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Thomson-Luque R, Stabler TC, Fürle K, Silva JC, Daubenberger C. Plasmodium falciparum merozoite surface protein 1 as asexual blood stage malaria vaccine candidate. Expert Rev Vaccines 2024; 23:160-173. [PMID: 38100310 DOI: 10.1080/14760584.2023.2295430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/12/2023] [Indexed: 12/17/2023]
Abstract
INTRODUCTION Malaria represents a public health challenge in tropical and subtropical regions, and currently deployed control strategies are likely insufficient to drive elimination of malaria. Development and improvement of malaria vaccines might be key to reduce disease burden. Vaccines targeting asexual blood stages of the parasite have shown limited efficacy when studied in human trials conducted over the past decades. AREAS COVERED Vaccine candidates based on the merozoite surface protein 1 (MSP1) were initially envisioned as one of the most promising approaches to provide immune protection against asexual blood-stage malaria. Successful immunization studies in monkey involved the use of the full-length MSP1 (MSP1FL) as vaccine construct. Vaccines using MSP1FL for immunization have the potential benefit of including numerous conserved B-cell and T-cell epitopes. This could result in improved parasite strain-transcending, protective immunity in the field. We review outcomes of clinical trials that utilized a variety of MSP1 constructs and formulations, including MSP1FL, either alone or in combination with other antigens, in both animal models and humans. EXPERT OPINION Novel approaches to analyze breadth and magnitude of effector functions of MSP1-targeting antibodies in volunteers undergoing experimental vaccination and controlled human malaria infection will help to define correlates of protective immunity.
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Affiliation(s)
- Richard Thomson-Luque
- Centre for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
- Sumaya-Biotech GmbH & Co. KG Heidelberg, Germany
| | - Thomas C Stabler
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- University of Basel Basel, Switzerland
- Swiss Tropical and Public Health Institute Allschwil, Switzerland
| | - Kristin Fürle
- Centre for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade NOVA de Lisboa (GHTM IHMT, UNL), Lisbon, Portugal
| | - Claudia Daubenberger
- University of Basel Basel, Switzerland
- Swiss Tropical and Public Health Institute Allschwil, Switzerland
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2
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Núñez A, Ntumngia FB, Guerra Y, Adams JH, Sáenz FE. Genetic diversity and natural selection of Plasmodium vivax reticulocyte invasion genes in Ecuador. Malar J 2023; 22:225. [PMID: 37537581 PMCID: PMC10398936 DOI: 10.1186/s12936-023-04640-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023] Open
Abstract
BACKGROUND Knowledge of the diversity of invasion ligands in malaria parasites in endemic regions is essential to understand how natural selection influences genetic diversity of these ligands and their feasibility as possible targets for future vaccine development. In this study the diversity of four genes for merozoite invasion ligands was studied in Ecuadorian isolates of Plasmodium vivax. METHODS Eighty-eight samples from P. vivax infected individuals from the Coast and Amazon region of Ecuador were obtained between 2012 and 2015. The merozoite invasion genes pvmsp-1-19, pvdbpII, pvrbp1a-2 and pvama1 were amplified, sequenced, and compared to the Sal-1 strain. Polymorphisms were mapped and genetic relationships between haplotypes were determined. RESULTS Only one nonsynonymous polymorphism was detected in pvmsp-1-19, while 44 nonsynonymous polymorphisms were detected in pvdbpII, 56 in pvrbp1a-2 and 33 in pvama1. While haplotypes appeared to be more related within each area of study and there was less relationship between parasites of the coastal and Amazon regions of the country, diversification processes were observed in the two Amazon regions. The highest haplotypic diversity for most genes occurred in the East Amazon of the country. The high diversity observed in Ecuadorian samples is closer to Brazilian and Venezuelan isolates, but lower than reported in other endemic regions. In addition, departure from neutrality was observed in Ecuadorian pvama1. Polymorphisms for pvdbpII and pvama1 were associated to B-cell epitopes. CONCLUSIONS pvdbpII and pvama1 genetic diversity found in Ecuadorian P. vivax was very similar to that encountered in other malaria endemic countries with varying transmission levels and segregated by geographic region. The highest diversity of P. vivax invasion genes in Ecuador was found in the Amazonian region. Although selection appeared to have small effect on pvdbpII and pvrbp1a-2, pvama1 was influenced by significant balancing selection.
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Affiliation(s)
- Andrés Núñez
- Centro de Investigación para la Salud en América Latina, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Francis B Ntumngia
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, FL, Tampa, USA
| | - Yasel Guerra
- Grupo de Bio-Quimioinformática, Universidad de Las Américas, Quito, Ecuador
| | - John H Adams
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, FL, Tampa, USA
| | - Fabián E Sáenz
- Centro de Investigación para la Salud en América Latina, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador.
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3
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Roller RF, Malik A, Carillo MA, Garg M, Rella A, Raulf M, Lepenies B, Seeberger PH, Varón Silva D. Semisynthesis of Functional Glycosylphosphatidylinositol‐Anchored Proteins. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202002479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Renée F. Roller
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Ankita Malik
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Maria A. Carillo
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
| | - Monika Garg
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Antonella Rella
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Marie‐Kristin Raulf
- Immunology Unit and Research Center for Emerging Infections and Zoonoses University of Veterinary Medicine Hannover Bünteweg 17 30559 Hannover Germany
- Institute for Parasitology, Center for infection Medicine University of Veterinary Medicine Hannover Bünteweg 17 30559 Hannover Germany
| | - Bernd Lepenies
- Immunology Unit and Research Center for Emerging Infections and Zoonoses University of Veterinary Medicine Hannover Bünteweg 17 30559 Hannover Germany
| | - Peter H. Seeberger
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Daniel Varón Silva
- Department of Biomolecular Systems Max Planck Institute of Colloids and Interfaces 14424 Potsdam Germany
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
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4
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Roller RF, Malik A, Carillo MA, Garg M, Rella A, Raulf M, Lepenies B, Seeberger PH, Varón Silva D. Semisynthesis of Functional Glycosylphosphatidylinositol-Anchored Proteins. Angew Chem Int Ed Engl 2020; 59:12035-12040. [PMID: 32307806 PMCID: PMC7383966 DOI: 10.1002/anie.202002479] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/30/2020] [Indexed: 12/23/2022]
Abstract
Glypiation is a common posttranslational modification of eukaryotic proteins involving the attachment of a glycosylphosphatidylinositol (GPI) glycolipid. GPIs contain a conserved phosphoglycan that is modified in a cell- and tissue-specific manner. GPI complexity suggests roles in biological processes and effects on the attached protein, but the difficulties to get homogeneous material have hindered studies. We disclose a one-pot intein-mediated ligation (OPL) to obtain GPI-anchored proteins. The strategy enables the glypiation of folded and denatured proteins with a natural linkage to the glycolipid. Using the strategy, glypiated eGFP, Thy1, and the Plasmodium berghei protein MSP119 were prepared. Glypiation did not alter the structure of eGFP and MSP119 proteins in solution, but it induced a strong pro-inflammatory response in vitro. The strategy provides access to glypiated proteins to elucidate the activity of this modification and for use as vaccine candidates against parasitic infections.
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Affiliation(s)
- Renée F. Roller
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Ankita Malik
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Maria A. Carillo
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
| | - Monika Garg
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Antonella Rella
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Marie‐Kristin Raulf
- Immunology Unit and Research Center for Emerging Infections and ZoonosesUniversity of Veterinary Medicine HannoverBünteweg 1730559HannoverGermany
- Institute for Parasitology, Center for infection MedicineUniversity of Veterinary Medicine HannoverBünteweg 1730559HannoverGermany
| | - Bernd Lepenies
- Immunology Unit and Research Center for Emerging Infections and ZoonosesUniversity of Veterinary Medicine HannoverBünteweg 1730559HannoverGermany
| | - Peter H. Seeberger
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Daniel Varón Silva
- Department of Biomolecular SystemsMax Planck Institute of Colloids and Interfaces14424PotsdamGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
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5
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Cheng CW, Putaporntip C, Jongwutiwes S. Polymorphism in merozoite surface protein-7E of Plasmodium vivax in Thailand: Natural selection related to protein secondary structure. PLoS One 2018; 13:e0196765. [PMID: 29718980 PMCID: PMC5931635 DOI: 10.1371/journal.pone.0196765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/19/2018] [Indexed: 11/18/2022] Open
Abstract
Merozoite surface protein 7 (MSP-7) is a multigene family expressed during malaria blood-stage infection. MSP-7 forms complex with MSP-1 prior to merozoite egress from erythrocytes, and could affect merozoite invasion of erythrocytes. To characterize sequence variation in the orthologue in P. vivax (PvMSP-7), a gene member encoding PvMSP-7E was analyzed among 92 Thai isolates collected from 3 major endemic areas of Thailand (Northwest: Tak, Northeast: Ubon Ratchathani, and South: Yala and Narathiwat provinces). In total, 52 distinct haplotypes were found to circulate in these areas. Although population structure based on this locus was observed between each endemic area, no genetic differentiation occurred between populations collected from different periods in the same endemic area, suggesting spatial but not temporal genetic variation. Sequence microheterogeneity in both N- and C- terminal regions was predicted to display 4 and 6 α-helical domains, respectively. Signals of purifying selection were observed in α-helices II-X, suggesting structural or functional constraint in these domains. By contrast, α-helix-I spanning the putative signal peptide was under positive selection, in which amino acid substitutions could alter predicted CD4+ T helper cell epitopes. The central region of PvMSP-7E comprised the 5’-trimorphic and the 3’-dimorphic subregions. Positive selection was identified in the 3’ dimorphic subregion of the central domain. A consensus of intrinsically unstructured or disordered protein was predicted to encompass the entire central domain that contained a number of putative B cell epitopes and putative protein binding regions. Evidences of intragenic recombination were more common in the central region than the remainders of the gene. These results suggest that the extent of sequence variation, recombination events and selective pressures in the PvMSP-7E locus seem to be differentially affected by protein secondary structure.
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Affiliation(s)
- Chew Weng Cheng
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Chaturong Putaporntip
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Somchai Jongwutiwes
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- * E-mail:
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6
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Na+ Influx Induced by New Antimalarials Causes Rapid Alterations in the Cholesterol Content and Morphology of Plasmodium falciparum. PLoS Pathog 2016; 12:e1005647. [PMID: 27227970 PMCID: PMC4881962 DOI: 10.1371/journal.ppat.1005647] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/28/2016] [Indexed: 12/27/2022] Open
Abstract
Among the several new antimalarials discovered over the past decade are at least three clinical candidate drugs, each with a distinct chemical structure, that disrupt Na+ homeostasis resulting in a rapid increase in intracellular Na+ concentration ([Na+]i) within the erythrocytic stages of Plasmodium falciparum. At present, events triggered by Na+ influx that result in parasite demise are not well-understood. Here we report effects of two such drugs, a pyrazoleamide and a spiroindolone, on intraerythrocytic P. falciparum. Within minutes following the exposure to these drugs, the trophozoite stage parasite, which normally contains little cholesterol, was made permeant by cholesterol-dependent detergents, suggesting it acquired a substantial amount of the lipid. Consistently, the merozoite surface protein 1 and 2 (MSP1 and MSP2), glycosylphosphotidylinositol (GPI)-anchored proteins normally uniformly distributed in the parasite plasma membrane, coalesced into clusters. These alterations were not observed following drug treatment of P. falciparum parasites adapted to grow in a low [Na+] growth medium. Both cholesterol acquisition and MSP1 coalescence were reversible upon the removal of the drugs, implicating an active process of cholesterol exclusion from trophozoites that we hypothesize is inhibited by high [Na+]i. Electron microscopy of drug-treated trophozoites revealed substantial morphological changes normally seen at the later schizont stage including the appearance of partial inner membrane complexes, dense organelles that resemble "rhoptries" and apparent nuclear division. Together these results suggest that [Na+]i disruptor drugs by altering levels of cholesterol in the parasite, dysregulate trophozoite to schizont development and cause parasite demise.
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7
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Weiss GE, Crabb BS, Gilson PR. Overlaying Molecular and Temporal Aspects of Malaria Parasite Invasion. Trends Parasitol 2016; 32:284-295. [DOI: 10.1016/j.pt.2015.12.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/02/2015] [Accepted: 12/10/2015] [Indexed: 12/31/2022]
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8
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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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9
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Lin CS, Uboldi AD, Epp C, Bujard H, Tsuboi T, Czabotar PE, Cowman AF. Multiple Plasmodium falciparum Merozoite Surface Protein 1 Complexes Mediate Merozoite Binding to Human Erythrocytes. J Biol Chem 2016; 291:7703-15. [PMID: 26823464 DOI: 10.1074/jbc.m115.698282] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Indexed: 11/06/2022] Open
Abstract
Successful invasion of human erythrocytes byPlasmodium falciparummerozoites is required for infection of the host and parasite survival. The early stages of invasion are mediated via merozoite surface proteins that interact with human erythrocytes. The nature of these interactions are currently not well understood, but it is known that merozoite surface protein 1 (MSP1) is critical for successful erythrocyte invasion. Here we show that the peripheral merozoite surface proteins MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 bind directly to MSP1, but independently of each other, to form multiple forms of the MSP1 complex on the parasite surface. These complexes have overlapping functions that interact directly with human erythrocytes. We also show that targeting the p83 fragment of MSP1 using inhibitory antibodies inhibits all forms of MSP1 complexes and disrupts parasite growthin vitro.
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Affiliation(s)
- Clara S Lin
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Alessandro D Uboldi
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Christian Epp
- the Department of Infectious Diseases, Parasitology, Universität Heidelberg, INF 324, 69120 Heidelberg, Germany
| | - Hermann Bujard
- the Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany, and
| | - Takafumi Tsuboi
- the Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Peter E Czabotar
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Alan F Cowman
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia,
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10
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Lin CS, Uboldi AD, Marapana D, Czabotar PE, Epp C, Bujard H, Taylor NL, Perugini MA, Hodder AN, Cowman AF. The merozoite surface protein 1 complex is a platform for binding to human erythrocytes by Plasmodium falciparum. J Biol Chem 2014; 289:25655-69. [PMID: 25074930 DOI: 10.1074/jbc.m114.586495] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum is the causative agent of the most severe form of malaria in humans. The merozoite, an extracellular stage of the parasite lifecycle, invades erythrocytes in which they develop. The most abundant protein on the surface of merozoites is merozoite surface protein 1 (MSP1), which consists of four processed fragments. Studies indicate that MSP1 interacts with other peripheral merozoite surface proteins to form a large complex. Successful invasion of merozoites into host erythrocytes is dependent on this protein complex; however, the identity of all components and its function remain largely unknown. We have shown that the peripheral merozoite surface proteins MSPDBL1 and MSPDBL2 are part of the large MSP1 complex. Using surface plasmon resonance, we determined the binding affinities of MSPDBL1 and MSPDBL2 to MSP1 to be in the range of 2-4 × 10(-7) m. Both proteins bound to three of the four proteolytically cleaved fragments of MSP1 (p42, p38, and p83). In addition, MSPDBL1 and MSPDBL2, but not MSP1, bound directly to human erythrocytes. This demonstrates that the MSP1 complex acts as a platform for display of MSPDBL1 and MSPDBL2 on the merozoite surface for binding to receptors on the erythrocyte and invasion.
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Affiliation(s)
- Clara S Lin
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Alessandro D Uboldi
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia
| | - Danushka Marapana
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Peter E Czabotar
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Christian Epp
- Department of Infectious Diseases, Parasitology, Universität Heidelberg, INF 324, D-69120 Heidelberg, Germany
| | - Hermann Bujard
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), INF 282, D-69120 Heidelberg, Germany, and
| | - Nicole L Taylor
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3082, Australia
| | - Matthew A Perugini
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3082, Australia
| | - Anthony N Hodder
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia,
| | - Alan F Cowman
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia,
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11
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Karthik L, Kumar G, Keswani T, Bhattacharyya A, Chandar SS, Bhaskara Rao KV. Protease inhibitors from marine actinobacteria as a potential source for antimalarial compound. PLoS One 2014; 9:e90972. [PMID: 24618707 PMCID: PMC3949715 DOI: 10.1371/journal.pone.0090972] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 02/06/2014] [Indexed: 02/04/2023] Open
Abstract
The study was planned to screen the marine actinobacterial extract for the protease inhibitor activity and its anti- Pf activity under in vitro and in vivo conditions. Out of 100 isolates, only 3 isolates exhibited moderate to high protease inhibitor activities on trypsin, chymotrypsin and proteinase K. Based on protease inhibitor activity 3 isolates were chosen for further studies. The potential isolate was characterized by polyphasic approach and identified as Streptomyces sp LK3 (JF710608). The lead compound was identified as peptide from Streptomyces sp LK3. The double-reciprocal plot displayed inhibition mode is non-competitive and it confirms the irreversible nature of protease inhibitor. The peptide from Streptomyces sp LK3 extract showed significant anti plasmodial activity (IC50: 25.78 µg/ml). In in vivo model, the highest level of parasitemia suppression (≈45%) was observed in 600 mg/kg of the peptide. These analyses revealed no significant changes were observed in the spleen and liver tissue during 8 dpi. The results confirmed up-regulation of TGF-β and down regulation of TNF-α in tissue and serum level in PbA infected peptide treated mice compared to PbA infection. The results obtained infer that the peptide possesses anti- Pf activity activity. It suggests that the extracts have novel metabolites and could be considered as a potential source for drug development.
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MESH Headings
- Actinobacteria/chemistry
- Actinobacteria/genetics
- Actinobacteria/metabolism
- Animals
- Antimalarials/chemistry
- Antimalarials/isolation & purification
- Antimalarials/pharmacology
- Aquatic Organisms/chemistry
- Aquatic Organisms/metabolism
- Base Composition
- Chymotrypsin/antagonists & inhibitors
- Chymotrypsin/metabolism
- Cluster Analysis
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Inhibitory Concentration 50
- Liver/drug effects
- Liver/metabolism
- Liver/pathology
- Malaria, Falciparum/drug therapy
- Malaria, Falciparum/parasitology
- Male
- Mice
- Models, Biological
- Models, Molecular
- Parasitic Sensitivity Tests
- Plasmodium falciparum/drug effects
- Protease Inhibitors/chemistry
- Protease Inhibitors/isolation & purification
- Protease Inhibitors/pharmacology
- Protein Conformation
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- Seawater/microbiology
- Spleen/drug effects
- Spleen/metabolism
- Spleen/pathology
- Trypsin/metabolism
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Affiliation(s)
- L. Karthik
- Environmental Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, Tamil nadu, India
| | - Gaurav Kumar
- Environmental Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, Tamil nadu, India
| | - Tarun Keswani
- Immunology Lab, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India
| | - Arindam Bhattacharyya
- Immunology Lab, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India
| | - S. Sarath Chandar
- Genetics Division, School of Bio Sciences and Technology, VIT University, Vellore, Tamil nadu, India
| | - K. V. Bhaskara Rao
- Environmental Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, Tamil nadu, India
- * E-mail:
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Crosnier C, Wanaguru M, McDade B, Osier FH, Marsh K, Rayner JC, Wright GJ. A library of functional recombinant cell-surface and secreted P. falciparum merozoite proteins. Mol Cell Proteomics 2013; 12:3976-86. [PMID: 24043421 PMCID: PMC3861738 DOI: 10.1074/mcp.o113.028357] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Malaria, an infectious disease caused by parasites of the Plasmodium genus, is one of the world's major public health concerns causing up to a million deaths annually, mostly because of P. falciparum infections. All of the clinical symptoms are associated with the blood stage of the disease, an obligate part of the parasite life cycle, when a form of the parasite called the merozoite recognizes and invades host erythrocytes. During erythrocyte invasion, merozoites are directly exposed to the host humoral immune system making the blood stage of the parasite a conceptually attractive therapeutic target. Progress in the functional and molecular characterization of P. falciparum merozoite proteins, however, has been hampered by the technical challenges associated with expressing these proteins in a biochemically active recombinant form. This challenge is particularly acute for extracellular proteins, which are the likely targets of host antibody responses, because they contain structurally critical post-translational modifications that are not added by some recombinant expression systems. Here, we report the development of a method that uses a mammalian expression system to compile a protein resource containing the entire ectodomains of 42 P. falciparum merozoite secreted and cell surface proteins, many of which have not previously been characterized. Importantly, we are able to recapitulate known biochemical activities by showing that recombinant MSP1-MSP7 and P12-P41 directly interact, and that both recombinant EBA175 and EBA140 can bind human erythrocytes in a sialic acid-dependent manner. Finally, we use sera from malaria-exposed immune adults to profile the relative immunoreactivity of the proteins and show that the majority of the antigens contain conformational (heat-labile) epitopes. We envisage that this resource of recombinant proteins will make a valuable contribution toward a molecular understanding of the blood stage of P. falciparum infections and facilitate the comparative screening of antigens as blood-stage vaccine candidates.
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Affiliation(s)
- Cécile Crosnier
- Cell Surface Signalling laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
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Zong S, Kron MW, Epp C, Engler T, Bujard H, Kochanek S, Kreppel F. ΔE1 and high-capacity adenoviral vectors expressing full-length codon-optimized merozoite surface protein 1 for vaccination against Plasmodium falciparum. J Gene Med 2013; 13:670-9. [PMID: 22095915 DOI: 10.1002/jgm.1627] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The merozoite surface protein (MSP)-1 of Plasmodium falciparum, the causative agent of malaria tropica, is considered to be a promising vaccine candidate. Although its stable cloning and expression has been difficult in the past, adenoviral vectors expressing the complex protein are described in the present study. METHODS Codon-optimized msp-1 was used to construct a set of first generation (ΔE1Ad) and high-capacity adenovirus (HC-Ad) vectors, and cellular and humoral immune responses induced by the vectors were characterized in detail in mice. RESULTS Generation of stable ΔE1Ad and HC-Ad vectors expressing full-length MSP-1 and their production to high vector titers was found to be feasible. Epitope identification and analysis of frequencies of specific CD8 T-cells revealed that MSP-1 expressing HC-Ad vectors induced higher frequencies of interferon-γ + CD8 T-cells than ΔE1 vectors. Irrespective of the vector format, higher titers of MSP-1 specific antibodies were generated by Ad vectors expressing MSP-1 from a chicken β-actin (CAG) promoter comprising the cytomegalovirus early enhancer element and the chicken β-actin promoter. CONCLUSIONS The findings of the present study suggest that Ad vectors expressing full-length codon-optimized MSP-1 are promising candidate vaccines against P. falciparum infections. Use of the HC-Ad vector type for delivery, as well as the CAG promoter to control MSP-1 expression, may further increase the efficacy of this vaccine candidate.
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Affiliation(s)
- Shan Zong
- Department of Gene Therapy, University of Ulm, Ulm, Germany
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Global identification of multiple substrates for Plasmodium falciparum SUB1, an essential malarial processing protease. Infect Immun 2011; 79:1086-97. [PMID: 21220481 DOI: 10.1128/iai.00902-10] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protozoan pathogen responsible for the most severe form of human malaria, Plasmodium falciparum, replicates asexually in erythrocytes within a membrane-bound parasitophorous vacuole (PV). Following each round of intracellular growth, the PV membrane (PVM) and host cell membrane rupture to release infectious merozoites in a protease-dependent process called egress. Previous work has shown that, just prior to egress, an essential, subtilisin-like parasite protease called PfSUB1 is discharged into the PV lumen, where it directly cleaves a number of important merozoite surface and PV proteins. These include the essential merozoite surface protein complex MSP1/6/7 and members of a family of papain-like putative proteases called SERA (serine-rich antigen) that are implicated in egress. To determine whether PfSUB1 has additional, previously unrecognized substrates, we have performed a bioinformatic and proteomic analysis of the entire late asexual blood stage proteome of the parasite. Our results demonstrate that PfSUB1 is responsible for the proteolytic processing of a range of merozoite, PV, and PVM proteins, including the rhoptry protein RAP1 (rhoptry-associated protein 1) and the merozoite surface protein MSRP2 (MSP7-related protein-2). Our findings imply multiple roles for PfSUB1 in the parasite life cycle, further supporting the case for considering the protease as a potential new antimalarial drug target.
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Merozoite surface proteins of the malaria parasite: The MSP1 complex and the MSP7 family. Int J Parasitol 2010; 40:1155-61. [PMID: 20451527 DOI: 10.1016/j.ijpara.2010.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/22/2010] [Accepted: 04/26/2010] [Indexed: 11/21/2022]
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Systematic genetic analysis of the Plasmodium falciparum MSP7-like family reveals differences in protein expression, location, and importance in asexual growth of the blood-stage parasite. EUKARYOTIC CELL 2010; 9:1064-74. [PMID: 20472690 DOI: 10.1128/ec.00048-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proteins located on Plasmodium falciparum merozoites, the invasive form of the parasite's asexual blood stage, are of considerable interest in vaccine research. Merozoite surface protein 7 (MSP7) forms a complex with MSP1 and is encoded by a member of a multigene family located on chromosome 13. The family codes for MSP7 and five MSP7-related proteins (MSRPs). In the present study, we have investigated the expression and the effect of msrp gene deletion at the asexual blood stage. In addition to msp7, msrp2, msrp3, and msrp5 are transcribed, and mRNA was easily detected by hybridization analysis, whereas mRNA for msrp1 and msrp4 could be detected only by reverse transcription (RT)-PCR. Notwithstanding evidence of transcription, antibodies to recombinant MSRPs failed to detect specific proteins, except for antibodies to MSRP2. Sequential proteolytic cleavages of MSRP2 resulted in 28- and 25-kDa forms. However, MSRP2 was absent from merozoites; the 25-kDa MSRP2 protein (MSRP2(25)) was soluble and secreted upon merozoite egress. The msrp genes were deleted by targeted disruption in the 3D7 line, leading to ablation of full-length transcripts. MSRP deletion mutants had no detectable phenotype, with growth and invasion characteristics comparable to those of the parental parasite; only the deletion of MSP7 led to a detectable growth phenotype. Thus, within this family some of the genes are transcribed at a significant level in asexual blood stages, but the corresponding proteins may or may not be detectable. Interactions of the expressed proteins with the merozoite also differ. These results highlight the potential for unexpected differences of protein expression levels within gene families.
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Woehlbier U, Epp C, Hackett F, Blackman MJ, Bujard H. Antibodies against multiple merozoite surface antigens of the human malaria parasite Plasmodium falciparum inhibit parasite maturation and red blood cell invasion. Malar J 2010; 9:77. [PMID: 20298576 PMCID: PMC2847572 DOI: 10.1186/1475-2875-9-77] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum merozoites expose at their surface a large protein complex, which is composed of fragments of merozoite surface protein 1 (MSP-1; called MSP-183, MSP-130, MSP-138, and MSP-142) plus associated processing products of MSP-6 and MSP-7. During erythrocyte invasion this complex, as well as an integral membrane protein called apical membrane antigen-1 (AMA-1), is shed from the parasite surface following specific proteolysis. Components of the MSP-1/6/7 complex and AMA-1 are presently under development as malaria vaccines. METHODS The specificities and effects of antibodies directed against MSP-1, MSP-6, MSP-7 on the growth of blood stage parasites were studied using ELISA and the pLDH-assay. To understand the mode of action of these antibodies, their effects on processing of MSP-1 and AMA-1 on the surface of merozoites were investigated. RESULTS Antibodies targeting epitopes located throughout the MSP-1/6/7 complex interfere with shedding of MSP-1, and as a consequence prevent erythrocyte invasion. Antibodies targeting the MSP-1/6/7 complex have no effect on the processing and shedding of AMA-1 and, similarly, antibodies blocking the shedding of AMA-1 do not affect cleavage of MSP-1, suggesting completely independent functions of these proteins during invasion. Furthermore, some epitopes, although eliciting highly inhibitory antibodies, are only poorly recognized by the immune system when presented in the structural context of the intact antigen. CONCLUSIONS The findings reported provide further support for the development of vaccines based on MSP-1/6/7 and AMA-1, which would possibly include a combination of these antigens.
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Affiliation(s)
- Ute Woehlbier
- Zentrum für Molekulare Biologie (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Child MA, Epp C, Bujard H, Blackman MJ. Regulated maturation of malaria merozoite surface protein-1 is essential for parasite growth. Mol Microbiol 2010; 78:187-202. [PMID: 20735778 PMCID: PMC2995310 DOI: 10.1111/j.1365-2958.2010.07324.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The malaria parasite Plasmodium falciparum invades erythrocytes where it replicates to produce invasive merozoites, which eventually egress to repeat the cycle. Merozoite surface protein-1 (MSP1), a prime malaria vaccine candidate and one of the most abundant components of the merozoite surface, is implicated in the ligand-receptor interactions leading to invasion. MSP1 is extensively proteolytically modified, first just before egress and then during invasion. These primary and secondary processing events are mediated respectively, by two parasite subtilisin-like proteases, PfSUB1 and PfSUB2, but the function and biological importance of the processing is unknown. Here, we examine the regulation and significance of MSP1 processing. We show that primary processing is ordered, with the primary processing site closest to the C-terminal end of MSP1 being cleaved last, irrespective of polymorphisms throughout the rest of the molecule. Replacement of the secondary processing site, normally refractory to PfSUB1, with a PfSUB1-sensitive site, is deleterious to parasite growth. Our findings show that correct spatiotemporal regulation of MSP1 maturation is crucial for the function of the protein and for maintenance of the parasite asexual blood-stage life cycle.
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Affiliation(s)
- Matthew A Child
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Roy SW, Weedall GD, da Silva RL, Polley SD, Ferreira MU. Sequence diversity and evolutionary dynamics of the dimorphic antigen merozoite surface protein-6 and other Msp genes of Plasmodium falciparum. Gene 2009; 443:12-21. [PMID: 19463923 DOI: 10.1016/j.gene.2009.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 04/30/2009] [Accepted: 05/11/2009] [Indexed: 11/30/2022]
Abstract
Immune evasion by Plasmodium falciparum is favored by extensive allelic diversity of surface antigens. Some of them, most notably the vaccine-candidate merozoite surface protein (MSP)-1, exhibit a poorly understood pattern of allelic dimorphism, in which all observed alleles group into two highly diverged allelic families with few or no inter-family recombinants. Here we describe contrasting levels and patterns of sequence diversity in genes encoding three MSP-1-associated surface antigens of P. falciparum, ranging from an ancient allelic dimorphism in the Msp-6 gene to a near lack of allelic divergence in Msp-9 to a more classical multi-allele polymorphism in Msp-7. Other members of the Msp-7 gene family exhibit very little polymorphism in non-repetitive regions. A comparison of P. falciparum Msp-6 sequences to an orthologous sequence from P. reichenowi provided evidence for distinct evolutionary histories of the 5' and 3' segments of the dimorphic region in PfMsp-6, consistent with one dimorphic lineage having arisen from recombination between now-extinct ancestral alleles. In addition, we uncovered two surprising patterns of evolution in repetitive sequence. First, in Msp-6, large deletions are associated with (nearly) identical sequence motifs at their borders. Second, a comparison of PfMsp-9 with the P. reichenowi ortholog indicated retention of a significant inter-unit diversity within an 18-base pair repeat within the coding region of P. falciparum, but homogenization in P. reichenowi.
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Affiliation(s)
- Scott W Roy
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Building 38A, Bethesda, MD 20894, USA.
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Koussis K, Withers-Martinez C, Yeoh S, Child M, Hackett F, Knuepfer E, Juliano L, Woehlbier U, Bujard H, Blackman MJ. A multifunctional serine protease primes the malaria parasite for red blood cell invasion. EMBO J 2009; 28:725-35. [PMID: 19214190 PMCID: PMC2647770 DOI: 10.1038/emboj.2009.22] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 01/14/2009] [Indexed: 11/16/2022] Open
Abstract
The malaria parasite Plasmodium falciparum replicates within an intraerythrocytic parasitophorous vacuole (PV). Rupture of the host cell allows release (egress) of daughter merozoites, which invade fresh erythrocytes. We previously showed that a subtilisin-like protease called PfSUB1 regulates egress by being discharged into the PV in the final stages of merozoite development to proteolytically modify the SERA family of papain-like proteins. Here, we report that PfSUB1 has a further role in ‘priming' the merozoite prior to invasion. The major protein complex on the merozoite surface comprises three proteins called merozoite surface protein 1 (MSP1), MSP6 and MSP7. We show that just before egress, all undergo proteolytic maturation by PfSUB1. Inhibition of PfSUB1 activity results in the accumulation of unprocessed MSPs on the merozoite surface, and erythrocyte invasion is significantly reduced. We propose that PfSUB1 is a multifunctional processing protease with an essential role in both egress of the malaria merozoite and remodelling of its surface in preparation for erythrocyte invasion.
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Deletion of the Plasmodium falciparum merozoite surface protein 7 gene impairs parasite invasion of erythrocytes. EUKARYOTIC CELL 2008; 7:2123-32. [PMID: 18820076 DOI: 10.1128/ec.00274-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Merozoite surface proteins have been implicated in the initial attachment to the host red blood cell membrane that begins the process of invasion, an important step in the life cycle of the malaria parasite. In Plasmodium falciparum, merozoite surface proteins include several glycosylphosphatidyl inositol-anchored proteins and peripheral proteins attached to the membrane through protein-protein interactions. The most abundant of these proteins is the merozoite surface protein 1 (MSP1) complex, encoded by at least three genes: msp1, msp6, and msp7. The msp7 gene is part of a six-member multigene family in Plasmodium falciparum. We have disrupted msp7 in the Plasmodium falciparum D10 parasite, as confirmed by Southern hybridization. Immunoblot and indirect immunofluorescence analyses confirmed the MSP7 null phenotype of D10DeltaMSP7 parasites. The synthesis, distribution, and processing of MSP1 were not affected in this parasite line. The level of expression and cellular distribution of the proteins MSP1, MSP3, MSP6, MSP9, and SERA5 remained comparable to those for the parental line. Furthermore, no significant change in the expression of MSP7-related proteins, except for that of MSRP5, was detected at the transcriptional level. The lack of MSP7 was not lethal at the asexual blood stage, but it did impair invasion of erythrocytes by merozoites to a significant degree. Despite this reduction in efficiency, D10DeltaMSP7 parasites did not show any obvious preference for alternate pathways of invasion.
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Lucchi NW, Tongren JE, Jain V, Nagpal AC, Kauth CW, Woehlbier U, Bujard H, Dash AP, Singh N, Stiles JK, Udhayakumar V. Antibody responses to the merozoite surface protein-1 complex in cerebral malaria patients in India. Malar J 2008; 7:121. [PMID: 18601721 PMCID: PMC2491629 DOI: 10.1186/1475-2875-7-121] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 07/04/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum infection causes cerebral malaria (CM) in a subset of patients with anti-malarial treatment protecting only about 70% to 80% of patients. Why a subset of malaria patients develops CM complications, including neurological sequelae or death, is still not well understood. It is believed that host immune factors may modulate CM outcomes and there is substantial evidence that cellular immune factors, such as cytokines, play an important role in this process. In this study, the potential relationship between the antibody responses to the merozoite surface protein (MSP)-1 complex (which consists of four fragments namely: MSP-1(83), MSP-1(30), MSP-1(38) and MSP-1(42)), MSP-6(36) and MSP-7(22) and CM was investigated. METHODS Peripheral blood antibody responses to recombinant antigens of the two major allelic forms of MSP-1 complex, MSP-6(36) and MSP-7(22) were compared between healthy subjects, mild malaria patients (MM) and CM patients residing in a malaria endemic region of central India. Total IgG and IgG subclass antibody responses were determined using ELISA method. RESULTS The prevalence and levels of IgG and its subclasses in the plasma varied for each antigen. In general, the prevalence of total IgG, IgG1 and IgG3 was higher in the MM patients and lower in CM patients compared to healthy controls. Significantly lower levels of total IgG antibodies to the MSP-1(f38), IgG1 levels to MSP-1(d83), MSP-1(19) and MSP-6(36) and IgG3 levels to MSP-1(f42) and MSP-7(22) were observed in CM patients as compared to MM patients. CONCLUSION These results suggest that there may be some dysregulation in the generation of antibody responses to some MSP antigens in CM patients and it is worth investigating further whether perturbations of antibody responses in CM patients contribute to pathogenesis.
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Affiliation(s)
- Naomi W Lucchi
- Malaria Branch, Division of Parasitic Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Coordinating Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Sanders PR, Cantin GT, Greenbaum DC, Gilson PR, Nebl T, Moritz RL, Yates JR, Hodder AN, Crabb BS. Identification of protein complexes in detergent-resistant membranes of Plasmodium falciparum schizonts. Mol Biochem Parasitol 2007; 154:148-57. [PMID: 17553576 DOI: 10.1016/j.molbiopara.2007.04.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/19/2007] [Accepted: 04/20/2007] [Indexed: 11/26/2022]
Abstract
Merozoite surface proteins of the human malaria parasite Plasmodium falciparum are involved in initial contact with target erythrocytes, a process that begins a cascade of events required for successful invasion of these cells. In order to identify complexes that may play a role in invasion we purified detergent-resistant membranes (DRMs), known to be enriched in merozoite surface proteins, and used blue native-polyacrylamide gel electrophoresis (BN-PAGE) to isolate high molecular weight complexes for identification by mass spectrometry. Sixty-two proteins were detected and these mostly belonged to expected DRM proteins classes including GPI-anchored, multi-membrane spanning and rhoptry proteins. Proteins from seven known complexes were identified including MSP-1/7, the low (RAP1/2 and RAP1/3), and high (RhopH1/H2/H3) molecular weight rhoptry complexes, and the invasion motor complex (GAP45/GAP50/myosinA). Remarkably, a large proportion of identified spectra were derived from only 4 proteins: the GPI-anchored proteins MSP-1 and Pf92, the putative GPI-anchored protein Pf113 and RAP-1, the core component of the two RAP complexes. Each of these proteins predominated in high molecular weight species suggesting their aggregation in much larger complexes than anticipated. To demonstrate that the procedure had isolated novel complexes we focussed on MSP-1, which predominated as a distinct species at approximately 500 kDa by BN-PAGE, approximately twice its expected size. Chemical cross-linking supports the existence of a stable MSP-1 oligomer of approximately 500 kDa, probably comprising a highly stable homodimeric species. Our observations also suggests that oligomerization of MSP-1 is likely to occur outside the C-terminal epidermal growth factor (EGF)-like domains. Confirmation of MSP-1 oligomerization, together with the isolation of a number of known complexes by BN-PAGE, makes it highly likely that novel interactions occur amongst members of this proteome.
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Affiliation(s)
- Paul R Sanders
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, Vic 3050, Australia
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Pachebat JA, Kadekoppala M, Grainger M, Dluzewski AR, Gunaratne RS, Scott-Finnigan TJ, Ogun SA, Ling IT, Bannister LH, Taylor HM, Mitchell GH, Holder AA. Extensive proteolytic processing of the malaria parasite merozoite surface protein 7 during biosynthesis and parasite release from erythrocytes. Mol Biochem Parasitol 2006; 151:59-69. [PMID: 17097159 DOI: 10.1016/j.molbiopara.2006.10.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 09/15/2006] [Accepted: 10/11/2006] [Indexed: 11/21/2022]
Abstract
In Plasmodium falciparum, merozoite surface protein 7 (MSP7) was originally identified as a 22kDa protein on the merozoite surface and associated with the MSP1 complex shed during erythrocyte invasion. MSP7 is synthesised in schizonts as a 351-amino acid precursor that undergoes proteolytic processing. During biosynthesis the MSP1 and MSP7 precursors form a complex that is targeted to the surface of developing merozoites. In the sequential proteolytic processing of MSP7, N- and C-terminal 20 and 33kDa products of primary processing, MSP7(20) and MSP7(33) are formed and MSP7(33) remains bound to full length MSP1. Later in the mature schizont, MSP7(20) disappears from the merozoite surface and on merozoite release MSP7(33) undergoes a secondary cleavage yielding the 22kDa MSP7(22) associated with MSP1. In free merozoites, both MSP7(22) and a further cleaved product, MSP7(19) present only in some parasite lines, were detected; these two derivatives are shed as part of the protein complex with MSP1 fragments during erythrocyte invasion. Primary processing of MSP7 is brefeldin A-sensitive while secondary processing is resistant to both calcium chelators and serine protease inhibitors. Primary processing of MSP7 occurs prior to that of MSP1 in a post-Golgi compartment, whereas the secondary cleavage occurs on the surface of the developing merozoite, possibly at the time of MSP1 primary processing and well before the secondary processing of MSP1.
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Affiliation(s)
- Justin A Pachebat
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW1 1AA, UK
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Kauth CW, Woehlbier U, Kern M, Mekonnen Z, Lutz R, Mu¨cke N, Langowski J, Bujard H. Interactions between Merozoite Surface Proteins 1, 6, and 7 of the Malaria Parasite Plasmodium falciparum. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84065-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kauth CW, Woehlbier U, Kern M, Mekonnen Z, Lutz R, Mücke N, Langowski J, Bujard H. Interactions between merozoite surface proteins 1, 6, and 7 of the malaria parasite Plasmodium falciparum. J Biol Chem 2006; 281:31517-27. [PMID: 16940297 DOI: 10.1074/jbc.m604641200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Merozoites of the malaria parasite Plasmodium falciparum expose at their surface a large multiprotein complex, composed of proteolytically processed, noncovalently associated products of at least three genes, msp-1, msp-6, and msp-7. During invasion of erythrocytes, this complex is shed from the surface except for a small glycosylphosphatidylinositol-anchored portion originating from MSP-1. The proteolytic cleavage separating the C-terminal portion of MSP-1 is required for successful invasion. Little is known about the structure and function of the abundant and essential multipartite complex. Using heterologously produced MSP-1, MSP-6, and MSP-7 in precursor and with the exception of MSP-7 in processed form, we have studied in vitro the complex formation between the different proteins to identify the interaction partners within the complex. Both MSP-6(36) and MSP-7 bind only to MSP-1 subunits that are shed, but although MSP-6(36) contacts just subunit p38, MSP-7 interacts with p83, p30, and p38. The intact C-terminal region of MSP-6 is required for the association with p38 as well as for its multimerization into tetramers. Furthermore, our data suggest that only the processed form and not the precursor form of MSP-1 interacts with MSP-6(36). MSP-6- as well as MSP-7-specific rabbit antibodies inhibit parasite multiplication in vitro as shown previously for antibodies directed against MSP-1. Our findings raise interesting questions with regard to proteolysis-mediated mechanisms of maturation of the MSP-1-MSP-6-MSP-7 complex and to the mode by which antibodies directed against this complex interfere with parasite multiplication.
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Affiliation(s)
- Christian W Kauth
- Zentrum fuer Molekulare Biologie der Universitaet Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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López R, Valbuena J, Rodríguez LE, Ocampo M, Vera R, Curtidor H, Puentes A, García J, Ramirez LE, Patarroyo ME. Plasmodium falciparum merozoite surface protein 6 (MSP-6) derived peptides bind erythrocytes and partially inhibit parasite invasion. Peptides 2006; 27:1685-92. [PMID: 16713025 DOI: 10.1016/j.peptides.2006.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 02/02/2006] [Accepted: 02/03/2006] [Indexed: 11/19/2022]
Abstract
This work shows that Plasmodium falciparum merozoite surface protein-6 (MSP-6) peptides specifically bind to membrane surface receptor on human erythrocytes. Three high activity binding peptides (HABPs) were found: peptides 31175 (41MYNNDKILSKNEVDTNIESN60) and 31178 (101YDIQATYQFPSTSGGNNVIP120) in the amino terminal region and 31191 (361EIDSTINNLVQEMIHLFSNNY380) at the carboxy terminal. Their binding to erythrocytes was saturable. HABPs 31191 and 31178 recognized 56 and 26 kDa receptors on erythrocyte membrane and inhibited in vitro Plasmodium falciparum merozoite invasion of erythrocytes by between 27% and 46% at 200 microg ml(-1) concentration, suggesting that these MSP-6 protein peptides play a possible role in the invasion process.
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Affiliation(s)
- Ramsés López
- Fundación Instituto de Inmunología de Colombia (FIDIC) and Universidad Nacional de Colombia, Colombia.
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28
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Woehlbier U, Epp C, Kauth CW, Lutz R, Long CA, Coulibaly B, Kouyaté B, Arevalo-Herrera M, Herrera S, Bujard H. Analysis of antibodies directed against merozoite surface protein 1 of the human malaria parasite Plasmodium falciparum. Infect Immun 2006; 74:1313-22. [PMID: 16428781 PMCID: PMC1360310 DOI: 10.1128/iai.74.2.1313-1322.2006] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 190-kDa merozoite surface protein 1 (MSP-1) of Plasmodium falciparum, an essential component in the parasite's life cycle, is a primary candidate for a malaria vaccine. Rabbit antibodies elicited by the heterologously produced MSP-1 processing products p83, p30, p38, and p42, derived from strain 3D7, were analyzed for the potential to inhibit in vitro erythrocyte invasion by the parasite and parasite growth. Our data show that (i) epitopes recognized by antibodies, which inhibit parasite replication, are distributed throughout the entire MSP-1 molecule; (ii) when combined, antibodies specific for different regions of MSP-1 inhibit in a strictly additive manner; (iii) anti-MSP-1 antibodies interfere with erythrocyte invasion as well as with the intraerythrocytic growth of the parasite; and (iv) antibodies raised against MSP-1 of strain 3D7 strongly cross-inhibit replication of the heterologous strain FCB-1. Accordingly, anti-MSP-1 antibodies appear to be capable of interfering with parasite multiplication at more than one level. Since the overall immunogenicity profile of MSP-1 in rabbits closely resembles that found in sera of Aotus monkeys immunized with parasite-derived MSP-1 and of humans semi-immune to malaria from whom highly inhibiting antigen-specific antibodies were recovered, we consider the findings reported here to be relevant for the development of MSP-1-based vaccines against malaria.
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Affiliation(s)
- Ute Woehlbier
- Zentrum fuer Molekulare Biologie (ZMBH), Universitaet Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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29
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Pearce JA, Mills K, Triglia T, Cowman AF, Anders RF. Characterisation of two novel proteins from the asexual stage of Plasmodium falciparum, H101 and H103. Mol Biochem Parasitol 2005; 139:141-51. [PMID: 15664649 DOI: 10.1016/j.molbiopara.2004.09.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2004] [Revised: 09/22/2004] [Accepted: 09/23/2004] [Indexed: 10/26/2022]
Abstract
The merozoite surface of the pathogenic malaria parasite Plasmodium falciparum is comprised of proteins that are important for the identification and invasion of human red cells. Merozoite surface protein (MSP)3 is a polymorphic protein associated with the surface of merozoites and is also a vaccine candidate. A distinct feature of the MSP3 sequence is three blocks of alanine-rich heptad repeats that are predicted to form an intramolecular coiled-coil. Three orthologues of MSP3 that also contain alanine-rich heptad repeats have been described in P. vivax and we therefore searched the P. falciparum genome database for MSP3 paralogues. We have identified two genes, H101 and H103 related to MSP3, however like another MSP3 paralogue, MSP6, H101 and H103 do not contain heptad repeats. H101 and H103 are expressed during the asexual cycle and immunofluorescence indicates H103 localises to the merozoite surface as a peripheral membrane protein. Transfected parasite lines that express truncated forms of H101 or H103 were viable and grew at the same rate as the parental parasite line. This result may reflect redundancy in function among members of the MSP3/MSP6 gene family as has been described for other families of paralogue genes in P. falciparum.
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Affiliation(s)
- J Andrew Pearce
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, Vic. 3050, Australia.
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30
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Pearce JA, Hodder AN, Anders RF. The alanine-rich heptad repeats are intact in the processed form of Plasmodium falciparum MSP3. Exp Parasitol 2005; 108:186-9. [PMID: 15582517 DOI: 10.1016/j.exppara.2004.07.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Revised: 07/23/2004] [Accepted: 07/26/2004] [Indexed: 11/23/2022]
Abstract
The potential of Plasmodium falciparum merozoite surface protein 3 as a component of an asexual-stage malaria vaccine is currently being assessed. The precursor form of MSP3 undergoes cleavage during schizogony to generate a mature processed form. It is unknown if this cleavage event is necessary for MSP3 function, but it may be an important consideration for assessing and developing MSP3 as an asexual-stage vaccine candidate. We have therefore determined the cleavage site in MSP3 by sequencing the N-terminus of the processed form of MSP3, which was isolated from parasite material. The position of the cleavage site indicates that the processed form of MSP3 retains the three blocks of alanine-rich heptad repeats, which are predicted to provide the structural framework for an intramolecular coiled-coil. The cleavage-site motif has many features in common with the published cleavage sites of MSP1(30), MSP6(36), and MSP7(22), which are all located on the merozoite surface and are implicated in the erythrocyte invasion process. The common cellular location and similar cleavage-site motifs suggest that these merozoite proteins may be cleaved by the same or related proteases.
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Affiliation(s)
- J Andrew Pearce
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Vic. 3050, Australia
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31
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Tewari R, Ogun SA, Gunaratne RS, Crisanti A, Holder AA. Disruption of Plasmodium berghei merozoite surface protein 7 gene modulates parasite growth in vivo. Blood 2004; 105:394-6. [PMID: 15339842 DOI: 10.1182/blood-2004-06-2106] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Merozoite invasion of red blood cells is crucial to the development of the parasite that causes malaria. Merozoite surface proteins (MSPs) mediate the first interaction between parasite and erythrocyte. In Plasmodium falciparum, they include a complex of products from at least 3 genes (msp1, msp6, and msp7), one of which, msp7, is part of a gene family containing 3 and 6 adjacent members in Plasmodium yoelii and Plasmodium falciparum, respectively. We have identified and disrupted msp7 in the Plasmodium berghei gene family. The protein is expressed in schizonts and colocalizes with MSP1. The synthesis and processing of MSP1 was unaffected in the parasite with the disrupted gene (MSP7ko). Disruption of msp7 was not lethal but affected blood-stage parasite growth. MSP7ko parasites initially grew more slowly than wild-type parasites. However, when reticulocytes were prevalent, the rate of increase in parasitemia was similar, suggesting that MSP7ko parasites prefer to invade and grow within reticulocytes.
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Affiliation(s)
- Rita Tewari
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
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32
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Pearce JA, Triglia T, Hodder AN, Jackson DC, Cowman AF, Anders RF. Plasmodium falciparum merozoite surface protein 6 is a dimorphic antigen. Infect Immun 2004; 72:2321-8. [PMID: 15039357 PMCID: PMC375173 DOI: 10.1128/iai.72.4.2321-2328.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Merozoite surface protein 1 (MSP1) is a highly polymorphic Plasmodium falciparum merozoite surface protein implicated in the invasion of human erythrocytes during the asexual cycle. It forms a complex with MSP6 and MSP7 on the merozoite surface, and this complex is released from the parasite around the time of erythrocyte invasion. MSP1 and many other merozoite surface proteins contain dimorphic elements in their protein structures, and here we show that MSP6 is also dimorphic. The sequences of eight MSP6 genes indicate that the alleles of each dimorphic form of MSP6 are highly conserved. The smaller 3D7-type MSP6 alleles are detected in parasites from all malarious regions of the world, whereas K1-type MSP6 alleles have only been detected in parasites from mainland Southeast Asia. Cleavage of MSP6, which produces the p36 fragment in 3D7-type MSP6 and associates with MSP1, also occurs in K1-type MSP6 but at a different site in the protein. Anti-3D7 MSP6 antibodies weakly inhibited erythrocyte invasion by homologous 3D7 merozoites but did not inhibit a parasite line expressing the K1-type MSP6 allele. Antibodies from hyperimmune individuals affinity purified on an MSP3 peptide cross-reacted with MSP6; therefore, MSP6 may also be a target of antibody-dependent cellular inhibition.
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Affiliation(s)
- J Andrew Pearce
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia.
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33
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Wang L, Crouch L, Richie TL, Nhan DH, Coppel RL. Naturally acquired antibody responses to the components of the Plasmodium falciparum merozoite surface protein 1 complex. Parasite Immunol 2004; 25:403-12. [PMID: 14651587 DOI: 10.1111/j.1365-3024.2003.00647.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Merozoite surface protein 6 (MSP6) and 7 (MSP7) of Plasmodium falciparum are peripheral membrane proteins whose cleaved products, MSP636, MSP722 and MSP719, are found on the merozoite surface as components of a non-covalently bound complex which also contains four polypeptides derived from merozoite surface protein 1 (MSP1). We have expressed both the precursor regions and the processed mature products of MSP6 and MSP7 in Escherichia coli and showed that these recombinant proteins react with human immune sera. In a set of sera collected from individuals living in malaria-endemic areas of Southern-central Vietnam, antibodies to the mature polypeptides of MSP636 and MSP722 were detected in 50.6 and 85.6% of the serum samples, whereas antibodies to the precursor regions of MSP6 and MSP7 were detected in only 12.1 and 42.5% of the serum samples, respectively. The predominant subclass of anti-MSP6 antibodies was IgG1, whereas the predominant subclass of anti-MSP7 antibodies was IgG3. In the same set of serum samples, the antibody responses to MSP119 are predominantly IgGI, whereas antibodies to merozoite surface protein 4 (MSP4) are mainly IgG3. This data is consistent with the proposition that, during malaria infection, variable proteins induce responses that are predominantly of the IgG3 isotype, and conserved proteins induce responses that are predominantly IgG1. The antibodies to MSP6, MSP7 and MSP119 all decreased at the time of infection, but increased during the convalescent period. No correlation was observed between the antibodies at the commencement of the study and absence of parasitaemia during surveillance in this population.
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Affiliation(s)
- Lina Wang
- Department of Microbiology and the Victoria Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
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34
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Li X, Chen H, Oo TH, Daly TM, Bergman LW, Liu SC, Chishti AH, Oh SS. A Co-ligand Complex Anchors Plasmodium falciparum Merozoites to the Erythrocyte Invasion Receptor Band 3. J Biol Chem 2004; 279:5765-71. [PMID: 14630931 DOI: 10.1074/jbc.m308716200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Plasmodium falciparum malaria, erythrocyte invasion by circulating merozoites may occur via two distinct pathways involving either a sialic acid-dependent or -independent mechanism. Earlier, we identified two nonglycosylated exofacial regions of erythrocyte band 3 termed 5ABC and 6A as an important host receptor in the sialic acid-independent invasion pathway. 5ABC, a major segment of this receptor, interacts with the 42-kDa processing product of merozoite surface protein 1 (MSP1(42)) through its 19-kDa C-terminal domain. Here, we show that two regions of merozoite surface protein 9 (MSP9), also known as acidic basic repeat antigen, interact directly with 5ABC during erythrocyte invasion by P. falciparum. Native MSP9 as well as recombinant polypeptides derived from two regions of MSP9 (MSP9/Delta1 and MSP9/Delta2) interacted with both 5ABC and intact erythrocytes. Soluble 5ABC added to the assay mixture drastically diminished the binding of MSP9 to erythrocytes. Recombinant MSP9/Delta1 and MSP9/Delta2 present in the culture medium blocked P. falciparum reinvasion into erythrocytes in vitro. Native MSP9 and MSP1(42), the two ligands binding to the 5ABC receptor, existed as a stable complex. Our results establish a novel concept wherein the merozoite exploits a specific complex of co-ligands on its surface to target a single erythrocyte receptor during invasion. This new paradigm poses a new challenge in the development of a vaccine for blood stage malaria.
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Affiliation(s)
- Xuerong Li
- Division of Cell Biology, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02135, USA
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35
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Kauth CW, Epp C, Bujard H, Lutz R. The merozoite surface protein 1 complex of human malaria parasite Plasmodium falciparum: interactions and arrangements of subunits. J Biol Chem 2003; 278:22257-64. [PMID: 12654909 DOI: 10.1074/jbc.m302299200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The major protein component at the surface of merozoites, the infectious form of blood stage malaria parasites, is the merozoite surface protein 1 (MSP-1) complex. In the human malaria parasite Plasmodium falciparum, this complex is generated by proteolytic cleavage of a 190-kDa glycosylphosphatidylinositol-anchored precursor into four major fragments, which remain non-covalently associated. Here, we describe the in vitro reconstitution of the MSP-1 complex of P. falciparum strain 3D7 from its heterologously produced subunits. We provide evidence for the arrangement of the subunits within the complex and show how they interact with each other. Our data indicate that the conformation assumed by the reassembled complex as well as by the heterologously produced 190-kDa precursor corresponds to the native one. Based on these results we propose a first structural model for the MSP-1 complex. Together with access to faithfully produced material, this information will advance further structure-function studies of MSP-1 that plays an essential role during invasion of erythrocytes by the parasite and that is considered a promising candidate for a malaria vaccine.
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Affiliation(s)
- Christian W Kauth
- Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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36
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Black CG, Wang L, Wu T, Coppel RL. Apical location of a novel EGF-like domain-containing protein of Plasmodium falciparum. Mol Biochem Parasitol 2003; 127:59-68. [PMID: 12615336 DOI: 10.1016/s0166-6851(02)00308-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using bioinformatics analyses of the unfinished malaria genome sequence, we have identified a novel protein of Plasmodium falciparum that contains two epidermal growth factor (EGF)-like domains near the C-terminus of the protein. The sequence contains a single open reading frame of 1572bp with the potential to encode a protein of 524 residues containing hydrophobic regions at the extreme N- and C-termini which appear to represent signal peptide and glycosylphosphatidylinositol (GPI)-attachment sites, respectively. RT-PCR analysis has confirmed that the novel gene is transcribed in asexual stages of P. falciparum. Antibodies to the EGF-like domains of the novel protein are highly specific and do not cross-react with the EGF-like domains of MSP1, MSP4, MSP5 or MSP8 expressed as GST fusion proteins. Antisera to the C-terminal fragments react with two bands of 80 and 36kDa in P. falciparum parasite lysates whereas antisera to the most N-terminal fusion protein only recognises the 80kDa band, suggesting that the novel protein may undergo processing in a similar way to MSP1 and MSP8, but with fewer cleavage events. Immunoblot analysis of stage-specific parasite samples reveals that the protein is present in trophozoites, schizonts and in isolated merozoites. The protein partitions in the detergent-enriched phase after Triton X-114 fractionation and is localised to the surfaces of trophozoites, schizonts and free merozoites in an apical distribution. Based on the accepted nomenclature in the field we now designate this protein MSP10. We have shown that the MSP10 fusion proteins are in a conformation that can be recognised by human immune sera and that there is very limited sequence diversity in an approximately lkb region of MSP10, encompassing the two EGF-like domains. A sequence similar to MSP10 can be identified in the available P. yoelii genomic sequence, offering the possibility of ascertaining whether this novel protein can induce host protective responses in an in vivo model.
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Affiliation(s)
- Casilda G Black
- Department of Microbiology and the Victorian Bioinformatics Consortium, P.O. Box 53, Monash University, 3800 Victoria, Australia.
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37
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Mello K, Daly TM, Morrisey J, Vaidya AB, Long CA, Bergman LW. A multigene family that interacts with the amino terminus of plasmodium MSP-1 identified using the yeast two-hybrid system. EUKARYOTIC CELL 2002; 1:915-25. [PMID: 12477792 PMCID: PMC138761 DOI: 10.1128/ec.1.6.915-925.2002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Merozoite surface protein 1 (MSP-1) is a high-molecular-weight protein expressed on the surface of the malaria merozoite in a noncovalent complex with other protein molecules. MSP-1 undergoes a series of proteolytic processing events, but no precise biological role for the various proteolytic fragments of MSP-1 or for the additional proteins present in the complex is known. Through the use of the yeast two-hybrid system, we have isolated genes encoding proteins that interact with a region of the amino-terminal proteolytic fragment of MSP-1 from the mouse parasite Plasmodium yoelii. This analysis has led to the isolation of two sequence-related molecules, one of which is the P. yoelii homologue of MSP-7 originally described in Plasmodium falciparum. BLAST analysis of the P. falciparum database has revealed that there are six related protein molecules present in this species encoded near each other on chromosome 13. In P. falciparum, we designated these molecules MSRP-1 to -5. Analysis of the P. yoelii database indicates a similar chromosomal organization for the two genes in the mouse parasite species. The three P. falciparum sequences with the highest degree of homology to the P. yoelii sequences isolated in the two-hybrid screen have been characterized at the molecular level (MSRP-1 to -3). Expression analysis indicated that the mRNAs are expressed at various levels in the different asexual stages. Immunofluorescence studies colocalized the expression of the MSRP molecules and the amino-terminal portion of MSP-1 to the surfaces of trophozoites. In vitro binding experiments confirmed the interaction between MSRP-1, MSRP-2, and the amino-terminal region of P. falciparum MSP-1.
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Affiliation(s)
- Kerrianne Mello
- Division of Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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38
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Abstract
Erythrocyte invasion by Plasmodium falciparum involves multiple ligand-receptor interactions and numerous apparent redundancies. The genome sequence of this parasite reveals new gene families encoding proteins that appear to mediate erythrocyte invasion.
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Affiliation(s)
- Alan F Cowman
- Walter and Eliza Hall Institute of Medical Research, PO Royal Melbourne Hospital, Melbourne, Victoria 3050, Australia.
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39
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Galinski MR, Ingravallo P, Corredor-Medina C, Al-Khedery B, Povoa M, Barnwell JW. Plasmodium vivax merozoite surface proteins-3beta and-3gamma share structural similarities with P. vivax merozoite surface protein-3alpha and define a new gene family. Mol Biochem Parasitol 2001; 115:41-53. [PMID: 11377738 DOI: 10.1016/s0166-6851(01)00267-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The genes encoding two merozoite surface proteins of Plasmodium vivax that are related to PvMSP3 [1] are reported. One of these genes was identified within P. vivax lambdagt11 clone 5.4, which was selected by immunoscreening with a Saimiri monkey antiserum. The insert DNA of this clone was used as a probe to isolate the complete gene from a P. vivax lambdaDASH genomic (g) DNA library. Antibodies to recombinant 5.4 and subsequent fusion proteins produce a pattern of circumferential surface fluorescence by indirect immunofluorescence assays (IFA) on segmented schizonts and free intact merozoites, and recognize a 125 kDa protein via western immunoblots. The gene, however, encodes a protein with a calculated size of 75677 Da, and 3' and 5' RACE analyses were employed to confirm the size of the gene and its coding region. The second related P. vivax gene was isolated by hybridization of a fragment of an orthologous P. knowlesi gene. The encoded proteins of all three related P. vivax genes have putative signal peptides, large central domains that contain >20% alanine residues bound by charged regions, are predicted to form alpha-helices with heptad repeat coiled-coil structures, and do not have a hydrophobic region that could anchor them to the surface of the merozoite. Although the overall identity in amino acid alignment among the three encoded proteins is low (<40%), the shared predicted structural features and motifs indicate that they are members of an intra-species family, which we are designating as the PvMSP-3 family with the reported members being Pvmsp-3alpha, Pvmsp-3beta, and Pvmsp-3gamma. We further demonstrate that this family also includes related proteins from P. knowlesi and P. falciparum.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- Base Sequence
- Blotting, Western
- DNA, Protozoan/analysis
- DNA, Protozoan/genetics
- Escherichia coli/genetics
- Escherichia coli/immunology
- Escherichia coli/metabolism
- Fluorescent Antibody Technique
- Genes, Protozoan
- Humans
- Malaria, Vivax/parasitology
- Molecular Sequence Data
- Plasmodium vivax/genetics
- Plasmodium vivax/growth & development
- Plasmodium vivax/metabolism
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Rabbits
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/immunology
- Recombinant Fusion Proteins/metabolism
- Saimiri
- Sequence Analysis, DNA
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Affiliation(s)
- M R Galinski
- Emory University, Department of Medicine, Emory Vaccine Research Center, Yerkes Primate Research Center, 954 Gatewood Road, 30329, Atlanta, GA, USA.
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40
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Daly TM, Long CA, Bergman LW. Interaction between two domains of the P. yoelii MSP-1 protein detected using the yeast two-hybrid system. Mol Biochem Parasitol 2001; 117:27-35. [PMID: 11551629 DOI: 10.1016/s0166-6851(01)00329-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several model systems of plasmodia have demonstrated the potential of the merozoite surface protein, MSP-1, to induce protective immunity. However, little is known about the function of this protein or its interaction with other surface molecules that may also serve as immunological targets. To identify potentially significant inter- and intra-molecular interactions involving MSP-1, we have utilized the yeast two-hybrid system. A cDNA activation domain library was constructed from the erythrocytic stages of the murine malarial parasite Plasmodium yoelii yoelii 17XL. A 795 bp region of Py17XL MSP-1 (bait), homologous to the Plasmodium falciparum MSP1(33) fragment, was inserted into a Gal4p DNA binding domain vector and used to screen the activation domain library (target). Several randomly selected clones that demonstrated bait-target interaction were found to express overlapping regions of Py17XL MSP-1. Deletion constructs further localized the peptide fragments retaining interaction indicating that a region within the MSP-1(38) fragment interacts with the MSP-1 bait domain. Subsequent studies confirmed this interaction, as both peptides were co-precipitated from cell lysate by a peptide tag-specific antibody. It was observed that the interaction of these two fragments significantly increased the half-life of the MSP-1(38) within yeast cells. The specific interaction described here demonstrates the potential of this approach to elucidate additional inter- or intra-molecular interactions of Py17XL MSP1 and other malarial proteins.
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Affiliation(s)
- T M Daly
- Department of Microbiology and Immunology, MCP Hahnemann University, 2900 Queen Lane, Philadelphia, PA 19129, USA
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41
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Pachebat JA, Ling IT, Grainger M, Trucco C, Howell S, Fernandez-Reyes D, Gunaratne R, Holder AA. The 22 kDa component of the protein complex on the surface of Plasmodium falciparum merozoites is derived from a larger precursor, merozoite surface protein 7. Mol Biochem Parasitol 2001; 117:83-9. [PMID: 11551634 DOI: 10.1016/s0166-6851(01)00336-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The gene coding for merozoite surface protein 7 has been identified and sequenced in three lines of Plasmodium falciparum. The gene encodes a 351 amino acid polypeptide that is the precursor of a 22-kDa protein (MSP7(22)) on the merozoite surface and non-covalently associated with merozoite surface protein 1 (MSP1) complex shed from the surface at erythrocyte invasion. A second 19-kDa component of the complex (MSP7(19)) was shown to be derived from MSP7(22) and the complete primary structure of this polypeptide was confirmed by mass spectrometry. The protein sequence contains several predicted helical and two beta elements, but has no similarity with sequences outside the Plasmodium databases. Four sites of sequence variation were identified in MSP7, all within the MSP7(22) region. The MSP7 gene is expressed in mature schizonts, at the same time as other merozoite surface protein genes. It is proposed that MSP7(22) is the result of cleavage by a protease that may also cleave MSP1 and MSP6. A related gene was identified and cloned from the rodent malaria parasite, Plasmodium yoelii YM; at the amino acid level this sequence was 23% identical and 50% similar to that of P. falciparum MSP7.
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Affiliation(s)
- J A Pachebat
- Division of Parasitology, National Institute for Medical Research, Mill Hill, NW7 1AA, London, UK
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Trucco C, Fernandez-Reyes D, Howell S, Stafford WH, Scott-Finnigan TJ, Grainger M, Ogun SA, Taylor WR, Holder AA. The merozoite surface protein 6 gene codes for a 36 kDa protein associated with the Plasmodium falciparum merozoite surface protein-1 complex. Mol Biochem Parasitol 2001; 112:91-101. [PMID: 11166390 DOI: 10.1016/s0166-6851(00)00350-9] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A complex of non-covalently bound polypeptides is located on the surface of the merozoite form of the human malaria parasite Plasmodium falciparum. Four of these polypeptides are derived by proteolytic processing of the merozoite surface protein 1 (MSP-1) precursor. Two components, a 22 and a 36 kDa polypeptide are not derived from MSP-1. The N-terminal sequence of the 36 kDa polypeptide has been determined, the corresponding gene cloned, and the protein characterised. The 36 kDa protein consists of 211 amino acids and is derived from a larger precursor of 371 amino acids. The precursor merozoite surface protein 6 (MSP-6) has been designated, and the 36 kDa protein, MSP-6(36). Mass spectrometric analysis of peptides released from the polypeptide by tryptic digestion confirmed that the gene identified codes for MSP-6(36). Antibodies were produced to a recombinant protein containing the C-terminal 45 amino acid residues of MSP-6(36). In immunofluorescence studies these antibodies bound to antigen at the parasite surface or in the parasitophorous vacuole within schizonts, with a pattern indistinguishable from that of antibodies to MSP-1. MSP-6(36) was present in the MSP-1 complex immunoprecipitated from the supernatant of in vitro parasite cultures, but was also immunoprecipitated from this supernatant in a form not bound to MSP-1. Examination of the MSP-6 gene in three parasite lines detected no sequence variation. The sequence of MSP-6(36) is related to that of the previously described merozoite surface protein 3 (MSP-3). The MSP-6(36) amino acid sequence has 50% identity and 85% similarity with the C-terminal region of MSP-3. The proteins share a specific sequence pattern (ILGWEFGGG-[AV]-P) and a glutamic acid-rich region. The remainder of MSP-6 and MSP-3 are unrelated, except at the N-terminus. Both MSP-6(36) and MSP-3 are partially associated with the parasite surface and partially released as soluble proteins on merozoite release. MSP-6(36) is a hydrophilic negatively charged polypeptide, but there are two clusters of hydrophobic amino acids at the C-terminus, located in two amphipathic helical structures identified from secondary structure predictions. It was suggested that this 35 residue C-terminal region may be involved in MSP-6(36) binding to MSP-1 or other molecules; alternatively, based on the secondary structure and coil formation predictions, the region may form an intramolecular anti-parallel coiled-coil structure.
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Affiliation(s)
- C Trucco
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London, UK.
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Guevara Patiño JA, Holder AA, McBride JS, Blackman MJ. Antibodies that inhibit malaria merozoite surface protein-1 processing and erythrocyte invasion are blocked by naturally acquired human antibodies. J Exp Med 1997; 186:1689-99. [PMID: 9362529 PMCID: PMC2199131 DOI: 10.1084/jem.186.10.1689] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/1997] [Revised: 08/12/1997] [Indexed: 02/05/2023] Open
Abstract
Merozoite surface protein-1 (MSP-1) of the human malaria parasite Plasmodium falciparum undergoes at least two endoproteolytic cleavage events during merozoite maturation and release, and erythrocyte invasion. We have previously demonstrated that mAbs which inhibit erythrocyte invasion and are specific for epitopes within a membrane-proximal, COOH-terminal domain of MSP-1 (MSP-119) prevent the critical secondary processing step which occurs on the surface of the extracellular merozoite at around the time of erythrocyte invasion. Certain other anti-MSP-119 mAbs, which themselves inhibit neither erythrocyte invasion nor MSP-1 secondary processing, block the processing-inhibitory activity of the first group of antibodies and are termed blocking antibodies. We have now directly quantitated antibody-mediated inhibition of MSP-1 secondary processing and invasion, and the effects on this of blocking antibodies. We show that blocking antibodies function by competing with the binding of processing-inhibitory antibodies to their epitopes on the merozoite. Polyclonal rabbit antibodies specific for certain MSP-1 sequences outside of MSP-119 also act as blocking antibodies. Most significantly, affinity-purified, naturally acquired human antibodies specific for epitopes within the NH2-terminal 83-kD domain of MSP-1 very effectively block the processing-inhibitory activity of the anti-MSP-119 mAb 12.8. The presence of these blocking antibodies also completely abrogates the inhibitory effect of mAb 12.8 on erythrocyte invasion by the parasite in vitro. Blocking antibodies therefore (a) are part of the human response to malarial infection; (b) can be induced by MSP-1 structures unrelated to the MSP-119 target of processing-inhibitory antibodies; and (c) have the potential to abolish protection mediated by anti-MSP-119 antibodies. Our results suggest that an effective MSP-119-based falciparum malaria vaccine should aim to induce an antibody response that prevents MSP-1 processing on the merozoite surface.
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MESH Headings
- Animals
- Antibodies, Blocking/pharmacology
- Antibodies, Blocking/physiology
- Antibodies, Protozoan/pharmacology
- Antibody Specificity
- Antigen Presentation/immunology
- Antigens, Protozoan/immunology
- Binding Sites, Antibody
- Binding, Competitive/immunology
- Erythrocytes/parasitology
- Humans
- Immunity, Innate
- Immunodominant Epitopes/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Merozoite Surface Protein 1
- Mice
- Plasmodium falciparum/immunology
- Plasmodium falciparum/metabolism
- Plasmodium falciparum/pathogenicity
- Protein Precursors/immunology
- Protein Precursors/metabolism
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Rabbits
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Affiliation(s)
- J A Guevara Patiño
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
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Trager W, Jensen JB. Continuous culture of Plasmodium falciparum: its impact on malaria research. Int J Parasitol 1997; 27:989-1006. [PMID: 9363481 DOI: 10.1016/s0020-7519(97)00080-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The methods developed by us in 1976 for the continuous culture of the erythrocytic stages of Plasmodium falciparum make this organism available to a large variety of scientists. As a result, much has been learned about P. falciparum during the past 20 years. Here we attempt to emphasize recent developments in the diverse aspects for which the culture method has been particularly useful: chemotherapy; drug resistance; vaccine development; pathogenesis; export of proteins into the host cell; cell biology, the mitochondrion and the plastid; innate resistance involving mutant human erythrocytes; gametocytogenesis; genetics, transfection; molecular biology; biochemistry; extracellular cultivation.
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Affiliation(s)
- W Trager
- Rockefeller University, New York, NY 10021, USA
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