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Santos-López J, de la Paz K, Fernández FJ, Vega MC. Structural biology of complement receptors. Front Immunol 2023; 14:1239146. [PMID: 37753090 PMCID: PMC10518620 DOI: 10.3389/fimmu.2023.1239146] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/16/2023] [Indexed: 09/28/2023] Open
Abstract
The complement system plays crucial roles in a wide breadth of immune and inflammatory processes and is frequently cited as an etiological or aggravating factor in many human diseases, from asthma to cancer. Complement receptors encompass at least eight proteins from four structural classes, orchestrating complement-mediated humoral and cellular effector responses and coordinating the complex cross-talk between innate and adaptive immunity. The progressive increase in understanding of the structural features of the main complement factors, activated proteolytic fragments, and their assemblies have spurred a renewed interest in deciphering their receptor complexes. In this review, we describe what is currently known about the structural biology of the complement receptors and their complexes with natural agonists and pharmacological antagonists. We highlight the fundamental concepts and the gray areas where issues and problems have been identified, including current research gaps. We seek to offer guidance into the structural biology of the complement system as structural information underlies fundamental and therapeutic research endeavors. Finally, we also indicate what we believe are potential developments in the field.
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Affiliation(s)
- Jorge Santos-López
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Karla de la Paz
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Research & Development, Abvance Biotech SL, Madrid, Spain
| | | | - M. Cristina Vega
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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2
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de Jong RM, Alkema M, Oulton T, Dumont E, Teelen K, Nakajima R, de Assis RR, Press KWD, Ngotho P, Tetteh KK, Felgner P, Marti M, Collins KA, Drakeley C, Bousema T, Stone WJ. The acquisition of humoral immune responses targeting Plasmodium falciparum sexual stages in controlled human malaria infections. Front Immunol 2022; 13:930956. [PMID: 35924245 PMCID: PMC9339717 DOI: 10.3389/fimmu.2022.930956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Individuals infected with P. falciparum develop antibody responses to intra-erythrocytic gametocyte proteins and exported gametocyte proteins present on the surface of infected erythrocytes. However, there is currently limited knowledge on the immunogenicity of gametocyte antigens and the specificity of gametocyte-induced antibody responses. In this study, we assessed antibody responses in participants of two controlled human malaria infection (CHMI) studies by ELISA, multiplexed bead-based antibody assays and protein microarray. By comparing antibody responses in participants with and without gametocyte exposure, we aimed to disentangle the antibody response induced by asexual and sexual stage parasites. We showed that after a single malaria infection, a significant anti-sexual stage humoral response is induced in malaria-naïve individuals, even after exposure to relatively low gametocyte densities (up to ~1,600 gametocytes/mL). In contrast to antibody responses to well-characterised asexual blood stage antigens that were detectable by day 21 after infection, responses to sexual stage antigens (including transmission blocking vaccine candidates Pfs48/45 and Pfs230) were only apparent at 51 days after infection. We found antigens previously associated with early gametocyte or anti-gamete immunity were highly represented among responses linked with gametocyte exposure. Our data provide detailed insights on the induction and kinetics of antibody responses to gametocytes and identify novel antigens that elicit antibody responses exclusively in individuals with gametocyte exposure. Our findings provide target identification for serological assays for surveillance of the malaria infectious reservoir, and support vaccine development by describing the antibody response to leading vaccine antigens after primary infection.
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Affiliation(s)
- Roos M. de Jong
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Manon Alkema
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Tate Oulton
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Elin Dumont
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Karina Teelen
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Rie Nakajima
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | - Rafael Ramiro de Assis
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | | | - Priscilla Ngotho
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Kevin K.A. Tetteh
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Phil Felgner
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Katharine A. Collins
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Will J.R. Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom,*Correspondence: Will J.R. Stone,
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3
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O'Flaherty K, Roe M, Fowkes FJ. The role of naturally acquired antimalarial antibodies in subclinical
Plasmodium
spp. infection. J Leukoc Biol 2022; 111:1097-1105. [PMID: 35060185 PMCID: PMC9303632 DOI: 10.1002/jlb.5mr1021-537r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/09/2021] [Indexed: 12/17/2022] Open
Affiliation(s)
- Katherine O'Flaherty
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
| | - Merryn Roe
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
| | - Freya J.I. Fowkes
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
- Centre for Epidemiology and Biostatistics Melbourne School of Population and Global Health, The University of Melbourne Melbourne Australia
- Department of Infectious Disease Monash University Melbourne Australia
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4
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Barry A, Bradley J, Stone W, Guelbeogo MW, Lanke K, Ouedraogo A, Soulama I, Nébié I, Serme SS, Grignard L, Patterson C, Wu L, Briggs JJ, Janson O, Awandu SS, Ouedraogo M, Tarama CW, Kargougou D, Zongo S, Sirima SB, Marti M, Drakeley C, Tiono AB, Bousema T. Higher gametocyte production and mosquito infectivity in chronic compared to incident Plasmodium falciparum infections. Nat Commun 2021; 12:2443. [PMID: 33903595 PMCID: PMC8076179 DOI: 10.1038/s41467-021-22573-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 03/09/2021] [Indexed: 11/09/2022] Open
Abstract
Plasmodium falciparum gametocyte kinetics and infectivity may differ between chronic and incident infections. In the current study, we assess parasite kinetics and infectivity to mosquitoes among children (aged 5-10 years) from Burkina Faso with (a) incident infections following parasite clearance (n = 48) and (b) chronic asymptomatic infections (n = 60). In the incident infection cohort, 92% (44/48) of children develop symptoms within 35 days, compared to 23% (14/60) in the chronic cohort. All individuals with chronic infection carried gametocytes or developed them during follow-up, whereas only 35% (17/48) in the incident cohort produce gametocytes before becoming symptomatic and receiving treatment. Parasite multiplication rate (PMR) and the relative abundance of ap2-g and gexp-5 transcripts are positively associated with gametocyte production. Antibody responses are higher and PMR lower in chronic infections. The presence of symptoms and sexual stage immune responses are associated with reductions in gametocyte infectivity to mosquitoes. We observe that most incident infections require treatment before the density of mature gametocytes is sufficient to infect mosquitoes. In contrast, chronic, asymptomatic infections represent a significant source of mosquito infections. Our observations support the notion that malaria transmission reduction may be expedited by enhanced case management, involving both symptom-screening and infection detection.
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Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Will Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Moussa W Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Samuel S Serme
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Catriona Patterson
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Lindsey Wu
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Jessica J Briggs
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Owen Janson
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Shehu S Awandu
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mireille Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Casimire W Tarama
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Désiré Kargougou
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Soumanaba Zongo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Sodiomon B Sirima
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Chris Drakeley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Teun Bousema
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands.
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5
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Alonso S, Vidal M, Ruiz-Olalla G, González R, Jairoce C, Manaca MN, Vázquez-Santiago M, Balcells R, Vala A, Rupérez M, Cisteró P, Fuente-Soro L, Angov E, Coppel RL, Gamain B, Cavanagh D, Beeson JG, Nhacolo A, Sevene E, Aponte JJ, Macete E, Aguilar R, Mayor A, Menéndez C, Dobaño C, Moncunill G. HIV infection and placental malaria reduce maternal transfer of multiple antimalarial antibodies in Mozambican women. J Infect 2021; 82:45-57. [PMID: 33636218 DOI: 10.1016/j.jinf.2021.02.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 10/22/2022]
Abstract
OBJECTIVES Maternal Plasmodium falciparum-specific antibodies may contribute to protect infants against severe malaria. Our main objective was to evaluate the impact of maternal HIV infection and placental malaria on the cord blood levels and efficiency of placental transfer of IgG and IgG subclasses. METHODS In a cohort of 341 delivering HIV-negative and HIV-positive mothers from southern Mozambique, we measured total IgG and IgG subclasses in maternal and cord blood pairs by quantitative suspension array technology against eight P. falciparum antigens: Duffy-binding like domains 3-4 of VAR2CSA from the erythrocyte membrane protein 1, erythrocyte-binding antigen 140, exported protein 1 (EXP1), merozoite surface proteins 1, 2 and 5, and reticulocyte-binding-homologue-4.2 (Rh4.2). We performed univariable and multivariable regression models to assess the association of maternal HIV infection, placental malaria, maternal variables and pregnancy outcomes on cord antibody levels and antibody transplacental transfer. RESULTS Maternal antibody levels were the main determinants of cord antibody levels. HIV infection and placental malaria reduced the transfer and cord levels of IgG and IgG1, and this was antigen-dependent. Low birth weight was associated with an increase of IgG2 in cord against EXP1 and Rh4.2. CONCLUSIONS We found lower maternally transferred antibodies in HIV-exposed infants and those born from mothers with placental malaria, which may underlie increased susceptibility to malaria in these children.
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Affiliation(s)
- Selena Alonso
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Marta Vidal
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Gemma Ruiz-Olalla
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Raquel González
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Chenjerai Jairoce
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - M Nelia Manaca
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Miquel Vázquez-Santiago
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Reyes Balcells
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Anifa Vala
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - María Rupérez
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique; Present address: London School of Hygiene and Tropical Medicine (LSHTM). Keppel Street, WC1E 7HT, London, UK
| | - Pau Cisteró
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Laura Fuente-Soro
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Evelina Angov
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Ross L Coppel
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | - Benoit Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Laboratoire d'Excellence GR-Ex, Paris, France
| | - David Cavanagh
- Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, King's Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
| | | | - Arsenio Nhacolo
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Esperança Sevene
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique; Department of Physiologic Science, Clinical Pharmacology, Faculty of Medicine, Eduardo Mondlane University, Maputo, Mozambique
| | - John J Aponte
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Eusébio Macete
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Ruth Aguilar
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Alfredo Mayor
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Clara Menéndez
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Carlota Dobaño
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique.
| | - Gemma Moncunill
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique.
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6
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Ompad DC, Kessler A, Van Eijk AM, Padhan TK, Haque MA, Sullivan SA, Tozan Y, Rocklöv J, Mohanty S, Pradhan MM, Sahu PK, Carlton JM. The effectiveness of malaria camps as part of the Durgama Anchalare Malaria Nirakaran (DAMaN) program in Odisha, India: study protocol for a cluster-assigned quasi-experimental study. Glob Health Action 2021; 14:1886458. [PMID: 33866961 PMCID: PMC8183513 DOI: 10.1080/16549716.2021.1886458] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The Indian state of Odisha has a longstanding battle with forest malaria. Many remote and rural villages have poor access to health care, a problem that is exacerbated during the rainy season when malaria transmission is at its peak. Approximately 62% of the rural population consists of tribal groups who are among the communities most negatively impacted by malaria. To address the persistently high rates of malaria in these remote regions, the Odisha State Malaria Control Program introduced 'malaria camps' in 2017 where teams of health workers visit villages to educate the population, enhance vector control methods, and perform village-wide screening and treatment. Malaria rates declined statewide, particularly in forested areas, following the introduction of the malaria camps, but the impact of the intervention is yet to be externally evaluated. This study protocol describes a cluster-assigned quasi-experimental stepped-wedge study with a pretest-posttest control group design that evaluates if malaria camps reduce the prevalence of malaria, compared to control villages which receive the usual malaria control interventions (e.g. IRS, ITNs), as detected by PCR.
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Affiliation(s)
- Danielle C. Ompad
- School of Global Public Health, New York University, New York, NY, USA,CONTACT Danielle C. Ompad NYU School of Global Public Health, 715 Broadway, Room 1011, New York, NY10003USA
| | - Anne Kessler
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Anna Maria Van Eijk
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Timir K. Padhan
- Department of Molecular & Infectious Diseases, Community Welfare Society Hospital, Rourkela, Odisha, India
| | - Mohammed A. Haque
- Department of Molecular & Infectious Diseases, Community Welfare Society Hospital, Rourkela, Odisha, India
| | - Steven A. Sullivan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Yesim Tozan
- School of Global Public Health, New York University, New York, NY, USA
| | - Joacim Rocklöv
- Department of Public Health and Clinical Medicine, Umea University, Umea, Sweden
| | - Sanjib Mohanty
- Department of Molecular & Infectious Diseases, Community Welfare Society Hospital, Rourkela, Odisha, India
| | - Madan M. Pradhan
- Department of Health & Family Welfare, State Vector Borne Disease Control Programme, Bhubaneswar, Odisha, India
| | - Praveen K. Sahu
- Department of Molecular & Infectious Diseases, Community Welfare Society Hospital, Rourkela, Odisha, India
| | - Jane M. Carlton
- School of Global Public Health, New York University, New York, NY, USA,Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
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7
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Suau R, Vidal M, Aguilar R, Ruiz-Olalla G, Vázquez-Santiago M, Jairoce C, Nhabomba AJ, Gyan B, Dosoo D, Asante KP, Owusu-Agyei S, Campo JJ, Izquierdo L, Cavanagh D, Coppel RL, Chauhan V, Angov E, Dutta S, Gaur D, Beeson JG, Moncunill G, Dobaño C. RTS,S/AS01 E malaria vaccine induces IgA responses against CSP and vaccine-unrelated antigens in African children in the phase 3 trial. Vaccine 2020; 39:687-698. [PMID: 33358704 DOI: 10.1016/j.vaccine.2020.12.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 11/05/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND The evaluation of immune responses to RTS,S/AS01 has traditionally focused on immunoglobulin (Ig) G antibodies that are only moderately associated with protection. The role of other antibody isotypes that could also contribute to vaccine efficacy remains unclear. Here we investigated whether RTS,S/AS01E elicits antigen-specific serum IgA antibodies to the vaccine and other malaria antigens, and we explored their association with protection. METHODS Ninety-five children (age 5-17 months old at first vaccination) from the RTS,S/AS01E phase 3 clinical trial who received 3 doses of RTS,S/AS01E or a comparator vaccine were selected for IgA quantification 1 month post primary immunization. Two sites with different malaria transmission intensities (MTI) and clinical malaria cases and controls, were included. Measurements of IgA against different constructs of the circumsporozoite protein (CSP) vaccine antigen and 16 vaccine-unrelated Plasmodium falciparum antigens were performed using a quantitative suspension array assay. RESULTS RTS,S vaccination induced a 1.2 to 2-fold increase in levels of serum/plasma IgA antibodies to all CSP constructs, which was not observed upon immunization with a comparator vaccine. The IgA response against 13 out of 16 vaccine-unrelated P. falciparum antigens also increased after vaccination, and levels were higher in recipients of RTS,S than in comparators. IgA levels to malaria antigens before vaccination were more elevated in the high MTI than the low MTI site. No statistically significant association of IgA with protection was found in exploratory analyses. CONCLUSIONS RTS,S/AS01E induces IgA responses in peripheral blood against CSP vaccine antigens and other P. falciparum vaccine-unrelated antigens, similar to what we previously showed for IgG responses. Collectively, data warrant further investigation of the potential contribution of vaccine-induced IgA responses to efficacy and any possible interplay, either synergistic or antagonistic, with protective IgG, as identifying mediators of protection by RTS,S/AS01E immunization is necessary for the design of improved second-generation vaccines. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov: NCT008666191.
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Affiliation(s)
- Roger Suau
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Marta Vidal
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Ruth Aguilar
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Gemma Ruiz-Olalla
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Miquel Vázquez-Santiago
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Chenjerai Jairoce
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929 Maputo, Mozambique.
| | - Augusto J Nhabomba
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929 Maputo, Mozambique
| | - Ben Gyan
- Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana.
| | - David Dosoo
- Kintampo Health Research Centre, Kintampo, Ghana.
| | | | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Kintampo, Ghana; Disease Control Department. London School of Hygiene and Tropical Medicine, London, UK
| | - Joseph J Campo
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - Luis Izquierdo
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain.
| | - David Cavanagh
- Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, King's Buildings, Edinburgh, UK.
| | - Ross L Coppel
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia.
| | - Virander Chauhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Evelina Angov
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA.
| | - Sheetij Dutta
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA.
| | - Deepak Gaur
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India; Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - James G Beeson
- Burnet Institute, Melbourne, Victoria, Australia; Central Clinical School, Monash University, Australia; Department of Medicine, University of Melbourne, Australia.
| | - Gemma Moncunill
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929 Maputo, Mozambique.
| | - Carlota Dobaño
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Carrer Rosselló 153 CEK Building, E-08036 Barcelona, Catalonia, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929 Maputo, Mozambique.
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8
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Ghoshal S, Chowdhury P, Ray S, Mitra M, Kanjilal SD, Sen S, Dasgupta AK, Sengupta S. Population genetic and biophysical evidences reveal that purifying selection shapes the genetic landscape of Plasmodium falciparum RH ligands in Chhattisgarh and West Bengal, India. Malar J 2020; 19:367. [PMID: 33054833 PMCID: PMC7557104 DOI: 10.1186/s12936-020-03433-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 10/01/2020] [Indexed: 11/17/2022] Open
Abstract
Background Reticulocyte binding protein-like homologs (RHs) are currently being evaluated as anti-erythrocytic stage vaccine targets against Plasmodium falciparum malaria. Present study explores the possible evolutionary drivers shaping the genetic organization of Pfrhs in Indian parasite population. It simultaneously evaluates a putative gain-of-function variant of PfRH5, a keystone member of PfRH family. Methods Receptor binding regions of Pfrh1, Pfrh2a/b, Pfrh4 and whole Pfrh5 were amplified using blood samples of P. falciparum malaria patients from Chhattisgarh and West Bengal and sequenced. Assembled sequences were analysed using MEGA7 and DnaSPv6. Binding affinities of recombinant PfRH5 proteins with basigin (BSG) were compared using in silico (CHARMM and AUTODOCK) and in vitro (Circular dichroism, fluorescence spectroscopy and isothermal titration calorimetry) methods. Results Pfrh1 (0.5), Pfrh2a/b (0.875), Pfrh4 (0.667) and Pfrh5 (0.778) sequence changes corresponded to low frequency (< 0.05) variants which resulted in an overall negative Tajima’s D. Since mismatch distribution of none of the Pfrh loci corroborated with the model of demographic expansion, a possible role of natural selection formulating Pfrh sequence diversity was investigated. Among the 5 members, Pfrh5 displayed very high dN/dS (5.7) ratio. Nevertheless, the model of selective sweep due to presence of any advantageous substitutions could not be invoked as polymorphic nonsynonymous sites (17/18) for Pfrh5 exceeded significantly over the divergent (62/86) ones (p = 0.0436). The majority of extant PfRH5 sequences (52/83) differed from the reference Pf3D7 allele by a single amino acid mismatch (C203Y). This non-conservative alteration was predicted to lower the total interaction energy of that PfRH5variant with BSG, compared to PfRH53D7. Biophysical evidences validated the proposition that PfRH5variant formed a more stable complex with BSG. Thermodynamic association constant for interaction of BSG with PfRH5variant was also found to be higher (Kavariant = 3.63E6 ± 2.02E6 M−1 and Ka3D7 = 1.31E6 ± 1.21E6 M−1). Conclusions Together, the study indicates that the genetic architecture of Pfrhs is principally shaped by purifying selection. The most abundant and ubiquitous PfRH5 variant harbouring 203Y, exhibits a greater affinity for BSG compared to PfRH53D7 possessing 203C allele. The study underscores the importance of selecting the functional allele that best represents circulating strains in natural parasite populations as vaccine targets.
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Affiliation(s)
- Sharmistha Ghoshal
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, West Bengal, India
| | - Pramita Chowdhury
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, West Bengal, India
| | - Sanhita Ray
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, West Bengal, India
| | - Mitashree Mitra
- School of Studies in Anthropology. Pt, Ravishankar Shukla University, Raipur, 492010, Chhattisgarh, India
| | - Sumana Datta Kanjilal
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education & Research, Kolkata, West Bengal, India
| | - Srikanta Sen
- Mitra Tower, Lake Town, Block-A, Kolkata, 700 089, India
| | - Anjan Kr Dasgupta
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, West Bengal, India
| | - Sanghamitra Sengupta
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, West Bengal, India.
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9
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Nagaoka H, Kanoi BN, Ntege EH, Aoki M, Fukushima A, Tsuboi T, Takashima E. Antibodies against a short region of PfRipr inhibit Plasmodium falciparum merozoite invasion and PfRipr interaction with Rh5 and SEMA7A. Sci Rep 2020; 10:6573. [PMID: 32313230 PMCID: PMC7171142 DOI: 10.1038/s41598-020-63611-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 03/30/2020] [Indexed: 12/29/2022] Open
Abstract
Plasmodium falciparum merozoite invasion into erythrocytes is an essential step of the blood-stage cycle, survival of parasites, and malaria pathogenesis. P. falciparum merozoite Rh5 interacting protein (PfRipr) forms a complex with Rh5 and CyRPA in sequential molecular events leading to erythrocyte invasion. Recently we described PfRipr as a conserved protein that induces strain-transcending growth inhibitory antibodies in in vitro assays. However, being a large and complex protein of 1086 amino acids (aa) with 87 cysteine residues, PfRipr is difficult to express in conventional expression systems towards vaccine development. In this study we sought to identify the most potent region of PfRipr that could be developed to overcome difficulties related to protein expression, as well as to elucidate the invasion inhibitory mechanism of anti-PfRipr antibodies. Using the wheat germ cell-free system, Ecto- PfRipr and truncates of approximately 200 aa were expressed as soluble proteins. We demonstrate that antibodies against PfRipr truncate 5 (PfRipr_5: C720-D934), a region within the PfRipr C-terminal EGF-like domains, potently inhibit merozoite invasion. Furthermore, the antibodies strongly block PfRipr/Rh5 interaction, as well as that between PfRipr and its erythrocyte-surface receptor, SEMA7A. Taken together, PfRipr_5 is a potential candidate for further development as a blood-stage malaria vaccine.
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Affiliation(s)
- Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Japan
| | - Bernard N Kanoi
- Division of Malaria Research, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Japan
| | - Edward H Ntege
- Division of Malaria Research, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Japan.,Department of Plastic and Reconstructive Surgery, University of the Ryukyus, School of Medicine and Hospital, Okinawa, Japan
| | - Masamitsu Aoki
- Sumitomo Dainippon Pharma Co., Ltd, 3-1-98, Kasugadenaka, Konohanaku, Osaka, 554-0022, Japan
| | - Akihisa Fukushima
- Sumitomo Dainippon Pharma Co., Ltd, 3-1-98, Kasugadenaka, Konohanaku, Osaka, 554-0022, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Japan.
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10
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Oyegue-Liabagui SL, Imboumy-Limoukou RK, Kouna CL, Bangueboussa F, Schmitt M, Florent I, Lekana-Douki JB. IgG antibody response against Plasmodium falciparum aminopeptidase 1 antigen in Gabonese children living in Makokou and Franceville. Clin Exp Immunol 2020; 200:287-298. [PMID: 32027020 DOI: 10.1111/cei.13425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2020] [Indexed: 11/28/2022] Open
Abstract
The search for novel chemical classes of anti-malarial compounds to cope with the current state of chemoresistance of malaria parasites has led to the identification of Plasmodium falciparum aminopeptidase 1 (PfA-M1) as a new therapeutic target. PfA-M1, known to be involved in the hemoglobin digestion cascade which helps to provide most of the amino acids necessary to the parasite's metabolism, is currently considered as a promising target for anti-malarial chemotherapy. However, its immunogenic properties have not yet been tested in the Gabonese population. In Gabon, the prevalence of malaria remains three times higher in semi-urban areas (60·12%) than in urban areas (17·06%). We show that malaria-specific PfA-M1 antibodies are present in children and increase with the level of infection. Children living in semi-urban areas have higher anti-PfA-M1 antibody titers (0·14 ± 0·02 AU) than those living in urban areas (0·08 ± 0·02 AU, P = 0·03), and their antibody titers increase with age (P < 0·0001). Moreover, anti-PfA-M1 antibody titers decrease in children with hyperparasitemia (0·027 ± 0·055 AU) but they remain high in children with low parasite density (0·21 ± 0·034 AU, P = 0·034). In conclusion, our results suggest that malaria-specific PfA-M1 antibodies may play an important role in the immune response of the host against P. falciparum in Gabonese children. Further studies on the role of PfA-M1 during anemia are needed.
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Affiliation(s)
- S L Oyegue-Liabagui
- Laboratoire de Recherches en Immunologie, Parasitologie et Microbiologie, Ecole Doctorale Régionale d'Afrique Centrale en Infectiologie Tropicale (ECODRAC), Université des Sciences et Techniques de Masuku, Franceville, Gabon
| | - R-K Imboumy-Limoukou
- Unité d'Evolution Epidémiologie et Résistances Parasitaires (UNEEREP), Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - C L Kouna
- Unité d'Evolution Epidémiologie et Résistances Parasitaires (UNEEREP), Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - F Bangueboussa
- Laboratoire de Recherches en Immunologie, Parasitologie et Microbiologie, Ecole Doctorale Régionale d'Afrique Centrale en Infectiologie Tropicale (ECODRAC), Université des Sciences et Techniques de Masuku, Franceville, Gabon.,Unité d'Evolution Epidémiologie et Résistances Parasitaires (UNEEREP), Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - M Schmitt
- Université de Haute-Alsace, Université de Strasbourg, Mulhouse, France
| | - I Florent
- Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Muséum National d'Histoire Naturelle, Paris, France
| | - J B Lekana-Douki
- Unité d'Evolution Epidémiologie et Résistances Parasitaires (UNEEREP), Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon.,Département de Parasitologie-Mycologie, Université des Sciences de la Santé, Libreville, Gabon
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11
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Scully EJ, Shabani E, Rangel GW, Grüring C, Kanjee U, Clark MA, Chaand M, Kurita R, Nakamura Y, Ferreira MU, Duraisingh MT. Generation of an immortalized erythroid progenitor cell line from peripheral blood: A model system for the functional analysis of Plasmodium spp. invasion. Am J Hematol 2019; 94:963-974. [PMID: 31148215 PMCID: PMC6984401 DOI: 10.1002/ajh.25543] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 02/06/2023]
Abstract
Malaria pathogenesis is caused by the replication of Plasmodium parasites within the red blood cells (RBCs) of the vertebrate host. This selective pressure has favored the evolution of protective polymorphisms in erythrocyte proteins, a subset of which serve as cognate receptors for parasite invasion ligands. Recently, the generation of RBCs from immortalized hematopoietic stem cells (HSCs) has offered a more tractable system for genetic manipulation and long-term in vitro culture, enabling elucidation of the functional determinants of host susceptibility in vitro. Here we report the generation of an immortalized erythroid progenitor cell line (EJ cells) from as few as 100 000 peripheral blood mononuclear cells. It offers a robust method for the creation of customized model systems from small volumes of peripheral blood. The EJ cell differentiation mirrored erythropoiesis of primary HSCs, yielding orthochromatic erythroblasts and enucleated RBCs after eight days (ejRBCs). The ejRBCs supported invasion by both P. vivax and P. falciparum. To demonstrate the genetic tractability of this system, we used CRISPR/Cas9 to disrupt the Duffy Antigen/Receptor for Chemokines (DARC) gene, which encodes the canonical receptor of P. vivax in humans. Invasion of P. vivax into this DARC-knockout cell line was strongly inhibited providing direct genetic evidence that P. vivax requires DARC for RBC invasion. Further, genetic complementation of DARC restored P. vivax invasion. Taken together, the peripheral blood immortalization method presented here offers the capacity to generate biologically representative model systems for studies of blood-stage malaria invasion from the peripheral blood of donors harboring unique genetic backgrounds, or rare polymorphisms.
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Affiliation(s)
- Erik J. Scully
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, United States of America
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
- Broad Institute, Cambridge, MA, United States of America
| | - Estela Shabani
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Gabriel W. Rangel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Christof Grüring
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Martha A. Clark
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Mudit Chaand
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Ryo Kurita
- Department of Research and Development, Central Blood Institute, Japanese Red Cross Society, Tokyo 135-8521, Japan
| | - Yukio Nakamura
- Cell Engineering Division, RIKEN BioResource Center, Ibaraki 305-0074, Japan
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, BR 05508-900
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
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12
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Dobaño C, Ubillos I, Jairoce C, Gyan B, Vidal M, Jiménez A, Santano R, Dosoo D, Nhabomba AJ, Ayestaran A, Aguilar R, Williams NA, Díez-Padrisa N, Lanar D, Chauhan V, Chitnis C, Dutta S, Gaur D, Angov E, Asante KP, Owusu-Agyei S, Valim C, Gamain B, Coppel RL, Cavanagh D, Beeson JG, Campo JJ, Moncunill G. RTS,S/AS01E immunization increases antibody responses to vaccine-unrelated Plasmodium falciparum antigens associated with protection against clinical malaria in African children: a case-control study. BMC Med 2019; 17:157. [PMID: 31409398 PMCID: PMC6693200 DOI: 10.1186/s12916-019-1378-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 06/27/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Vaccination and naturally acquired immunity against microbial pathogens may have complex interactions that influence disease outcomes. To date, only vaccine-specific immune responses have routinely been investigated in malaria vaccine trials conducted in endemic areas. We hypothesized that RTS,S/A01E immunization affects acquisition of antibodies to Plasmodium falciparum antigens not included in the vaccine and that such responses have an impact on overall malaria protective immunity. METHODS We evaluated IgM and IgG responses to 38 P. falciparum proteins putatively involved in naturally acquired immunity to malaria in 195 young children participating in a case-control study nested within the African phase 3 clinical trial of RTS,S/AS01E (MAL055 NCT00866619) in two sites of different transmission intensity (Kintampo high and Manhiça moderate/low). We measured antibody levels by quantitative suspension array technology and applied regression models, multimarker analysis, and machine learning techniques to analyze factors affecting their levels and correlates of protection. RESULTS RTS,S/AS01E immunization decreased antibody responses to parasite antigens considered as markers of exposure (MSP142, AMA1) and levels correlated with risk of clinical malaria over 1-year follow-up. In addition, we show for the first time that RTS,S vaccination increased IgG levels to a specific group of pre-erythrocytic and blood-stage antigens (MSP5, MSP1 block 2, RH4.2, EBA140, and SSP2/TRAP) which levels correlated with protection against clinical malaria (odds ratio [95% confidence interval] 0.53 [0.3-0.93], p = 0.03, for MSP1; 0.52 [0.26-0.98], p = 0.05, for SSP2) in multivariable logistic regression analyses. CONCLUSIONS Increased antibody responses to specific P. falciparum antigens in subjects immunized with this partially efficacious vaccine upon natural infection may contribute to overall protective immunity against malaria. Inclusion of such antigens in multivalent constructs could result in more efficacious second-generation multistage vaccines.
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Affiliation(s)
- Carlota Dobaño
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain. .,Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique.
| | - Itziar Ubillos
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Chenjerai Jairoce
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Ben Gyan
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.,Kintampo Health Research Centre, Kintampo, Ghana
| | - Marta Vidal
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Alfons Jiménez
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain.,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - Rebeca Santano
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - David Dosoo
- Kintampo Health Research Centre, Kintampo, Ghana
| | - Augusto J Nhabomba
- Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Aintzane Ayestaran
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Ruth Aguilar
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Nana Aba Williams
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - Núria Díez-Padrisa
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain
| | - David Lanar
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Virander Chauhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Chetan Chitnis
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India.,Malaria Parasite Biology and Vaccines Unit, Institut Pasteur, Paris, France
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Deepak Gaur
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India.,Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Evelina Angov
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | | | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Kintampo, Ghana.,Disease Control Department, London School of Hygiene and Tropical Medicine, London, UK
| | - Clarissa Valim
- Department of Osteopathic Medical Specialties, Michigan State University, 909 Fee Road, Room B 309 West Fee Hall, East Lansing, MI, 48824, USA.,Department of Immunology and Infectious Diseases, Harvard T.H. Chen School of Public Health, 675 Huntington Ave., Boston, MA, 02115, USA
| | - Benoit Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Ross L Coppel
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | - David Cavanagh
- Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, King's Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
| | - James G Beeson
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
| | - Joseph J Campo
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain.,Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique
| | - Gemma Moncunill
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Carrer Rosselló 153, E-08036, Barcelona, Catalonia, Spain. .,Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique.
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13
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Mensah-Brown HE, Aspeling-Jones H, Delimini RK, Asante KP, Amlabu E, Bah SY, Beeson JG, Wright GJ, Conway DJ, Awandare GA. Antibody Reactivity to Merozoite Antigens in Ghanaian Adults Correlates With Growth Inhibitory Activity Against Plasmodium falciparum in Culture. Open Forum Infect Dis 2019; 6:ofz254. [PMID: 31294045 PMCID: PMC6611546 DOI: 10.1093/ofid/ofz254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 05/24/2019] [Indexed: 01/22/2023] Open
Abstract
Background Plasmodium falciparum uses a repertoire of merozoite-stage proteins for invasion of erythrocytes. Antibodies against some of these proteins halt the replication cycle of the parasite by preventing erythrocyte invasion and are implicated as contributors to protective immunity against malaria. Methods We assayed antibody reactivity against a panel of 9 recombinant antigens based on erythrocyte-binding antigen (EBA) and reticulocyte-like homolog (Rh) proteins in plasma from children with malaria and healthy adults residing in 3 endemic areas in Ghana using enzyme-linked immunosorbent assay. Purified immunoglobulin (Ig)G from adult plasma samples was also tested for invasion inhibition against 7 different P falciparum culture lines, including clinical isolates. Results Antibodies against the antigens increased in an age-dependent manner in children. Breadth of reactivity to the different antigens was strongly associated with in vitro parasite growth inhibitory activity of IgG purified from the adults. The strongest predictors of breadth of antibody reactivity were age and transmission intensity, and a combination of reactivities to Rh2, Rh4, and Rh5 correlated strongly with invasion inhibition. Conclusions Growth inhibitory activity was significantly associated with breadth of antibody reactivity to merozoite antigens, encouraging the prospect of a multicomponent blood-stage vaccine.
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Affiliation(s)
- Henrietta E Mensah-Brown
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | | | - Rupert K Delimini
- Department of Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana
| | | | - Emmanuel Amlabu
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Kogi State University, Anyigba, Nigeria
| | - Saikou Y Bah
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | - James G Beeson
- The Burnet Institute for Medical Research and Public Health, Melbourne, Australia.,Department of Microbiology, Monash University, Clayton, Australia
| | - Gavin J Wright
- Pathogens and Microbes Programme, Wellcome Trust Sanger Institute, United Kingdom
| | - David J Conway
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
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14
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Targets of complement-fixing antibodies in protective immunity against malaria in children. Nat Commun 2019; 10:610. [PMID: 30723225 PMCID: PMC6363798 DOI: 10.1038/s41467-019-08528-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/07/2019] [Indexed: 12/31/2022] Open
Abstract
Antibodies against P. falciparum merozoites fix complement to inhibit blood-stage replication in naturally-acquired and vaccine-induced immunity; however, specific targets of these functional antibodies and their importance in protective immunity are unknown. Among malaria-exposed individuals, we show that complement-fixing antibodies to merozoites are more strongly correlated with protective immunity than antibodies that inhibit growth quantified using the current reference assay for merozoite vaccine evaluation. We identify merozoite targets of complement-fixing antibodies and identify antigen-specific complement-fixing antibodies that are strongly associated with protection from malaria in a longitudinal study of children. Using statistical modelling, combining three different antigens targeted by complement-fixing antibodies could increase the potential protective effect to over 95%, and we identify antigens that were common in the most protective combinations. Our findings support antibody-complement interactions against merozoite antigens as important anti-malaria immune mechanisms, and identify specific merozoite antigens for further evaluation as vaccine candidates. Antibodies against Plasmodium falciparum merozoites that fix complement can inhibit blood-stage replication. Here, Reiling et al. show that complement-fixing antibodies strongly correlate with protective immunity in children, identify the merozoite targets, and predict antigen combinations that should result in strong protection.
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15
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Abstract
Eukaryotic pathogens must survive in different hosts, respond to changing environments, and exploit specialized niches to propagate. Plasmodium parasites cause human malaria during bloodstream infections, where they must persist long enough to be transmitted. Parasites have evolved diverse strategies of variant gene expression that control critical biological processes of blood-stage infections, including antigenic variation, erythrocyte invasion, innate immune evasion, and nutrient acquisition, as well as life-cycle transitions. Epigenetic mechanisms within the parasite are being elucidated, with discovery of epigenomic marks associated with gene silencing and activation, and the identification of epigenetic regulators and chromatin proteins that are required for the switching and maintenance of gene expression. Here, we review the key epigenetic processes that facilitate transition through the parasite life cycle and epigenetic regulatory mechanisms utilized by Plasmodium parasites to survive changing environments and consider epigenetic switching in the context of the outcome of human infections.
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Affiliation(s)
- Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
| | - Kristen M Skillman
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
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16
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Ubillos I, Jiménez A, Vidal M, Bowyer PW, Gaur D, Dutta S, Gamain B, Coppel R, Chauhan V, Lanar D, Chitnis C, Angov E, Beeson J, Cavanagh D, Campo JJ, Aguilar R, Dobaño C. Optimization of incubation conditions of Plasmodium falciparum antibody multiplex assays to measure IgG, IgG 1-4, IgM and IgE using standard and customized reference pools for sero-epidemiological and vaccine studies. Malar J 2018; 17:219. [PMID: 29859096 PMCID: PMC5984756 DOI: 10.1186/s12936-018-2369-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022] Open
Abstract
Background The quantitative suspension array technology (qSAT) is a useful platform for malaria immune marker discovery. However, a major challenge for large sero-epidemiological and malaria vaccine studies is the comparability across laboratories, which requires the access to standardized control reagents for assay optimization, to monitor performance and improve reproducibility. Here, the Plasmodium falciparum antibody reactivities of the newly available WHO reference reagent for anti-malaria human plasma (10/198) and of additional customized positive controls were examined with seven in-house qSAT multiplex assays measuring IgG, IgG1–4 subclasses, IgM and IgE against a panel of 40 antigens. The different positive controls were tested at different incubation times and temperatures (4 °C overnight, 37 °C 2 h, room temperature 1 h) to select the optimal conditions. Results Overall, the WHO reference reagent had low IgG2, IgG4, IgM and IgE, and also low anti-CSP antibody levels, thus this reagent was enriched with plasmas from RTS,S-vaccinated volunteers to be used as standard for CSP-based vaccine studies. For the IgM assay, another customized plasma pool prepared with samples from malaria primo-infected adults with adequate IgM levels proved to be more adequate as a positive control. The range and magnitude of IgG and IgG1–4 responses were highest when the WHO reference reagent was incubated with antigen-coupled beads at 4 °C overnight. IgG levels measured in the negative control did not vary between incubations at 37 °C 2 h and 4 °C overnight, indicating no difference in unspecific binding. Conclusions With this study, the immunogenicity profile of the WHO reference reagent, including seven immunoglobulin isotypes and subclasses, and more P. falciparum antigens, also those included in the leading RTS,S malaria vaccine, was better characterized. Overall, incubation of samples at 4 °C overnight rendered the best performance for antibody measurements against the antigens tested. Although the WHO reference reagent performed well to measure IgG to the majority of the common P. falciparum blood stage antigens tested, customized pools may need to be used as positive controls depending on the antigens (e.g. pre-erythrocytic proteins of low natural immunogenicity) and isotypes/subclasses (e.g. IgM) under study. Electronic supplementary material The online version of this article (10.1186/s12936-018-2369-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Itziar Ubillos
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain
| | - Alfons Jiménez
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Marta Vidal
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain
| | - Paul W Bowyer
- Bacteriology Division, MHRA-NIBSC, South Mimms, Potter Bars, EN6 3QG, UK
| | - Deepak Gaur
- Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.,Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Sheetij Dutta
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Benoit Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Ross Coppel
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Virander Chauhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - David Lanar
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Chetan Chitnis
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Evelina Angov
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - James Beeson
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
| | - David Cavanagh
- Institute of Immunology & Infection Research and Centre for Immunity, Infection & Evolution, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, King's Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
| | - Joseph J Campo
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain
| | - Ruth Aguilar
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain
| | - Carlota Dobaño
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Carrer Rosselló 153 (CEK Building), 08036, Barcelona, Catalonia, Spain.
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17
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Fernández FJ, Gómez S, Vega MC. Pathogens' toolbox to manipulate human complement. Semin Cell Dev Biol 2017; 85:98-109. [PMID: 29221973 DOI: 10.1016/j.semcdb.2017.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/30/2017] [Accepted: 12/03/2017] [Indexed: 12/15/2022]
Abstract
The surveillance and pathogen fighting functions of the complement system have evolved to protect mammals from life-threatening infections. In turn, pathogens have developed complex molecular mechanisms to subvert, divert and evade the effector functions of the complement. The study of complement immunoevasion by pathogens sheds light on their infection drivers, knowledge that is essential to implement therapies. At the same time, complement evasion also acts as a discovery ground that reveals important aspects of how complement works under physiological conditions. In recent years, complex interrelationships between infection insults and the onset of autoimmune and complement dysregulation diseases have led to propose that encounters with pathogens can act as triggering factors for disease. The correct management of these diseases involves the recognition of their triggering factors and the development and administration of complement-associated molecular therapies. Even more recently, unsuspected proteins from pathogens have been shown to possess moonlighting functions as virulence factors, raising the possibility that behind the first line of virulence factors there be many more pathogen proteins playing secondary, helping and supporting roles for the pathogen to successfully establish infections. In an era where antibiotics have a progressively reduced effect on the management and control of infectious diseases worldwide, knowledge on the mechanisms of pathogenic invasion and evasion look more necessary and pressing than ever.
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Affiliation(s)
| | - Sara Gómez
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
| | - M Cristina Vega
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
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18
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Mechanisms of naturally acquired immunity to P. falciparum and approaches to identify merozoite antigen targets. Parasitology 2017; 145:839-847. [PMID: 29144217 DOI: 10.1017/s0031182017001949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Malaria is one the most serious infectious diseases with over 200 million clinical cases annually. Most cases of the severe disease are caused by Plasmodium falciparum. The blood stage of Plasmodium parasite is entirely responsible for malaria-associated pathology. The population most susceptible to severe malaria are children under the age of 5, with low levels of immunity. It is only after many years of repeated exposure that individuals living in endemic areas develop clinical immunity. This form of protection prevents clinical episodes by substantially reducing parasite burden. Naturally acquired immunity predominantly targets blood-stage parasites with antibody responses being the main mediators of protection. The targets of clinical immunity are the extracellular merozoite and the infected erythrocyte surface, with the extremely diverse PfEMP1 proteins the main target here. This observation provides a strong rationale that an effective anti-malaria vaccine targeting blood-stage parasites is achievable. Thus the identification of antigenic targets of naturally acquired immunity remains an important step towards the formulation of novel vaccine combinations before testing their efficacy in clinical trials. This review summarizes the main findings to date defining antigenic targets present on the extracellular merozoite associated with naturally acquired immunity to P. falciparum malaria.
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19
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Lim C, Dankwa S, Paul AS, Duraisingh MT. Host Cell Tropism and Adaptation of Blood-Stage Malaria Parasites: Challenges for Malaria Elimination. Cold Spring Harb Perspect Med 2017; 7:a025494. [PMID: 28213436 PMCID: PMC5666624 DOI: 10.1101/cshperspect.a025494] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Plasmodium falciparum and Plasmodium vivax account for most of the mortality and morbidity associated with malaria in humans. Research and control efforts have focused on infections caused by P. falciparum and P. vivax, but have neglected other malaria parasite species that infect humans. Additionally, many related malaria parasite species infect nonhuman primates (NHPs), and have the potential for transmission to humans. For malaria elimination, the varied and specific challenges of all of these Plasmodium species will need to be considered. Recent advances in molecular genetics and genomics have increased our knowledge of the prevalence and existing diversity of the human and NHP Plasmodium species. We are beginning to identify the extent of the reservoirs of each parasite species in humans and NHPs, revealing their origins as well as potential for adaptation in humans. Here, we focus on the red blood cell stage of human infection and the host cell tropism of each human Plasmodium species. Determinants of tropism are unique among malaria parasite species, presenting a complex challenge for malaria elimination.
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Affiliation(s)
- Caeul Lim
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Selasi Dankwa
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Aditya S Paul
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
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20
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Gupta ED, Anand G, Singh H, Chaddha K, Bharti PK, Singh N, Sharma YD, Gaur D. Naturally Acquired Human Antibodies Against Reticulocyte-Binding Domains of Plasmodium vivax Proteins, PvRBP2c and PvRBP1a, Exhibit Binding-Inhibitory Activity. J Infect Dis 2017; 215:1558-1568. [PMID: 28379500 DOI: 10.1093/infdis/jix170] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/29/2017] [Indexed: 12/14/2022] Open
Abstract
Background Crucial gaps in our understanding of Plasmodium vivax reticulocyte invasion and protective immunity have hampered development of vivax vaccines. P. vivax exclusively invades reticulocytes that is mediated by the P. vivax reticulocyte-binding proteins (PvRBPs) specifically PvRBP2c and PvRBP1a. Vivax infections in Duffy-null individuals have suggested the evolution of alternate invasion pathways that may be mediated by the PvRBPs. Thus, PvRBPs appear as potential targets for efficacious P. vivax neutralization. However, there are limited data validating their vaccine efficacy. In the absence of vivax invasion assays, binding-inhibitory activity of antibodies has been reported to be associated with protection and a measure of vaccine potential. Methods -based analysis was performed of the PvRBP reticulocyte-binding properties and binding-inhibitory activity of specific anti-PvRBP2c/PvRBP1a human antibodies. Results PvRBP2c and PvRBP1a displayed a distinct reticulocyte-binding specificity, and their specific reticulocyte-binding domains were mapped within their N-terminal regions. Importantly, naturally acquired antibodies against the reticulocyte-binding domains efficaciously blocked reticulocyte binding of native PvRBPs, suggesting that the human immune system produced functional binding-inhibitory antibodies through exposure to vivax malaria. Conclusions Reticulocyte-binding domains of PvRBP2c/PvRBP1a are targets of naturally acquired binding-inhibitory antibodies, substantiating their promise as candidate antigens against which vaccine-inducible immunity could potentially be boosted through natural infections.
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Affiliation(s)
- Enna Dogra Gupta
- Malaria Group, International Centre for Genetic Engineering and Biotechnology
| | - Gaurav Anand
- Malaria Group, International Centre for Genetic Engineering and Biotechnology
| | - Hina Singh
- Malaria Group, International Centre for Genetic Engineering and Biotechnology
| | - Kritika Chaddha
- Laboratory of Malaria & Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, and
| | - Praveen K Bharti
- National Institute for Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Neeru Singh
- National Institute for Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Yagya Dutta Sharma
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, and
| | - Deepak Gaur
- Malaria Group, International Centre for Genetic Engineering and Biotechnology.,Laboratory of Malaria & Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, and
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21
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Tijani MK, Babalola OA, Odaibo AB, Anumudu CI, Asinobi AO, Morenikeji OA, Asuzu MC, Langer C, Reiling L, Beeson JG, Wahlgren M, Nwuba RI, Persson KEM. Acquisition, maintenance and adaptation of invasion inhibitory antibodies against Plasmodium falciparum invasion ligands involved in immune evasion. PLoS One 2017; 12:e0182187. [PMID: 28787025 PMCID: PMC5546579 DOI: 10.1371/journal.pone.0182187] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 07/13/2017] [Indexed: 11/18/2022] Open
Abstract
Erythrocyte-binding antigens (EBAs) and P. falciparum reticulocyte-binding homologue proteins (PfRhs) are two important protein families that can vary in expression and utilization by P. falciparum to evade inhibitory antibodies. We evaluated antibodies at repeated time-points among individuals living in an endemic region in Nigeria over almost one year against these vaccine candidates. Antibody levels against EBA140, EBA175, EBA181, PfRh2, PfRh4, and MSP2, were measured by ELISA. We also used parasites with disrupted EBA140, EBA175 and EBA181 genes to show that all these were targets of invasion inhibitory antibodies. However, antigenic targets of inhibitory antibodies were not stable and changed substantially over time in most individuals, independent of age. Antibodies levels measured by ELISA also varied within and between individuals over time and the antibodies against EBA181, PfRh2 and MSP2 declined more rapidly in younger individuals (≤15 years) compared with older (>15). The breadth of high antibody responses over time was more influenced by age than by the frequency of infection. High antibody levels were associated with a more stable invasion inhibitory response, which could indicate that during the long process of formation of immunity, many changes not only in levels but also in functional responses are needed. This is an important finding in understanding natural immunity against malaria, which is essential for making an efficacious vaccine.
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Affiliation(s)
- Muyideen K. Tijani
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Oluwatoyin A. Babalola
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Alex B. Odaibo
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Chiaka I. Anumudu
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Adanze O. Asinobi
- Department of Paediatrics, University College Hospital, University of Ibadan, Ibadan, Nigeria
| | - Olajumoke A. Morenikeji
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Michael C. Asuzu
- Department of Preventive Medicine and Primary Care, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Christine Langer
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Linda Reiling
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - James G. Beeson
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Roseangela I. Nwuba
- Cellular Parasitology Programme, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Kristina E. M. Persson
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Department of Laboratory Medicine, University Hospital, Lund University, Lund, Sweden
- * E-mail:
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22
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Hill DL, Schofield L, Wilson DW. IgG opsonization of merozoites: multiple immune mechanisms for malaria vaccine development. Int J Parasitol 2017; 47:585-595. [PMID: 28668325 DOI: 10.1016/j.ijpara.2017.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 04/12/2017] [Accepted: 05/12/2017] [Indexed: 02/07/2023]
Abstract
Global eradication of the human-infecting malaria parasite Plasmodium falciparum, the major cause of malaria mortality, is unlikely to be achieved without an effective vaccine. However, our limited understanding of how protective immune responses target malaria parasites in humans, and how to best elicit these immune responses through vaccination, has hampered vaccine development. The red blood cell invading stage of the parasite lifecycle (merozoite) displays antigens that are attractive vaccine candidates as they are accessible to antibodies and raise high antibody titres in naturally immune individuals. The number of merozoite antigens that elicit an immune response, and their structural and functional diversity, has led to a large number of lead antigens being pursued as vaccine candidates. Despite being seemingly spoilt for choice in terms of vaccine candidates, there is still a lack of consensus on exactly how merozoite antibodies reduce parasitemia and malaria disease. In this review we describe the various immune mechanisms that can result from IgG opsonization of merozoites, and highlight recent developments that support a role for these functional antibodies in naturally acquired and vaccine-induced immunity.
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Affiliation(s)
- Danika L Hill
- Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom; The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia.
| | - Louis Schofield
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, Australia
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia; Burnet Institute, 85 Commercial Road, Melbourne 3004, Victoria, Australia.
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23
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McCallum FJ, Persson KEM, Fowkes FJI, Reiling L, Mugyenyi CK, Richards JS, Simpson JA, Williams TN, Gilson PR, Hodder AN, Sanders PR, Anders RF, Narum DL, Chitnis C, Crabb BS, Marsh K, Beeson JG. Differing rates of antibody acquisition to merozoite antigens in malaria: implications for immunity and surveillance. J Leukoc Biol 2017; 101:913-925. [PMID: 27837017 PMCID: PMC5346181 DOI: 10.1189/jlb.5ma0716-294r] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/28/2016] [Accepted: 10/19/2016] [Indexed: 12/18/2022] Open
Abstract
Antibodies play a key role in acquired human immunity to Plasmodium falciparum (Pf) malaria and target merozoites to reduce or prevent blood-stage replication and the development of disease. Merozoites present a complex array of antigens to the immune system, and currently, there is only a partial understanding of the targets of protective antibodies and how responses to different antigens are acquired and boosted. We hypothesized that there would be differences in the rate of acquisition of antibodies to different antigens and how well they are boosted by infection, which impacts the acquisition of immunity. We examined responses to a range of merozoite antigens in 2 different cohorts of children and adults with different age structures and levels of malaria exposure. Overall, antibodies were associated with age, exposure, and active infection, and the repertoire of responses increased with age and active infection. However, rates of antibody acquisition varied between antigens and different regions within an antigen following exposure to malaria, supporting our hypothesis. Antigen-specific responses could be broadly classified into early response types in which antibodies were acquired early in childhood exposure and late response types that appear to require substantially more exposure for the development of substantial levels. We identified antigen-specific responses that were effectively boosted after recent infection, whereas other responses were not. These findings advance our understanding of the acquisition of human immunity to malaria and are relevant to the development of malaria vaccines targeting merozoite antigens and the selection of antigens for use in malaria surveillance.
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Affiliation(s)
- Fiona J McCallum
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
- Department of Drug Evaluation, Australian Army Malaria Institute, Brisbane, Australia
| | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
- Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia
- Departments of Epidemiology and Preventive Medicine and Infectious Diseases, Monash University, Melbourne, Australia
| | - Linda Reiling
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Cleopatra K Mugyenyi
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jack S Richards
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
- Department of Microbiology, Monash University, Melbourne, Australia
- Department of Medicine, University of Melbourne, Parkville, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia
| | - Thomas N Williams
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Medicine, Imperial College of Science, Technology and Medicine, London, United Kingdom
| | - Paul R Gilson
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Anthony N Hodder
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Paul R Sanders
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Robin F Anders
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Latrobe University, Melbourne, Australia
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Brendan S Crabb
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Kevin Marsh
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia;
- Department of Microbiology, Monash University, Melbourne, Australia
- Department of Medicine, University of Melbourne, Parkville, Australia
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24
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The association between naturally acquired IgG subclass specific antibodies to the PfRH5 invasion complex and protection from Plasmodium falciparum malaria. Sci Rep 2016; 6:33094. [PMID: 27604417 PMCID: PMC5015043 DOI: 10.1038/srep33094] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
Abstract
Understanding the targets and mechanisms of human immunity to malaria is important for advancing the development of highly efficacious vaccines and serological tools for malaria surveillance. The PfRH5 and PfRipr proteins form a complex on the surface of P. falciparum merozoites that is essential for invasion of erythrocytes and are vaccine candidates. We determined IgG subclass responses to these proteins among malaria-exposed individuals in Papua New Guinea and their association with protection from malaria in a longitudinal cohort of children. Cytophilic subclasses, IgG1 and IgG3, were predominant with limited IgG2 and IgG4, and IgG subclass-specific responses were higher in older children and those with active infection. High IgG3 to PfRH5 and PfRipr were significantly and strongly associated with reduced risk of malaria after adjusting for potential confounding factors, whereas associations for IgG1 responses were generally weaker and not statistically significant. Results further indicated that malaria exposure leads to the co-acquisition of IgG1 and IgG3 to PfRH5 and PfRipr, as well as to other PfRH invasion ligands, PfRH2 and PfRH4. These findings suggest that IgG3 responses to PfRH5 and PfRipr may play a significant role in mediating naturally-acquired immunity and support their potential as vaccine candidates and their use as antibody biomarkers of immunity.
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25
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Teo A, Feng G, Brown GV, Beeson JG, Rogerson SJ. Functional Antibodies and Protection against Blood-stage Malaria. Trends Parasitol 2016; 32:887-898. [PMID: 27546781 DOI: 10.1016/j.pt.2016.07.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/09/2016] [Accepted: 07/14/2016] [Indexed: 01/06/2023]
Abstract
Numerous efforts to understand the functional roles of antibodies demonstrated that they can protect against malaria. However, it is unclear which antibody responses are the best correlates of immunity, and which antibody functions are most important in protection from disease. Understanding the role of antibodies in protection against malaria is crucial for antimalarial vaccine design. In this review, the specific functional properties of naturally acquired and vaccine-induced antibodies that correlate to protection from the blood stages of Plasmodium falciparum malaria are re-examined and the gaps in knowledge related to antibody function in malarial immunity are highlighted.
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Affiliation(s)
- Andrew Teo
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Gaoqian Feng
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Australia
| | - Graham V Brown
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia; Victorian Infectious Diseases Service, Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - James G Beeson
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia; Victorian Infectious Diseases Service, Doherty Institute for Infection and Immunity, Melbourne, Australia.
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26
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Boyle MJ, Reiling L, Osier FH, Fowkes FJI. Recent insights into humoral immunity targeting Plasmodium falciparum and Plasmodium vivax malaria. Int J Parasitol 2016; 47:99-104. [PMID: 27451359 DOI: 10.1016/j.ijpara.2016.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 01/02/2023]
Abstract
Recent efforts in malaria control have led to marked reductions in malaria incidence. However, new strategies are needed to sustain malaria elimination and eradication and achieve the World Health Organization goal of a malaria-free world. The development of highly effective vaccines would contribute to this goal and would be facilitated by a comprehensive understanding of humoral immune responses targeting Plasmodium falciparum and Plasmodium vivax malaria. New tools are required to facilitate the identification of vaccine candidates and the development of vaccines that induce functional and protective immunity. Here we discuss recent published findings, and unpublished work presented at the 2016 Molecular Approaches to Malaria conference, that highlight advancements in understanding humoral immune responses in the context of vaccine development. Highlights include the increased application of 'omics' and 'Big data' platforms to identify vaccine candidates, and the identification of novel functions of antibody responses that mediate protection. The application of these strategies and a global approach will increase the likelihood of rapid development of highly efficacious vaccines.
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Affiliation(s)
- Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, Melbourne, Victoria 3004, Australia; Menzies School of Medical Research, Darwin, Northern Territory 0810, Australia.
| | - Linda Reiling
- Burnet Institute for Medical Research and Public Health, Melbourne, Victoria 3004, Australia
| | - Faith H Osier
- KEMRI Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, Melbourne, Victoria 3004, Australia; Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria 3010, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria 3004, Australia; Department of Infectious Diseases, Monash University, Melbourne, Victoria 3004, Australia
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27
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Han JH, Lee SK, Wang B, Muh F, Nyunt MH, Na S, Ha KS, Hong SH, Park WS, Sattabongkot J, Tsuboi T, Han ET. Identification of a reticulocyte-specific binding domain of Plasmodium vivax reticulocyte-binding protein 1 that is homologous to the PfRh4 erythrocyte-binding domain. Sci Rep 2016; 6:26993. [PMID: 27244695 PMCID: PMC4886630 DOI: 10.1038/srep26993] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/03/2016] [Indexed: 12/17/2022] Open
Abstract
The Plasmodium vivax reticulocyte-binding protein (RBP) family was identified based on the annotation of adhesive ligands in the P. vivax genome. Reticulocyte-specific interactions with the PvRBPs (PvRBP1 and PvRBP2) were previously reported. Plasmodium falciparum reticulocyte-binding protein homologue 4 (PfRh4, a homologue of PvRBP1) was observed to possess erythrocyte-binding activity via complement receptor 1 on the erythrocyte surface. However, the reticulocyte-binding mechanisms of P. vivax are unclear because of the large molecular mass of PvRBP1 (>326 kDa) and the difficulty associated with in vitro cultivation. In the present study, 34 kDa of PvRBP1a (PlasmoDB ID: PVX_098585) and 32 kDa of PvRBP1b (PVX_098582) were selected from a 30 kDa fragment of PfRh4 for reticulocyte-specific binding activity analysis. Both PvRBP1a and PvRBP1b were found to be localized at the microneme in the mature schizont-stage parasites. Naturally acquired immune responses against PvRBP1a-34 and PvRBP1b-32 were observed lower than PvDBP-RII. The reticulocyte-specific binding activities of PvRBP1a-34 and PvRBP1b-32 were significantly higher than normocyte binding activity and were significantly reduced by chymotrypsin treatment. PvRBP1a and 1b, bind to reticulocytes and that this suggests that these ligands may have an important role in P. vivax merozoite invasion.
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Affiliation(s)
- Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Seong-Kyun Lee
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea.,Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People's Republic of China
| | - Fauzi Muh
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Myat Htut Nyunt
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea.,Department of Medical Research, Yangon, Myanmar
| | - Sunghun Na
- Department of Obstetrics and Gynecology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Won Sun Park
- Department of Physiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
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28
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Rosa TFA, Flammersfeld A, Ngwa CJ, Kiesow M, Fischer R, Zipfel PF, Skerka C, Pradel G. The Plasmodium falciparum blood stages acquire factor H family proteins to evade destruction by human complement. Cell Microbiol 2016; 18:573-90. [PMID: 26457721 PMCID: PMC5063132 DOI: 10.1111/cmi.12535] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/29/2015] [Accepted: 10/06/2015] [Indexed: 01/24/2023]
Abstract
The acquisition of regulatory proteins is a means of blood-borne pathogens to avoid destruction by the human complement. We recently showed that the gametes of the human malaria parasite Plasmodium falciparum bind factor H (FH) from the blood meal of the mosquito vector to assure successful sexual reproduction, which takes places in the mosquito midgut. While these findings provided a first glimpse of a complex mechanism used by Plasmodium to control the host immune attack, it is hitherto not known, how the pathogenic blood stages of the malaria parasite evade destruction by the human complement. We now show that the human complement system represents a severe threat for the replicating blood stages, particularly for the reinvading merozoites, with complement factor C3b accumulating on the surfaces of the intraerythrocytic schizonts as well as of free merozoites. C3b accumulation initiates terminal complement complex formation, in consequence resulting in blood stage lysis. To inactivate C3b, the parasites bind FH as well as related proteins FHL-1 and CFHR-1 to their surface, and FH binding is trypsin-resistant. Schizonts acquire FH via two contact sites, which involve CCP modules 5 and 20. Blockage of FH-mediated protection via anti-FH antibodies results in significantly impaired blood stage replication, pointing to the plasmodial complement evasion machinery as a promising malaria vaccine target.
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Affiliation(s)
- Thiago F A Rosa
- Division of Cellular and Applied Infection Biology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Ansgar Flammersfeld
- Division of Cellular and Applied Infection Biology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Che J Ngwa
- Division of Cellular and Applied Infection Biology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Meike Kiesow
- Division of Cellular and Applied Infection Biology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstr. 6, 52074, Aachen, Germany
| | - Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Beutenbergstr. 11a, 07745, Jena, Germany
| | - Christine Skerka
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Beutenbergstr. 11a, 07745, Jena, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstr. 6, 52074, Aachen, Germany
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Beeson JG, Drew DR, Boyle MJ, Feng G, Fowkes FJI, Richards JS. Merozoite surface proteins in red blood cell invasion, immunity and vaccines against malaria. FEMS Microbiol Rev 2016; 40:343-72. [PMID: 26833236 PMCID: PMC4852283 DOI: 10.1093/femsre/fuw001] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2016] [Indexed: 01/11/2023] Open
Abstract
Malaria accounts for an enormous burden of disease globally, with Plasmodium falciparum accounting for the majority of malaria, and P. vivax being a second important cause, especially in Asia, the Americas and the Pacific. During infection with Plasmodium spp., the merozoite form of the parasite invades red blood cells and replicates inside them. It is during the blood-stage of infection that malaria disease occurs and, therefore, understanding merozoite invasion, host immune responses to merozoite surface antigens, and targeting merozoite surface proteins and invasion ligands by novel vaccines and therapeutics have been important areas of research. Merozoite invasion involves multiple interactions and events, and substantial processing of merozoite surface proteins occurs before, during and after invasion. The merozoite surface is highly complex, presenting a multitude of antigens to the immune system. This complexity has proved challenging to our efforts to understand merozoite invasion and malaria immunity, and to developing merozoite antigens as malaria vaccines. In recent years, there has been major progress in this field, and several merozoite surface proteins show strong potential as malaria vaccines. Our current knowledge on this topic is reviewed, highlighting recent advances and research priorities. The authors summarize current knowledge of merozoite surface proteins of malaria parasites; their function in invasion, processing of surface proteins before, during and after invasion, their importance as targets of immunity, and the current status of malaria vaccines that target merozoite surface proteins.
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Affiliation(s)
- James G Beeson
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Microbiology, Monash University, Clayton, Victoria, Australia Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
| | - Damien R Drew
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Gaoqian Feng
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Epidemiology and Preventive Medicine, Monash University, Clayton, Victoria, Australia School of Population Health, University of Melbourne, Parkville, Victoria, Australia
| | - Jack S Richards
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Microbiology, Monash University, Clayton, Victoria, Australia Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
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Gene Models, Expression Repertoire, and Immune Response of Plasmodium vivax Reticulocyte Binding Proteins. Infect Immun 2015; 84:677-85. [PMID: 26712206 PMCID: PMC4771344 DOI: 10.1128/iai.01117-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 12/07/2015] [Indexed: 11/20/2022] Open
Abstract
Members of the Plasmodium vivax reticulocyte binding protein (PvRBP) family are believed to mediate specific invasion of reticulocytes by P. vivax. In this study, we performed molecular characterization of genes encoding members of this protein family. Through cDNA sequencing, we constructed full-length gene models and verified genes that are protein coding and those that are pseudogenes. We also used quantitative PCR to measure their in vivo transcript abundances in clinical P. vivax isolates. Like genes encoding related invasion ligands of P. falciparum, Pvrbp expression levels vary broadly across different parasite isolates. Through antibody measurements, we found that host immune pressure may be the driving force behind the distinctly high diversity of one of the family members, PvRBP2c. Mild yet significant negative correlation was found between parasitemia and the PvRBP2b antibody level, suggesting that antibodies to the protein may interfere with invasion.
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31
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Deroost K, Pham TT, Opdenakker G, Van den Steen PE. The immunological balance between host and parasite in malaria. FEMS Microbiol Rev 2015; 40:208-57. [PMID: 26657789 DOI: 10.1093/femsre/fuv046] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2015] [Indexed: 12/16/2022] Open
Abstract
Coevolution of humans and malaria parasites has generated an intricate balance between the immune system of the host and virulence factors of the parasite, equilibrating maximal parasite transmission with limited host damage. Focusing on the blood stage of the disease, we discuss how the balance between anti-parasite immunity versus immunomodulatory and evasion mechanisms of the parasite may result in parasite clearance or chronic infection without major symptoms, whereas imbalances characterized by excessive parasite growth, exaggerated immune reactions or a combination of both cause severe pathology and death, which is detrimental for both parasite and host. A thorough understanding of the immunological balance of malaria and its relation to other physiological balances in the body is of crucial importance for developing effective interventions to reduce malaria-related morbidity and to diminish fatal outcomes due to severe complications. Therefore, we discuss in this review the detailed mechanisms of anti-malarial immunity, parasite virulence factors including immune evasion mechanisms and pathogenesis. Furthermore, we propose a comprehensive classification of malaria complications according to the different types of imbalances.
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Affiliation(s)
- Katrien Deroost
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium The Francis Crick Institute, Mill Hill Laboratory, London, NW71AA, UK
| | - Thao-Thy Pham
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Ghislain Opdenakker
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Philippe E Van den Steen
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
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32
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Lim NTY, Harder MJ, Kennedy AT, Lin CS, Weir C, Cowman AF, Call MJ, Schmidt CQ, Tham WH. Characterization of Inhibitors and Monoclonal Antibodies That Modulate the Interaction between Plasmodium falciparum Adhesin PfRh4 with Its Erythrocyte Receptor Complement Receptor 1. J Biol Chem 2015; 290:25307-21. [PMID: 26324715 DOI: 10.1074/jbc.m115.657171] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum parasites must invade red blood cells to survive within humans. Entry into red blood cells is governed by interactions between parasite adhesins and red blood cell receptors. Previously we identified that P. falciparum reticulocyte binding protein-like homologue 4 (PfRh4) binds to complement receptor 1 (CR1) to mediate entry of malaria parasites into human red blood cells. In this report we characterize a collection of anti-PfRh4 monoclonal antibodies and CR1 protein fragments that modulate the interaction between PfRh4 and CR1. We identify an anti-PfRh4 monoclonal that blocks PfRh4-CR1 interaction in vitro, inhibits PfRh4 binding to red blood cells, and as a result abolishes the PfRh4-CR1 invasion pathway in P. falciparum. Epitope mapping of anti-PfRh4 monoclonal antibodies identified distinct functional regions within PfRh4 involved in modulating its interaction with CR1. Furthermore, we designed a set of protein fragments based on extensive mutagenesis analyses of the PfRh4 binding site on CR1 and determined their interaction affinities using surface plasmon resonance. These CR1 protein fragments bind tightly to PfRh4 and also function as soluble inhibitors to block PfRh4 binding to red blood cells and to inhibit the PfRh4-CR1 invasion pathway. Our findings can aid future efforts in designing specific single epitope antibodies to block P. falciparum invasion via complement receptor 1.
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Affiliation(s)
- Nicholas T Y Lim
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia
| | - Markus J Harder
- the Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstrasse 20, D-89081 Ulm, Germany
| | - Alexander T Kennedy
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and
| | - Clara S Lin
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and
| | - Christopher Weir
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and the School of Chemistry, University of Edinburgh, Edinburgh EH93JJ, Scotland, United Kingdom
| | - Alan F Cowman
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and
| | - Melissa J Call
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and
| | - Christoph Q Schmidt
- the Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstrasse 20, D-89081 Ulm, Germany
| | - Wai-Hong Tham
- From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and
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33
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de Koning-Ward TF, Gilson PR, Crabb BS. Advances in molecular genetic systems in malaria. Nat Rev Microbiol 2015; 13:373-87. [DOI: 10.1038/nrmicro3450] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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34
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Boyle MJ, Reiling L, Feng G, Langer C, Osier FH, Aspeling-Jones H, Cheng YS, Stubbs J, Tetteh KKA, Conway DJ, McCarthy JS, Muller I, Marsh K, Anders RF, Beeson JG. Human antibodies fix complement to inhibit Plasmodium falciparum invasion of erythrocytes and are associated with protection against malaria. Immunity 2015; 42:580-90. [PMID: 25786180 PMCID: PMC4372259 DOI: 10.1016/j.immuni.2015.02.012] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 12/01/2014] [Accepted: 02/23/2015] [Indexed: 11/26/2022]
Abstract
Antibodies play major roles in immunity to malaria; however, a limited understanding of mechanisms mediating protection is a major barrier to vaccine development. We have demonstrated that acquired human anti-malarial antibodies promote complement deposition on the merozoite to mediate inhibition of erythrocyte invasion through C1q fixation and activation of the classical complement pathway. Antibody-mediated complement-dependent (Ab-C′) inhibition was the predominant invasion-inhibitory activity of human antibodies; most antibodies were non-inhibitory without complement. Inhibitory activity was mediated predominately via C1q fixation, and merozoite surface proteins 1 and 2 were identified as major targets. Complement fixation by antibodies was very strongly associated with protection from both clinical malaria and high-density parasitemia in a prospective longitudinal study of children. Ab-C′ inhibitory activity could be induced by human immunization with a candidate merozoite surface-protein vaccine. Our findings demonstrate that human anti-malarial antibodies have evolved to function by fixing complement for potent invasion-inhibitory activity and protective immunity. Antibodies function with complement to inhibit P. falciparum replication Antibodies fix C1q to block invasion and lyse merozoites Complement-fixing antibodies are strongly associated with immunity in children Antibody-complement inhibition can be induced by human vaccination
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Affiliation(s)
- Michelle J Boyle
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia; Department of Medical Biology, University of Melbourne, Royal Parade, Melbourne, VIC 3010, Australia
| | - Linda Reiling
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia
| | - Gaoqian Feng
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia
| | - Christine Langer
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia
| | - Faith H Osier
- Centre for Geographic Medicine Research, Kenya Medical Research Institute, Coast, PO Box 230, 80108 Kilifi, Kenya
| | | | - Yik Sheng Cheng
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia; Department of Medical Biology, University of Melbourne, Royal Parade, Melbourne, VIC 3010, Australia
| | - Janine Stubbs
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia
| | - Kevin K A Tetteh
- London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E7HT, UK
| | - David J Conway
- London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E7HT, UK
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, University of Queensland, 300 Herston Road, Herston, QLD 4006, Australia
| | - Ivo Muller
- Walter and Eliza Hall Institute, Royal Parade, Melbourne, VIC 3050, Australia
| | - Kevin Marsh
- Centre for Geographic Medicine Research, Kenya Medical Research Institute, Coast, PO Box 230, 80108 Kilifi, Kenya
| | - Robin F Anders
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - James G Beeson
- The Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, VIC 3004, Australia; Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
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35
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Rono J, Färnert A, Murungi L, Ojal J, Kamuyu G, Guleid F, Nyangweso G, Wambua J, Kitsao B, Olotu A, Marsh K, Osier FH. Multiple clinical episodes of Plasmodium falciparum malaria in a low transmission intensity setting: exposure versus immunity. BMC Med 2015; 13:114. [PMID: 25967134 PMCID: PMC4445794 DOI: 10.1186/s12916-015-0354-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 04/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Epidemiological studies indicate that some children experience many more episodes of clinical malaria than their age mates in a given location. Whether this is as a result of the micro-heterogeneity of malaria transmission with some children effectively getting more exposure to infectious mosquitoes than others, or reflects a failure in the acquisition of immunity needs to be elucidated. Here, we investigated the determinants of increased susceptibility to clinical malaria by comparing the intensity of exposure to Plasmodium falciparum and the acquisition of immunity in children at the extreme ends of the over-dispersed distribution of the incidence of clinical malaria. METHODS The study was nested within a larger cohort in an area where the intensity of malaria transmission was low. We identified children who over a five-year period experienced 5 to 16 clinical malaria episodes (children at the tail-end of the over-dispersed distribution, n = 35), remained malaria-free (n = 12) or had a single episode (n = 26). We quantified antibodies against seven Plasmodium falciparum merozoite antigens in plasma obtained at six cross-sectional surveys spanning these five years. We analyzed the antibody responses to identify temporal dynamics that associate with disease susceptibility. RESULTS Children experiencing multiple episodes of malaria were more likely to be parasite positive by microscopy at cross-sectional surveys (X (2) test for trend 14.72 P = 0.001) and had a significantly higher malaria exposure index, than those in the malaria-free or single episode groups (Kruskal-Wallis test P = 0.009). In contrast, the five-year temporal dynamics of anti-merozoite antibodies were similar in the three groups. Importantly in all groups, antibody levels were below the threshold concentrations previously observed to be correlated with protective immunity. CONCLUSIONS We conclude that in the context of a low malaria transmission setting, susceptibility to clinical malaria is not accounted for by anti-merozoite antibodies but appears to be a consequence of increased parasite exposure. We hypothesize that intensive exposure is a prerequisite for protective antibody concentrations, while little to modest exposure may manifest as multiple clinical infections with low levels of antibodies. These findings have implications for interventions that effectively lower malaria transmission intensity.
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Affiliation(s)
- Josea Rono
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
- Infectious Diseases Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
| | - Anna Färnert
- Infectious Diseases Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
| | - Linda Murungi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - John Ojal
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Gathoni Kamuyu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Fatuma Guleid
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - George Nyangweso
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Juliana Wambua
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Barnes Kitsao
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Ally Olotu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK.
| | - Faith Ha Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
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36
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Schmidt CQ, Kennedy AT, Tham WH. More than just immune evasion: Hijacking complement by Plasmodium falciparum. Mol Immunol 2015; 67:71-84. [PMID: 25816986 DOI: 10.1016/j.molimm.2015.03.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 03/04/2015] [Accepted: 03/04/2015] [Indexed: 12/24/2022]
Abstract
Malaria remains one of the world's deadliest diseases. Plasmodium falciparum is responsible for the most severe and lethal form of human malaria. P. falciparum's life cycle involves two obligate hosts: human and mosquito. From initial entry into these hosts, malaria parasites face the onslaught of the first line of host defence, the complement system. In this review, we discuss the complex interaction between complement and malaria infection in terms of hosts immune responses, parasite survival and pathogenesis of severe forms of malaria. We will focus on the role of complement receptor 1 and its associated polymorphisms in malaria immune complex clearance, as a mediator of parasite rosetting and as an entry receptor for P. falciparum invasion. Complement evasion strategies of P. falciparum parasites will also be highlighted. The sexual forms of the malaria parasites recruit the soluble human complement regulator Factor H to evade complement-mediated killing within the mosquito host. A novel evasion strategy is the deployment of parasite organelles to divert complement attack from infective blood stage parasites. Finally we outline the future challenge to understand the implications of these exploitation mechanisms in the interplay between successful infection of the host and pathogenesis observed in severe malaria.
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Affiliation(s)
- Christoph Q Schmidt
- Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstraße 20, Ulm, Germany.
| | - Alexander T Kennedy
- Department of Medical Biology, University of Melbourne and Division of Infection and Immunity, The Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia
| | - Wai-Hong Tham
- Department of Medical Biology, University of Melbourne and Division of Infection and Immunity, The Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia.
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Ahmed Ismail H, Tijani MK, Langer C, Reiling L, White MT, Beeson JG, Wahlgren M, Nwuba R, Persson KEM. Subclass responses and their half-lives for antibodies against EBA175 and PfRh2 in naturally acquired immunity against Plasmodium falciparum malaria. Malar J 2014; 13:425. [PMID: 25373511 PMCID: PMC4232678 DOI: 10.1186/1475-2875-13-425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/25/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Plasmodium falciparum EBA175 and PfRh2 belong to two main families involved in parasite invasion, and both are potential vaccine candidates. Current knowledge is limited regarding which target antigens and subclasses of antibodies are actually important for protection, and how naturally acquired immunity is achieved. METHODS Repeated blood samples were collected from individuals in Nigeria over a period of almost one year. ELISA was used to analyse subclasses of IgG responses. RESULTS For both EBA175 (region III-V) and (a fragment of) PfRh2, the dominant antibody responses consisted of IgG1 and IgG3 followed by IgG2, while for PfRh2 there was also a relatively prominent response for IgG4. High levels of IgG1, IgG2 and IgG3 for EBA175 and total IgG for PfRh2 correlated significantly with a lower parasitaemia during the study period. Children with HbAS had higher levels of some subclasses compared to children with HbAA, while in adults the pattern was the opposite. The half-lives of IgG2 and IgG4 against EBA175 were clearly shorter than those for IgG1 and IgG3. CONCLUSION EBA175 and PfRh2 are potential targets for protective antibodies since both correlated with lower parasitaemia. The shorter half-lives for IgG2 and IgG4 might explain why these subclasses are often considered less important in protection against malaria. Triggering the right subclass responses could be of critical importance in a successful vaccine. Further studies are needed to evaluate the role of haemoglobin polymorphisms and their malaria protective effects in this process.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Nobels väg 16, 17177 Stockholm, Sweden.
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Elliott SR, Fowkes FJ, Richards JS, Reiling L, Drew DR, Beeson JG. Research priorities for the development and implementation of serological tools for malaria surveillance. F1000PRIME REPORTS 2014; 6:100. [PMID: 25580254 PMCID: PMC4229730 DOI: 10.12703/p6-100] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Surveillance is a key component of control and elimination programs. Malaria surveillance has been typically reliant on case reporting by health services, entomological estimates and parasitemia (Plasmodium species) point prevalence. However, these techniques become less sensitive and relatively costly as transmission declines. There is great potential for the development and application of serological biomarkers of malaria exposure as sero-surveillance tools to strengthen malaria control and elimination. Antibodies to malaria antigens are sensitive biomarkers of population-level malaria exposure and can be used to identify hotspots of malaria transmission, estimate transmission levels, monitor changes over time or the impact of interventions on transmission, confirm malaria elimination, and monitor re-emergence of malaria. Sero-surveillance tools could be used in reference laboratories or developed as simple point-of-care tests for community-based surveillance, and different applications and target populations dictate the technical performance required from assays that are determined by properties of antigens and antibody responses. To advance the development of sero-surveillance tools for malaria elimination, major gaps in our knowledge need to be addressed through further research. These include greater knowledge of potential antigens, the sensitivity and specificity of antibody responses, and the longevity of these responses and defining antigens and antibodies that differentiate between exposure to Plasmodium falciparum and P. vivax. Additionally, a better understanding of the influence of host factors, such as age, genetics, and comorbidities on antibody responses in different populations is needed.
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Affiliation(s)
| | - Freya J.I. Fowkes
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Epidemiology and Preventive Medicine, Monash University99 Commercial Road, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
| | - Jack S. Richards
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
- Department of Microbiology, Monash UniversityVictoria 3800Australia
| | - Linda Reiling
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
| | - Damien R. Drew
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
| | - James G. Beeson
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
- Department of Microbiology, Monash UniversityVictoria 3800Australia
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Osier FH, Mackinnon MJ, Crosnier C, Fegan G, Kamuyu G, Wanaguru M, Ogada E, McDade B, Rayner JC, Wright GJ, Marsh K. New antigens for a multicomponent blood-stage malaria vaccine. Sci Transl Med 2014; 6:247ra102. [PMID: 25080477 PMCID: PMC4856877 DOI: 10.1126/scitranslmed.3008705] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An effective blood-stage vaccine against Plasmodium falciparum remains a research priority, but the number of antigens that have been translated into multicomponent vaccines for testing in clinical trials remains limited. Investigating the large number of potential targets found in the parasite proteome has been constrained by an inability to produce natively folded recombinant antigens for immunological studies. We overcame these constraints by generating a large library of biochemically active merozoite surface and secreted full-length ectodomain proteins. We then systematically examined the antibody reactivity against these proteins in a cohort of Kenyan children (n = 286) who were sampled at the start of a malaria transmission season and prospectively monitored for clinical episodes of malaria over the ensuing 6 months. We found that antibodies to previously untested or little-studied proteins had superior or equivalent potential protective efficacy to the handful of current leading malaria vaccine candidates. Moreover, cumulative responses to combinations comprising 5 of the 10 top-ranked antigens, including PF3D7_1136200, MSP2, RhopH3, P41, MSP11, MSP3, PF3D7_0606800, AMA1, Pf113, and MSRP1, were associated with 100% protection against clinical episodes of malaria. These data suggest not only that there are many more potential antigen candidates for the malaria vaccine development pipeline but also that effective vaccination may be achieved by combining a selection of these antigens.
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MESH Headings
- Age Factors
- Antibodies, Protozoan/blood
- Antigens, Protozoan/immunology
- Biomarkers/blood
- Child
- Child, Preschool
- Humans
- Infant
- Infant, Newborn
- Kenya/epidemiology
- Malaria Vaccines/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Merozoites/immunology
- Peptide Fragments/immunology
- Plasmodium falciparum/immunology
- Prospective Studies
- Protozoan Proteins/immunology
- Seroepidemiologic Studies
- Time Factors
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Affiliation(s)
- Faith H Osier
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Margaret J Mackinnon
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Cécile Crosnier
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gregory Fegan
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Gathoni Kamuyu
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Madushi Wanaguru
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Edna Ogada
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Brian McDade
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Kevin Marsh
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya.
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40
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Barry AE, Arnott A. Strategies for designing and monitoring malaria vaccines targeting diverse antigens. Front Immunol 2014; 5:359. [PMID: 25120545 PMCID: PMC4112938 DOI: 10.3389/fimmu.2014.00359] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 07/13/2014] [Indexed: 01/28/2023] Open
Abstract
After more than 50 years of intensive research and development, only one malaria vaccine candidate, “RTS,S,” has progressed to Phase 3 clinical trials. Despite only partial efficacy, this candidate is now forecast to become the first licensed malaria vaccine. Hence, more efficacious second-generation malaria vaccines that can significantly reduce transmission are urgently needed. This review will focus on a major obstacle hindering development of effective malaria vaccines: parasite antigenic diversity. Despite extensive genetic diversity in leading candidate antigens, vaccines have been and continue to be formulated using recombinant antigens representing only one or two strains. These vaccine strains represent only a small fraction of the diversity circulating in natural parasite populations, leading to escape of non-vaccine strains and challenging investigators’ abilities to measure strain-specific efficacy in vaccine trials. Novel strategies are needed to overcome antigenic diversity in order for vaccine development to succeed. Many studies have now cataloged the global diversity of leading Plasmodium falciparum and Plasmodium vivax vaccine antigens. In this review, we describe how population genetic approaches can be applied to this rich data source to predict the alleles that best represent antigenic diversity, polymorphisms that contribute to it, and to identify key polymorphisms associated with antigenic escape. We also suggest an approach to summarize the known global diversity of a given antigen to predict antigenic diversity, how to select variants that best represent the strains circulating in natural parasite populations and how to investigate the strain-specific efficacy of vaccine trials. Use of these strategies in the design and monitoring of vaccine trials will not only shed light on the contribution of genetic diversity to the antigenic diversity of malaria, but will also maximize the potential of future malaria vaccine candidates.
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Affiliation(s)
- Alyssa E Barry
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research , Parkville, VIC , Australia ; Department of Medical Biology, The University of Melbourne , Parkville, VIC , Australia
| | - Alicia Arnott
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research , Parkville, VIC , Australia ; Department of Medical Biology, The University of Melbourne , Parkville, VIC , Australia
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41
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Osier FH, Feng G, Boyle MJ, Langer C, Zhou J, Richards JS, McCallum FJ, Reiling L, Jaworowski A, Anders RF, Marsh K, Beeson JG. Opsonic phagocytosis of Plasmodium falciparum merozoites: mechanism in human immunity and a correlate of protection against malaria. BMC Med 2014; 12:108. [PMID: 24980799 PMCID: PMC4098671 DOI: 10.1186/1741-7015-12-108] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 06/06/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An understanding of the mechanisms mediating protective immunity against malaria in humans is currently lacking, but critically important to advance the development of highly efficacious vaccines. Antibodies play a key role in acquired immunity, but the functional basis for their protective effect remains unclear. Furthermore, there is a strong need for immune correlates of protection against malaria to guide vaccine development. METHODS Using a validated assay to measure opsonic phagocytosis of Plasmodium falciparum merozoites, we investigated the potential role of this functional activity in human immunity against clinical episodes of malaria in two independent cohorts (n = 109 and n = 287) experiencing differing levels of malaria transmission and evaluated its potential as a correlate of protection. RESULTS Antibodies promoting opsonic phagocytosis of merozoites were cytophilic immunoglobulins (IgG1 and IgG3), induced monocyte activation and production of pro-inflammatory cytokines, and were directed against major merozoite surface proteins (MSPs). Consistent with protective immunity in humans, opsonizing antibodies were acquired with increasing age and malaria exposure, were boosted on re-infection, and levels were related to malaria transmission intensity. Opsonic phagocytosis was strongly associated with a reduced risk of clinical malaria in longitudinal studies in children with current or recent infections. In contrast, antibodies to the merozoite surface in standard immunoassays, or growth-inhibitory antibodies, were not significantly associated with protection. In multivariate analyses including several antibody responses, opsonic phagocytosis remained significantly associated with protection against malaria, highlighting its potential as a correlate of immunity. Furthermore, we demonstrate that human antibodies against MSP2 and MSP3 that are strongly associated with protection in this population are effective in opsonic phagocytosis of merozoites, providing a functional link between these antigen-specific responses and protection for the first time. CONCLUSIONS Opsonic phagocytosis of merozoites appears to be an important mechanism contributing to protective immunity in humans. The opsonic phagocytosis assay appears to be a strong correlate of protection against malaria, a valuable biomarker of immunity, and provides a much-needed new tool for assessing responses to blood-stage malaria vaccines and measuring immunity in populations.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - James G Beeson
- Centre for Biomedical Research, The Burnet Institute, 85 Commercial Road, 3004 Melbourne, Victoria, Australia.
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42
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Affiliation(s)
- Gavin J. Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Malaria Programme, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- * E-mail: (GJW); (JCR)
| | - Julian C. Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- * E-mail: (GJW); (JCR)
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43
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Hill DL, Eriksson EM, Li Wai Suen CSN, Chiu CY, Ryg-Cornejo V, Robinson LJ, Siba PM, Mueller I, Hansen DS, Schofield L. Opsonising antibodies to P. falciparum merozoites associated with immunity to clinical malaria. PLoS One 2013; 8:e74627. [PMID: 24040299 PMCID: PMC3767630 DOI: 10.1371/journal.pone.0074627] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 08/04/2013] [Indexed: 11/19/2022] Open
Abstract
Naturally acquired humoral immunity to the malarial parasite Plasmodium falciparum can protect against disease, although the precise mechanisms remain unclear. Although antibody levels can be measured by ELISA, few studies have investigated functional antibody assays in relation to clinical outcomes. In this study we applied a recently developed functional assay of antibody-mediated opsonisation of merozoites, to plasma samples from a longitudinal cohort study conducted in a malaria endemic region of Papua New Guinea (PNG). Phagocytic activity was quantified by flow cytometry using a standardized and high-throughput protocol, and was subsequently evaluated for association with protection from clinical malaria and high-density parasitemia. Opsonising antibody responses were found to: i) increase with age, ii) be enhanced by concurrent infection, and iii) correlate with protection from clinical episodes and high-density parasitemia. Stronger protective associations were observed in individuals with no detectable parasitemia at baseline. This study presents the first evidence for merozoite phagocytosis as a correlate of acquired immunity and clinical protection against P. falciparum malaria.
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Affiliation(s)
- Danika L. Hill
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Emily M. Eriksson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Connie S. N. Li Wai Suen
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Chris Y. Chiu
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Victoria Ryg-Cornejo
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Leanne J. Robinson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Vector Borne Disease Unit, Papua New Guinea Institute of Medical Research, Goroka, Eastern Highlands Province, Papua, New Guinea
| | - Peter M. Siba
- Vector Borne Disease Unit, Papua New Guinea Institute of Medical Research, Goroka, Eastern Highlands Province, Papua, New Guinea
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
- Barcelona Center for International Health, University of Barcelona, Barcelona, Spain
| | - Diana S. Hansen
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Louis Schofield
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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Persson KEM, Fowkes FJI, McCallum FJ, Gicheru N, Reiling L, Richards JS, Wilson DW, Lopaticki S, Cowman AF, Marsh K, Beeson JG. Erythrocyte-binding antigens of Plasmodium falciparum are targets of human inhibitory antibodies and function to evade naturally acquired immunity. THE JOURNAL OF IMMUNOLOGY 2013; 191:785-94. [PMID: 23776178 DOI: 10.4049/jimmunol.1300444] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Abs that inhibit Plasmodium falciparum invasion of erythrocytes form an important component of human immunity against malaria, but key target Ags are largely unknown. Phenotypic variation by P. falciparum mediates the evasion of inhibitory Abs, contributing to the capacity of P. falciparum to cause repeat and chronic infections. However, Ags involved in mediating immune evasion have not been defined, and studies of the function of human Abs are limited. In this study, we used novel approaches to determine the importance of P. falciparum erythrocyte-binding Ags (EBAs), which are important invasion ligands, as targets of human invasion-inhibitory Abs and define their role in contributing to immune evasion through variation in function. We evaluated the invasion-inhibitory activity of acquired Abs from malaria-exposed children and adults from Kenya, using P. falciparum with disruption of genes encoding EBA140, EBA175, and EBA181, either individually or combined as EBA140/EBA175 or EBA175/EBA181 double knockouts. Our findings provide important new evidence that variation in the expression and function of the EBAs plays an important role in evasion of acquired Abs and that a substantial amount of phenotypic diversity results from variation in expression of different EBAs that contributes to immune evasion by P. falciparum. All three EBAs were identified as important targets of naturally acquired inhibitory Abs demonstrated by differential inhibition of parental parasites greater than EBA knockout lines. This knowledge will help to advance malaria vaccine development and suggests that multiple invasion ligands need to be targeted to overcome the capacity of P. falciparum for immune evasion.
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Affiliation(s)
- Kristina E M Persson
- Karolinska Institutet, Microbiology, Tumor and Cell Biology, 17177 Stockholm, Sweden.
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Richards JS, Arumugam TU, Reiling L, Healer J, Hodder AN, Fowkes FJI, Cross N, Langer C, Takeo S, Uboldi AD, Thompson JK, Gilson PR, Coppel RL, Siba PM, King CL, Torii M, Chitnis CE, Narum DL, Mueller I, Crabb BS, Cowman AF, Tsuboi T, Beeson JG. Identification and prioritization of merozoite antigens as targets of protective human immunity to Plasmodium falciparum malaria for vaccine and biomarker development. THE JOURNAL OF IMMUNOLOGY 2013; 191:795-809. [PMID: 23776179 DOI: 10.4049/jimmunol.1300778] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of effective malaria vaccines and immune biomarkers of malaria is a high priority for malaria control and elimination. Ags expressed by merozoites of Plasmodium falciparum are likely to be important targets of human immunity and are promising vaccine candidates, but very few Ags have been studied. We developed an approach to assess Ab responses to a comprehensive repertoire of merozoite proteins and investigate whether they are targets of protective Abs. We expressed 91 recombinant proteins, located on the merozoite surface or within invasion organelles, and screened them for quality and reactivity to human Abs. Subsequently, Abs to 46 proteins were studied in a longitudinal cohort of 206 Papua New Guinean children to define Ab acquisition and associations with protective immunity. Ab responses were higher among older children and those with active parasitemia. High-level Ab responses to rhoptry and microneme proteins that function in erythrocyte invasion were identified as being most strongly associated with protective immunity compared with other Ags. Additionally, Abs to new or understudied Ags were more strongly associated with protection than were Abs to current vaccine candidates that have progressed to phase 1 or 2 vaccine trials. Combinations of Ab responses were identified that were more strongly associated with protective immunity than responses to their single-Ag components. This study identifies Ags that are likely to be key targets of protective human immunity and facilitates the prioritization of Ags for further evaluation as vaccine candidates and/or for use as biomarkers of immunity in malaria surveillance and control.
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Affiliation(s)
- Jack S Richards
- Department of Immunology, Burnet Institute, Melbourne 3001, Victoria, Australia
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