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Raghavan SSR, Dagil R, Lopez-Perez M, Conrad J, Bassi MR, Quintana MDP, Choudhary S, Gustavsson T, Wang Y, Gourdon P, Ofori MF, Christensen SB, Minja DTR, Schmiegelow C, Nielsen MA, Barfod L, Hviid L, Salanti A, Lavstsen T, Wang K. Cryo-EM reveals the conformational epitope of human monoclonal antibody PAM1.4 broadly reacting with polymorphic malarial protein VAR2CSA. PLoS Pathog 2022; 18:e1010924. [PMCID: PMC9668162 DOI: 10.1371/journal.ppat.1010924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/10/2022] [Indexed: 11/17/2022] Open
Abstract
Malaria during pregnancy is a major global health problem caused by infection with Plasmodium falciparum parasites. Severe effects arise from the accumulation of infected erythrocytes in the placenta. Here, erythrocytes infected by late blood-stage parasites adhere to placental chondroitin sulphate A (CS) via VAR2CSA-type P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins. Immunity to placental malaria is acquired through exposure and mediated through antibodies to VAR2CSA. Through evolution, the VAR2CSA proteins have diversified in sequence to escape immune recognition but retained their overall macromolecular structure to maintain CS binding affinity. This structural conservation may also have allowed development of broadly reactive antibodies to VAR2CSA in immune women. Here we show the negative stain and cryo-EM structure of the only known broadly reactive human monoclonal antibody, PAM1.4, in complex with VAR2CSA. The data shows how PAM1.4’s broad VAR2CSA reactivity is achieved through interactions with multiple conserved residues of different sub-domains forming conformational epitope distant from the CS binding site on the VAR2CSA core structure. Thus, while PAM1.4 may represent a class of antibodies mediating placental malaria immunity by inducing phagocytosis or NK cell-mediated cytotoxicity, it is likely that broadly CS binding-inhibitory antibodies target other epitopes at the CS binding site. Insights on both types of broadly reactive monoclonal antibodies may aid the development of a vaccine against placental malaria.
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Affiliation(s)
- Sai Sundar Rajan Raghavan
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Robert Dagil
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Mary Lopez-Perez
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Julian Conrad
- Swedish National Cryo-EM Facility, Science for Life Laboratories, Solna, Sweden
| | - Maria Rosaria Bassi
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Maria del Pilar Quintana
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Swati Choudhary
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Tobias Gustavsson
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Yong Wang
- Joint Research Centre for Engineering Biology, Zhejiang University-University of Edinburgh Institute, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Michael Fokuo Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Sebastian Boje Christensen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | | | - Christentze Schmiegelow
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Morten Agertoug Nielsen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
- * E-mail: (TL); (KW)
| | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (TL); (KW)
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Doritchamou JY, Renn JP, Jenkins B, Fried M, Duffy PE. A single full-length VAR2CSA ectodomain variant purifies broadly neutralizing antibodies against placental malaria isolates. eLife 2022; 11:76264. [PMID: 35103596 PMCID: PMC8959597 DOI: 10.7554/elife.76264] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Placental malaria (PM) is a deadly syndrome most frequent and severe in first pregnancies. PM results from accumulation of Plasmodium falciparum-infected erythrocytes (IE) that express the surface antigen VAR2CSA and bind to chondroitin sulfate A (CSA) in the placenta. Women become PM-resistant over successive pregnancies as they develop anti-adhesion and anti-VAR2CSA antibodies, supporting VAR2CSA as the leading PM-vaccine candidate. However, the first VAR2CSA subunit vaccines failed to induce broadly neutralizing antibody and it is known that naturally acquired antibodies target both variant-specific and conserved epitopes. It is crucial to determine whether effective vaccines will require incorporation of many or only a single VAR2CSA variants. Here, IgG from multigravidae was sequentially purified on five full-length VAR2CSA ectodomain variants, thereby depleting IgG reactivity to each. The five VAR2CSA variants purified ~0.7% of total IgG and yielded both strain-transcending and strain-specific reactivity to VAR2CSA and IE-surface antigen. In two independent antibody purification/depletion experiments with permutated order of VAR2CSA variants, IgG purified on the first VAR2CSA antigen displayed broad cross-reactivity to both recombinant and native VAR2CSA variants, and inhibited binding of all isolates to CSA. IgG remaining after depletion on all variants showed significantly reduced binding-inhibition activity compared to initial total IgG. These findings demonstrate that a single VAR2CSA ectodomain variant displays conserved epitopes that are targeted by neutralizing (or binding-inhibitory) antibodies shared by multiple parasite strains, including maternal isolates. This suggests that a broadly effective PM-vaccine can be achieved with a limited number of VAR2CSA variants. Contracting malaria during pregnancy – especially a first pregnancy – can lead to a severe, placental form of the disease that is often fatal. Red blood cells infected with the malaria parasite Plasmodium falciparum display a protein, VAR2CSA, which can recognize and bind CSA molecules present on placental cells and in placental blood spaces. This leads to the infected blood cells accumulating in the placenta and inducing harmful inflammation. Having been exposed to the parasite in prior pregnancies generates antibodies that target VAR2CSA, stopping the infected blood cells from latching onto placental CSA or tagging them for immune destruction. Overall, this makes placental malaria less severe in following pregnancies, and suggests that vaccines could be developed based on VAR2CSA. However, this protein has regions that can vary in structure, meaning that P. falciparaum can generate many VAR2CSA variants. Individuals exposed to the parasite naturally generate antibodies that block a wide array of variants from attaching to CSA. In contrast, first-generation vaccines based on VAR2CSA fragments have only induced variant-specific antibodies, therefore offering limited protection against infection. As a response, Doritchamou et al. set out to find VAR2CSA structures that could be recognized by antibodies targeting an array of variants. Blood was obtained from women who had had multiple pregnancies and were immune to malaria. Their plasma was passed over five different large VAR2CSA variants in order to isolate and purify antibodies that attached to these structures. Doritchamou et al. found that antibodies binding to individual VAR2CSA structures could also recognise a wide array of VAR2CSA variants and blocked all tested parasites from sticking to CSA. While further research is needed, these findings highlight antibodies that cross-react to diverse VAR2CSA variants and could be used to design more effective vaccines targeting placental malaria.
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Affiliation(s)
- Justin Ya Doritchamou
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, United States
| | - Jonathan P Renn
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, United States
| | - Bethany Jenkins
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, United States
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Rockville, United States
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Bethesda, United States
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3
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Doritchamou JYA, Duffy PE. Can complement fix placental malaria? BMC Med 2021; 19:231. [PMID: 34503499 PMCID: PMC8431923 DOI: 10.1186/s12916-021-02083-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/02/2021] [Indexed: 12/03/2022] Open
Affiliation(s)
- Justin Y A Doritchamou
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, USA
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, USA.
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4
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Opi DH, Boyle MJ, McLean ARD, Reiling L, Chan JA, Stanisic DI, Ura A, Mueller I, Fowkes FJI, Rogerson SJ, Beeson JG. Reduced risk of placental parasitemia associated with complement fixation on Plasmodium falciparum by antibodies among pregnant women. BMC Med 2021; 19:201. [PMID: 34425801 PMCID: PMC8383393 DOI: 10.1186/s12916-021-02061-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 07/13/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The pathogenesis of malaria in pregnancy (MiP) involves accumulation of P. falciparum-infected red blood cells (pRBCs) in the placenta, contributing to poor pregnancy outcomes. Parasite accumulation is primarily mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1). Magnitude of IgG to pRBCs has been associated with reduced risk of MiP in some studies, but associations have been inconsistent. Further, antibody effector mechanisms are poorly understood, and the role of antibody complement interactions is unknown. METHODS Studying a longitudinal cohort of pregnant women (n=302) from a malaria-endemic province in Papua New Guinea (PNG), we measured the ability of antibodies to fix and activate complement using placental binding pRBCs and PfEMP1 recombinant domains. We determined antibody-mediated complement inhibition of pRBC binding to the placental receptor, chondroitin sulfate A (CSA), and associations with protection against placental parasitemia. RESULTS Some women acquired antibodies that effectively promoted complement fixation on placental-binding pRBCs. Complement fixation correlated with IgG1 and IgG3 antibodies, which dominated the response. There was, however, limited evidence for membrane attack complex activity or pRBC lysis or killing. Importantly, a higher magnitude of complement fixing antibodies was prospectively associated with reduced odds of placental infection at delivery. Using genetically modified P. falciparum and recombinant PfEMP1 domains, we found that complement-fixing antibodies primarily targeted a specific variant of PfEMP1 (known as VAR2CSA). Furthermore, complement enhanced the ability of antibodies to inhibit pRBC binding to CSA, which was primarily mediated by complement C1q protein. CONCLUSIONS These findings provide new insights into mechanisms mediating immunity to MiP and reveal potential new strategies for developing malaria vaccines that harness antibody-complement interactions.
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Affiliation(s)
- D Herbert Opi
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia. .,Department of Immunology, Monash University, Melbourne, Australia. .,Department of Medicine at the Doherty Institute, University of Melbourne, Melbourne, Australia.
| | - Michelle J Boyle
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Human Malaria Immunology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | - Linda Reiling
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia
| | - Jo-Anne Chan
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Department of Immunology, Monash University, Melbourne, Australia.,Department of Medicine at the Doherty Institute, University of Melbourne, Melbourne, Australia
| | - Danielle I Stanisic
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea.,Institute for Glycomics, Griffith University, Southport, Queensland, Australia
| | - Alice Ura
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia.,Institute Pasteur, Paris, France
| | - Freya J I Fowkes
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Department of Infectious Diseases, Monash University, Melbourne, Australia.,Centre for Epidemiology and Biostatistics, University of Melbourne, Melbourne, Australia.,Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Medicine at the Doherty Institute, University of Melbourne, Melbourne, Australia
| | - James G Beeson
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia. .,Department of Immunology, Monash University, Melbourne, Australia. .,Department of Medicine at the Doherty Institute, University of Melbourne, Melbourne, Australia. .,Department of Microbiology, Monash University, Clayton, Australia.
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5
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Aitken EH, Damelang T, Ortega-Pajares A, Alemu A, Hasang W, Dini S, Unger HW, Ome-Kaius M, Nielsen MA, Salanti A, Smith J, Kent S, Hogarth PM, Wines BD, Simpson JA, Chung AW, Rogerson SJ. Developing a multivariate prediction model of antibody features associated with protection of malaria-infected pregnant women from placental malaria. eLife 2021; 10:e65776. [PMID: 34181872 PMCID: PMC8241440 DOI: 10.7554/elife.65776] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/16/2021] [Indexed: 12/15/2022] Open
Abstract
Background Plasmodium falciparum causes placental malaria, which results in adverse outcomes for mother and child. P. falciparum-infected erythrocytes that express the parasite protein VAR2CSA on their surface can bind to placental chondroitin sulfate A. It has been hypothesized that naturally acquired antibodies towards VAR2CSA protect against placental infection, but it has proven difficult to identify robust antibody correlates of protection from disease. The objective of this study was to develop a prediction model using antibody features that could identify women protected from placental malaria. Methods We used a systems serology approach with elastic net-regularized logistic regression, partial least squares discriminant analysis, and a case-control study design to identify naturally acquired antibody features mid-pregnancy that were associated with protection from placental malaria at delivery in a cohort of 77 pregnant women from Madang, Papua New Guinea. Results The machine learning techniques selected 6 out of 169 measured antibody features towards VAR2CSA that could predict (with 86% accuracy) whether a woman would subsequently have active placental malaria infection at delivery. Selected features included previously described associations with inhibition of placental binding and/or opsonic phagocytosis of infected erythrocytes, and network analysis indicated that there are not one but multiple pathways to protection from placental malaria. Conclusions We have identified candidate antibody features that could accurately identify malaria-infected women as protected from placental infection. It is likely that there are multiple pathways to protection against placental malaria. Funding This study was supported by the National Health and Medical Research Council (Nos. APP1143946, GNT1145303, APP1092789, APP1140509, and APP1104975).
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Affiliation(s)
- Elizabeth H Aitken
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Timon Damelang
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Amaya Ortega-Pajares
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Agersew Alemu
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Wina Hasang
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Saber Dini
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of MelbourneMelbourneAustralia
| | - Holger W Unger
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
- Department of Obstetrics and Gynaecology, Royal Darwin HospitalDarwinAustralia
- Menzies School of Health ResearchDarwinAustralia
| | - Maria Ome-Kaius
- Walter and Eliza Hall Institute of Medical ResearchParkvilleAustralia
| | - Morten A Nielsen
- Centre for Medical Parasitology, Department of Microbiology and immunology, University of CopenhagenCopenhagenDenmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of Microbiology and immunology, University of CopenhagenCopenhagenDenmark
- Department of Infectious Disease, Copenhagen University HospitalCopenhagenDenmark
| | - Joe Smith
- Seattle Children’s Research InstituteSeattleUnited States
- Department of Pediatrics, University of WashingtonSeattleUnited States
| | - Stephen Kent
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - P Mark Hogarth
- Seattle Children’s Research InstituteSeattleUnited States
- Immune Therapies Group, Centre for Biomedical Research, Burnet InstituteMelbourneAustralia
- Department of Clinical Pathology, University of MelbourneMelbourneAustralia
- Department of Immunology and Pathology, Monash UniversityMelbourneAustralia
| | - Bruce D Wines
- Immune Therapies Group, Centre for Biomedical Research, Burnet InstituteMelbourneAustralia
- Department of Clinical Pathology, University of MelbourneMelbourneAustralia
- Department of Immunology and Pathology, Monash UniversityMelbourneAustralia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of MelbourneMelbourneAustralia
| | - Amy W Chung
- Department of Microbiology and Immunology, University of Melbourne, the Doherty InstituteMelbourneAustralia
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne, the Doherty InstituteMelbourneAustralia
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6
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Gamain B, Chêne A, Viebig NK, Tuikue Ndam N, Nielsen MA. Progress and Insights Toward an Effective Placental Malaria Vaccine. Front Immunol 2021; 12:634508. [PMID: 33717176 PMCID: PMC7947914 DOI: 10.3389/fimmu.2021.634508] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/06/2021] [Indexed: 12/03/2022] Open
Abstract
In areas where Plasmodium falciparum transmission is endemic, clinical immunity against malaria is progressively acquired during childhood and adults are usually protected against the severe clinical consequences of the disease. Nevertheless, pregnant women, notably during their first pregnancies, are susceptible to placental malaria and the associated serious clinical outcomes. Placental malaria is characterized by the massive accumulation of P. falciparum infected erythrocytes and monocytes in the placental intervillous spaces leading to maternal anaemia, hypertension, stillbirth and low birth weight due to premature delivery, and foetal growth retardation. Remarkably, the prevalence of placental malaria sharply decreases with successive pregnancies. This protection is associated with the development of antibodies directed towards the surface of P. falciparum-infected erythrocytes from placental origin. Placental sequestration is mediated by the interaction between VAR2CSA, a member of the P. falciparum erythrocyte membrane protein 1 family expressed on the infected erythrocytes surface, and the placental receptor chondroitin sulfate A. VAR2CSA stands today as the leading candidate for a placental malaria vaccine. We recently reported the safety and immunogenicity of two VAR2CSA-derived placental malaria vaccines (PRIMVAC and PAMVAC), spanning the chondroitin sulfate A-binding region of VAR2CSA, in both malaria-naïve and P. falciparum-exposed non-pregnant women in two distinct Phase I clinical trials (ClinicalTrials.gov, NCT02658253 and NCT02647489). This review discusses recent advances in placental malaria vaccine development, with a focus on the recent clinical data, and discusses the next clinical steps to undertake in order to better comprehend vaccine-induced immunity and accelerate vaccine development.
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Affiliation(s)
- Benoît Gamain
- Université de Paris, Inserm, Biologie Intégrée du Globule Rouge, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France
| | - Arnaud Chêne
- Université de Paris, Inserm, Biologie Intégrée du Globule Rouge, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France
| | - Nicola K Viebig
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Heidelberg, Germany
| | | | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
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7
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Damelang T, Aitken EH, Hasang W, Lopez E, Killian M, Unger HW, Salanti A, Shub A, McCarthy E, Kedzierska K, Lappas M, Kent SJ, Rogerson SJ, Chung AW. Antibody mediated activation of natural killer cells in malaria exposed pregnant women. Sci Rep 2021; 11:4130. [PMID: 33602987 PMCID: PMC7893158 DOI: 10.1038/s41598-021-83093-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/25/2021] [Indexed: 12/21/2022] Open
Abstract
Immune effector responses against Plasmodium falciparum include antibody-mediated activation of innate immune cells, which can induce Fc effector functions, including antibody-dependent cellular cytotoxicity, and the secretion of cytokines and chemokines. These effector functions are regulated by the composition of immunoglobulin G (IgG) Fc N-linked glycans. However, a role for antibody-mediated natural killer (NK) cells activation or Fc N-linked glycans in pregnant women with malaria has not yet been established. Herein, we studied the capacity of IgG antibodies from pregnant women, with placental malaria or non-placental malaria, to induce NK cell activation in response to placental malaria-associated antigens DBL2 and DBL3. Antibody-mediated NK cell activation was observed in pregnant women with malaria, but no differences were associated with susceptibility to placental malaria. Elevated anti-inflammatory glycosylation patterns of IgG antibodies were observed in pregnant women with or without malaria infection, which were not seen in healthy non-pregnant controls. This suggests that pregnancy-associated anti-inflammatory Fc N-linked glycans may dampen the antibody-mediated activation of NK cells in pregnant women with malaria infection. Overall, although anti-inflammatory glycans and antibody-dependent NK cell activation were detected in pregnant women with malaria, a definitive role for these antibody features in protecting against placental malaria remains to be proven.
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Affiliation(s)
- Timon Damelang
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Elizabeth H Aitken
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Wina Hasang
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Ester Lopez
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Martin Killian
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
- Department of Internal Medicine, Centre Hospitalier Universitaire de Saint-Etienne, Saint-Etienne, France
- Groupe sur l'Immunité des Muqueuses et Agents Pathogènes, Université Jean Monnet Saint-Etienne, Saint-Etienne, France
| | - Holger W Unger
- Liverpool School of Tropical Medicine, Liverpool, UK
- Department of Obstetrics and Gynaecology, Royal Darwin Hospital, Darwin, NT, Australia
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Ali Salanti
- Department for Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Disease, Copenhagen University Hospital, Copenhagen, Denmark
| | - Alexis Shub
- Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, VIC, Australia
| | - Elizabeth McCarthy
- Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, VIC, Australia
| | - Katherine Kedzierska
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Martha Lappas
- Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, VIC, Australia
| | - Stephen J Kent
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
- Infectious Diseases Department, Alfred Health, Melbourne Sexual Health Centre, Monash University, Melbourne, VIC, Australia
| | - Stephen J Rogerson
- Department of Medicine, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Amy W Chung
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia.
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8
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Tomlinson A, Semblat JP, Gamain B, Chêne A. VAR2CSA-Mediated Host Defense Evasion of Plasmodium falciparum Infected Erythrocytes in Placental Malaria. Front Immunol 2021; 11:624126. [PMID: 33633743 PMCID: PMC7900151 DOI: 10.3389/fimmu.2020.624126] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/23/2020] [Indexed: 12/04/2022] Open
Abstract
Over 30 million women living in P. falciparum endemic areas are at risk of developing malaria during pregnancy every year. Placental malaria is characterized by massive accumulation of infected erythrocytes in the intervillous space of the placenta, accompanied by infiltration of immune cells, particularly monocytes. The consequent local inflammation and the obstruction of the maternofetal exchanges can lead to severe clinical outcomes for both mother and child. Even if protection against the disease can gradually be acquired following successive pregnancies, the malaria parasite has developed a large panel of evasion mechanisms to escape from host defense mechanisms and manipulate the immune system to its advantage. Infected erythrocytes isolated from placentas of women suffering from placental malaria present a unique phenotype and express the pregnancy-specific variant VAR2CSA of the Plasmodium falciparum Erythrocyte Membrane Protein (PfEMP1) family at their surface. The polymorphic VAR2CSA protein is able to mediate the interaction of infected erythrocytes with a variety of host cells including placental syncytiotrophoblasts and leukocytes but also with components of the immune system such as non-specific IgM. This review summarizes the described VAR2CSA-mediated host defense evasion mechanisms employed by the parasite during placental malaria to ensure its survival and persistence.
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Affiliation(s)
- Alice Tomlinson
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Jean-Philippe Semblat
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Benoît Gamain
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Arnaud Chêne
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, Paris, France.,Institut National de la Transfusion Sanguine, Paris, France.,Laboratory of Excellence GR-Ex, Paris, France
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9
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Doritchamou JYA, Suurbaar J, Tuikue Ndam N. Progress and new horizons toward a VAR2CSA-based placental malaria vaccine. Expert Rev Vaccines 2021; 20:215-226. [PMID: 33472449 DOI: 10.1080/14760584.2021.1878029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Introduction: Several malaria vaccines are under various phases of development with some promising results. In placental malaria (PM) a deliberately anti-disease approach is considered as many studies have underlined the key role of VAR2CSA protein, which therefore represents the leading vaccine candidate. However, evidence indicates that VAR2CSA antigenic polymorphism remains an obstacle to overcome.Areas covered: This review analyzes the progress made thus far in developing a VAR2CSA-based vaccine, and addresses the current issues and challenges that must be overcome to develop an effective PM vaccine.Expert opinion: Phase I trials of PAMVAC and PRIMVAC VAR2CSA vaccines have shown more or less satisfactory results with regards to safety and immunogenicity. The second generation of VAR2CSA-based vaccines could benefit from optimization approaches to broaden the activity spectrum against various placenta-binding isolates through continued advances in the structural understanding of the interaction with CSA.
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Affiliation(s)
- Justin Yai Alamou Doritchamou
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jennifer Suurbaar
- Université de Paris, MERIT, IRD, F-75006 Paris, France.,Noguchi Memorial Institute for Medical Research, Department of Immunology, University of Ghana, Accra, Ghana
| | - Nicaise Tuikue Ndam
- Université de Paris, MERIT, IRD, F-75006 Paris, France.,Noguchi Memorial Institute for Medical Research, Department of Immunology, University of Ghana, Accra, Ghana
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10
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Gnidehou S, Yanow SK. VAR2CSA Antibodies in Non-Pregnant Populations. Trends Parasitol 2020; 37:65-76. [PMID: 33067131 DOI: 10.1016/j.pt.2020.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 11/18/2022]
Abstract
The Plasmodium falciparum protein VAR2CSA is a critical mediator of placental malaria, and VAR2CSA antibodies (IgGs) are important to protect pregnant women. Although infrequently detected outside pregnancy, VAR2CSA IgGs were reported in men and children from Colombia and Brazil and in select African populations. These findings raise questions about the specificity of VAR2CSA IgGs and the mechanisms by which they are acquired outside pregnancy. Here we review the data on VAR2CSA IgGs in men and children from different malaria-endemic regions. We discuss experimental factors that may affect interpretation of the serological data and consider the biological relevance of VAR2CSA IgGs in non-pregnant populations. We propose potential mechanisms for the acquisition of VARCSA IgGs outside of pregnancy. We identify knowledge gaps and research priorities.
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Affiliation(s)
- Sedami Gnidehou
- Campus Saint-Jean, University of Alberta, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
| | - Stephanie K Yanow
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; School of Public Health, University of Alberta, Edmonton, AB, Canada
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11
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Lubow J, Collins KL. Vpr Is a VIP: HIV Vpr and Infected Macrophages Promote Viral Pathogenesis. Viruses 2020; 12:E809. [PMID: 32726944 PMCID: PMC7472745 DOI: 10.3390/v12080809] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 02/06/2023] Open
Abstract
HIV infects several cell types in the body, including CD4+ T cells and macrophages. Here we review the role of macrophages in HIV infection and describe complex interactions between viral proteins and host defenses in these cells. Macrophages exist in many forms throughout the body, where they play numerous roles in healthy and diseased states. They express pattern-recognition receptors (PRRs) that bind viral, bacterial, fungal, and parasitic pathogens, making them both a key player in innate immunity and a potential target of infection by pathogens, including HIV. Among these PRRs is mannose receptor, a macrophage-specific protein that binds oligosaccharides, restricts HIV replication, and is downregulated by the HIV accessory protein Vpr. Vpr significantly enhances infection in vivo, but the mechanism by which this occurs is controversial. It is well established that Vpr alters the expression of numerous host proteins by using its co-factor DCAF1, a component of the DCAF1-DDB1-CUL4 ubiquitin ligase complex. The host proteins targeted by Vpr and their role in viral replication are described in detail. We also discuss the structure and function of the viral protein Env, which is stabilized by Vpr in macrophages. Overall, this literature review provides an updated understanding of the contributions of macrophages and Vpr to HIV pathogenesis.
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Affiliation(s)
- Jay Lubow
- Department of Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Kathleen L. Collins
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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12
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Kwenti TE. Malaria and HIV coinfection in sub-Saharan Africa: prevalence, impact, and treatment strategies. Res Rep Trop Med 2018; 9:123-136. [PMID: 30100779 PMCID: PMC6067790 DOI: 10.2147/rrtm.s154501] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Malaria and HIV, two of the world's most deadly diseases, are widespread, but their distribution overlaps greatly in sub-Saharan Africa. Consequently, malaria and HIV coinfection (MHC) is common in the region. In this paper, pertinent publications on the prevalence, impact, and treatment strategies of MHC obtained by searching major electronic databases (PubMed, PubMed Central, Google Scholar, ScienceDirect, and Scopus) were reviewed, and it was found that the prevalence of MHC in SSA was 0.7%-47.5% overall. Prevalence was 0.7%-47.5% in nonpregnant adults, 1.2%-27.8% in children, and 0.94%-37% in pregnant women. MHC was associated with an increased frequency of clinical parasitemia and severe malaria, increased parasite and viral load, and impaired immunity to malaria in nonpregnant adults, children, and pregnant women, increased in placental malaria and related outcomes in pregnant women, and impaired antimalarial drug efficacy in nonpregnant adults and pregnant women. Although a few cases of adverse events have been reported in coinfected patients receiving antimalarial and antiretroviral drugs concurrently, available data are very limited and have not prompted major revision in treatment guidelines for both diseases. Artemisinin-based combination therapy and cotrimoxazole are currently the recommended drugs for treatment and prevention of malaria in HIV-infected children and adults. However, concurrent administration of cotrimoxazole and sulfadoxine-pyrimethamine in HIV-infected pregnant women is not recommended, because of high risk of sulfonamide toxicity. Further research is needed to enhance our understanding of the impact of malaria on HIV, drug-drug interactions in patients receiving antimalarials and antiretroviral drugs concomitantly, and the development of newer, safer, and more cost-effective drugs and vaccines to prevent malaria in HIV-infected pregnant women.
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Affiliation(s)
- Tebit E Kwenti
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, University of Buea,
- Regional Hospital Buea, Buea, Cameroon,
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13
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Hommel M, Chan JA, Umbers AJ, Langer C, Rogerson SJ, Smith JD, Beeson JG. Evaluating antibody functional activity and strain-specificity of vaccine candidates for malaria in pregnancy using in vitro phagocytosis assays. Parasit Vectors 2018; 11:69. [PMID: 29378634 PMCID: PMC5789608 DOI: 10.1186/s13071-018-2653-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 01/16/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria in pregnancy is a major cause of poor maternal and infant health, and is associated with the sequestration of P. falciparum-infected erythrocytes (IE) in the placenta. The leading vaccine candidate for pregnancy malaria, VAR2CSA, has been shown to induce antibodies that inhibit IE adhesion to the placental receptor chondroitin sulfate A (CSA), potentially preventing placental infection. However, the ability of vaccination-induced antibodies to promote opsonic phagocytosis is not well defined, but likely to be an important component of protective immunity. METHODS We investigated the use of an opsonic phagocytosis assay to evaluate antibodies induced by pregnancy malaria vaccine candidate antigens based on VAR2CSA. Opsonic phagocytosis was measured by flow cytometry and visualized by electron microscopy. We measured vaccine-induced antibody reactivity to placental type IEs from different geographical origins, and the functional ability of antibodies raised in immunized rabbits to induce phagocytosis by a human monocyte cell line. RESULTS Immunization-induced antibodies showed a mixture of strain-specific and cross-reactive antibody recognition of different placental-binding parasite lines. Antibodies generated against the DBL5 and DBL3 domains of VAR2CSA effectively promoted the opsonic phagocytosis of IEs by human monocytes; however, these functional antibodies were largely allele-specific and not cross-reactive. This has significant implications for the development of vaccines aiming to achieve a broad coverage against diverse parasite strains. Using competition ELISAs, we found that acquired human antibodies among pregnant women targeted both cross-reactive and allele-specific epitopes, consistent with what we observed with vaccine-induced antibodies. CONCLUSIONS Vaccines based on domains of VAR2CSA induced opsonic phagocytosis of IEs in a strain-specific manner. Assays measuring this phagocytic activity have the potential to aid the development and evaluation of vaccines against malaria in pregnancy.
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Affiliation(s)
| | | | | | | | - Stephen J Rogerson
- Department of Medicine, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Joseph D Smith
- Center for Infectious Diseases Research, Seattle, WA, USA
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia. .,Department of Medicine, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia. .,Department of Microbiology and Central Clinical School, Monash University, Clayton, VIC, Australia.
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14
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Phyo AP, Win KK, Thu AM, Swe LL, Htike H, Beau C, Sriprawat K, Winterberg M, Proux S, Imwong M, Ashley EA, Nosten F. Poor response to artesunate treatment in two patients with severe malaria on the Thai-Myanmar border. Malar J 2018; 17:30. [PMID: 29334942 PMCID: PMC5769511 DOI: 10.1186/s12936-018-2182-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/10/2018] [Indexed: 11/22/2022] Open
Abstract
Background Malaria has declined dramatically along the Thai–Myanmar border in recent years due to malaria control and elimination programmes. However, at the same time, artemisinin resistance has spread, raising concerns about the efficacy of parenteral artesunate for the treatment of severe malaria. Case presentation In November 2015 and April 2017, two patients were treated for severe malaria with parenteral artesunate. Quinine was added within 24 h due to an initial poor response to treatment. The first patient died within 24 h of starting treatment and the second did not clear his peripheral parasitaemia until 11 days later. Genotyping revealed artemisinin resistance Kelch-13 markers. Conclusions Reliable efficacy of artesunate for the treatment of severe malaria may no longer be assured in areas where artemisinin resistance has emerged. Empirical addition of parenteral quinine to artesunate for treatment is recommended as a precautionary measure. Electronic supplementary material The online version of this article (10.1186/s12936-018-2182-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand. .,Myanmar Oxford Clinical Research Unit, Yangon, Myanmar.
| | - Kyaw Kyaw Win
- Mae Tao Clinic, 702, Moo 1, Tha Sai Luad, Mae Sot, Tak, 63110, Thailand
| | - Aung Myint Thu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand
| | - Lei Lei Swe
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand
| | - Htike Htike
- Mae Tao Clinic, 702, Moo 1, Tha Sai Luad, Mae Sot, Tak, 63110, Thailand
| | - Candy Beau
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand
| | - Kanlaya Sriprawat
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand
| | - Markus Winterberg
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Stephane Proux
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Elizabeth A Ashley
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.,Myanmar Oxford Clinical Research Unit, Yangon, Myanmar
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, PO Box 46, Mae Sot, Tak, 63110, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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15
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A versatile, high through-put, bead-based phagocytosis assay for Plasmodium falciparum. Sci Rep 2017; 7:14705. [PMID: 29089635 PMCID: PMC5665980 DOI: 10.1038/s41598-017-13900-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/02/2017] [Indexed: 11/08/2022] Open
Abstract
Antibody-mediated phagocytosis is an important immune effector mechanism against Plasmodium falciparum-infected erythrocytes (IE); however, current phagocytosis assays use IE collected from infected individuals or from in vitro cultures of P. falciparum, making them prone to high variation. A simple, high-throughput flow cytometric assay was developed that uses THP-1 cells and fluorescent beads covalently-coupled with the malarial antigen VAR2CSA. The assay is highly repeatable, provides both the overall percent phagocytosis and semi-quantitates the number of antigen-coupled beads internalized.
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16
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Abstract
One hundred and twenty-five million women in malaria-endemic areas become pregnant each year (see Dellicour et al. PLoS Med7: e1000221 [2010]) and require protection from infection to avoid disease and death for themselves and their offspring. Chloroquine prophylaxis was once a safe approach to prevention but has been abandoned because of drug-resistant parasites, and intermittent presumptive treatment with sulfadoxine-pyrimethamine, which is currently used to protect pregnant women throughout Africa, is rapidly losing its benefits for the same reason. No other drugs have yet been shown to be safe, tolerable, and effective as prevention for pregnant women, although monthly dihydroartemisinin-piperaquine has shown promise for reducing poor pregnancy outcomes. Insecticide-treated nets provide some benefits, such as reducing placental malaria and low birth weight. However, this leaves a heavy burden of maternal, fetal, and infant morbidity and mortality that could be avoided. Women naturally acquire resistance to Plasmodium falciparum over successive pregnancies as they acquire antibodies against parasitized red cells that bind chondroitin sulfate A in the placenta, suggesting that a vaccine is feasible. Pregnant women are an important reservoir of parasites in the community, and women of reproductive age must be included in any elimination effort, but several features of malaria during pregnancy will require special consideration during the implementation of elimination programs.
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Affiliation(s)
- Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD 20892
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Bethesda, MD 20892
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17
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Chandrasiri UP, Fowkes FJI, Beeson JG, Richards JS, Kamiza S, Maleta K, Ashorn P, Rogerson SJ. Association between malaria immunity and pregnancy outcomes among Malawian pregnant women receiving nutrient supplementation. Malar J 2016; 15:547. [PMID: 27829430 PMCID: PMC5103486 DOI: 10.1186/s12936-016-1597-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/31/2016] [Indexed: 11/24/2022] Open
Abstract
Background Malaria antibody responses measured at delivery have been associated with protection from maternal anaemia and low birth weight deliveries. Whether malarial antibodies present in the first half of pregnancy may protect from these or other poor birth outcomes is unclear. To determine whether malaria antibodies in the first half of pregnancy predict pregnancy outcomes, antibodies were measured to a range of merozoite antigens and to antigens expressed on the surface of parasitized red blood cells (pRBCs) in plasma samples collected at 14–20 weeks of gestation from Malawian women. The latter antibodies were measured as total IgG to pRBCs, and antibodies promoting opsonic phagocytosis of pRBCs. Associations between antibodies and maternal haemoglobin in late pregnancy or newborn size were investigated, after adjusting for potential covariates. Results Antibodies to pRBC surface antigens were associated with higher haemoglobin concentration at 36 weeks. Total IgG to pRBCs was associated with 0.4 g/l [(95% confidence interval (0.04, 0.8)] increase in haemoglobin, and opsonizing antibody with 0.5 (0.05, 0.9) increase in haemoglobin for each 10% increase in antibody. These antibodies were not associated with birthweight, placental malaria, or newborn anthropometrics. Antibodies to merozoite antigens and non-placental-binding IEs were not associated with decreased risk of any of these outcomes. In some instances, they were negatively associated with outcomes of interest. Conclusion Antibodies to placental-binding infected erythrocytes may be associated with higher haemoglobin levels in pregnancy, whereas antibodies to other malaria antigens may instead be markers of malaria exposure. Trial registration clinicaltrials.gov NCT01239693. Registered Nov 10, 2010.
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Affiliation(s)
- Upeksha P Chandrasiri
- Department of Medicine at the Doherty Institute of Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Melbourne, VIC, Australia
| | - Freya J I Fowkes
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Prahran, VIC, Australia.,Department of Epidemiology, Centre for Epidemiology and Biostatistics, University of Melbourne, Melbourne, VIC, Australia.,Department of Preventive Medicine and Infectious Diseases, Monash University, Clayton, VIC, Australia
| | - James G Beeson
- Department of Medicine at the Doherty Institute of Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Melbourne, VIC, Australia.,Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Prahran, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Jack S Richards
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Prahran, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Steve Kamiza
- University of Malawi College of Medicine, Blantyre, Malawi
| | - Kenneth Maleta
- Faculty of Public Health and Family Medicine, University of Malawi College of Medicine, Blantyre, Malawi
| | - Per Ashorn
- Centre for Child Health Research, University of Tampere School of Medicine and Tampere University Hospital, Tampere, Finland.,Department of Paediatrics, Tampere University Hospital, Tampere, Finland
| | - Stephen J Rogerson
- Department of Medicine at the Doherty Institute of Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Melbourne, VIC, Australia.
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18
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Chan JA, Howell KB, Langer C, Maier AG, Hasang W, Rogerson SJ, Petter M, Chesson J, Stanisic DI, Duffy MF, Cooke BM, Siba PM, Mueller I, Bull PC, Marsh K, Fowkes FJI, Beeson JG. A single point in protein trafficking by Plasmodium falciparum determines the expression of major antigens on the surface of infected erythrocytes targeted by human antibodies. Cell Mol Life Sci 2016; 73:4141-58. [PMID: 27193441 PMCID: PMC5042999 DOI: 10.1007/s00018-016-2267-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/22/2016] [Accepted: 05/06/2016] [Indexed: 11/30/2022]
Abstract
Antibodies to blood-stage antigens of Plasmodium falciparum play a pivotal role in human immunity to malaria. During parasite development, multiple proteins are trafficked from the intracellular parasite to the surface of P. falciparum-infected erythrocytes (IEs). However, the relative importance of different proteins as targets of acquired antibodies, and key pathways involved in trafficking major antigens remain to be clearly defined. We quantified antibodies to surface antigens among children, adults, and pregnant women from different malaria-exposed regions. We quantified the importance of antigens as antibody targets using genetically engineered P. falciparum with modified surface antigen expression. Genetic deletion of the trafficking protein skeleton-binding protein-1 (SBP1), which is involved in trafficking the surface antigen PfEMP1, led to a dramatic reduction in antibody recognition of IEs and the ability of human antibodies to promote opsonic phagocytosis of IEs, a key mechanism of parasite clearance. The great majority of antibody epitopes on the IE surface were SBP1-dependent. This was demonstrated using parasite isolates with different genetic or phenotypic backgrounds, and among antibodies from children, adults, and pregnant women in different populations. Comparisons of antibody reactivity to parasite isolates with SBP1 deletion or inhibited PfEMP1 expression suggest that PfEMP1 is the dominant target of acquired human antibodies, and that other P. falciparum IE surface proteins are minor targets. These results establish SBP1 as part of a critical pathway for the trafficking of major surface antigens targeted by human immunity, and have key implications for vaccine development, and quantifying immunity in populations.
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Affiliation(s)
- Jo-Anne Chan
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC, 3001, Australia
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Katherine B Howell
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Christine Langer
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC, 3001, Australia
| | - Alexander G Maier
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Wina Hasang
- Department of Medicine, University of Melbourne, Parkville, VIC, Australia
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne, Parkville, VIC, Australia
| | - Michaela Petter
- Department of Medicine, University of Melbourne, Parkville, VIC, Australia
| | - Joanne Chesson
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | | | - Michael F Duffy
- Department of Medicine, University of Melbourne, Parkville, VIC, Australia
| | - Brian M Cooke
- Programs in Infection and Immunity and Cardiovascular Disease, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | - Peter M Siba
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Peter C Bull
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute, Kilifi, Kenya
| | - Kevin Marsh
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute, Kilifi, Kenya
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC, 3001, Australia
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Melbourne School of Public Health, University of Melbourne, Parkville, VIC, Australia
- Department of Epidemiology and Preventive Medicine and Department of Infectious Diseases, Monash University, Melbourne, VIC, Australia
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC, 3001, Australia.
- Department of Medicine, University of Melbourne, Parkville, VIC, Australia.
- Department of Microbiology, Monash University, Melbourne, VIC, Australia.
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19
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Mitchell RA, Altszuler R, Frevert U, Nardin EH. Skin scarification with Plasmodium falciparum peptide vaccine using synthetic TLR agonists as adjuvants elicits malaria sporozoite neutralizing immunity. Sci Rep 2016; 6:32575. [PMID: 27624667 PMCID: PMC5021941 DOI: 10.1038/srep32575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 08/10/2016] [Indexed: 12/19/2022] Open
Abstract
Malaria eradication will require a combination of vector control, chemotherapy and an easily administered vaccine. Sterile immunity can be elicited in humans by immunization with sporozoites, the infective stage injected by bite of the mosquito vector, however, whole parasite vaccines present formidable logistical challenges for production, storage and administration. The “gold standard” for infectious disease eradiation, the Smallpox Eradication Programme, utilized mass immunization using the skin scarification (SS) route. SS may more closely mimic the natural route of malaria infection initiated by sporozoites injected by mosquito bite which elicits both neutralizing antibodies and protective cell mediated immunity. We investigated the potential of SS immunization using a malaria repeat peptide containing a protective B cell epitope of Plasmodium falciparum, the most lethal human species, and delivery vehicles containing TLR agonists as adjuvants. In a murine model, SS immunization with peptide in combination with TLR-7/8 and -9 agonists elicited high levels of systemic sporozoite neutralizing antibody, Th1- type CD4+ T cells and resistance to challenge by bites of infected mosquitoes. SS provides the potential to elicit humoral immunity to target Plasmodium at multiple stages of its complex life cycle.
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Affiliation(s)
- Robert A Mitchell
- Department of Microbiology, Division of Parasitology, New York University School of Medicine, New York, NY, USA
| | - Rita Altszuler
- Department of Microbiology, Division of Parasitology, New York University School of Medicine, New York, NY, USA
| | - Ute Frevert
- Department of Microbiology, Division of Parasitology, New York University School of Medicine, New York, NY, USA
| | - Elizabeth H Nardin
- Department of Microbiology, Division of Parasitology, New York University School of Medicine, New York, NY, USA
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20
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Humphreys EH, Shah AR, Rutherford GW. Artemisinin-based combination therapy for uncomplicated P. falciparummalaria in children with HIV. Hippokratia 2016. [DOI: 10.1002/14651858.cd008556.pub2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Eliza H Humphreys
- University of California, San Francisco; Global Health Sciences; 50 Beale Street Suite 1200 San Francisco California USA 94105
| | - Anita R Shah
- Boston Children's Hospital; Boston Massachusetts USA
| | - George W Rutherford
- University of California, San Francisco; Global Health Sciences; 50 Beale Street Suite 1200 San Francisco California USA 94105
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21
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Joice R, Frantzreb C, Pradham A, Seydel KB, Kamiza S, Wirth DF, Duraisingh MT, Molyneux ME, Taylor TE, Marti M, Milner DA. Evidence for spleen dysfunction in malaria-HIV co-infection in a subset of pediatric patients. Mod Pathol 2016; 29:381-90. [PMID: 26916076 PMCID: PMC4811692 DOI: 10.1038/modpathol.2016.27] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 12/08/2015] [Accepted: 12/21/2015] [Indexed: 01/31/2023]
Abstract
The spleen has an important role in the clearance of malaria parasites, and the role of HIV co-infection on this process is yet to be described. Using a combination of histological and molecular methods, we systematically evaluated parasite load across multiple organs from HIV-positive and HIV-negative cases of an autopsy study of pediatric comatose children with malaria infection (n=103) in Blantyre, Malawi. Quantification of parasite load across organs was done using histology. A subset of cases was further characterized for parasite localization and stage of development using immunohistochemistry-based labeling of parasite and host cells (5 HIV-positive, 10 HIV-negative), and quantitative RT-PCR (qRT-PCR) of asexual and sexual-specific genes (4 HIV-positive, 5 HIV-negative). The results were compared with clinical information including HIV status. The HIV-positive rate was 21% for the group studied (20 of 95) and HIV-positive patients had a significantly shorter duration of time between onset of illness and death, and were significantly older than HIV-negative patients. We found that spleens of HIV-positive cases had significantly higher parasite loads compared with those of HIV-negative cases in each of the three methods we used: (i) standard histology, (ii) immunohistochemistry-based labeling of Plasmodium lactate dehydrogenase (pLDH), and (iii) molecular detection of asexual parasite transcript apical membrane antigen 1 (AMA1). Immunohistochemistry-based labeling of macrophage marker CD163 in a subset of spleens revealed fewer activated macrophages containing engulfed parasites and a greater number of free unphagocytosed parasites in the HIV-positive cases. The mechanism by which HIV infection is associated with more rapid progression to severe cerebral malaria disease is possibly impairment of parasite destruction by splenic macrophages, supported by published in vitro studies showing inefficient phagocytosis of malaria parasites by HIV-infected macrophages.
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Affiliation(s)
- Regina Joice
- The Harvard School of Public Health, Boston, Massachusetts, USA
| | - Charles Frantzreb
- The Harvard School of Public Health, Boston, Massachusetts, USA
- The Brigham & Women’s Hospital, Boston, Massachusetts, USA
| | - Alana Pradham
- The Brigham & Women’s Hospital, Boston, Massachusetts, USA
| | - Karl B. Seydel
- The Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Steve Kamiza
- University of Malawi, College of Medicine, Blantyre, Malawi
| | - Dyann F. Wirth
- The Harvard School of Public Health, Boston, Massachusetts, USA
| | | | - Malcolm E Molyneux
- College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
- University of Malawi, College of Medicine, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Terrie E. Taylor
- The Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Matthias Marti
- The Harvard School of Public Health, Boston, Massachusetts, USA
| | - Danny A. Milner
- The Harvard School of Public Health, Boston, Massachusetts, USA
- The Brigham & Women’s Hospital, Boston, Massachusetts, USA
- The Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
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McDonald CR, Tran V, Kain KC. Complement Activation in Placental Malaria. Front Microbiol 2015; 6:1460. [PMID: 26733992 PMCID: PMC4685051 DOI: 10.3389/fmicb.2015.01460] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 12/07/2015] [Indexed: 01/06/2023] Open
Abstract
Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.
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Affiliation(s)
- Chloe R McDonald
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Department of Global Health and Population, Harvard School of Public Health, BostonMA, USA
| | - Vanessa Tran
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, Toronto ON, Canada
| | - Kevin C Kain
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, TorontoON, Canada
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Marra CM, Tantalo LC, Sahi SK, Dunaway SB, Lukehart SA. Reduced Treponema pallidum-Specific Opsonic Antibody Activity in HIV-Infected Patients With Syphilis. J Infect Dis 2015; 213:1348-54. [PMID: 26655298 DOI: 10.1093/infdis/jiv591] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 11/30/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Human immunodeficiency virus (HIV)-infected individuals may have poorer serological responses to syphilis treatment and may be more likely to experience neurosyphilis. Treponema pallidum is cleared from sites of infection by opsonization, ingestion, and killing by macrophages. METHODS Serum samples from 235 individuals with syphilis were tested for T. pallidum-specific opsonic activity. Blood T. pallidum concentrations were determined by real-time polymerase chain reaction amplification of the tp0574 gene, and T. pallidum was detected in cerebrospinal fluid (CSF) by reverse-transcriptase polymerase chain reaction of 16S ribosomal RNA. RESULTS Opsonic activity was higher with higher serum rapid plasma reagin titers (P < .001), and in those treated for uncomplicated syphilis before serum collection (P < .001). Opsonic activity was lower in HIV-infected than in HIV-uninfected individuals even after the above factors were taken into account (P = .006). In participants in whom blood T. pallidum was detectable, those with the highest opsonic activity had lower blood T. pallidum concentrations. In multivariable analyses, there was not a significant relationship between opsonic activity and detection of T. pallidum in CSF or CSF-VDRL reactivity. CONCLUSIONS Serum T. pallidum-specific opsonic activity is significantly lower in HIV-infected individuals. Impaired T. pallidum-specific immune responses could contribute to differences in the course of disease or treatment response.
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Affiliation(s)
| | | | | | | | - Sheila A Lukehart
- Department Medicine (Infectious Diseases) Department Global Health, Harborview Medical Center, University of Washington, Seattle
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24
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Babakhanyan A, Fang R, Wey A, Salanti A, Sama G, Efundem C, Leke RJI, Chen JJ, Leke RGF, Taylor DW. Comparison of the specificity of antibodies to VAR2CSA in Cameroonian multigravidae with and without placental malaria: a retrospective case-control study. Malar J 2015; 14:480. [PMID: 26626275 PMCID: PMC4666123 DOI: 10.1186/s12936-015-1023-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/26/2015] [Indexed: 11/10/2022] Open
Abstract
Background Antibodies (Ab) to VAR2CSA prevent Plasmodium falciparum-infected erythrocytes from sequestrating in the placenta, i.e., prevent placental malaria (PM). The specificity of Ab to VAR2CSA associated with absence of PM is unknown. Accordingly, differences in the specificity of Ab to VAR2CSA were compared between multigravidae with and without PM who had Ab to VAR2CSA. Methods In a retrospective case–control study, plasma collected from Cameroonian multigravidae with (n = 96) and without (n = 324) PM were screened in 21 assays that measured antibody levels to full length VAR2CSA (FV2), individual VAR2CSA DBL domains, VAR2CSA domains from different genetic backgrounds (variants), as well as proportion of high avidity Ab to FV2. Results Multigravidae with and without PM had similar levels of Ab to FV2, the six VAR2CSA DBL domains and different variants, while the proportion of high avidity Ab to FV2 was significantly higher in women without PM at delivery (p = 0.0030) compared to women with PM. In a logistic regression model adjusted for gravidity and age, the percentage of high avidity Ab to FV2 was associated with reduced likelihood of PM in multigravidae. A 5 % increase in proportion of high avidity Ab to FV2 was associated with a nearly 15 % lower likelihood of PM. Conclusion Ab avidity to FV2 may be an important indicator of immunity to PM. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1023-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna Babakhanyan
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, BSB 320, Honolulu, HI, 96813, USA.
| | - Rui Fang
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, BSB 320, Honolulu, HI, 96813, USA.
| | - Andrew Wey
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, BSB 320, Honolulu, HI, 96813, USA.
| | - Ali Salanti
- Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark.
| | - Grace Sama
- Faculty of Medicine and Biomedical Research, Biotechnology Centre, University of Yaounde 1, Yaounde, Cameroon.
| | - Canisia Efundem
- Faculty of Medicine and Biomedical Research, Biotechnology Centre, University of Yaounde 1, Yaounde, Cameroon.
| | - Robert J I Leke
- Faculty of Medicine and Biomedical Research, Biotechnology Centre, University of Yaounde 1, Yaounde, Cameroon.
| | - John J Chen
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, BSB 320, Honolulu, HI, 96813, USA.
| | - Rose G F Leke
- Faculty of Medicine and Biomedical Research, Biotechnology Centre, University of Yaounde 1, Yaounde, Cameroon.
| | - Diane W Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, BSB 320, Honolulu, HI, 96813, USA.
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Fried M, Duffy PE. Designing a VAR2CSA-based vaccine to prevent placental malaria. Vaccine 2015; 33:7483-8. [PMID: 26469717 PMCID: PMC5077158 DOI: 10.1016/j.vaccine.2015.10.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 09/23/2015] [Accepted: 10/02/2015] [Indexed: 11/29/2022]
Abstract
Placental malaria (PM) due to Plasmodium falciparum is a major cause of maternal, fetal and infant mortality, but the mechanisms of pathogenesis and protective immunity are relatively well-understood for this condition, providing a path for vaccine development. P. falciparum parasites bind to chondroitin sulfate A (CSA) to sequester in the placenta, and women become resistant over 1–2 pregnancies as they acquire antibodies that block adhesion to CSA. The protein VAR2CSA, a member of the PfEMP1 variant surface antigen family, mediates parasite adhesion to CSA, and is the leading target for a vaccine to prevent PM. Obstacles to PM vaccine development include the large size (~350 kD), high cysteine content, and sequence variation of VAR2CSA. A number of approaches have been taken to identify the combination of VAR2CSA domains and alleles that can induce broadly active antibodies that block adhesion of heterologous parasite isolates to CSA. This review summarizes these approaches, which have examined VAR2CSA fragments for binding activity, antigenicity with naturally acquired antibodies, and immunogenicity in animals for inducing anti-adhesion or surface-reactive antibodies. Two products are expected to enter human clinical studies in the near future based on N-terminal VAR2CSA fragments that have high binding affinity for CSA, and additional proteins preferentially expressed by placental parasites are also being examined for their potential contribution to a PM vaccine.
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Affiliation(s)
- Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, 5640 Fishers Lane, TWB1/Room 1111, Rockville, MD, USA.
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, 5640 Fishers Lane, TWB1/Room 1111, Rockville, MD, USA.
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Doritchamou J, Sabbagh A, Jespersen JS, Renard E, Salanti A, Nielsen MA, Deloron P, Tuikue Ndam N. Identification of a Major Dimorphic Region in the Functionally Critical N-Terminal ID1 Domain of VAR2CSA. PLoS One 2015; 10:e0137695. [PMID: 26393516 PMCID: PMC4579133 DOI: 10.1371/journal.pone.0137695] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 08/19/2015] [Indexed: 01/18/2023] Open
Abstract
The VAR2CSA protein of Plasmodium falciparum is transported to and expressed on the infected erythrocyte surface where it plays a key role in placental malaria (PM). It is the current leading candidate for a vaccine to prevent PM. However, the antigenic polymorphism integral to VAR2CSA poses a challenge for vaccine development. Based on detailed analysis of polymorphisms in the sequence of its ligand-binding N-terminal region, currently the main focus for vaccine development, we assessed var2csa from parasite isolates infecting pregnant women. The results reveal for the first time the presence of a major dimorphic region in the functionally critical N-terminal ID1 domain. Parasite isolates expressing VAR2CSA with particular motifs present within this domain are associated with gravidity- and parasite density-related effects. These observations are of particular interest in guiding efforts with respect to optimization of the VAR2CSA-based vaccines currently under development.
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Affiliation(s)
- Justin Doritchamou
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France; UMR216 - MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Audrey Sabbagh
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Jakob S Jespersen
- Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | | | - Ali Salanti
- Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Morten A Nielsen
- Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Philippe Deloron
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France; UMR216 - MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Nicaise Tuikue Ndam
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France; UMR216 - MERIT, Institut de Recherche pour le Développement, Paris, France
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27
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Jenkins R, Omollo R, Ongecha M, Sifuna P, Othieno C, Ongeri L, Kingora J, Ogutu B. Prevalence of malaria parasites in adults and its determinants in malaria endemic area of Kisumu County, Kenya. Malar J 2015; 14:263. [PMID: 26152272 PMCID: PMC4495611 DOI: 10.1186/s12936-015-0781-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 06/29/2015] [Indexed: 11/23/2022] Open
Abstract
Background The prevalence of malaria parasites in adults in Africa is less well researched than in children. Therefore, a
demographic surveillance site was used to conduct a household survey of adults in the malaria endemic area of Maseno division in Kisumu County near Lake Victoria. Methods A random survey of 1,190 adults living in a demographic health surveillance site in a malaria endemic area of 70,805 population size was conducted, measuring presence of malaria parasites by slide microscopy. Data were analysed using STATA to calculate the prevalence of malaria and associated risk factors. Results The adult prevalence of presence of malaria parasites in Maseno was 28% (95% CI: 25.4–31.0%). Gender was a significant sociodemographic risk factor in both univariate (OR 1.5, p = 0.005) and multivariate (OR 1.4, p = 0.019) analyses. Females were 50% more likely to have malaria than men. Conclusions Presence of malaria parasites is common in the adult population of this endemic area, and the rate is greatly increased in women. The presence of such an adult pool of malaria parasites represents a key reservoir factor in transmission of parasites to children, and is relevant for plans to eradicate malaria.
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Affiliation(s)
- Rachel Jenkins
- Health Services Research Department, Institute of Psychiatry, Kings College London, de Crespigny Park, London, SE5 8AF, UK.
| | | | | | - Peter Sifuna
- Kombewa Health and Demographic Surveillance Site, Kombewa, Kenya.
| | - Caleb Othieno
- Department of Psychiatry, University of Nairobi, Nairobi, Kenya.
| | | | - James Kingora
- Kenya Medical Training Kenya Medical Training College, Nairobi, Kenya.
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McLEAN ARD, ATAIDE R, SIMPSON JA, BEESON JG, FOWKES FJI. Malaria and immunity during pregnancy and postpartum: a tale of two species. Parasitology 2015; 142:999-1015. [PMID: 25731914 PMCID: PMC4453920 DOI: 10.1017/s0031182015000074] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/19/2014] [Accepted: 01/16/2015] [Indexed: 11/07/2022]
Abstract
It is well established that pregnant women are at an increased risk of Plasmodium falciparum infection when compared to non-pregnant individuals and limited epidemiological data suggest Plasmodium vivax risk also increases with pregnancy. The risk of P. falciparum declines with successive pregnancies due to the acquisition of immunity to pregnancy-specific P. falciparum variants. However, despite similar declines in P. vivax risk with successive pregnancies, there is a paucity of evidence P. vivax-specific immunity. Cross-species immunity, as well as immunological and physiological changes that occur during pregnancy may influence the susceptibility to both P. vivax and P. falciparum. The period following delivery, the postpartum period, is relatively understudied and available epidemiological data suggests that it may also be a period of increased risk of infection to Plasmodium spp. Here we review the literature and directly compare and contrast the epidemiology, clinical pathogenesis and immunological features of P. vivax and P. falciparum in pregnancy, with a particular focus on studies performed in areas co-endemic for both species. Furthermore, we review the intriguing epidemiology literature of both P. falciparum and P. vivax postpartum and relate observations to the growing literature pertaining to malaria immunology in the postpartum period.
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Affiliation(s)
- A. R. D. McLEAN
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - R. ATAIDE
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
| | - J. A. SIMPSON
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - J. G. BEESON
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - F. J. I. FOWKES
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Epidemiology and Preventive Medicine and Department of Infectious Diseases, Monash University, Commercial Road, Melbourne, Victoria 3004, Australia
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Abstract
INTRODUCTION Placental malaria (PM) is a major public health problem that constitutes a significant health concern for the mother, and especially for the developing fetus and offspring. Current means of prevention have limitations, including a restricted window of intervention that excludes the first trimester of pregnancy, and the fact that very few drugs can be used for this purpose. The identification of the VAR2CSA antigen, specific to PM parasites, offers an excellent opportunity to develop a vaccine against this disease. Proof of concept of a first-generation vaccine is nearing completion, and two clinical trials are underway. AREAS COVERED This review focuses on PM, which is mainly caused by Plasmodium falciparum. The review highlights recent advances and the key milestones that led to the identification of the optimal vaccine target within the large VAR2CSA protein. The paper also points out how future improvements can strengthen this process to achieve an effective vaccine in the field. EXPERT OPINION The approach taken to develop a P. falciparum erythrocyte membrane protein 1-based vaccine to protect pregnant women is very promising in view of the current difficulties of achieving a sterilizing vaccine against malaria parasite. This approach could help us to control the deleterious effect of malaria infections that characterize severe clinical forms.
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Chronic HIV infection impairs nonopsonic phagocytosis of malaria parasites. J Acquir Immune Defic Syndr 2015; 68:128-32. [PMID: 25415293 DOI: 10.1097/qai.0000000000000427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Malaria-specific immune responses are altered in HIV/malaria-coinfected individuals and are associated with higher parasite burdens and more severe clinical disease. Monocyte/macrophage phagocytosis is a major mechanism of malaria parasite clearance. We hypothesized that phagocytosis of malaria-parasitized erythrocytes is impaired in coinfected individuals and could contribute to the increased parasite burdens observed. We show that nonopsonic phagocytosis of Plasmodium falciparum parasitized erythrocytes is impaired in monocytes isolated from HIV-infected individuals. The observed defects in phagocytic capacity were rescued after 6 months of antiretroviral therapy, demonstrating the importance of HIV treatment and immune reconstitution in the context of coinfection.
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31
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Antigen reversal identifies targets of opsonizing IgGs against pregnancy-associated malaria. Infect Immun 2014; 82:4842-53. [PMID: 25156731 DOI: 10.1128/iai.02097-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Clinical immunity to pregnancy associated-malaria (PAM) in multigravida women has been attributed to antibodies that recognize VAR2CSA on the infected erythrocyte (IE) surface. The size and complexity of VAR2CSA have focused efforts on selecting one or more of its six Duffy binding-like (DBL) domains for vaccine development. Presently, however, there is no consensus as to which DBL domain(s) would be most effective in eliciting immunity. This is because antibodies to a number of the DBL domains have been found to block the adhesion of VAR2CSA-expressing erythrocytes to chondroitin sulfate A (CSA)-a major criterion for evaluating vaccine candidacy. Opsonization of IEs by cytophilic antibodies that recognize VAR2CSA represents an important yet understudied effector mechanism in acquired immunity to PAM. To date, no studies have sought to determine the targets of those antibodies. In this study, we found that IgGs from multigravida Malian women showed (i) higher reactivity to recombinant DBL domains by enzyme-linked immunosorbent assay (ELISA), (ii) more binding to VAR2CSA-expressing IEs, and (iii) greater opsonization of these IEs by human monocytic cells than IgGs from malaria-exposed Malian men and malaria-naive American adults. Preincubation of IgGs from multigravida women with recombinant DBL2χ, DBL3χ, or DBL5ε domains significantly diminished opsonization of VAR2CSA-expressing IEs by human monocytes. These data identify the DBL2χ, DBL3χ, and DBL5ε domains as the primary targets of opsonizing IgGs for the first time. Our study introduces a new approach to determining the antigenic targets of opsonizing IgGs in phagocytosis assays.
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Hasang W, Dembo EG, Wijesinghe R, Molyneux ME, Kublin JG, Rogerson S. HIV-1 infection and antibodies to Plasmodium falciparum in adults. J Infect Dis 2014; 210:1407-14. [PMID: 24795481 DOI: 10.1093/infdis/jiu262] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Coinfection with human immunodeficiency virus (HIV) may increase susceptibility to malaria by compromising naturally acquired immunity. METHODS In 339 adults (64% HIV infected), we measured antibodies to Plasmodium falciparum variant surface antigens (VSA) and antibodies that opsonise infected erythrocytes using parasite lines FCR3, E8B, and R29, and antibodies to merozoite antigens AMA-1 and MSP2. We determined the relationship between malaria antibodies, HIV infection, markers of immune compromise, and risk of incident parasitemia. RESULTS HIV-infected adults had significantly lower mean levels of opsonizing antibody to all parasite lines (P < .0001), and lower levels of antibody to AMA-1 (P = .01) and MSP2 (P < .0001). Levels of immunoglobulin G (IgG) to VSA were not affected by HIV status. Opsonising antibody titres against some isolates were positively correlated with CD4 count. There were negative associations between human immunodeficiency virus type 1 (HIV-1) viral load and opsonizing antibodies to FCR3 (P = .04), and levels of IgG to AMA-1 (P ≤ .03) and MSP2-3D7 (P = .05). Lower opsonizing antibody levels on enrollment were seen in those who became parasitemic during follow-up, independent of HIV infection (P ≤ .04 for each line). CONCLUSIONS HIV-1 infection decreases opsonizing antibodies to VSA, and antibody to merozoite antigens. Opsonizing antibodies were associated with lack of parasitemia during follow up, suggesting a role in protection.
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Affiliation(s)
- Wina Hasang
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Edson G Dembo
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Blantyre
| | - Rushika Wijesinghe
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne
| | - Malcolm E Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Blantyre The Liverpool School of Tropical Medicine, United Kingdom
| | - James G Kublin
- Fred Hutchison Cancer Research Center, Seattle, Washington
| | - Stephen Rogerson
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia
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Chan JA, Fowkes FJI, Beeson JG. Surface antigens of Plasmodium falciparum-infected erythrocytes as immune targets and malaria vaccine candidates. Cell Mol Life Sci 2014; 71:3633-57. [PMID: 24691798 PMCID: PMC4160571 DOI: 10.1007/s00018-014-1614-3] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/19/2022]
Abstract
Understanding the targets and mechanisms of human immunity to malaria caused by Plasmodium falciparum is crucial for advancing effective vaccines and developing tools for measuring immunity and exposure in populations. Acquired immunity to malaria predominantly targets the blood stage of infection when merozoites of Plasmodium spp. infect erythrocytes and replicate within them. During the intra-erythrocytic development of P. falciparum, numerous parasite-derived antigens are expressed on the surface of infected erythrocytes (IEs). These antigens enable P. falciparum-IEs to adhere in the vasculature and accumulate in multiple organs, which is a key process in the pathogenesis of disease. IE surface antigens, often referred to as variant surface antigens, are important targets of acquired protective immunity and include PfEMP1, RIFIN, STEVOR and SURFIN. These antigens are highly polymorphic and encoded by multigene families, which generate substantial antigenic diversity to mediate immune evasion. The most important immune target appears to be PfEMP1, which is a major ligand for vascular adhesion and sequestration of IEs. Studies are beginning to identify specific variants of PfEMP1 linked to disease pathogenesis that may be suitable for vaccine development, but overcoming antigenic diversity in PfEMP1 remains a major challenge. Much less is known about other surface antigens, or antigens on the surface of gametocyte-IEs, the effector mechanisms that mediate immunity, and how immunity is acquired and maintained over time; these are important topics for future research.
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Amuta E, Houmsou R, Wama E, Ameh M. Malarial Infection among Antenatal and Maternity Clinics Attendees at the Federal Medical Centre, Makurdi, Benue State, Nigeria. Infect Dis Rep 2014; 6:5050. [PMID: 24757507 PMCID: PMC3987244 DOI: 10.4081/idr.2014.5050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/29/2013] [Accepted: 12/20/2013] [Indexed: 11/22/2022] Open
Abstract
This study assessed the level of malarial infection in relation to some epidemiological factors, gravidity and pregnancy period of antenatal clinic attendees of the Federal Medical Centre, Makurdi, Benue State, Nigeria. We also assessed malarial infection in placental blood in relation to gravidity of pregnant women at delivery in the maternity clinic of the same hospital. Thin and thick blood films were prepared for microscopic examination. A questionnaire was administered to each pregnant woman at the antenatal clinic to collect data on educational level, occupation, gravidity, pregnancy period, malaria preventive measures and malaria symptoms. Of the 163 pregnant women examined at the antenatal clinic, 68.3% (111/163) were infected with malaria. Pregnant women that are illiterates (χ(2) =15.44, P=0.100) and those that are farmers (χ(2) =9.20, P=0.270) had the highest infection rate with no significant difference respectively. Malarial infection was significantly higher in the multigravidae, 57.6% (34/59) (χ(2) =5.16, P=0.007) and non-significant in the pregnant women at their third trimester of pregnancy, 60.9% (53/89) (χ(2) =4.45, P=0.108). Placental malaria was significantly higher in the primigravidae among pregnant women at delivery (χ(2) =9.33, P=0.000). A significant difference (χ(2) =33.52, P=0.000) was observed between pregnant women that did not use any malaria preventive methods, 91.2% (31/34) and those that used single, 64.3% (65/101) and combined, 46.4% (13/28) methods of prevention. Malaria remains highly prevalent among antenatal clinics attendees in Makurdi, Nigeria. Combined method of prevention (insecticides treated nets and insecticide spray) yielded good results and its use is advocated in preventing malaria among the pregnant women.
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Affiliation(s)
- Elizabeth Amuta
- Department of Biological Sciences, University of Agriculture , Makurdi, Nigeria
| | - Robert Houmsou
- Departement of Biological Sciences, Taraba State University , Jalingo, Nigeria
| | - Emmanuel Wama
- Departement of Biological Sciences, Taraba State University , Jalingo, Nigeria
| | - Mary Ameh
- Department of Biological Sciences, Benue State University Makurdi , Nigeria
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Ataíde R, Mayor A, Rogerson SJ. Malaria, primigravidae, and antibodies: knowledge gained and future perspectives. Trends Parasitol 2013; 30:85-94. [PMID: 24388420 DOI: 10.1016/j.pt.2013.12.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/08/2013] [Accepted: 12/08/2013] [Indexed: 10/25/2022]
Abstract
Pregnant women have an increased risk of malaria infection, independent of previously acquired immunity. Women in their first pregnancy and children under the age of five are the primary victims of malaria worldwide. Pregnant women develop antibodies against placenta-adhesive parasites in a parity-dependent manner. Various efforts to understand the targets, quality, and quantity of this antibody response could aid the design of an effective vaccine against placental malaria. This review focuses on the research that has led to the current understanding of the antibody response that primigravidae (PG) acquire to Plasmodium falciparum malaria and draws from this knowledge to suggest serology and PG as sentinels for malaria transmission.
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Affiliation(s)
- Ricardo Ataíde
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Australia.
| | - Alfredo Mayor
- Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde da Manhiça (CISM), Manhiça, Mozambique
| | - Stephen J Rogerson
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Australia
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Chandrasiri UP, Randall LM, Saad AA, Bashir AM, Rogerson SJ, Adam I. Low antibody levels to pregnancy-specific malaria antigens and heightened cytokine responses associated with severe malaria in pregnancy. J Infect Dis 2013; 209:1408-17. [PMID: 24277742 DOI: 10.1093/infdis/jit646] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Pregnant women living in unstable malaria transmission settings may develop severe malaria (SM). The pathogenesis of SM in pregnancy is poorly understood. METHODS To determine whether SM in pregnancy is associated with lower malarial antibody responses and higher cytokine responses, plasma samples were collected from 121 Sudanese pregnant women of whom 39 were diagnosed with SM. Antibodies to pregnancy-specific and non-pregnancy-specific Plasmodium falciparum variant surface antigens (VSA) and concentrations of cytokines TNF, IFNγ, IL-1β, IL-6, IL-8 and IL-10 were measured. RESULTS Pregnant women with SM demonstrated significantly lower antibody levels to pregnancy-specific VSA (P = .020) and higher plasma IFNγ (P = .020), IL-10 (P = .0002) and IL-6 levels (P < .0001) than uninfected pregnant women. Concentrations of inflammatory cytokines IL-1β (P = .001), IL-6 (P = .004) and IL-8 (P = .020) were inversely correlated with antibodies to VAR2CSA-DBL5 in pregnant women with SM. Lower haemoglobin levels and higher parasite densities were associated with lack of pregnancy-specific antibodies (P = .028) and higher levels of inflammatory cytokines, in particular IL-6 and IL-8. CONCLUSIONS Pregnant women with SM lack pregnancy-specific malaria immunity, and this correlates with heightened inflammatory cytokine concentrations, low haemoglobin levels and high parasite density, suggesting that failure of antibody to control parasitaemia may contribute to SM pathogenesis.
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Affiliation(s)
- Upeksha P Chandrasiri
- Department of Medicine, The University of Melbourne, Melbourne Victoria 3052, Australia
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A model of parity-dependent immunity to placental malaria. Nat Commun 2013; 4:1609. [PMID: 23511473 PMCID: PMC3615483 DOI: 10.1038/ncomms2605] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 02/14/2013] [Indexed: 11/08/2022] Open
Abstract
Plasmodium falciparum placental infection during pregnancy is harmful for both mother and child. Protection from placental infection is parity-dependent, that is, acquired over consecutive pregnancies. However, the infection status of the placenta can only be assessed at delivery. Here, to better understand the mechanism underlying this parity-dependence, we fitted a model linking malaria dynamics within the general population to observed placental histology. Our results suggest that immunity resulting in less prolonged infection is a greater determinant of the parity-specific patterns than immunity that prevents placental sequestration. Our results also suggest the time when maternal blood first flows into the placenta is a high-risk period. Therefore, preventative strategies implementable before or early in pregnancy, such as insecticide-treated net usage in women of child-bearing age or any future vaccine, could substantially reduce the number of women who experience placental infection.
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Chang CC, Crane M, Zhou J, Mina M, Post JJ, Cameron BA, Lloyd AR, Jaworowski A, French MA, Lewin SR. HIV and co-infections. Immunol Rev 2013; 254:114-42. [PMID: 23772618 PMCID: PMC3697435 DOI: 10.1111/imr.12063] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Despite significant reductions in morbidity and mortality secondary to availability of effective combination anti-retroviral therapy (cART), human immunodeficiency virus (HIV) infection still accounts for 1.5 million deaths annually. The majority of deaths occur in sub-Saharan Africa where rates of opportunistic co-infections are disproportionately high. In this review, we discuss the immunopathogenesis of five common infections that cause significant morbidity in HIV-infected patients globally. These include co-infection with Mycobacterium tuberculosis, Cryptococcus neoformans, hepatitis B virus, hepatitis C virus, and Plasmodium falciparum. Specifically, we review the natural history of each co-infection in the setting of HIV, the specific immune defects induced by HIV, the effects of cART on the immune response to the co-infection, the pathogenesis of immune restoration disease (IRD) associated with each infection, and advances in the areas of prevention of each co-infection via vaccination. Finally, we discuss the opportunities and gaps in knowledge for future research.
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Affiliation(s)
- Christina C Chang
- Department of Infectious Diseases, Alfred Hospital and Monash University, Melbourne, Australia
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Conroy AL, McDonald CR, Kain KC. Malaria in pregnancy: diagnosing infection and identifying fetal risk. Expert Rev Anti Infect Ther 2013; 10:1331-42. [PMID: 23241190 DOI: 10.1586/eri.12.123] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Despite increased malaria control efforts, recent reports indicate that over 1.2 million deaths due to malaria occurred in 2010. Pregnant women represent a particularly vulnerable risk group as malaria infection can lead to life-threatening disease for the mother and fetus. With 125 million women at risk of malaria in pregnancy every year, better diagnostic tools are needed for timely identification and treatment of malaria infection. Diagnostic surveillance tools are also needed to estimate disease burden and inform public health policies. In this review, the authors focus on malaria diagnostics in pregnancy and discuss considerations for different Plasmodium species and geographic regions. The authors also look at promising diagnostic modalities to monitor fetal and maternal health in pregnancy and discuss implementation barriers for low resource settings.
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Affiliation(s)
- Andrea L Conroy
- Sandra Rotman Laboratories, Sandra Rotman Centre, University Health Network - Toronto General Hospital, University of Toronto, M5G 1L7, Canada
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Iriemenam NC, Pandey JP, Williamson J, Blackstock AJ, Yesupriya A, Namboodiri AM, Rocca KM, van Eijk AM, Ayisi J, Oteino J, Lal RB, ter Kuile FO, Steketee R, Nahlen B, Slutsker L, Shi YP. Association between immunoglobulin GM and KM genotypes and placental malaria in HIV-1 negative and positive women in western Kenya. PLoS One 2013; 8:e53948. [PMID: 23326546 PMCID: PMC3543394 DOI: 10.1371/journal.pone.0053948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/06/2012] [Indexed: 01/24/2023] Open
Abstract
Immunoglobulin (Ig) GM and KM allotypes, genetic markers of γ and κ chains, are associated with humoral immune responsiveness. Previous studies have shown the relationships between GM6-carrying haplotypes and susceptibility to malaria infection in children and adults; however, the role of the genetic markers in placental malaria (PM) infection and PM with HIV co-infection during pregnancy has not been investigated. We examined the relationship between the gene polymorphisms of Ig GM6 and KM allotypes and the risk of PM infection in pregnant women with known HIV status. DNA samples from 728 pregnant women were genotyped for GM6 and KM alleles using polymerase chain reaction-restriction fragment length polymorphism method. Individual GM6 and KM genotypes and the combined GM6 and KM genotypes were assessed in relation to PM in HIV-1 negative and positive women, respectively. There was no significant effect of individual GM6 and KM genotypes on the risk of PM infection in HIV-1 negative and positive women. However, the combination of homozygosity for GM6(+) and KM3 was associated with decreased risk of PM (adjusted OR, 0.25; 95% CI, 0.08-0.8; P = 0.019) in HIV-1 negative women while in HIV-1 positive women the combination of GM6(+/-) with either KM1-3 or KM1 was associated with increased risk of PM infection (adjusted OR, 2.10; 95% CI, 1.18-3.73; P = 0.011). Hardy-Weinberg Equilibrium (HWE) tests further showed an overall significant positive F(is) (indication of deficit in heterozygotes) for GM6 while there was no deviation for KM genotype frequency from HWE in the same population. These findings suggest that the combination of homozygous GM6(+) and KM3 may protect against PM in HIV-1 negative women while the HIV-1 positive women with heterozygous GM6(+/-) combined with KM1-3 or KM1 may be more susceptible to PM infection. The deficit in heterozygotes for GM6 further suggests that GM6 could be under selection likely by malaria infection.
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Affiliation(s)
- Nnaemeka C. Iriemenam
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Janardan P. Pandey
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail: (YPS); (JPP)
| | - John Williamson
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Anna J. Blackstock
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- Atlanta Research and Education Foundation/VA Medical Center, Decatur, Georgia, United States of America
| | - Ajay Yesupriya
- National Office of Public Health Genomics, Coordinating Center for Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Aryan M. Namboodiri
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Keith M. Rocca
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Anna Maria van Eijk
- Centre for Vector Biology and Control Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | - John Ayisi
- Centre for Vector Biology and Control Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | - Juliana Oteino
- New Nyanza Provincial General Hospital, Ministry of Health, Kisumu, Kenya
| | - Renu B. Lal
- Division of AIDS, STD, TB Laboratory Research, National Center for HIV, STD, TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Feiko O. ter Kuile
- Child and Reproductive Health Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Richard Steketee
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Bernard Nahlen
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Laurence Slutsker
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ya Ping Shi
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail: (YPS); (JPP)
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Monocytes and macrophages in malaria: protection or pathology? Trends Parasitol 2012; 29:26-34. [PMID: 23142189 DOI: 10.1016/j.pt.2012.10.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/12/2012] [Accepted: 10/16/2012] [Indexed: 02/07/2023]
Abstract
Recruitment and activation of monocytes and macrophages are essential for clearance of malaria infection, but these have also been associated with adverse clinical outcomes. In this review we discuss recent discoveries on how distinct molecular interactions between monocytes, macrophages, and malaria parasites may alter the balance between protection and pathology in malaria-infected individuals. The immunopathology of severe malaria often originates from excessive immune activation by parasites. The involvement of monocytes and macrophages in these events is highlighted, and priorities for future research to clarify the roles of these cells in malaria are proposed. Knowledge of the factors influencing the balance between protection and pathology can assist in the design of therapeutics aimed at modulating monocyte and macrophage functions to improve outcomes.
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Tutterrow YL, Salanti A, Avril M, Smith JD, Pagano IS, Ako S, Fogako J, Leke RGF, Taylor DW. High avidity antibodies to full-length VAR2CSA correlate with absence of placental malaria. PLoS One 2012; 7:e40049. [PMID: 22761948 PMCID: PMC3383675 DOI: 10.1371/journal.pone.0040049] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 05/31/2012] [Indexed: 11/29/2022] Open
Abstract
VAR2CSA mediates sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, increasing the risk of poor pregnancy outcomes. Naturally acquired antibodies (Ab) to placental parasites at delivery have been associated with improved pregnancy outcomes, but Ab levels and how early in pregnancy Ab must be present in order to eliminate placental parasites before delivery remains unknown. Antibodies to individual Duffy-binding like domains of VAR2CSA have been studied, but the domains lack many of the conformational epitopes present in full-length VAR2CSA (FV2). Thus, the purpose of this study was to describe the acquisition of Ab to FV2 in women residing in high and low transmission areas and determine how Ab levels during pregnancy correlate with clearance of placental parasites. Plasma samples collected monthly throughout pregnancy from pregnant women living in high and low transmission areas in Cameroon were evaluated for Ab to FV2 and the proportion of high avidity Ab (i.e., Ab that remain bound in the presence of 3M NH4SCN) was assessed. Ab levels and proportion of high avidity Ab were compared between women with placental malaria (PM+) and those without (PM−) at delivery. Results showed that PM− women had significantly higher Ab levels (p = 0.0047) and proportion of high avidity Ab (p = 0.0009) than PM+ women throughout pregnancy. Specifically, women with moderate to high Ab levels (>5,000 MFI) and those with ≥35% high avidity Ab at 5–6 months were found to have 2.3 (95% CI, 1.0–4.9) and 7.6-fold (p = 0.0013, 95% CI: 1.2–50.0) reduced risk of placental malaria, respectively. These data show that high levels of Ab to FV2, particularly those with high avidity for FV2, produced by mid-pregnancy are important in clearing parasites from the placenta. Both high Ab levels and proportion of high avidity Ab to FV2 may serve as correlates of protection for assessing immunity against placental malaria.
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Affiliation(s)
- Yeung Lo Tutterrow
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawai'i-Mānoa, Honolulu, Hawaii, United States of America
| | - Ali Salanti
- Department of International Health, Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Marion Avril
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Joseph D. Smith
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Ian S. Pagano
- Cancer Research Center, University of Hawaii-Mānoa, Honolulu, Hawaii, United States of America
| | - Simon Ako
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Josephine Fogako
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Rose G. F. Leke
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Diane Wallace Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawai'i-Mānoa, Honolulu, Hawaii, United States of America
- * E-mail:
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González R, Ataíde R, Naniche D, Menéndez C, Mayor A. HIV and malaria interactions: where do we stand? Expert Rev Anti Infect Ther 2012; 10:153-65. [PMID: 22339190 DOI: 10.1586/eri.11.167] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reversing the spread of HIV infection and the incidence of malaria constitute two of the Millenium Development Goals. However, despite recent achievements, both diseases still entail global heath problems. Furthermore, their overlapping geographical distribution raises concerns and challenges for potential immunological, clinical and therapeutic interactions. It has been reported that HIV infection increases malaria susceptibility and reduces the efficacy of antimalarial drugs. On the other hand, the effect of malaria on HIV-infected individuals has also been explored, with the parasitic infection increasing the risk of HIV disease progression and mother-to-child transmission of HIV. The spread of malaria and parasite resistance to antimalarials could also be accelerated by HIV-associated immunosuppresion. Current knowledge of the epidemiological, clinical, immunological and therapeutic interactions of the two diseases is reviewed in this article. We focus on the latest available data, pointing out key future research areas and challenges of the field.
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Affiliation(s)
- Raquel González
- Barcelona Centre for International Heath Research (CRESIB), Hospital Clínic/IDIBAPS, Universitat de Barcelona, Spain
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Ludlow LE, Zhou J, Tippett E, Cheng WJ, Hasang W, Rogerson SJ, Jaworowski A. HIV-1 inhibits phagocytosis and inflammatory cytokine responses of human monocyte-derived macrophages to P. falciparum infected erythrocytes. PLoS One 2012; 7:e32102. [PMID: 22363802 PMCID: PMC3283736 DOI: 10.1371/journal.pone.0032102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 01/23/2012] [Indexed: 11/21/2022] Open
Abstract
HIV-1 infection increases the risk and severity of malaria by poorly defined mechanisms. We investigated the effect of HIV-1Ba-L infection of monocyte-derived macrophages (MDM) on phagocytosis of opsonised P. falciparum infected erythrocytes (IE) and subsequent proinflammatory cytokine secretion. Compared to mock-infected MDM, HIV-1 infection significantly inhibited phagocytosis of IE (median (IQR) (10 (0–28) versus (34 (27–108); IE internalised/100 MDM; p = 0.001) and decreased secretion of IL-6 (1,116 (352–3,387) versus 1,552 (889–6,331); pg/mL; p = 0.0078) and IL-1β (16 (7–21) versus 33 (27–65); pg/mL; p = 0.0078). Thus inadequate phagocytosis and cytokine production may contribute to impaired control of malaria in HIV-1 infected individuals.
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Affiliation(s)
- Louise E Ludlow
- Department of Medicine (RMH), University of Melbourne, Post Office Royal Melbourne Hospital, Melbourne, Victoria, Australia.
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Kane EG, Taylor-Robinson AW. Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites. Malar Res Treat 2012; 2011:764845. [PMID: 22363896 PMCID: PMC3272661 DOI: 10.4061/2011/764845] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 01/05/2023] Open
Abstract
Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal.
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Affiliation(s)
- Elizabeth G. Kane
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Faculty of Medicine, University of Liverpool, Liverpool L69 3GA, UK
| | - Andrew W. Taylor-Robinson
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Bigey P, Gnidehou S, Doritchamou J, Quiviger M, Viwami F, Couturier A, Salanti A, Nielsen MA, Scherman D, Deloron P, Tuikue Ndam N. The NTS-DBL2X region of VAR2CSA induces cross-reactive antibodies that inhibit adhesion of several Plasmodium falciparum isolates to chondroitin sulfate A. J Infect Dis 2011; 204:1125-33. [PMID: 21881129 DOI: 10.1093/infdis/jir499] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Binding to chondroitin sulfate A by VAR2CSA, a parasite protein expressed on infected erythrocytes, allows placental sequestration of Plasmodium falciparum-infected erythrocytes. This leads to severe consequences such as maternal anemia, stillbirths, and intrauterine growth retardation. The latter has been clearly associated to increased morbidity and mortality of the infants. Acquired anti-VAR2CSA antibodies have been associated with improved pregnancy outcomes, suggesting a vaccine could prevent the syndrome. However, identifying functionally important regions in the large VAR2CSA protein is difficult. METHODS Using genetic immunization, we raised polyclonal antisera against overlapping segments of VAR2CSA in mice and rabbits. The adhesion-inhibition capacities of induced antisera and of specific antibodies purified from plasma of malaria-exposed pregnant women were assessed on laboratory-adapted parasite lines and field isolates expressing VAR2CSA. Competition enzyme-linked immunosorbent assay (ELISA) was employed to analyze functional resemblance between antibodies induced in animals and those naturally acquired by immune multigravidae. RESULTS Antibodies targeting the N-terminal sequence (NTS) up to DBL2X (NTS-DBL2X) efficiently blocked parasite adhesion to chondroitin sulfate A in a manner similar to that of antibodies raised against the entire VAR2CSA extracellular domain. Interestingly, naturally acquired antibodies and those induced by vaccination against NTS-DBL2X target overlapping strain-transcendent anti-adhesion epitopes. CONCLUSIONS This study highlights an important step achieved toward development of a protective vaccine against placental malaria.
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Affiliation(s)
- Pascal Bigey
- Unité de Pharmacologie Chimique et Génétique, Université Paris Descartes, ENSCP Chimie ParisTech, CNRS UMR8151, Inserm U 1022, France
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Silver KL, Conroy AL, Leke RGF, Leke RJI, Gwanmesia P, Molyneux ME, Wallace DT, Rogerson SJ, Kain KC. Circulating soluble endoglin levels in pregnant women in Cameroon and Malawi--associations with placental malaria and fetal growth restriction. PLoS One 2011; 6:e24985. [PMID: 21966395 PMCID: PMC3178568 DOI: 10.1371/journal.pone.0024985] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 08/19/2011] [Indexed: 11/21/2022] Open
Abstract
Placental infections with Plasmodium falciparum are associated with fetal growth restriction resulting in low birth weight (LBW). The mechanisms that mediate these effects have yet to be completely described; however, they are likely to involve inflammatory processes and dysregulation of angiogenesis. Soluble endoglin (sEng), a soluble receptor of transforming growth factor (TGF)-β previously associated with preeclampsia in pregnant women and with severe malaria in children, regulates the immune system and influences angiogenesis. We hypothesized that sEng may play a role in development of LBW associated with placental malaria (PM). Plasma levels of sEng were measured in women (i) followed prospectively throughout pregnancy in Cameroon (n = 52), and (ii) in a case-control study at delivery in Malawi (n = 479). The relationships between sEng levels and gravidity, peripheral and placental parasitemia, gestational age, and adverse outcomes of PM including maternal anemia and LBW were determined. In the longitudinal cohort from Cameroon, 28 of 52 women (54%) experienced at least one malaria infection during pregnancy. In Malawi we enrolled two aparasitemic gravidity-matched controls for every case with PM. sEng levels varied over the course of gestation and were significantly higher in early and late gestation as compared to delivery (P<0.006 and P<0.0001, respectively). Circulating sEng levels were higher in primigravidae than multigravidae from both Cameroon and Malawi, irrespective of malarial infection status (p<0.046 and p<0.001, respectively). Peripheral parasitemia in Cameroonian women and PM in Malawian women were each associated with elevated sEng levels following correction for gestational age and gravidity (p = 0.006 and p = 0.033, respectively). Increased sEng was also associated with the delivery of LBW infants in primigravid Malawian women (p = 0.017); the association was with fetal growth restriction (p = 0.003) but not pre-term delivery (p = 0.286). Increased circulating maternal sEng levels are associated with P. falciparum infection in pregnancy and with fetal growth restriction in primigravidae with PM.
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Affiliation(s)
- Karlee L. Silver
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Andrea L. Conroy
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Rose G. F. Leke
- Faculty of Medicine and Biomedical Research, University of Yaoundé, Yaoundé, Cameroon
| | - Robert J. I. Leke
- Faculty of Medicine and Biomedical Research, University of Yaoundé, Yaoundé, Cameroon
| | - Philomina Gwanmesia
- Faculty of Medicine and Biomedical Research, University of Yaoundé, Yaoundé, Cameroon
| | - Malcolm E. Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- College of Medicine, University of Malawi, Blantyre, Malawi
- School of Tropical Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Diane Taylor Wallace
- Department of Biology, Georgetown University, Washington, D.C., United States of America
- Department of Tropical Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, United States of America
| | - Stephen J. Rogerson
- Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Kevin C. Kain
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Ataíde R, Mwapasa V, Molyneux ME, Meshnick SR, Rogerson SJ. Antibodies that induce phagocytosis of malaria infected erythrocytes: effect of HIV infection and correlation with clinical outcomes. PLoS One 2011; 6:e22491. [PMID: 21811621 PMCID: PMC3139654 DOI: 10.1371/journal.pone.0022491] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 06/28/2011] [Indexed: 12/05/2022] Open
Abstract
HIV infection increases the burden of disease of malaria in pregnancy, in part by impairing the development of immunity. We measured total IgG and phagocytic antibodies against variant surface antigens of placental-type CS2 parasites in 187 secundigravidae (65% HIV infected). In women with placental malaria infection, phagocytic antibodies to CS2VSA were decreased in the presence of HIV (p = 0.011) and correlated positively with infant birth weight (coef = 3.57, p = 0.025), whereas total IgG to CS2VSA did not. Phagocytic antibodies to CS2VSA are valuable tools to study acquired immunity to malaria in the context of HIV co-infection. Secundigravidae may be an informative group for identification of correlates of immunity.
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Affiliation(s)
- Ricardo Ataíde
- Department of Medicine (RMH/WH), University of Melbourne, Post Office Royal Melbourne Hospital, Melbourne, Victoria, Australia.
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Complement activation: a critical mediator of adverse fetal outcomes in placental malaria? Trends Parasitol 2011; 27:294-9. [DOI: 10.1016/j.pt.2011.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/17/2011] [Accepted: 02/22/2011] [Indexed: 11/19/2022]
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Avril M, Cartwright MM, Hathaway MJ, Smith JD. Induction of strain-transcendent antibodies to placental-type isolates with VAR2CSA DBL3 or DBL5 recombinant proteins. Malar J 2011; 10:36. [PMID: 21314945 PMCID: PMC3055221 DOI: 10.1186/1475-2875-10-36] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 02/11/2011] [Indexed: 11/23/2022] Open
Abstract
Background Pregnancy associated malaria is a severe clinical syndrome associated with sequestration of Plasmodium falciparum-infected erythrocytes in the placenta. Placental binding is mediated by VAR2CSA, which adheres to chondroitin sulphate A (CSA). VAR2CSA is a large and polymorphic protein that has six Duffy binding-like (DBL) domains. There is still limited understanding as to how effective individual VAR2CSA domains are at generating inhibitory antibodies or the number of domain variants needed for universal vaccine coverage. Methods To investigate the immunogenic properties of single domain VAR2CSA recombinant proteins, rats or rabbits were immunized with five of the six VAR2CSA domains produced in Pichia pastoris. Immune plasma was analysed against a geographically diverse panel of CSA-binding lab lines to assess antibody breadth and inhibitory activity. Results Of the five domains, DBL3, and to a lesser extent DBL5, induced antibodies that cross-reacted on five diverse CSA-binding parasite lines by flow cytometry. By comparison, anti-DBL6 antibodies were highly strain-specific and anti-DBL1 and anti-DBL4 antibodies were poorly reactive by flow cytometry. From this series of recombinant proteins, adhesion-blocking activity was restricted to a single rat immunized against a DBL4 recombinant protein. Conclusions Single domain VAR2CSA recombinant proteins produced in P. pastoris had limited efficacy in eliciting adhesion blocking antibody responses, but VAR2CSA DBL3 and DBL5 domains contain strain-transcendent epitopes that can be targeted by vaccination and may have application for vaccine development.
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Affiliation(s)
- Marion Avril
- Seattle Biomedical Research Institute, 307 Westlake Ave N, Suite 500, Seattle Washington, 98109-5219, USA
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