryn A Moore
- Burnet Institute for Medical Research and Public Health, Melbourne
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne
| | - Linda Reiling
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Zaw Lin
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Wina Hasang
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
| | - Marion Avril
- Center for Infectious Diseases Research, Seattle, Washington
| | - Laurens Manning
- Papua New Guinea Institute of Medical Research, Madang
- University of Western Australia, Perth
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville
| | - Moses Laman
- Papua New Guinea Institute of Medical Research, Madang
| | | | - Joseph D Smith
- Center for Infectious Diseases Research, Seattle, Washington
| | - Stephen J Rogerson
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, Melbourne
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- Department of Infectious Diseases, Monash University, Melbourne, Victoria, Australia
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, Melbourne
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
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