{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T12:44:58Z","timestamp":1791895498381,"version":"4.3.4"},"reference-count":43,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,8,10]],"date-time":"2021-08-10T00:00:00Z","timestamp":1628553600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100009708","name":"Novo Nordisk Fonden","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100009708","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011054","name":"Danish International Development Agency","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100011054","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011054","name":"Danish International Development Agency","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100011054","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:p>The highly conserved <jats:italic>Plasmodium falciparum<\/jats:italic> cysteine-rich protective antigen (PfCyRPA) is a key target for next-generation vaccines against blood-stage malaria. PfCyRPA constitute the core of a ternary complex, including the reticulocyte binding-like homologous protein 5 (PfRh5) and the Rh5-interacting protein (PfRipr), and is fundamental for merozoite invasion of erythrocytes. In this study, we show that monoclonal antibodies (mAbs) specific to PfCyRPA neutralize the <jats:italic>in vitro<\/jats:italic> growth of Ghanaian field isolates as well as numerous laboratory-adapted parasite lines. We identified subsets of mAbs with neutralizing activity that bind to distinct sites on PfCyRPA and that in combination potentiate the neutralizing effect. As antibody responses against multiple merozoite invasion proteins are thought to improve the efficacy of blood-stage vaccines, we also demonstrated that combinations of PfCyRPA- and PfRh5 specific mAbs act synergistically to neutralize parasite growth. Yet, we identified prominent strain-dependent neutralization potencies, which our results suggest is independent of PfCyRPA expression level and polymorphism, demonstrating the importance of addressing functional converseness when evaluating blood-stage vaccine candidates. Finally, our results suggest that blood-stage vaccine efficacy can be improved by directing the antibody response towards defined protective epitopes on multiple parasite antigens.<\/jats:p>","DOI":"10.3389\/fimmu.2021.716305","type":"journal-article","created":{"date-parts":[[2021,8,10]],"date-time":"2021-08-10T07:44:00Z","timestamp":1628581440000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":18,"title":["Strain-Dependent Inhibition of Erythrocyte Invasion by Monoclonal Antibodies Against Plasmodium falciparum CyRPA"],"prefix":"10.3389","volume":"12","author":[{"given":"Anne S.","family":"Knudsen","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kasper H.","family":"Bj\u00f6rnsson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria R.","family":"Bassi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melanie R.","family":"Walker","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andreas","family":"Kok","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bogdan","family":"Cristinoi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anja R.","family":"Jensen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lea","family":"Barfod","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,8,10]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2020.594653","article-title":"Naturally Acquired Humoral Immunity Against Plasmodium Falciparum Malaria","volume":"11","author":"Gonzales","year":"2020","journal-title":"Front Immunol"},{"key":"B2","unstructured":"World Malaria Report 20202020"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1008115","article-title":"A Field Trial to Assess a Blood-Stage Malaria Vaccine","volume":"365","author":"Thera","year":"2011","journal-title":"N Engl J Med"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1016\/j.vaccine.2009.03.014","article-title":"A Randomized Controlled Phase 2 Trial of the Blood Stage AMA1-C1\/Alhydrogel Malaria Vaccine in Children in Mali","volume":"27","author":"Sagara","year":"2009","journal-title":"Vaccine"},{"key":"B5","doi-asserted-by":"publisher","first-page":"e4708","DOI":"10.1371\/journal.pone.0004708","article-title":"Blood Stage Malaria Vaccine Eliciting High Antigen-Specific Antibody Concentrations Confers No Protection to Young Children in Western Kenya","volume":"4","author":"Ogutu","year":"2009","journal-title":"PloS One"},{"key":"B6","doi-asserted-by":"publisher","first-page":"2ra5","DOI":"10.1126\/scitranslmed.3000257","article-title":"Extreme Polymorphism in a Vaccine Antigen and Risk of Clinical Malaria: Implications for Vaccine Development","volume":"1","author":"Takala","year":"2009","journal-title":"Sci Transl Med"},{"key":"B7","doi-asserted-by":"publisher","first-page":"e1003943","DOI":"10.1371\/journal.ppat.1003943","article-title":"Plasmodium Falciparum Erythrocyte Invasion: Combining Function With Immune Evasion","volume":"10","author":"Wright","year":"2014","journal-title":"PloS Pathog"},{"key":"B8","doi-asserted-by":"publisher","first-page":"43","DOI":"10.1016\/j.chom.2018.06.008","article-title":"Malaria Vaccines: Recent Advances and New Horizons","volume":"24","author":"Draper","year":"2018","journal-title":"Cell Host Microbe"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.1038\/nature10606","article-title":"Basigin Is a Receptor Essential for Erythrocyte Invasion by Plasmodium Falciparum","volume":"480","author":"Crosnier","year":"2011","journal-title":"Nature"},{"key":"B10","doi-asserted-by":"publisher","first-page":"e1004670","DOI":"10.1371\/journal.ppat.1004670","article-title":"Revealing the Sequence and Resulting Cellular Morphology of Receptor-Ligand Interactions During Plasmodium Falciparum Invasion of Erythrocytes","volume":"11","author":"Weiss","year":"2015","journal-title":"PloS Pathog"},{"key":"B11","doi-asserted-by":"publisher","first-page":"60","DOI":"10.1016\/j.chom.2016.06.004","article-title":"Essential Role of the PfRh5\/PfRipr\/CyRPA Complex During Plasmodium Falciparum Invasion of Erythrocytes","volume":"20","author":"Volz","year":"2016","journal-title":"Cell Host Microbe"},{"key":"B12","doi-asserted-by":"publisher","DOI":"10.1016\/j.pt.2020.04.003","article-title":"The RH5-CyRPA-Ripr Complex as a Malaria Vaccine Target","volume":"36","author":"Ragotte","year":"2020","journal-title":"Trends Parasitol"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-018-0779-6","article-title":"Structure of Plasmodium Falciparum Rh5-CyRPA-Ripr Invasion Complex","volume":"565","author":"Wong","year":"2019","journal-title":"Nature"},{"key":"B14","doi-asserted-by":"publisher","first-page":"824730","DOI":"10.1101\/824730","article-title":"An Open Dataset of Plasmodium Falciparum Genome Variation in 7,000 Worldwide Samples","author":"Pearson","year":"2019","journal-title":"bioRxiv"},{"key":"B15","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1415466112","article-title":"Multiprotein Complex Between the GPI-Anchored CyRPA With PfRH5 and PfRipr Is Crucial for Plasmodium Falciparum Erythrocyte Invasion","volume":"112","author":"Reddy","year":"2015","journal-title":"Proc Natl Acad Sci USA"},{"key":"B16","doi-asserted-by":"publisher","first-page":"e0198371","DOI":"10.1371\/journal.pone.0198371","article-title":"Kinetics of Antibody Responses to PfRH5-Complex Antigens in Ghanaian Children With Plasmodium Falciparum Malaria","volume":"13","author":"Partey","year":"2018","journal-title":"PloS One"},{"key":"B17","doi-asserted-by":"publisher","first-page":"e0243943","DOI":"10.1371\/journal.pone.0243943","article-title":"Acquisition and Decay of IgM and IgG Responses to Merozoite Antigens After Plasmodium Falciparum Malaria in Ghanaian Children","volume":"15","author":"Walker","year":"2020","journal-title":"PloS One"},{"key":"B18","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.1103177","article-title":"Passive Immunoprotection of Plasmodium Falciparum-Infected Mice Designates the CyRPA as Candidate Malaria Vaccine Antigen","volume":"188","author":"Dreyer","year":"2012","journal-title":"J Immunol"},{"key":"B19","doi-asserted-by":"publisher","DOI":"10.7554\/eLife.20383","article-title":"Structure of the Malaria Vaccine Candidate Antigen CyRPA and Its Complex With a Parasite Invasion Inhibitory Antibody","volume":"6","author":"Favuzza","year":"2017","journal-title":"Elife"},{"key":"B20","doi-asserted-by":"publisher","DOI":"10.7554\/eLife.21347","article-title":"Structural Basis for Inhibition of Erythrocyte Invasion by Antibodies to Plasmodium Falciparum Protein CyRPA","volume":"6","author":"Chen","year":"2017","journal-title":"Elife"},{"key":"B21","doi-asserted-by":"publisher","first-page":"e13030","DOI":"10.1111\/cmi.13030","article-title":"Neutralising Antibodies Block the Function of Rh5\/Ripr\/CyRPA Complex During Invasion of Plasmodium Falciparum Into Human Erythrocytes","volume":"21","author":"Healer","year":"2019","journal-title":"Cell Microbiol"},{"key":"B22","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1702944114","article-title":"Synergistic Malaria Vaccine Combinations Identified by Systematic Antigen Screening","volume":"114","author":"Bustamante","year":"2017","journal-title":"Proc Natl Acad Sci USA"},{"key":"B23","doi-asserted-by":"publisher","first-page":"11802","DOI":"10.1038\/s41598-020-67877-8","article-title":"Bliss\u2019 and Loewe\u2019s Additive and Synergistic Effects in Plasmodium Falciparum Growth Inhibition by AMA1-RON2L, RH5, RIPR and CyRPA Antibody Combinations","volume":"10","author":"Azasi","year":"2020","journal-title":"Sci Rep"},{"key":"B24","doi-asserted-by":"publisher","first-page":"93","DOI":"10.1186\/1475-2875-13-93","article-title":"Towards a Comprehensive Plasmodium Falciparum Merozoite Cell Surface and Secreted Recombinant Protein Library","volume":"13","author":"Zenonos","year":"2014","journal-title":"Malar J"},{"key":"B25","doi-asserted-by":"publisher","DOI":"10.1128\/IAI.73.6.3677-3685.2005","article-title":"Phase 1 Clinical Trial of Apical Membrane Antigen 1: An Asexual Blood-Stage Vaccine for Plasmodium Falciparum Malaria","volume":"73","author":"Malkin","year":"2005","journal-title":"Infect Immun"},{"key":"B26","doi-asserted-by":"publisher","first-page":"216","DOI":"10.1016\/j.cell.2019.05.025","article-title":"Human Antibodies That Slow Erythrocyte Invasion Potentiate Malaria-Neutralizing Antibodies","volume":"178","author":"Alanine","year":"2019","journal-title":"Cell"},{"key":"B27","doi-asserted-by":"publisher","first-page":"e00149","DOI":"10.1002\/prp2.149","article-title":"Analysis of Drug Combinations: Current Methodological Landscape","volume":"3","author":"Foucquier","year":"2015","journal-title":"Pharmacol Res Perspect"},{"key":"B28","article-title":"The Search for Synergy: A Critical Review From a Response Surface Perspective","volume":"47","author":"Greco","year":"1995","journal-title":"Pharmacol Rev"},{"key":"B29","doi-asserted-by":"publisher","first-page":"e1002991","DOI":"10.1371\/journal.ppat.1002991","article-title":"Enhancing Blockade of Plasmodium Falciparum Erythrocyte Invasion: Assessing Combinations of Antibodies Against PfRH5 and Other Merozoite Antigens","volume":"8","author":"Williams","year":"2012","journal-title":"PloS Pathog"},{"key":"B30","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.48.11.4097-4102.2004","article-title":"Modified Fixed-Ratio Isobologram Method for Studying In Vitro Interactions Between Atovaquone and Proguanil or Dihydroartemisinin Against Drug-Resistant Strains of Plasmodium Falciparum","volume":"48","author":"Fivelman","year":"2004","journal-title":"Antimicrob Agents Chemother"},{"key":"B31","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1009198107","article-title":"Isolation of Viable Plasmodium Falciparum Merozoites to Define Erythrocyte Invasion Events and Advance Vaccine and Drug Development","volume":"107","author":"Boyle","year":"2010","journal-title":"Proc Natl Acad Sci USA"},{"key":"B32","doi-asserted-by":"publisher","first-page":"161","DOI":"10.1186\/s12936-016-1213-x","article-title":"Generation of Plasmodium Falciparum Parasite-Inhibitory Antibodies by Immunization With Recombinantly-Expressed CyRPA","volume":"15","author":"Favuzza","year":"2016","journal-title":"Malar J"},{"key":"B33","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jiaa608","article-title":"Antibody Combinations Targeting the Essential Antigens CyRPA, RH5 and MSP-119 Potently Neutralize Plasmodium Falciparum Clinical Isolates From India and Africa","volume":"223","author":"Singh","year":"2020","journal-title":"J Infect Dis"},{"key":"B34","doi-asserted-by":"publisher","DOI":"10.1038\/nature11174","article-title":"Analysis of Plasmodium Falciparum Diversity in Natural Infections by Deep Sequencing","volume":"487","author":"Manske","year":"2012","journal-title":"Nature"},{"key":"B35","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1111\/j.1365-3024.1987.tb00483.x","article-title":"Kinetic Constraints on the Development of a Malaria Vaccine","volume":"9","author":"Saul","year":"1987","journal-title":"Parasite Immunol"},{"key":"B36","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.1302045","article-title":"Neutralization of Plasmodium Falciparum Merozoites by Antibodies Against Pfrh5","volume":"192","author":"Douglas","year":"2014","journal-title":"J Immunol"},{"key":"B37","doi-asserted-by":"publisher","first-page":"1953","DOI":"10.1038\/s41467-019-09894-4","article-title":"A Defined Mechanistic Correlate of Protection Against Plasmodium Falciparum Malaria in Non-Human Primates","volume":"10","author":"Douglas","year":"2019","journal-title":"Nat Commun"},{"key":"B38","doi-asserted-by":"publisher","first-page":"e8138","DOI":"10.1371\/journal.pone.0008138","article-title":"High Antibody Titer Against Apical Membrane Antigen-1 Is Required to Protect Against Malaria in the Aotus Model","volume":"4","author":"Dutta","year":"2009","journal-title":"PloS One"},{"key":"B39","doi-asserted-by":"publisher","DOI":"10.1016\/j.chom.2014.11.017","article-title":"A PfRH5-Based Vaccine Is Efficacious Against Heterologous Strain Blood-Stage Plasmodium Falciparum Infection in Aotus Monkeys","volume":"17","author":"Douglas","year":"2015","journal-title":"Cell Host Microbe"},{"key":"B40","doi-asserted-by":"publisher","DOI":"10.1093\/emboj\/cdg096","article-title":"Phenotypic Variation of Plasmodium Falciparum Merozoite Proteins Directs Receptor Targeting for Invasion of Human Erythrocytes","volume":"22","author":"Duraisingh","year":"2003","journal-title":"EMBO J"},{"key":"B41","doi-asserted-by":"publisher","DOI":"10.1172\/JCI32138","article-title":"Variation in Use of Erythrocyte Invasion Pathways by Plasmodium Falciparum Mediates Evasion of Human Inhibitory Antibodies","volume":"118","author":"Persson","year":"2008","journal-title":"J Clin Invest"},{"key":"B42","doi-asserted-by":"publisher","DOI":"10.1126\/science.1115257","article-title":"Molecular Mechanism for Switching of P. Falciparum Invasion Pathways Into Human Erythrocytes","volume":"309","author":"Stubbs","year":"2005","journal-title":"Science"},{"key":"B43","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijpara.2008.09.007","article-title":"Morphology and Kinetics of the Three Distinct Phases of Red Blood Cell Invasion by Plasmodium Falciparum Merozoites","volume":"39","author":"Gilson","year":"2009","journal-title":"Int J Parasitol"}],"container-title":["Frontiers in Immunology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2021.716305\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,8,10]],"date-time":"2021-08-10T07:44:09Z","timestamp":1628581449000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2021.716305\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,8,10]]},"references-count":43,"alternative-id":["10.3389\/fimmu.2021.716305"],"URL":"https:\/\/doi.org\/10.3389\/fimmu.2021.716305","relation":{},"ISSN":["1664-3224"],"issn-type":[{"value":"1664-3224","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,8,10]]},"article-number":"716305"}}