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Takashima E, Otsuki H, Morita M, Ito D, Nagaoka H, Yuguchi T, Hassan I, Tsuboi T. The Need for Novel Asexual Blood-Stage Malaria Vaccine Candidates for Plasmodium falciparum. Biomolecules 2024; 14:100. [PMID: 38254700 PMCID: PMC10813614 DOI: 10.3390/biom14010100] [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: 10/03/2023] [Revised: 12/25/2023] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Extensive control efforts have significantly reduced malaria cases and deaths over the past two decades, but in recent years, coupled with the COVID-19 pandemic, success has stalled. The WHO has urged the implementation of a number of interventions, including vaccines. The modestly effective RTS,S/AS01 pre-erythrocytic vaccine has been recommended by the WHO for use in sub-Saharan Africa against Plasmodium falciparum in children residing in moderate to high malaria transmission regions. A second pre-erythrocytic vaccine, R21/Matrix-M, was also recommended by the WHO on 3 October 2023. However, the paucity and limitations of pre-erythrocytic vaccines highlight the need for asexual blood-stage malaria vaccines that prevent disease caused by blood-stage parasites. Few asexual blood-stage vaccine candidates have reached phase 2 clinical development, and the challenges in terms of their efficacy include antigen polymorphisms and low immunogenicity in humans. This review summarizes the history and progress of asexual blood-stage malaria vaccine development, highlighting the need for novel candidate vaccine antigens/molecules.
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Affiliation(s)
- Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; (M.M.); (H.N.); (T.Y.); (I.H.)
| | - Hitoshi Otsuki
- Division of Medical Zoology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Yonago 683-8503, Japan; (H.O.); (D.I.)
| | - Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; (M.M.); (H.N.); (T.Y.); (I.H.)
| | - Daisuke Ito
- Division of Medical Zoology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Yonago 683-8503, Japan; (H.O.); (D.I.)
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; (M.M.); (H.N.); (T.Y.); (I.H.)
| | - Takaaki Yuguchi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; (M.M.); (H.N.); (T.Y.); (I.H.)
| | - Ifra Hassan
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; (M.M.); (H.N.); (T.Y.); (I.H.)
| | - Takafumi Tsuboi
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
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2
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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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3
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Wichers JS, Mesén-Ramírez P, Fuchs G, Yu-Strzelczyk J, Stäcker J, von Thien H, Alder A, Henshall I, Liffner B, Nagel G, Löw C, Wilson D, Spielmann T, Gao S, Gilberger TW, Bachmann A, Strauss J. PMRT1, a Plasmodium-Specific Parasite Plasma Membrane Transporter, Is Essential for Asexual and Sexual Blood Stage Development. mBio 2022; 13:e0062322. [PMID: 35404116 PMCID: PMC9040750 DOI: 10.1128/mbio.00623-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 12/12/2022] Open
Abstract
Membrane transport proteins perform crucial roles in cell physiology. The obligate intracellular parasite Plasmodium falciparum, an agent of human malaria, relies on membrane transport proteins for the uptake of nutrients from the host, disposal of metabolic waste, exchange of metabolites between organelles, and generation and maintenance of transmembrane electrochemical gradients for its growth and replication within human erythrocytes. Despite their importance for Plasmodium cellular physiology, the functional roles of a number of membrane transport proteins remain unclear, which is particularly true for orphan membrane transporters that have no or limited sequence homology to transporter proteins in other evolutionary lineages. Therefore, in the current study, we applied endogenous tagging, targeted gene disruption, conditional knockdown, and knockout approaches to investigate the subcellular localization and essentiality of six membrane transporters during intraerythrocytic development of P. falciparum parasites. They are localized at different subcellular structures-the food vacuole, the apicoplast, and the parasite plasma membrane-and four out of the six membrane transporters are essential during asexual development. Additionally, the plasma membrane resident transporter 1 (PMRT1; PF3D7_1135300), a unique Plasmodium-specific plasma membrane transporter, was shown to be essential for gametocytogenesis and functionally conserved within the genus Plasmodium. Overall, we reveal the importance of four orphan transporters to blood stage P. falciparum development, which have diverse intracellular localizations and putative functions. IMPORTANCE Plasmodium falciparum-infected erythrocytes possess multiple compartments with designated membranes. Transporter proteins embedded in these membranes not only facilitate movement of nutrients, metabolites, and other molecules between these compartments, but also are common therapeutic targets and can confer antimalarial drug resistance. Orphan membrane transporters in P. falciparum without sequence homology to transporters in other evolutionary lineages and divergent from host transporters may constitute attractive targets for novel intervention approaches. Here, we localized six of these putative transporters at different subcellular compartments and probed their importance during asexual parasite growth by using reverse genetic approaches. In total, only two candidates turned out to be dispensable for the parasite, highlighting four candidates as putative targets for therapeutic interventions. This study reveals the importance of several orphan transporters to blood stage P. falciparum development.
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Affiliation(s)
- Jan Stephan Wichers
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | | | - Gwendolin Fuchs
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | - Jing Yu-Strzelczyk
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Jan Stäcker
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Heidrun von Thien
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Arne Alder
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | - Isabelle Henshall
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Benjamin Liffner
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Georg Nagel
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Christian Löw
- Centre for Structural Systems Biology, Hamburg, Germany
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Danny Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia
- Burnet Institute, Melbourne, Victoria, Australia
| | - Tobias Spielmann
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Shiqiang Gao
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Tim-Wolf Gilberger
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | - Anna Bachmann
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | - Jan Strauss
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
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4
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Collins CR, Hackett F, Howell SA, Snijders AP, Russell MRG, Collinson LM, Blackman MJ. The malaria parasite sheddase SUB2 governs host red blood cell membrane sealing at invasion. eLife 2020; 9:e61121. [PMID: 33287958 PMCID: PMC7723409 DOI: 10.7554/elife.61121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/26/2020] [Indexed: 12/26/2022] Open
Abstract
Red blood cell (RBC) invasion by malaria merozoites involves formation of a parasitophorous vacuole into which the parasite moves. The vacuole membrane seals and pinches off behind the parasite through an unknown mechanism, enclosing the parasite within the RBC. During invasion, several parasite surface proteins are shed by a membrane-bound protease called SUB2. Here we show that genetic depletion of SUB2 abolishes shedding of a range of parasite proteins, identifying previously unrecognized SUB2 substrates. Interaction of SUB2-null merozoites with RBCs leads to either abortive invasion with rapid RBC lysis, or successful entry but developmental arrest. Selective failure to shed the most abundant SUB2 substrate, MSP1, reduces intracellular replication, whilst conditional ablation of the substrate AMA1 produces host RBC lysis. We conclude that SUB2 activity is critical for host RBC membrane sealing following parasite internalisation and for correct functioning of merozoite surface proteins.
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Affiliation(s)
- Christine R Collins
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Fiona Hackett
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Steven A Howell
- Protein Analysis and Proteomics Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Ambrosius P Snijders
- Protein Analysis and Proteomics Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Matthew RG Russell
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
- Faculty of Infectious Diseases, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
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5
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Kaslow DC. Malaria vaccine research & innovation: the intersection of IA2030 and zero malaria. NPJ Vaccines 2020; 5:109. [PMID: 33298967 PMCID: PMC7677906 DOI: 10.1038/s41541-020-00259-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 10/30/2020] [Indexed: 12/17/2022] Open
Affiliation(s)
- David C Kaslow
- PATH, 2201 Westlake Avenue, Suite 200, Seattle, WA, 98121, USA.
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6
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A malaria parasite subtilisin propeptide-like protein is a potent inhibitor of the egress protease SUB1. Biochem J 2020; 477:525-540. [PMID: 31942933 PMCID: PMC6993865 DOI: 10.1042/bcj20190918] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 12/23/2022]
Abstract
Subtilisin-like serine peptidases (subtilases) play important roles in the life cycle of many organisms, including the protozoan parasites that are the causative agent of malaria, Plasmodium spp. As with other peptidases, subtilase proteolytic activity has to be tightly regulated in order to prevent potentially deleterious uncontrolled protein degradation. Maturation of most subtilases requires the presence of an N-terminal propeptide that facilitates folding of the catalytic domain. Following its proteolytic cleavage, the propeptide acts as a transient, tightly bound inhibitor until its eventual complete removal to generate active protease. Here we report the identification of a stand-alone malaria parasite propeptide-like protein, called SUB1-ProM, encoded by a conserved gene that lies in a highly syntenic locus adjacent to three of the four subtilisin-like genes in the Plasmodium genome. Template-based modelling and ab initio structure prediction showed that the SUB1-ProM core structure is most similar to the X-ray crystal structure of the propeptide of SUB1, an essential parasite subtilase that is discharged into the parasitophorous vacuole (PV) to trigger parasite release (egress) from infected host cells. Recombinant Plasmodium falciparum SUB1-ProM was found to be a fast-binding, potent inhibitor of P. falciparum SUB1, but not of the only other essential blood-stage parasite subtilase, SUB2, or of other proteases examined. Mass-spectrometry and immunofluorescence showed that SUB1-ProM is expressed in the PV of blood stage P. falciparum, where it may act as an endogenous inhibitor to regulate SUB1 activity in the parasite.
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7
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Wilcox CR, Jones CE. Beyond Passive Immunity: Is There Priming of the Fetal Immune System Following Vaccination in Pregnancy and What Are the Potential Clinical Implications? Front Immunol 2018; 9:1548. [PMID: 30061881 PMCID: PMC6054988 DOI: 10.3389/fimmu.2018.01548] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/22/2018] [Indexed: 02/06/2023] Open
Abstract
Infection is responsible for over half a million neonatal deaths worldwide every year, and vaccination in pregnancy is becoming increasingly recognized as an important strategy for the protection of young infants. Increasing evidence suggests that exposure to maternal infection in utero may "prime" the developing immune system, even in the absence of infant infection. It is also possible that in utero priming may occur following maternal vaccination, with antigen-specific cellular immune responses detectable in utero and at birth. However, this remains a topic of some controversy. This review focuses on the evidence for in utero priming and the clinical implications for vaccination in pregnancy, considering whether in utero priming following vaccination could provide protection independent of antibody-mediated passive immunity, the possible effects of vaccination on subsequent infant vaccinations, their potential "non-specific" effects, and how the design and timing of vaccination might affect prenatal priming. Looking forward, we describe other possible options for quantifying antigen-specific cellular responses, including MHC tetramers, novel proliferation and cytokine-based assays, and animal models. Together, these may help us address future research questions and establish more robust evidence of fetal immune system priming.
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Affiliation(s)
- Christopher R. Wilcox
- NIHR Clinical Research Facility, Southampton Centre for Biomedical Research, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Christine E. Jones
- Faculty of Medicine, Institute for Life Sciences, University of Southampton, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
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8
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Good MF, Miller LH. Interpreting challenge data from early phase malaria blood stage vaccine trials. Expert Rev Vaccines 2018; 17:189-196. [PMID: 29382292 DOI: 10.1080/14760584.2018.1435278] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION As the quest for an effective blood stage malaria vaccine continues, there is increasing reliance on the use of controlled human malaria infections (CHMI) in non-endemic settings to test vaccine efficacy at the earliest possible time. This is seen as a way to accelerate vaccine research and quickly eliminate candidates with poor efficacy. Areas covered: The data from these studies need to be carefully examined and interpreted in light of the very different roles that antibody and cellular immunity play in protection and within the context of the distinct clinical sensitivities of volunteers living in malaria-non-endemic countries compared to those living in endemic countries. With current strategies, it is likely that vaccines with protective immunological 'signatures' will be missed and potentially good candidates discarded. Expert commentary: Efficacy data from early phase vaccine trials in non-endemic countries should not be used to decide whether or not to proceed to vaccine trials in endemic countries.
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Affiliation(s)
- Michael F Good
- a Institute for Glycomics , Griffith University , Queensland , Australia.,b Department of Medical Microbiology and Immunology, University of Alberta , Edmonton , Canada
| | - Louis H Miller
- c Malaria Cell Biology Section, National Institute of Allergy and Infectious Diseases , National Institutes of Health , Bethesda , MD , USA
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9
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Kemp DJ. Antigenic diversity and variation in blood stages ofPlasmodium falciparum. Immunol Cell Biol 2017; 70 ( Pt 3):201-7. [PMID: 1360446 DOI: 10.1038/icb.1992.25] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- D J Kemp
- Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia
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10
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Merozoite Surface Protein 1 from Plasmodium falciparum Is a Major Target of Opsonizing Antibodies in Individuals with Acquired Immunity against Malaria. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00155-17. [PMID: 28877929 DOI: 10.1128/cvi.00155-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/31/2017] [Indexed: 11/20/2022]
Abstract
Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.
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11
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Sherling ES, Knuepfer E, Brzostowski JA, Miller LH, Blackman MJ, van Ooij C. The Plasmodium falciparum rhoptry protein RhopH3 plays essential roles in host cell invasion and nutrient uptake. eLife 2017; 6. [PMID: 28252384 PMCID: PMC5365315 DOI: 10.7554/elife.23239] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/26/2017] [Indexed: 11/18/2022] Open
Abstract
Merozoites of the protozoan parasite responsible for the most virulent form of malaria, Plasmodium falciparum, invade erythrocytes. Invasion involves discharge of rhoptries, specialized secretory organelles. Once intracellular, parasites induce increased nutrient uptake by generating new permeability pathways (NPP) including a Plasmodium surface anion channel (PSAC). RhopH1/Clag3, one member of the three-protein RhopH complex, is important for PSAC/NPP activity. However, the roles of the other members of the RhopH complex in PSAC/NPP establishment are unknown and it is unclear whether any of the RhopH proteins play a role in invasion. Here we demonstrate that RhopH3, the smallest component of the complex, is essential for parasite survival. Conditional truncation of RhopH3 substantially reduces invasive capacity. Those mutant parasites that do invade are defective in nutrient import and die. Our results identify a dual role for RhopH3 that links erythrocyte invasion to formation of the PSAC/NPP essential for parasite survival within host erythrocytes. DOI:http://dx.doi.org/10.7554/eLife.23239.001 Malaria is a life-threatening disease that affects millions of people around the world. The parasites that cause malaria have a complex life cycle that involves infecting both mosquitoes and mammals, including humans. In humans, the parasites spend part of their life cycle inside red blood cells, which causes the symptoms of the disease. In order to survive and multiply, malaria parasites need to make the red blood cell more permeable so that it can absorb nutrients from the blood stream and get rid of the toxic waste products they generate. It remains unclear how the parasites do this, but previous research has shown that the parasites produce channel-like proteins that make red blood cells more permeable to nutrients. One of the proteins involved in this process forms part of a complex with two other proteins, called RhopH2 and RhopH3. It is not known what these other two proteins do, and whether they are necessary for creating the new nutrient channels. Sherling et al. studied the RhopH3 protein to see if it is required to make red blood cells more permeable. The experiments used a genetically modified version of the parasite, in which RhopH3 no longer interacted with the two other proteins. The findings show that RhopH3 has two important roles: first, parasites need it to invade the red blood cells, and second, parasites cannot get nutrients into the red blood cell without RhopH3. Most antimalarial drugs work by preventing parasite replication in red blood cells, but parasites are becoming increasingly resistant to these drugs. Understanding which proteins allow parasites to invade and grow within blood cells will further the development of new malaria medication. The next step will be to understand the molecular mechanisms by which RhopH3 promotes invasion and subsequently facilitates nutrient uptake, and will help researchers to explore its potential as a drug target. DOI:http://dx.doi.org/10.7554/eLife.23239.002
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Affiliation(s)
- Emma S Sherling
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Ellen Knuepfer
- Malaria Parasitology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Louis H Miller
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Christiaan van Ooij
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
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12
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Bowman NM, Juliano JJ, Snider CJ, Kharabora O, Meshnick SR, Vulule J, John CC, Moormann AM. Longevity of Genotype-Specific Immune Responses to Plasmodium falciparum Merozoite Surface Protein 1 in Kenyan Children from Regions of Different Malaria Transmission Intensity. Am J Trop Med Hyg 2016; 95:580-7. [PMID: 27481054 DOI: 10.4269/ajtmh.15-0710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 06/02/2016] [Indexed: 01/06/2023] Open
Abstract
Naturally acquired immunity to Plasmodium falciparum presents a changing landscape as malaria control programs and vaccine initiatives are implemented. Determining which immunologic indicators remain surrogates of past infection, as opposed to mediators of protection, led us to compare stability of immune responses across regions with divergent malaria transmission intensities. A repeat cross-sectional study of Kenyan children from a malaria-holoendemic area and an epidemic-prone area was used to examine longitudinal antibody and interferon-gamma (IFN-γ) responses to the 3D7 and FVO variants of merozoite surface protein 1 (MSP1). Antibodies to MSP1 were common in both study populations and did not significantly wane over a 21-month time period. IFN-γ responses were less frequent and rapidly disappeared in children after a prolonged period of no malaria transmission. Antibody and IFN-γ responses rarely correlated with each other; however, MSP1-specific IFN-γ response correlated with lack of concurrent P. falciparum parasitemia of the same genotype, though only statistically significantly in the malaria-holoendemic region (odds ratio = 0.31, 95% confidence interval = 0.12-0.84). This study affirms that antimalarial antibodies are informative for evaluation of history of malaria exposure within individuals, whereas cell-mediated immunity, though short lived under natural exposure conditions, might provide an assessment of recent infection and protection from parasitemia.
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Affiliation(s)
- Natalie M Bowman
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina
| | - Jonathan J Juliano
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina.
| | - Cynthia J Snider
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Oksana Kharabora
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John Vulule
- Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Chandy C John
- Ryan White Center for Pediatric Infectious Disease and Global Health, Indiana University, Indianapolis, Indiana
| | - Ann M Moormann
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
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13
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Genetic diversity of Plasmodium falciparum parasite by microsatellite markers after scale-up of insecticide-treated bed nets in western Kenya. Malar J 2015; 13 Suppl 1:495. [PMID: 26651480 PMCID: PMC4675068 DOI: 10.1186/s12936-015-1003-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/19/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND An initial study of genetic diversity of Plasmodium falciparum in Asembo, western Kenya showed that the parasite maintained overall genetic stability 5 years after insecticide-treated bed net (ITN) introduction in 1997. This study investigates further the genetic diversity of P. falciparum 10 years after initial ITN introduction in the same study area and compares this with two other neighbouring areas, where ITNs were introduced in 1998 (Gem) and 2004 (Karemo). METHODS From a cross-sectional survey conducted in 2007, 235 smear-positive blood samples collected from children ≤15-year-old in the original study area and two comparison areas were genotyped employing eight neutral microsatellites. Differences in multiple infections, allele frequency, parasite genetic diversity and parasite population structure between the three areas were assessed. Further, molecular data reported previously (1996 and 2001) were compared to the 2007 results in the original study area Asembo. RESULTS Overall proportion of multiple infections (MA) declined with time in the original study area Asembo (from 95.9 %-2001 to 87.7 %-2007). In the neighbouring areas, MA was lower in the site where ITNs were introduced in 1998 (Gem 83.7 %) compared to where they were introduced in 2004 (Karemo 96.7 %) in 2007. Overall mean allele count (MAC ~ 2.65) and overall unbiased heterozygosity (H e ~ 0.77) remained unchanged in 1996, 2001 and 2007 in Asembo and was the same level across the two neighbouring areas in 2007. Overall parasite population differentiation remained low over time and in the three areas at FST < 0.04. Both pairwise and multilocus linkage disequilibrium showed limited to no significant association between alleles in Asembo (1996, 2001 and 2007) and between three areas. CONCLUSIONS This study showed the P. falciparum high genetic diversity and parasite population resilience on samples collected 10 years apart and in different areas in western Kenya. The results highlight the need for long-term molecular monitoring after implementation and use of combined and intensive prevention and intervention measures in the region.
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14
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Guimarães LO, Wunderlich G, Alves JMP, Bueno MG, Röhe F, Catão-Dias JL, Neves A, Malafronte RS, Curado I, Domingues W, Kirchgatter K. Merozoite surface protein-1 genetic diversity in Plasmodium malariae and Plasmodium brasilianum from Brazil. BMC Infect Dis 2015; 15:529. [PMID: 26572971 PMCID: PMC4647813 DOI: 10.1186/s12879-015-1238-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 10/20/2015] [Indexed: 01/23/2023] Open
Abstract
Background The merozoite surface protein 1 (MSP1) gene encodes the major surface antigen of invasive forms of the Plasmodium erythrocytic stages and is considered a candidate vaccine antigen against malaria. Due to its polymorphisms, MSP1 is also useful for strain discrimination and consists of a good genetic marker. Sequence diversity in MSP1 has been analyzed in field isolates of three human parasites: P. falciparum, P. vivax, and P. ovale. However, the extent of variation in another human parasite, P. malariae, remains unknown. This parasite shows widespread, uneven distribution in tropical and subtropical regions throughout South America, Asia, and Africa. Interestingly, it is genetically indistinguishable from P. brasilianum, a parasite known to infect New World monkeys in Central and South America. Methods Specific fragments (1 to 5) covering 60 % of the MSP1 gene (mainly the putatively polymorphic regions), were amplified by PCR in isolates of P. malariae and P. brasilianum from different geographic origin and hosts. Sequencing of the PCR-amplified products or cloned PCR fragments was performed and the sequences were used to construct a phylogenetic tree by the maximum likelihood method. Data were computed to give insights into the evolutionary and phylogenetic relationships of these parasites. Results Except for fragment 4, sequences from all other fragments consisted of unpublished sequences. The most polymorphic gene region was fragment 2, and in samples where this region lacks polymorphism, all other regions are also identical. The low variability of the P. malariae msp1 sequences of these isolates and the identification of the same haplotype in those collected many years apart at different locations is compatible with a low transmission rate. We also found greater diversity among P. brasilianum isolates compared with P. malariae ones. Lastly, the sequences were segregated according to their geographic origins and hosts, showing a strong genetic and geographic structure. Conclusions Our data show that there is a low level of sequence diversity and a possible absence of allelic dimorphism of MSP1 in these parasites as opposed to other Plasmodium species. P. brasilianum strains apparently show greater divergence in comparison to P. malariae, thus P. malariae could derive from P. brasilianum, as it has been proposed. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1238-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lilian O Guimarães
- Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil.
| | - Gerhard Wunderlich
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, 05508-900, Brazil.
| | - João M P Alves
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, 05508-900, Brazil.
| | - Marina G Bueno
- Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508-270, Brazil.
| | - Fabio Röhe
- Wildlife Conservation Society, Rio de Janeiro, RJ, 22461-000, Brazil.
| | - José L Catão-Dias
- Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508-270, Brazil.
| | - Amanda Neves
- Laboratório de Protozoologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil.
| | - Rosely S Malafronte
- Laboratório de Protozoologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. .,Departamento de Moléstias Infecciosas e Parasitárias, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, 01246-903, Brazil.
| | - Izilda Curado
- Laboratório de Imunoepidemiologia, Superintendência de Controle de Endemias, São Paulo, SP, 01027-000, Brazil.
| | - Wilson Domingues
- Laboratório de Soroepidemiologia e Imunobiologia, Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil.
| | - Karin Kirchgatter
- Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil.
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15
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Mohamad D, Suppian R, Mohd Nor N. Immunomodulatory effects of recombinant BCG expressing MSP-1C of Plasmodium falciparum on LPS- or LPS+IFN-γ-stimulated J774A.1 cells. Hum Vaccin Immunother 2014; 10:1880-6. [PMID: 25424796 DOI: 10.4161/hv.28695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Macrophage phagocytosis is the first line of defense of the innate immune system against malaria parasite infection. This study evaluated the immunomodulatory effects of BCG and recombinant BCG (rBCG) strains expressing the C-terminus of the merozoite surface protein-1 (MSP-1C) of Plasmodium falciparum on mouse macrophage cell line J774A.1 in the presence or absence of lipopolysaccharide (LPS) or LPS + IFN-γ. The rBCG strain significantly enhanced phagocytic activity, production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, nitric oxide (NO), and inducible nitric oxide synthase (iNOS) as compared with parental BCG strain, and these activities increased in the presence of LPS and LPS+IFN-γ. Furthermore, the rBCG strain also significantly reduced the macrophage viability as well as the rBCG growth suggesting the involvement of macrophage apoptosis. Taken together, these data indicate that the rBCG strain has an immunomodulatory effect on macrophages, thus strengthen the rational use of rBCG to control malaria infection.
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Affiliation(s)
- Dhaniah Mohamad
- a School of Health Sciences; Health Campus; Universiti Sains Malaysia; Kelantan, Malaysia
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16
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Roy SW, Ferreira MU. A new model for the origins of allelic dimorphism in Plasmodium falciparum. Parasitol Int 2014; 64:229-37. [PMID: 25251164 DOI: 10.1016/j.parint.2014.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/11/2014] [Accepted: 09/12/2014] [Indexed: 11/17/2022]
Abstract
In his landmark 1987 study of the merozoite surface protein-1 locus in Plasmodium falciparum, Kazuyuki Tanabe and coauthors introduced the phenomenon of allelic dimorphism, in which antigenic diversity is arranged into two maximally diverged haplotypes. Further work has extended this finding to other loci in P. falciparum. Each of the loci at which allelic dimorphism is observed encodes major surface antigens of blood-stage malaria parasites, and is consequently a major vaccine target, thus understanding the origins and implications of allelic dimorphism is of crucial importance. Here we examine the essential features of allelic dimorphism in dimorphic malarial surface antigens. From sequence analysis, we conclude that the ancestral population may have been recombining/multimorphic rather than dimorphic. We hypothesize a pathway to allelic dimorphism in which an ancestral allele-rich recombining population could have undergone a severe population bottleneck, putatively caused by the lateral transfer of P. falciparum from apes to humans. This bottleneck produced a reduction in allelic diversity, favoring the survival of the most divergent alleles, which in turn led to recombination suppression by strong natural selection against recombinants.
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Affiliation(s)
- Scott W Roy
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA.
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo, SP, Brazil.
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17
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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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18
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Cavanagh DR, Kocken CHM, White JH, Cowan GJM, Samuel K, Dubbeld MA, der Wel AVV, Thomas AW, McBride JS, Arnot DE. Antibody responses to a novel Plasmodium falciparum merozoite surface protein vaccine correlate with protection against experimental malaria infection in Aotus monkeys. PLoS One 2014; 9:e83704. [PMID: 24421900 PMCID: PMC3885447 DOI: 10.1371/journal.pone.0083704] [Citation(s) in RCA: 8] [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: 09/05/2013] [Accepted: 11/06/2013] [Indexed: 11/29/2022] Open
Abstract
The Block 2 region of the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum has been identified as a target of protective immunity by a combination of seroepidemiology and parasite population genetics. Immunogenicity studies in small animals and Aotus monkeys were used to determine the efficacy of recombinant antigens derived from this region of MSP-1 as a potential vaccine antigen. Aotus lemurinus griseimembra monkeys were immunized three times with a recombinant antigen derived from the Block 2 region of MSP-1 of the monkey-adapted challenge strain, FVO of Plasmodium falciparum, using an adjuvant suitable for use in humans. Immunofluorescent antibody assays (IFA) against erythrocytes infected with P. falciparum using sera from the immunized monkeys showed that the MSP-1 Block 2 antigen induced significant antibody responses to whole malaria parasites. MSP-1 Block 2 antigen-specific enzyme-linked immunosorbent assays (ELISA) showed no significant differences in antibody titers between immunized animals. Immunized animals were challenged with the virulent P. falciparum FVO isolate and monitored for 21 days. Two out of four immunized animals were able to control their parasitaemia during the follow-up period, whereas two out of two controls developed fulminating parasitemia. Parasite-specific serum antibody titers measured by IFA were four-fold higher in protected animals than in unprotected animals. In addition, peptide-based epitope mapping of serum antibodies from immunized Aotus showed distinct differences in epitope specificities between protected and unprotected animals.
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Affiliation(s)
- David R. Cavanagh
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Clemens H. M. Kocken
- Biomedical Primate Research Center, Department of Parasitology, Rijswijk, The Netherlands
| | - John H. White
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Graeme J. M. Cowan
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Kay Samuel
- Scottish National Blood Transfusion Service, Cell Therapy Group, University of Edinburgh, Edinburgh, United Kingdom
| | - Martin A. Dubbeld
- Biomedical Primate Research Center, Department of Parasitology, Rijswijk, The Netherlands
| | | | - Alan W. Thomas
- Biomedical Primate Research Center, Department of Parasitology, Rijswijk, The Netherlands
| | - Jana S. McBride
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - David E. Arnot
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
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19
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Pusic K, Clements D, Kobuch S, Hui G. Antibody and T cell responses in reciprocal prime-boost studies with full-length and truncated merozoite surface protein 1-42 vaccines. PLoS One 2013; 8:e75939. [PMID: 24098747 PMCID: PMC3786974 DOI: 10.1371/journal.pone.0075939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/16/2013] [Indexed: 11/18/2022] Open
Abstract
The P. falciparum Merozoite Surface Protein 1-42 (MSP1-42) is one of the most studied malaria subunit vaccine candidates. The N-terminal fragment of MSP1-42, MSP1-33, is primarily composed of allelic sequences, and has been shown to possess T helper epitopes that influence protective antibody responses toward the C-terminal region, MSP1-19. A truncated MSP1-42 vaccine, Construct 33-I, consisting of exclusively conserved T epitope regions of MSP1-33 expressed in tandem with MSP1-19, was previously shown to be a more effective immunogen than the full-length MSP1-42 vaccine. Here, by way of reciprocal priming/boosting immunization regimens, we studied the immunogenicity of Construct 33-I in the context of recognition by immune responses induced by the full-length native MSP1-42 protein, in order to gauge the effects of pre- and post-exposures to MSP1-42 on vaccine induced responses. Judging by immune responsiveness, antibody and T cell responses, Construct 33-I was effective as the priming antigen followed by full-length MSP1-42 boosting, as well as the boosting antigen following full-length MSP1-42 priming. In particular, Construct 33-I priming elicited the broadest responsiveness in immunized animals subsequently exposed to MSP1-42. Moreover, Construct 33-I, with its conserved MSP1-33 specific T cell epitopes, was equally well recognized by homologous and heterologous allelic forms of MSP1-42. Serum antibodies raised against Construct 33-I efficiently inhibited the growth of parasites carrying the heterologous MSP1-42 allele. These results suggest that Construct 33-I maintains and/or enhances its immunogenicity in an allelic or strain transcending fashion when deployed in populations having prior or subsequent exposures to native MSP1-42s.
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Affiliation(s)
- Kae Pusic
- University of Hawaii, School of Medicine, Department of Tropical Medicine, Honolulu, Hawaii, United States of America
- * E-mail:
| | - Danielle Clements
- University of Hawaii, School of Medicine, Department of Tropical Medicine, Honolulu, Hawaii, United States of America
| | - Sophie Kobuch
- University of Hawaii, School of Medicine, Department of Tropical Medicine, Honolulu, Hawaii, United States of America
| | - George Hui
- University of Hawaii, School of Medicine, Department of Tropical Medicine, Honolulu, Hawaii, United States of America
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20
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Pusic KM, Hashimoto CN, Lehrer A, Aniya C, Clements DE, Hui GS. T cell epitope regions of the P. falciparum MSP1-33 critically influence immune responses and in vitro efficacy of MSP1-42 vaccines. PLoS One 2011; 6:e24782. [PMID: 21931852 PMCID: PMC3172285 DOI: 10.1371/journal.pone.0024782] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 08/17/2011] [Indexed: 12/01/2022] Open
Abstract
The C-terminal 42 kDa fragments of the P. falciparum Merozoite Surface Protein 1, MSP1-42 is a leading malaria vaccine candidate. MSP1-33, the N-terminal processed fragment of MSP1-42, is rich in T cell epitopes and it is hypothesized that they enhance antibody response toward MSP1-19. Here, we gave in vivo evidence that T cell epitope regions of MSP1-33 provide functional help in inducing anti-MSP1-19 antibodies. Eleven truncated MSP1-33 segments were expressed in tandem with MSP1-19, and immunogenicity was evaluated in Swiss Webster mice and New Zealand White rabbits. Analyses of anti-MSP1-19 antibody responses revealed striking differences in these segments' helper function despite that they all possess T cell epitopes. Only a few fragments induced a generalized response (100%) in outbred mice. These were comparable to or surpassed the responses observed with the full length MSP1-42. In rabbits, only a subset of truncated antigens induced potent parasite growth inhibitory antibodies. Notably, two constructs were more efficacious than MSP1-42, with one containing only conserved T cell epitopes. Moreover, another T cell epitope region induced high titers of non-inhibitory antibodies and they interfered with the inhibitory activities of anti-MSP1-42 antibodies. In mice, this region also induced a skewed TH2 cellular response. This is the first demonstration that T cell epitope regions of MSP1-33 positively or negatively influenced antibody responses. Differential recognition of these regions by humans may play critical roles in vaccine induced and/or natural immunity to MSP1-42. This study provides the rational basis to re-engineer more efficacious MSP1-42 vaccines by selective inclusion and exclusion of MSP1-33 specific T cell epitopes.
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Affiliation(s)
- Kae M Pusic
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, United States of America.
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21
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Sheehy SH, Duncan CJA, Elias SC, Collins KA, Ewer KJ, Spencer AJ, Williams AR, Halstead FD, Moretz SE, Miura K, Epp C, Dicks MDJ, Poulton ID, Lawrie AM, Berrie E, Moyle S, Long CA, Colloca S, Cortese R, Gilbert SC, Nicosia A, Hill AVS, Draper SJ. Phase Ia clinical evaluation of the Plasmodium falciparum blood-stage antigen MSP1 in ChAd63 and MVA vaccine vectors. Mol Ther 2011; 19:2269-76. [PMID: 21862998 DOI: 10.1038/mt.2011.176] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Efficacy trials of antibody-inducing protein-in-adjuvant vaccines targeting the blood-stage Plasmodium falciparum malaria parasite have so far shown disappointing results. The induction of cell-mediated responses in conjunction with antibody responses is thought to be one alternative strategy that could achieve protective efficacy in humans. Here, we prepared chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) replication-deficient vectors encoding the well-studied P. falciparum blood-stage malaria antigen merozoite surface protein 1 (MSP1). A phase Ia clinical trial was conducted in healthy adults of a ChAd63-MVA MSP1 heterologous prime-boost immunization regime. The vaccine was safe and generally well tolerated. Fewer systemic adverse events (AEs) were observed following ChAd63 MSP1 than MVA MSP1 administration. Exceptionally strong T-cell responses were induced, and these displayed a mixed of CD4(+) and CD8(+) phenotype. Substantial MSP1-specific serum immunoglobulin G (IgG) antibody responses were also induced, which were capable of recognizing native parasite antigen, but these did not reach titers sufficient to neutralize P. falciparum parasites in vitro. This viral vectored vaccine regime is thus a leading approach for the induction of strong cellular and humoral immunogenicity against difficult disease targets in humans. Further studies are required to assess whether this strategy can achieve protective efficacy against blood-stage malaria infection.
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Affiliation(s)
- Susanne H Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, University of Oxford, Churchill Hospital, Oxford, UK.
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22
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Patarroyo ME, Bermúdez A, Patarroyo MA. Structural and Immunological Principles Leading to Chemically Synthesized, Multiantigenic, Multistage, Minimal Subunit-Based Vaccine Development. Chem Rev 2011; 111:3459-507. [DOI: 10.1021/cr100223m] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manuel Elkin Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad Nacional de Colombia
| | - Adriana Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
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23
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Lozano JM, Lesmes LP, Carreño LF, Gallego GM, Patarroyo ME. Development of designed site-directed pseudopeptide-peptido-mimetic immunogens as novel minimal subunit-vaccine candidates for malaria. Molecules 2010; 15:8856-89. [PMID: 21135800 PMCID: PMC6259129 DOI: 10.3390/molecules15128856] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Accepted: 10/28/2010] [Indexed: 11/16/2022] Open
Abstract
Synthetic vaccines constitute the most promising tools for controlling and preventing infectious diseases. When synthetic immunogens are designed from the pathogen native sequences, these are normally poorly immunogenic and do not induce protection, as demonstrated in our research. After attempting many synthetic strategies for improving the immunogenicity properties of these sequences, the approach consisting of identifying high binding motifs present in those, and then performing specific changes on amino-acids belonging to such motifs, has proven to be a workable strategy. In addition, other strategies consisting of chemically introducing non-natural constraints to the backbone topology of the molecule and modifying the α-carbon asymmetry are becoming valuable tools to be considered in this pursuit. Non-natural structural constraints to the peptide backbone can be achieved by introducing peptide bond isosters such as reduced amides, partially retro or retro-inverso modifications or even including urea motifs. The second can be obtained by strategically replacing L-amino-acids with their enantiomeric forms for obtaining both structurally site-directed designed immunogens as potential vaccine candidates and their Ig structural molecular images, both having immuno-therapeutic effects for preventing and controlling malaria.
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MESH Headings
- Animals
- Haplorhini
- Humans
- Malaria Vaccines/chemical synthesis
- Malaria Vaccines/chemistry
- Malaria Vaccines/immunology
- Malaria Vaccines/pharmacology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/prevention & control
- Mice
- Mice, Inbred BALB C
- Peptidomimetics/chemical synthesis
- Peptidomimetics/chemistry
- Peptidomimetics/immunology
- Peptidomimetics/pharmacology
- Vaccines, Subunit/chemical synthesis
- Vaccines, Subunit/chemistry
- Vaccines, Subunit/immunology
- Vaccines, Subunit/pharmacology
- Vaccines, Synthetic/chemistry
- Vaccines, Synthetic/immunology
- Vaccines, Synthetic/pharmacology
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Affiliation(s)
- José Manuel Lozano
- Fundación Instituto de Inmunología de Colombia (FIDIC), Universidad del Rosario and Universidad Nacional de Colombia, Bogotá DC, Colombia.
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Ngoundou-Landji J, Nwuba RI, Anumudu CI, Odaibo AB, Matondo Maya WD, Awobode HO, Okafor CM, Morenikeji OA, Asinobi A, Nwagwu M, Holder AA, Ntoumi F. Fine specificity of anti-MSP119 antibodies and multiplicity of Plasmodium falciparum merozoite surface protein 1 types in individuals in Nigeria with sub-microscopic infection. Malar J 2010; 9:287. [PMID: 20955565 PMCID: PMC2965716 DOI: 10.1186/1475-2875-9-287] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 10/18/2010] [Indexed: 12/03/2022] Open
Abstract
Background The absence of antibodies specific for the 19 kDa C-terminal domain of merozoite surface protein 1 (MSP119) has been associated with high-density malaria parasitaemia in African populations. The hypothesis that a high prevalence and/or level of anti-MSP119 antibodies that may inhibit erythrocyte invasion would be present in apparently healthy individuals who harbour a sub-microscopic malaria infection was tested in this study. Methods Plasma samples were collected from residents in a region in Nigeria hyperendemic for malaria, who had no detectable parasitaemia by microscopy. Using a competition-based enzyme-linked-immunosorbent assay with two invasion-inhibitory monoclonal antibodies (mAbs) 12.10 and 12.8, the levels and prevalence of specific antibodies were measured. The minimum multiplicity of infection was determined using PCR. The prevalence of anaemia was also measured. Results Plasma samples from 85% of individuals contained antibodies that bound to MSP119. The inhibition of mAb 12.10 binding was strongly correlated with the prevalence (Spearman correlation test, p < 0.0001) and mean titre of anti-MSP119 antibodies (Spearman correlation test, p < 0.001) in the samples. Comparing samples from individuals with multiple infection (group M) and single infection (Group S), group M contained a higher (p = 0.04) prevalence of anti-MSP119 antibodies that competed with mAb 12.10. Using a logistic regression model, it was found that the presence of antibodies competitive with mAb 12.10 was affected negatively by anaemia (p = 0.0016) and positively by the carriage of multiple parasite genotypes (p = 0.04). Conclusions In the search for correlates of protection against malaria, which will be essential to evaluate clinical trials of malaria vaccines based on MSP1, this study examines some potential assays and the factors that need to taken into account during their evaluation, using samples from individuals naturally exposed to malaria infection.
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Shuaibu MN, Kikuchi M, Cherif MS, Helegbe GK, Yanagi T, Hirayama K. Selection and identification of malaria vaccine target molecule using bioinformatics and DNA vaccination. Vaccine 2010; 28:6868-75. [PMID: 20709002 DOI: 10.1016/j.vaccine.2010.08.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 07/21/2010] [Accepted: 08/02/2010] [Indexed: 11/24/2022]
Abstract
Following a genome-wide search for a blood stage malaria DNA-based vaccine using web-based bioinformatic tools, 29 genes from the annotated Plasmodium yoelii genome sequence (www.PlasmoDB.org and www.tigr.org) were identified as encoding GPI-anchored proteins. Target genes were those with orthologues in P. falciparum, containing an N-terminal signal sequence containing hydrophobic amino acid stretch and signal P criteria, a transmembrane-like domain and GPI anchor motif. Focusing on the blood stage, we extracted mRNA from pRBCs, PCR-amplified 22 out of the 29 selected genes, and eventually cloned nine of these into a DNA vaccine plasmid, pVAX 200-DEST. Biojector-mediated delivery of the nine DNA vaccines was conducted using ShimaJET to C57BL/6 mice at a dose of 4 μg/mouse three times at an interval of 3 weeks. Two weeks after the second booster, immunized mice were challenged with P. y. yoelii 17XL-parasitized RBCs and the level of parasitaemia, protection and survival was assessed. Immunization with one gene (PY03470) resulted in 2-4 days of delayed onset and level of parasitaemia and was associated with increased survival compared to non-immunized mice. Antibody production was, however, low following DNA vaccination, as determined by immunofluorescence assay. Recombinant protein from this gene, GPI8p transamidase-related protein (rPyTAM) in PBS or emulsified with GERBU adjuvant was also used to immunize another set of C57BL/6 mice with 10-20 μg/mouse three times at 3-week interval. Higher antibody response was obtained as determined by ELISA with similar protective effects as observed after DNA vaccination.
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Affiliation(s)
- M N Shuaibu
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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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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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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Singh B, Cabrera-Mora M, Jiang J, Galinski M, Moreno A. Genetic linkage of autologous T cell epitopes in a chimeric recombinant construct improves anti-parasite and anti-disease protective effect of a malaria vaccine candidate. Vaccine 2010; 28:2580-92. [PMID: 20097151 DOI: 10.1016/j.vaccine.2010.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 12/28/2009] [Accepted: 01/13/2010] [Indexed: 10/19/2022]
Abstract
We have reported the design of polyvalent synthetic and recombinant chimeras that include promiscuous T cell epitopes as a viable delivery system for pre-erythrocytic subunit malaria vaccines. To further assess the ability of several Plasmodium T cell epitopes to enhance vaccine potency, we designed a synthetic gene encoding four Plasmodium yoelii merozoite surface protein 1 (PyMSP1) CD4(+) promiscuous T cell epitopes fused in tandem to the homologous carboxyl terminal PyMSP1(19) fragment. This Recombinant Modular Chimera (PyRMC-MSP1(19)) was tested for immunogenicity and protective efficacy in comparative experiments with a recombinant protein expressing only the PyMSP1(19) fragment. Both proteins induced comparable antibody responses. However PyRMC-MSP1(19) elicited higher anti-parasite antibody titers and more robust protection against both hyper-parasitemia and malarial anemia. Most importantly, passive transfer of anti-PyRMC-MSP1(19), but not anti-PyMSP1(19) antibodies protected against heterologous challenge. These studies show that protective efficacy can be significantly improved by inclusion of an array of autologous promiscuous T cell epitopes in vaccine constructs.
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Affiliation(s)
- Balwan Singh
- Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, United States
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Antibody-dependent transplacental transfer of malaria blood-stage antigen using a human ex vivo placental perfusion model. PLoS One 2009; 4:e7986. [PMID: 19956710 PMCID: PMC2777305 DOI: 10.1371/journal.pone.0007986] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/17/2009] [Indexed: 02/05/2023] Open
Abstract
Prenatal exposure to allergens or antigens released by infections during pregnancy can stimulate an immune response or induce immunoregulatory networks in the fetus affecting susceptibility to infection and disease later in life. How antigen crosses from the maternal to fetal environment is poorly understood. One hypothesis is that transplacental antigen transfer occurs as immune complexes, via receptor-mediated transport across the syncytiotrophoblastic membrane and endothelium of vessels in fetal villi. This hypothesis has never been directly tested. Here we studied Plasmodium falciparum merozoite surface protein 1 (MSP1) that is released upon erythrocyte invasion. We found MSP1 in cord blood from a third of newborns of malaria-infected women and in >90% following treatment with acid dissociation demonstrating MSP1 immune complexes. Using an ex vivo human placental model that dually perfuses a placental cotyledon with independent maternal and fetal circuits, immune-complexed MSP1 transferred from maternal to fetal circulation. MSP1 alone or with non-immune plasma did not transfer; pre-incubation with human plasma containing anti-MSP1 was required. MSP1 bound to IgG was detected in the fetal perfusate. Laser scanning confocal microscopy demonstrated MSP1 in the fetal villous stroma, predominantly in fetal endothelial cells. MSP1 co-localized with IgG in endothelial cells, but not with placental macrophages. Thus we show, for the first time, antibody-dependent transplacental transfer of an antigen in the form of immune complexes. These studies imply frequent exposure of the fetus to certain antigens with implications for management of maternal infections during pregnancy and novel approaches to deliver vaccines or drugs to the fetus.
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Identification of a vaccine candidate antigen, PfMAg-1, from Plasmodium falciparum with monoclonal antibody M26-32. Parasitol Res 2009; 105:1723-32. [PMID: 19777263 DOI: 10.1007/s00436-009-1617-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
Monoclonal antibody M26-32 has been shown to strongly inhibit the growth of Plasmodium falciparum in vitro. To identify the target antigen of M26-32, a P. falciparum Dd2 asexual stage cDNA expression library was screened with this antibody, and a full open reading frame cDNA was obtained. This gene, named pfmag-1, encodes a polypeptide of 589 amino acids. The protein PfMAg-1 was characterized as a membrane-associated protein that expressed on the surface of merozoite during erythrocytic stage. Remarkably, at the C terminus of PfMAg-1, there are 14 copies of a deca-peptide sequence of QTDEIKND (H/N) I. This tandem repeat domain was identified to harbor the epitope of the protective M26-32 monoclonal antibody, and was also recognized by sera of patients infected with P. falciparum. Rabbit antibody elicited against this deca-peptide repeat domain effectively inhibited P. falciparum invasion in vitro. Our work suggests that PfMAg-1 is a promising malaria vaccine candidate.
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The carboxy-terminus of merozoite surface protein 1: structure, specific antibodies and immunity to malaria. Parasitology 2009; 136:1445-56. [PMID: 19627632 DOI: 10.1017/s0031182009990515] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYOver the last 30 years, evidence has been gathered suggesting that merozoite surface protein 1 (MSP1) is a target of protective immunity against malaria. In a variety of experimental approaches usingin vitromethodology, animal models and sero-epidemiological techniques, the importance of antibody against MSP1 has been established but we are still finding out what are the mechanisms involved. Now that clinical trials of MSP1 vaccines are underway and the early results have been disappointing, it is increasingly clear that we need to know more about the mechanisms of immunity, because a better understanding will highlight the limitations of our current assays and identify the improvements required. Understanding the structure of MSP1 will help us design and engineer better antigens that are more effective than the first generation of vaccine candidates. This review is focused on the carboxy-terminus of MSP1.
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Malhotra I, Dent A, Mungai P, Wamachi A, Ouma JH, Narum DL, Muchiri E, Tisch DJ, King CL. Can prenatal malaria exposure produce an immune tolerant phenotype? A prospective birth cohort study in Kenya. PLoS Med 2009; 6:e1000116. [PMID: 19636353 PMCID: PMC2707618 DOI: 10.1371/journal.pmed.1000116] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 06/17/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Malaria in pregnancy can expose the fetus to malaria-infected erythrocytes or their soluble products, thereby stimulating T and B cell immune responses to malaria blood stage antigens. We hypothesized that fetal immune priming, or malaria exposure in the absence of priming (putative tolerance), affects the child's susceptibility to subsequent malaria infections. METHODS AND FINDINGS We conducted a prospective birth cohort study of 586 newborns residing in a malaria-holoendemic area of Kenya who were examined biannually to age 3 years for malaria infection, and whose malaria-specific cellular and humoral immune responses were assessed. Newborns were classified as (i) sensitized (and thus exposed), as demonstrated by IFNgamma, IL-2, IL-13, and/or IL-5 production by cord blood mononuclear cells (CBMCs) to malaria blood stage antigens, indicative of in utero priming (n = 246), (ii) exposed not sensitized (mother Plasmodium falciparum [Pf]+ and no CBMC production of IFNgamma, IL-2, IL-13, and/or IL-5, n = 120), or (iii) not exposed (mother Pf-, no CBMC reactivity, n = 220). Exposed not sensitized children had evidence for prenatal immune experience demonstrated by increased IL-10 production and partial reversal of malaria antigen-specific hyporesponsiveness with IL-2+IL-15, indicative of immune tolerance. Relative risk data showed that the putatively tolerant children had a 1.61 (95% confidence interval [CI] 1.10-2.43; p = 0.024) and 1.34 (95% CI 0.95-1.87; p = 0.097) greater risk for malaria infection based on light microscopy (LM) or PCR diagnosis, respectively, compared to the not-exposed group, and a 1.41 (95%CI 0.97-2.07, p = 0.074) and 1.39 (95%CI 0.99-2.07, p = 0.053) greater risk of infection based on LM or PCR diagnosis, respectively, compared to the sensitized group. Putatively tolerant children had an average of 0.5 g/dl lower hemoglobin levels (p = 0.01) compared to the other two groups. Exposed not sensitized children also had 2- to 3-fold lower frequency of malaria antigen-driven IFNgamma and/or IL-2 production (p<0.001) and higher IL-10 release (p<0.001) at 6-month follow-ups, when compared to sensitized and not-exposed children. Malaria blood stage-specific IgG antibody levels were similar among the three groups. CONCLUSIONS These results show that a subset of children exposed to malaria in utero acquire a tolerant phenotype to blood-stage antigens that persists into childhood and is associated with an increased susceptibility to malaria infection and anemia. This finding could have important implications for malaria vaccination of children residing in endemic areas.
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MESH Headings
- Adult
- Animals
- Antibodies, Protozoan/blood
- Antigens, Protozoan/blood
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- Cells, Cultured
- Cytokines/immunology
- Cytokines/metabolism
- Female
- Fetal Blood/immunology
- Humans
- Immune Tolerance
- Infant, Newborn
- Kenya/epidemiology
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Male
- Maternal-Fetal Exchange/immunology
- Membrane Proteins/immunology
- Membrane Proteins/metabolism
- Merozoite Surface Protein 1/immunology
- Merozoite Surface Protein 1/metabolism
- Plasmodium falciparum
- Pregnancy
- Pregnancy Complications, Parasitic/epidemiology
- Pregnancy Complications, Parasitic/immunology
- Prospective Studies
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- T-Lymphocytes/parasitology
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Affiliation(s)
- Indu Malhotra
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Arlene Dent
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Peter Mungai
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Vector Borne Diseases, Nairobi, Kenya
| | - Alex Wamachi
- Kenya Medical Research Institute, Nairobi, Kenya
| | - John H. Ouma
- Division of Vector Borne Diseases, Nairobi, Kenya
| | - David L. Narum
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Eric Muchiri
- Division of Vector Borne Diseases, Nairobi, Kenya
| | - Daniel J. Tisch
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Christopher L. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
- * E-mail:
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Combe A, Giovannini D, Carvalho TG, Spath S, Boisson B, Loussert C, Thiberge S, Lacroix C, Gueirard P, Ménard R. Clonal Conditional Mutagenesis in Malaria Parasites. Cell Host Microbe 2009; 5:386-96. [DOI: 10.1016/j.chom.2009.03.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 02/20/2009] [Accepted: 03/27/2009] [Indexed: 11/26/2022]
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Patarroyo ME, Cifuentes G, Bermúdez A, Patarroyo MA. Strategies for developing multi-epitope, subunit-based, chemically synthesized anti-malarial vaccines. J Cell Mol Med 2009; 12:1915-35. [PMID: 19012725 PMCID: PMC4506160 DOI: 10.1111/j.1582-4934.2008.00174.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
An anti-malarial vaccine against the extremely lethal Plasmodium falciparum is desperately needed. Peptides from this parasite's proteins involved in invasion and having high red blood cell-binding ability were identified; these conserved peptides were not immun genic or protection-inducing when used for immunizing Aotus monkeys. Modifying some critical binding residues in these high-activi binding peptides' (HABPs') attachment to red blood cells (RBC) allowed them to induce immunogenicity and protection against expermental challenge and acquire the ability to bind to specific HLA-DRp1* alleles. These modified HABPs adopted certain characterist structural configurations as determined by circular dichroism (CD) and 1H nuclear magnetic resonance (NMR) associated with certain HLA-DRβ1* haplotype binding activities and characteristics, such as a 2-Å-distance difference between amino acids fitting into HLA-DRp1 Pockets 1 to 9, residues participating in binding to HLA-DR pockets and residues making contact with the TCR, suggesting haplotyp and allele-conscious TCR. This has been demonstrated in HLA-DR-like genotyped monkeys and provides the basis for designing high effective, subunit-based, multi-antigen, multi-stage, synthetic vaccines, for immediate human use, malaria being one of them.
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Affiliation(s)
- M E Patarroyo
- Fundación Instituto de Inmunólogia de Colombia (FIDIC), Bogotá, Colombia.
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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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Arnot DE, Cavanagh DR, Remarque EJ, Creasey AM, Sowa MPK, Morgan WD, Holder AA, Longacre S, Thomas AW. Comparative testing of six antigen-based malaria vaccine candidates directed toward merozoite-stage Plasmodium falciparum. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2008; 15:1345-55. [PMID: 18550731 PMCID: PMC2546674 DOI: 10.1128/cvi.00172-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 05/29/2008] [Indexed: 11/20/2022]
Abstract
Immunogenicity testing of Plasmodium falciparum antigens being considered as malaria vaccine candidates was undertaken in rabbits. The antigens compared were recombinant baculovirus MSP-1(19) and five Pichia pastoris candidates, including two versions of MSP-1(19), AMA-1 (domains I and II), AMA-1+MSP-1(19), and fused AMA-1/MSP-1(19)). Animals were immunized with equimolar amounts of each antigen, formulated in Montanide ISA720. The specificities and titers of antibodies were compared using immunofluorescence assays and enzyme-linked immunosorbent assay (ELISA). The antiparasite activity of immunoglobulin G (IgG) in in vitro cultures was determined by growth inhibition assay, flow cytometry, lactate dehydrogenase assay, and microscopy. Baculovirus MSP-1(19) immunizations produced the highest parasite-specific antibody titers in immunofluorescence assays. In ELISAs, baculovirus-produced MSP-1(19) induced more antibodies than any other single MSP-1(19) immunogen and three times more MSP-1(19) specific antibodies than the AMA-1/MSP-1(19) fusion. Antibodies induced by baculovirus MSP-1(19) gave the highest levels of growth inhibition in HB3 and 3D7 parasite cultures, followed by AMA-1+MSP-1(19) and the AMA-1/MSP-1(19) fusion. With the FCR3 isolate (homologous to the AMA-1 construct), antibodies to the three AMA-1-containing candidates gave the highest levels of growth inhibition at high IgG concentrations, but antibodies to baculovirus MSP-1(19) inhibited as well or better at lower IgG concentrations. The two P. pastoris-produced MSP-1(19)-induced IgGs conferred the lowest growth inhibition. Comparative analysis of immunogenicity of vaccine antigens can be used to prioritize candidates before moving to expensive GMP production and clinical testing. The assays used have given discriminating readouts but it is not known whether any of them accurately reflect clinical protection.
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Affiliation(s)
- David E Arnot
- Centre for Medical Parasitology, Institute for International Health, Immunology and Microbiology, University of Copenhagen, Denmark.
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Malhotra I, Wamachi AN, Mungai PL, Mzungu E, Koech D, Muchiri E, Moormann AM, King CL. Fine specificity of neonatal lymphocytes to an abundant malaria blood-stage antigen: epitope mapping of Plasmodium falciparum MSP1(33). THE JOURNAL OF IMMUNOLOGY 2008; 180:3383-90. [PMID: 18292564 DOI: 10.4049/jimmunol.180.5.3383] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cord blood T cells have been reported to respond to a variety of exogenous Ags, including environmental allergens and various viruses and parasites, as demonstrated by enhanced proliferation and cytokine secretion. This finding is evidence that Ags in the maternal environment transplacentally prime and result in fetal development of memory T cells. Some studies suggest these neonatal T cell responses may arise by nonspecific activation of T cells that express TCRs with low binding affinity, thus lacking fine lymphocyte specificity. To address this question, we examined malaria Ag stimulation of human cord and adult blood mononuclear cells in samples from residents of a malaria endemic area in Kenya. We constructed overlapping 18-mer peptides derived from sequences contained in dimorphic alleles of the C-terminal 33-kDa fragment of Plasmodium falciparum merozoite protein 1. This study identified a dominant T cell epitope for one MSP1(33) allele (MAD20) and two T cell epitopes for the second allele (K1); these epitopes were nonoverlapping and allele specific. In a given donor, peptide-specific proliferation and IFN-gamma secretion were highly concordant. However, IL-10 and IL-13 secretion were not correlated. Importantly, the fine specificity of lymphocyte proliferation and cytokine secretion in cord and adult blood mononuclear cells was similar. Cord blood cells obtained from malaria-infected pregnant women were 4-fold more likely to acquire a peptide-specific immune response. We conclude that the fetal malaria response functions in a fully adaptive manner and that this response may serve to help protect the infant from severe malaria during infancy.
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Affiliation(s)
- Indu Malhotra
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH 44106, USA.
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Wengelnik K, Vial HJ. Characterisation of the phosphatidylinositol synthase gene of Plasmodium species. Res Microbiol 2006; 158:51-9. [PMID: 17223316 DOI: 10.1016/j.resmic.2006.11.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 11/14/2006] [Accepted: 11/15/2006] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol (PI) is a versatile lipid that not only serves as a structural component of cellular membranes, but also plays important roles in membrane anchorage of proteins and in signal transduction through distinct phosphorylated derivatives of the inositol head group. PI is synthesised by PI synthase from CDP-diacylglycerol and myo-inositol. The enzymatic activity in Plasmodium falciparum and P. knowlesi has previously been characterised at the biochemical level. Here we characterise the PI synthase gene of P. falciparum and P. knowlesi. The cDNA sequence identified a highly spliced gene consisting of nine exons and encoding a protein of 209 and 207 amino acids, respectively. High sequence conservation enabled the prediction of the PI synthase genes of P. berghei, P. chabaudi and P. vivax. All Plasmodium PI synthase proteins appear to be highly hydrophobic, although no consensus for the number and location of distinct transmembrane domains could be detected. The P. falciparum PI synthase (PfPIS) gene successfully complemented a Saccharomyces cerevisiae PIS1 deletion mutant, demonstrating its enzymatic function. Complementation efficiency was dramatically improved when hybrid constructs between N-terminal S. cerevisiae and C-terminal P. falciparum sequences were used. Determination of in vitro PIS activities of complemented yeast strains confirmed the enzymatic function of the Plasmodium protein.
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Affiliation(s)
- Kai Wengelnik
- UMR5539, CNRS-Université Montpellier II, Place Eugène Bataillon, cc 107, 34095 Montpellier Cedex 05, France.
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Serrano ML, Pérez HA, Medina JD. Structure of C-terminal fragment of merozoite surface protein-1 from Plasmodium vivax determined by homology modeling and molecular dynamics refinement. Bioorg Med Chem 2006; 14:8359-65. [PMID: 17035028 DOI: 10.1016/j.bmc.2006.09.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 09/07/2006] [Accepted: 09/07/2006] [Indexed: 10/24/2022]
Abstract
One current vaccine candidate against Plasmodium vivax targeting asexual blood stage is the major merozoite surface protein-1 of P. vivax (PvMSP-1). Vaccine trials with PvMSP-1(19) and PvMSP-1(33) have succeeded in protecting monkeys and a large proportion of individuals, naturally exposed to P. vivax transmission, develop specific antibodies to PvMSP-1(19). This study presents a model for the three-dimensional structure of the C-terminal 19kDa fragment of P. vivax MSP-1 determined by means of homology modeling and molecular dynamics refinement. The structure proved to be consistent with MSP-1(19) of known crystal or solution structures. The presence of a main binding pocket, well suited for protein-protein interactions, was determined by CASTp. Corrections reported to the sequence of PvMSP-1(19) Belem strain were also inspected. Our model is currently used as a basis to understand antibody interactions with PvMSP-1(19).
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Affiliation(s)
- María Luisa Serrano
- Laboratorio de Modelado Molecular, Unidad de Química Medicinal, Facultad de Farmacia, Universidad Central de Venezuela, Caracas 1041-A, Venezuela.
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Dobaño C, Rogerson SJ, Taylor TE, McBride JS, Molyneux ME. Expression of merozoite surface protein markers by Plasmodium falciparum-infected erythrocytes in peripheral blood and tissues of children with fatal malaria. Infect Immun 2006; 75:643-52. [PMID: 17118989 PMCID: PMC1828492 DOI: 10.1128/iai.01527-06] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sequestration of Plasmodium falciparum-infected erythrocytes is a pathological feature of fatal cerebral malaria. P. falciparum is genetically diverse among, and often within, patients. Preferential sequestration of certain genotypes might be important in pathogenesis. We compared circulating parasites with parasites sequestered in the brain, spleen, liver, and lung in the same Malawian children with fatal malaria, classifying serotypes using antibodies to merozoite surface proteins 1 and 2 and immunofluorescence in order to differentiate parasites and to quantify the proportions of each serotype. We found (i) similar distributions of various serotypes in different tissues and (ii) concordance between parasite serotypes in peripheral blood and parasite serotypes in tissues. No serotypes predominated in the brain in cerebral malaria, and parasites belonging to a single serotype did not cluster within individual vessels or within single tissues. These findings do not support the hypothesis that cerebral malaria is caused by cerebral sequestration of certain virulent types.
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Affiliation(s)
- Carlota Dobaño
- Centre de Salut Internacional, Hospital Clínic/IDIBAPS, Universitat de Barcelona, E-08036 Barcelona, Spain.
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41
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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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42
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Sanders PR, Kats LM, Drew DR, O'Donnell RA, O'Neill M, Maier AG, Coppel RL, Crabb BS. A set of glycosylphosphatidyl inositol-anchored membrane proteins of Plasmodium falciparum is refractory to genetic deletion. Infect Immun 2006; 74:4330-8. [PMID: 16790807 PMCID: PMC1489731 DOI: 10.1128/iai.00054-06] [Citation(s) in RCA: 71] [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] Open
Abstract
Targeted gene disruption has proved to be a powerful approach for studying the function of important ligands involved in erythrocyte invasion by the extracellular merozoite form of the human malaria parasite, Plasmodium falciparum. Merozoite invasion proceeds via a number of seemingly independent alternate pathways, such that entry can proceed with parasites lacking particular ligand-receptor interactions. To date, most focus in this regard has been on single-pass (type 1) membrane proteins that reside in the secretory organelles. Another class of merozoite proteins likely to include ligands for erythrocyte receptors are the glycosylphosphatidyl inositol (GPI)-anchored membrane proteins that coat the parasite surface and/or reside in the apical organelles. Several of these are prominent vaccine candidates, although their functions remain unknown. Here, we systematically attempted to disrupt the genes encoding seven of the known GPI-anchored merozoite proteins of P. falciparum by using a double-crossover gene-targeting approach. Surprisingly, and in apparent contrast to other merozoite antigen classes, most of the genes (six of seven) encoding GPI-anchored merozoite proteins are refractory to genetic deletion, with the exception being the gene encoding merozoite surface protein 5 (MSP-5). No distinguishable growth rate or invasion pathway phenotype was detected for the msp-5 knockout line, although its presence as a surface-localized protein was confirmed.
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Affiliation(s)
- Paul R Sanders
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3050, Australia
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43
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Gilson PR, Nebl T, Vukcevic D, Moritz RL, Sargeant T, Speed TP, Schofield L, Crabb BS. Identification and stoichiometry of glycosylphosphatidylinositol-anchored membrane proteins of the human malaria parasite Plasmodium falciparum. Mol Cell Proteomics 2006; 5:1286-99. [PMID: 16603573 DOI: 10.1074/mcp.m600035-mcp200] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most proteins that coat the surface of the extracellular forms of the human malaria parasite Plasmodium falciparum are attached to the plasma membrane via glycosylphosphatidylinositol (GPI) anchors. These proteins are exposed to neutralizing antibodies, and several are advanced vaccine candidates. To identify the GPI-anchored proteome of P. falciparum we used a combination of proteomic and computational approaches. Focusing on the clinically relevant blood stage of the life cycle, proteomic analysis of proteins labeled with radioactive glucosamine identified GPI anchoring on 11 proteins (merozoite surface protein (MSP)-1, -2, -4, -5, -10, rhoptry-associated membrane antigen, apical sushi protein, Pf92, Pf38, Pf12, and Pf34). These proteins represent approximately 94% of the GPI-anchored schizont/merozoite proteome and constitute by far the largest validated set of GPI-anchored proteins in this organism. Moreover MSP-1 and MSP-2 were present in similar copy number, and we estimated that together these proteins comprise approximately two-thirds of the total membrane-associated surface coat. This is the first time the stoichiometry of MSPs has been examined. We observed that available software performed poorly in predicting GPI anchoring on P. falciparum proteins where such modification had been validated by proteomics. Therefore, we developed a hidden Markov model (GPI-HMM) trained on P. falciparum sequences and used this to rank all proteins encoded in the completed P. falciparum genome according to their likelihood of being GPI-anchored. GPI-HMM predicted GPI modification on all validated proteins, on several known membrane proteins, and on a number of novel, presumably surface, proteins expressed in the blood, insect, and/or pre-erythrocytic stages of the life cycle. Together this work identified 11 and predicted a further 19 GPI-anchored proteins in P. falciparum.
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Affiliation(s)
- Paul R Gilson
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia
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44
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Sanders PR, Gilson PR, Cantin GT, Greenbaum DC, Nebl T, Carucci DJ, McConville MJ, Schofield L, Hodder AN, Yates JR, Crabb BS. Distinct protein classes including novel merozoite surface antigens in Raft-like membranes of Plasmodium falciparum. J Biol Chem 2005; 280:40169-76. [PMID: 16203726 DOI: 10.1074/jbc.m509631200] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins coat the surface of extracellular Plasmodium falciparum merozoites, of which several are highly validated candidates for inclusion in a blood-stage malaria vaccine. Here we determined the proteome of gradient-purified detergent-resistant membranes of mature blood-stage parasites and found that these membranes are greatly enriched in GPI-anchored proteins and their putative interacting partners. Also prominent in detergent-resistant membranes are apical organelle (rhoptry), multimembrane-spanning, and proteins destined for export into the host erythrocyte cytosol. Four new GPI-anchored proteins were identified, and a number of other novel proteins that are predicted to localize to the merozoite surface and/or apical organelles were detected. Three of the putative surface proteins possessed six-cysteine (Cys6) motifs, a distinct fold found in adhesive surface proteins expressed in other life stages. All three Cys6 proteins, termed Pf12, Pf38, and Pf41, were validated as merozoite surface antigens recognized strongly by antibodies present in naturally infected individuals. In addition to the merozoite surface, Pf38 was particularly prominent in the secretory apical organelles. A different cysteine-rich putative GPI-anchored protein, Pf92, was also localized to the merozoite surface. This insight into merozoite surfaces provides new opportunities for understanding both erythrocyte invasion and anti-parasite immunity.
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Affiliation(s)
- Paul R Sanders
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3050 Australia
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Vijay Kumar S, Ranjan S, Saxena V, Rajesh V, Roy SK, Kochar D, Ranjan A, Das A. Plasmodium falciparum: Genetic diversity of C-terminal region of MSP-1 in isolates from Indian sub-continent. Exp Parasitol 2005; 110:384-8. [PMID: 15907839 DOI: 10.1016/j.exppara.2005.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2005] [Revised: 03/29/2005] [Accepted: 03/30/2005] [Indexed: 11/24/2022]
Abstract
Malaria parasites exhibit sequence diversity for a number of stage specific antigens. Several studies have proved that merozoite surface protein-1 (MSP-1) is an effective target eliciting a protective immune response. The MSP-1(42) region comprising two EGF-like domains is involved in generating protective immune response in humans and other experimental animals. Searching for point mutations in this region is essential in view of vaccine development. We have investigated the sequence variations in Plasmodium falciparum MSP-1 carboxy terminal region in field isolates from different regions in India. Our study reveals the presence of eight variant types of MSP-1(19) in the Indian sub-continent, which comprise of E-TSR-L, Q-TSR-L, E-TSG-L, Q-KNG-L, Q-KNG-F, E-KNG-L, E-KNG-F, and E-KYG-F. The last named allele is a novel variant being reported for the first time.
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Affiliation(s)
- S Vijay Kumar
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, India
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46
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Perez-Leal O, Sierra AY, Barrero CA, Moncada C, Martinez P, Cortes J, Lopez Y, Salazar LM, Hoebeke J, Patarroyo MA. Identifying and characterising the Plasmodium falciparum merozoite surface protein 10 Plasmodium vivax homologue. Biochem Biophys Res Commun 2005; 331:1178-84. [PMID: 15883000 DOI: 10.1016/j.bbrc.2005.04.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Indexed: 10/25/2022]
Abstract
Plasmodium vivax malaria is one of the most prevalent parasitic diseases in Asia and Latin-America. The difficulty of maintaining this parasite culture in vitro has hampered identifying and characterising proteins implied in merozoite invasion of red blood cells. We have been able to identify an open reading frame in P. vivax encoding the Plasmodium falciparum merozoite surface protein 10 homologous protein using the partial sequences from this parasite's genome reported during 2004. This new protein contains 479 amino-acids, two epidermal growth factor-like domains, hydrophobic regions at the N- and C-termini, being compatible with a signal peptide and a glycosylphosphatidylinositol anchor site, respectively. The protein is expressed during the parasite's asexual stage and is recognised by polyclonal sera in parasite lysate using Western blot. P. vivax-infected patients' sera highly recognised recombinant protein by ELISA.
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Affiliation(s)
- Oscar Perez-Leal
- Molecular Biology Department, Fundacion Instituto de Inmunologia de Colombia, Bogota, Colombia
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47
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Lozano JM, Espejo F, Vera R, Vargas LE, Rosas J, Lesmes L, Torres E, Cortés J, Silva Y, Patarroyo ME. Protection against malaria induced by chirally modified Plasmodium falciparum's MSP-1 42 pseudopeptides. Biochem Biophys Res Commun 2005; 329:1053-66. [PMID: 15752762 DOI: 10.1016/j.bbrc.2005.01.165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Indexed: 10/25/2022]
Abstract
The C-terminal portion of the Plasmodium falciparum blood stage MSP-1 antigen plays a key role in invasion of human erythrocytes. The MSP-1(1282-1301) non-polymorphic 1585 peptide, from the processed MSP-1(42) fragment, is poorly immunogenic and highly alpha-helical [Angew. Chem. Int. Ed. 40 (2001) 4654]. Assessing the alpha-carbon asymmetry and its implication in the host immune response is proposed in this work to overcome the 1585 peptide's immunological properties. Accordingly, the effect of incorporating single D-amino acids and psi-[CH(2)-NH] isoster bonds into the 1585 peptide was examined both at the immunogenic and 3D-structure levels. Therefore, specific binding to RBCs is promoted by site-directed chiral modifications on the native peptide as well as by simultaneously combining specific D-substitutions with psi-[CH(2)-NH] isoster bonds transforming this molecule into a high specific HLAbeta1*1101 allele binder. D-analog pseudopeptide immunized animals induced antibodies selectively recognizing a recombinant as well as native MSP-1(42) and MSP-1(33) fragments. Protection and low parasitemia levels were induced in Aotus monkeys immunized with the EVLYL(dK)PLAGVYRSLKKQLE analog. Peptide alpha-carbon chiral transformation is therefore an important target for structural modulation and, consequently, represents a novel approach towards designing multi-component subunit-based malarial vaccines.
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Affiliation(s)
- José Manuel Lozano
- Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá D.C., Colombia.
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48
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Abstract
Studies of malaria proteases have focused on two general groups, corresponding to activities specific to malaria parasites: (1) proteases involved in hemoglobin degradation which are active in the food vacuole and which exhibit optimal activity at low pH; and (2) proteases specific to schizonts and/or merozoites which are involved in merozoite maturation and red blood cell invasion and which exhibit optimal activity at neutral pH. In this paper, Catherine Braun Breton and Luis H. Pereira da Silva will focus on those activities necessary for the release of infectious merozoites and the entry of the parasite into its host cell.
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Affiliation(s)
- C Braun Breton
- Unit of Experimental Parasitology, Institut Pasteur, 75724 Paris Cedex 15, France
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49
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Abstract
The merozoite is the invasive form of the asexual stage of Plasmodium species. At least two polymorphic glycoproteins have been found on its surface in the human malaria parasite Plasmodium falciparum. The best-characterized of these is known as merozoite surface antigen-1 (MSA1) (185-200 kDa) (Ref. 1). Similar molecules are found in other malaria species. The other merozoite surface antigen, MSA2 (35-48 kDa) (Ref. 2), is distinct from MSA1 but is equally polymorphic. In this review, Juan Cooper condenses the body of structural information on MSA1 known to date. A database compiled from MSA1 sequences from several species used together with sequence comparisons and predicted secondary structure reveals interesting features of this molecule.
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Affiliation(s)
- J A Cooper
- Zentrum für Molekulare Biologie, Universität Heidelberg, Im Neuenheimer Feld 282, 6900 Heidelberg, Germany
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50
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Affiliation(s)
- D Walliker
- Department of Genetics, University of Edinburgh, EH9 3JN, UK
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