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Fernandes GM, Rodrigues-Mattos GH, Torres LM, Guedes KS, Fontes CJF, Ntumngia FB, Adams JH, Brito CFA, Kano FS, de Sousa TN, Carvalho LH. Natural genetic diversity of the DBL domain of a novel member of the Plasmodium vivax erythrocyte binding-like proteins (EBP2) in the Amazon rainforest. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2024; 123:105628. [PMID: 38936525 DOI: 10.1016/j.meegid.2024.105628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 06/20/2024] [Accepted: 06/23/2024] [Indexed: 06/29/2024]
Abstract
In malaria parasites, the erythrocyte binding-like proteins (EBL) are a family of invasion proteins that are attractive vaccine targets. In the case of Plasmodium vivax, the widespread malaria parasite, blood-stage vaccines have been largely focused on a single EBL candidate, the Duffy binding-like domain (DBL) of the Duffy binding protein (DBPII), due to its well-characterized role in the reticulocyte invasion. A novel P. vivax EBL family member, the Erythrocyte binding protein (EBP2, also named EBP or DBP2), binds preferentially to reticulocytes and may mediate an alternative P. vivax invasion pathway. To gain insight into the natural genetic diversity of the DBL domain of EBP2 (region II; EBP2-II), we analyzed ebp2-II gene sequences of 71 P. vivax isolates collected in different endemic settings of the Brazilian Amazon rainforest, where P. vivax is the predominant malaria-associated species. Although most of the substitutions in the ebp2-II gene were non-synonymous and suggested positive selection, the results showed that the DBL domain of the EBP2 was much less polymorphic than that of DBPII. The predominant EBP2 haplotype in the Amazon region corresponded to the C127 reference sequence first described in Cambodia (25% C127-like haplotype). An overview of ebp2-II gene sequences available at GenBank (n = 352) from seven countries (Cambodia, Madagascar, Myanmar, PNG, South Korea, Thailand, Vietnam) confirmed the C127-like haplotype as highly prevalent worldwide. Two out of 43 haplotypes (5 to 20 inferred per country) showed a global frequency of 60%. The results presented here open new avenues of research pursuit while suggesting that a vaccine based on the DBL domain of EBP2 should target a few haplotypes for broad coverage.
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Affiliation(s)
- Gabriela M Fernandes
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil; Universidade Federal de Minas Gerais (UFMG), Departamento de Parasitologia, Belo Horizonte, Brazil
| | - Guilherme H Rodrigues-Mattos
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Letícia M Torres
- Faculdade Ciências Médicas de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Karla S Guedes
- Julio Muller School Hospital, Faculdade de Medicina, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil
| | - Cor J F Fontes
- Julio Muller School Hospital, Faculdade de Medicina, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil
| | - Francis B Ntumngia
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - John H Adams
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Cristiana F A Brito
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Flora S Kano
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Taís N de Sousa
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil; Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden.
| | - Luzia H Carvalho
- Biologia Molecular e Imunologia da Malária, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
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Deb B, Das A, Vilvadrinath R, Jangra A, Shukla MS, Akhouri RR, Goel S. Glycophorin B-PfEMP1 interaction mediates robust rosetting in Plasmodium falciparum. Int J Biol Macromol 2024; 262:129868. [PMID: 38309398 DOI: 10.1016/j.ijbiomac.2024.129868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/15/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
P. falciparumerythrocyte membrane protein 1 (PfEMP1) is the major parasite protein responsible for rosetting by binding to host receptors such as heparan sulfate, CR1 on RBC surface. Usually monomeric protein-carbohydrate interactions are weak [1], therefore PfEMP1 binds to plasma proteins like IgM or α2-macroglobulin that facilitate its clustering on parasitized RBC surface and augment rosetting [2,3]. We show that 3D7A expresses PfEMP1, PF3D7_0412900, and employs its CIDRγ2 domain to interact with glycophorin B on uninfected RBC to form large rosettes but more importantly even in the absence of plasma proteins. Overall, we established the role of PF3D7_0412900 in rosetting as antibodies against CIDRγ2 domain reduced rosetting and also identified its receptor, glycophorin B which could provide clue why glycophorin B null phenotype, S-s-U- RBCs prevalent in malaria endemic areas is protective against severe malaria.
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Affiliation(s)
- Bijayeeta Deb
- Indian Institute of Science Education and Research (IISER) Tirupati, India
| | - Adrita Das
- Indian Institute of Science Education and Research (IISER) Tirupati, India
| | - Ramya Vilvadrinath
- Indian Institute of Science Education and Research (IISER) Tirupati, India
| | - Arvind Jangra
- Indian Institute of Science Education and Research (IISER) Tirupati, India
| | | | | | - Suchi Goel
- Indian Institute of Science Education and Research (IISER) Tirupati, India.
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Lee SK, Nguyen TK, Mohring F, Han JH, Firdaus ER, Na SH, Park WS, Moon RW, Han ET. Merozoite surface protein 1 paralog is involved in the human erythrocyte invasion of a zoonotic malaria, Plasmodium knowlesi. Front Cell Infect Microbiol 2023; 13:1314533. [PMID: 38111629 PMCID: PMC10726050 DOI: 10.3389/fcimb.2023.1314533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 11/15/2023] [Indexed: 12/20/2023] Open
Abstract
The zoonotic malaria parasite Plasmodium knowlesi is an important public health concern in Southeast Asia. Invasion of host erythrocytes is essential for parasite growth, and thus, understanding the repertoire of parasite proteins that enable this process is vital for identifying vaccine candidates and how some species are able to cause zoonotic infection. Merozoite surface protein 1 (MSP1) is found in all malaria parasite species and is perhaps the most well-studied as a potential vaccine candidate. While MSP1 is encoded by a single gene in P. falciparum, all other human infective species (P. vivax, P. knowlesi, P. ovale, and P. malariae) additionally encode a divergent paralogue known as MSP1P, and little is known about its role or potential functional redundancy with MSP1. We, therefore, studied the function of P. knowlesi merozoite surface protein 1 paralog (PkMSP1P), using both recombinant protein and CRISPR-Cas9 genome editing. The recombinant 19-kDa C-terminus of PkMSP1P (PkMSP1P-19) was shown to bind specifically to human reticulocytes. However, immunoblotting data suggested that PkMSP1P-19-induced antibodies can recognize PkMSP1-19 and vice versa, confounding our ability to separate the properties of these two proteins. Targeted disruption of the pkmsp1p gene profoundly impacts parasite growth, demonstrating for the first time that PkMSP1P is important in in vitro growth of P. knowlesi and likely plays a distinct role from PkMSP1. Importantly, the MSP1P KO also enabled functional characterization of the PkMSP1P-19 antibodies, revealing clear immune cross-reactivity between the two paralogues, highlighting the vital importance of genetic studies in contextualizing recombinant protein studies.
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Affiliation(s)
- Seong-Kyun Lee
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Tuyet Kha Nguyen
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Franziska Mohring
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Egy Rahman Firdaus
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Sung-Hun Na
- Department of Obstetrics and Gynecology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Won-Sun Park
- Department of Physiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Robert W. Moon
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
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Bouyssou I, Martínez FJ, Campagne P, Ma L, Doderer-Lang C, Chitnis CE, Ménard D. Plasmodium vivax blood stage invasion pathways: Contribution of omics technologies in deciphering molecular and cellular mechanisms. C R Biol 2022; 345:91-133. [PMID: 36847467 DOI: 10.5802/crbiol.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 11/25/2022]
Abstract
Vivax malaria is an infectious disease caused by Plasmodium vivax, a parasitic protozoan transmitted by female Anopheline mosquitoes. Historically, vivax malaria has often been regarded as a benign self-limiting infection due to the observation of low parasitemia in Duffy-positive patients in endemic transmission areas and the virtual absence of infections in Duffy-negative individuals in Sub Saharan Africa. However, the latest estimates show that the burden of the disease is not decreasing in many countries and cases of vivax infections in Duffy-negative individuals are increasingly reported throughout Africa. This raised questions about the accuracy of diagnostics and the evolution of interactions between humans and parasites. For a long time, our knowledge on P. vivax biology has been hampered due to the limited access to biological material and the lack of robust in vitro culture methods. Consequently, little is currently known about P. vivax blood stage invasion mechanisms. The introduction of omics technologies with novel and accessible techniques such as third generation sequencing and RNA sequencing at single cell level, two-dimensional electrophoresis, liquid chromatography, and mass spectrometry, has progressively improved our understanding of P. vivax genetics, transcripts, and proteins. This review aims to provide broad insights into P. vivax invasion mechanisms generated by genomics, transcriptomics, and proteomics and to illustrate the importance of integrated multi-omics studies.
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Plasmodium knowlesi Duffy binding protein alpha region II (PkDBPαII) in clinical isolates from Peninsular Malaysia and Malaysian Borneo exhibit different immune responses in animal models. Parasitol Res 2022; 121:3443-3454. [PMID: 36152079 DOI: 10.1007/s00436-022-07665-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 09/09/2022] [Indexed: 10/14/2022]
Abstract
Plasmodium knowlesi utilizes the Duffy binding protein alpha (PkDBPα) to facilitate its invasion into human erythrocytes. PkDBPα region II (PkDBPαII) from Peninsular Malaysia and Malaysian Borneo has been shown to occur as distinct haplotypes, and the predominant haplotypes from these geographical areas demonstrated differences in binding activity to human erythrocytes in erythrocyte binding assays. This study aimed to determine the effects of genetic polymorphisms in PkDBPαII to immune responses in animal models. The recombinant PkDBPαII (~ 45 kDa) of Peninsular Malaysia (PkDBPαII-H) and Malaysian Borneo (PkDBPαII-S) were expressed in a bacterial expression system, purified, and used in mice and rabbit immunization. The profile of cytokines IL-1ra, IL-2, IL-6, IL-10, TNF-α, and IFN-γ in immunized mice spleen was determined via ELISA. The titer and IgG subtype distribution of raised antibodies was characterized. Immunized rabbit sera were purified and used to perform an in vitro merozoite invasion inhibition assay. The PkDBPαII-immunized mice sera of both groups showed high antibody titer and a similar IgG subtype distribution pattern: IgG2b > IgG1 > IgG2a > IgG3. The PkDBPαII-H group was shown to have higher IL-1ra (P = 0.141) and IL-6 (P = 0.049) concentrations, with IL-6 levels significantly higher than that of the PkDBPαII-S group (P ≤ 0.05). Merozoite invasion inhibition assay using purified anti-PkDBPαII antibodies showed a significantly higher inhibition rate in the PkDBPαII-H group than the PkDBPαII-S group (P ≤ 0.05). Besides, anti-PkDBPαII-H antibodies were able to exhibit inhibition activity at a lower concentration than anti-PkDBPαII-S antibodies. PkDBPαII was shown to be immunogenic, and the PkDBPαII haplotype from Peninsular Malaysia exhibited higher responses in cytokines IL-1ra and IL-6, antibody IgM level, and merozoite invasion inhibition assay than the Malaysian Borneo haplotype. This suggests that polymorphisms in the PkDBPαII affect the level of immune responses in the host.
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De SL, Ntumngia FB, Nicholas J, Adams JH. Progress towards the development of a P. vivax vaccine. Expert Rev Vaccines 2021; 20:97-112. [PMID: 33481638 PMCID: PMC7994195 DOI: 10.1080/14760584.2021.1880898] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/21/2021] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Plasmodium vivax causes significant public health problems in endemic regions. A vaccine to prevent disease is critical, considering the rapid spread of drug-resistant parasite strains, and the development of hypnozoites in the liver with potential for relapse. A minimally effective vaccine should prevent disease and transmission while an ideal vaccine provides sterile immunity. AREAS COVERED Despite decades of research, the complex life cycle, technical challenges and a lack of funding have hampered progress of P. vivax vaccine development. Here, we review the progress of potential P. vivax vaccine candidates from different stages of the parasite life cycle. We also highlight the challenges and important strategies for rational vaccine design. These factors can significantly increase immune effector mechanisms and improve the protective efficacy of these candidates in clinical trials to generate sustained protection over longer periods of time. EXPERT OPINION A vaccine that presents functionally-conserved epitopes from multiple antigens from various stages of the parasite life cycle is key to induce broadly neutralizing strain-transcending protective immunity to effectively disrupt parasite development and transmission.
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Affiliation(s)
- Sai Lata De
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - Francis B. Ntumngia
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - Justin Nicholas
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
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7
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Ntumngia FB, Thomson-Luque R, Pires CV, Adams JH. The role of the human Duffy antigen receptor for chemokines in malaria susceptibility: current opinions and future treatment prospects. JOURNAL OF RECEPTOR, LIGAND AND CHANNEL RESEARCH 2016; 9:1-11. [PMID: 28943755 PMCID: PMC5608092 DOI: 10.2147/jrlcr.s99725] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Duffy antigen receptor for chemokine (DARC) is a nonspecific receptor for several proinflammatory cytokines. It is homologous to the G-protein chemokine receptor superfamily, which is suggested to function as a scavenger in many inflammatory-and proinflammatory-related diseases. G-protein chemokine receptors are also known to play a critical role in infectious diseases; they are commonly used as entry vehicles by infectious agents. A typical example is the chemokine receptor CCR5 or CXCR4 used by HIV for infecting target cells. In malaria, DARC is considered an essential receptor that mediates the entry of the human and zoonotic malaria parasites Plasmodium vivax and Plasmodium knowlesi into human reticulocytes and erythrocytes, respectively. This process is mediated through interaction with the parasite ligand known as the Duffy binding protein (DBP). Most therapeutic strategies have been focused on blocking the interaction between DBP and DARC by targeting the parasite ligand, while strategies targeting the receptor, DARC, have not been intensively investigated. The rapid increase in drug resistance and the lack of new effective drugs or a vaccine for malaria constitute a major threat and a need for novel therapeutics to combat disease. This review explores strategies that can be used to target the receptor. Inhibitors of DARC, which block DBP-DARC interaction, can potentially provide an effective strategy for preventing malaria caused by P. vivax.
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Affiliation(s)
- Francis B Ntumngia
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Richard Thomson-Luque
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Camilla V Pires
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
| | - John H Adams
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
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Singh B, Gupta PK, Chauhan V, Chitnis C. Novel and cost-effective refolding of a recombinant receptor binding domain of Plasmodium falciparum EBA-175. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.09.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yalcindag E, Rougeron V, Elguero E, Arnathau C, Durand P, Brisse S, Diancourt L, Aubouy A, Becquart P, D'Alessandro U, Fontenille D, Gamboa D, Maestre A, Ménard D, Musset L, Noya O, Veron V, Wide A, Carme B, Legrand E, Chevillon C, Ayala FJ, Renaud F, Prugnolle F. Patterns of selection onPlasmodium falciparumerythrocyte-binding antigens after the colonization of the New World. Mol Ecol 2014; 23:1979-93. [DOI: 10.1111/mec.12696] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erhan Yalcindag
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
- Department of Botany and Zoology; Faculty of Science; Masaryk University; Kotlářská 2 611 37 Brno Czech Republic
| | - Virginie Rougeron
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
- Centre International de Recherches Médicales de Franceville (CIRMF); BP 769 Franceville Gabon
| | - Eric Elguero
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Céline Arnathau
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Patrick Durand
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Sylvain Brisse
- Institut Pasteur; Plate-forme Génotypage des Pathogènes et Santé Publique; 28 Rue du docteur Roux 75724 Paris France
| | - Laure Diancourt
- Institut Pasteur; Plate-forme Génotypage des Pathogènes et Santé Publique; 28 Rue du docteur Roux 75724 Paris France
| | - Agnes Aubouy
- Institut de Recherche pour le Développement (IRD); UMR152; Université Paul Sabatier; 35 Chemin des Maraîchers 31062 Toulouse France
| | - Pierre Becquart
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | | | - Didier Fontenille
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Dionicia Gamboa
- Instituto de Medicina Tropical Alexander Von Humboldt; Universidad Peruana Cayetano Heredia; AP 4314 Lima 100 Peru
| | - Amanda Maestre
- Grupo Salud y Comunidad; Facultad de Medicina; Universidad de Antioquía; Medellín Colombia
| | - Didier Ménard
- Molecular Epidemiology Unit; Pasteur Institute of Cambodia; 5 Boulevard Monivong - PO Box 983 Phnom Penh Cambodia
| | - Lise Musset
- Parasitology laboratory; Institut Pasteur de Guyane; BP6010 97306 Cayenne Cedex French Guiana
| | - Oscar Noya
- Centro para Estudios Sobre Malaria; Instituto de Altos Estudios en Salud “Dr. Arnoldo Gabaldón”-INH; Ministerio del Poder Popular para la Salud; Instituto de Medicina Tropical; Universidad Central de Venezuela; Caracas Venezuela
| | | | - Albina Wide
- Centro para Estudios Sobre Malaria; Instituto de Altos Estudios en Salud “Dr. Arnoldo Gabaldón”-INH; Ministerio del Poder Popular para la Salud; Instituto de Medicina Tropical; Universidad Central de Venezuela; Caracas Venezuela
| | - Bernard Carme
- Centre d'Investigation Clinique Epidémiologie Clinique Antilles; Guyane CIC-EC 802; Cayenne General Hospital; Cayenne French Guiana
| | - Eric Legrand
- Parasitology laboratory; Institut Pasteur de Guyane; BP6010 97306 Cayenne Cedex French Guiana
| | - Christine Chevillon
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology; University of California; Irvine CA 92697 USA
| | - François Renaud
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
| | - Franck Prugnolle
- MIVEGEC (Laboratoire Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle); UMR CNRS 5290/IRD 224; Université Montpellier 1; Université Montpellier 2; CHRU de Montpellier; 39 Avenue Charles Flahault 34295 Montpellier France
- Centre International de Recherches Médicales de Franceville (CIRMF); BP 769 Franceville Gabon
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Mueller I, Galinski MR, Tsuboi T, Arevalo-Herrera M, Collins WE, King CL. Natural acquisition of immunity to Plasmodium vivax: epidemiological observations and potential targets. ADVANCES IN PARASITOLOGY 2013; 81:77-131. [PMID: 23384622 DOI: 10.1016/b978-0-12-407826-0.00003-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Population studies show that individuals acquire immunity to Plasmodium vivax more quickly than Plasmodium falciparum irrespective of overall transmission intensity, resulting in the peak burden of P. vivax malaria in younger age groups. Similarly, actively induced P. vivax infections in malaria therapy patients resulted in faster and generally more strain-transcending acquisition of immunity than P. falciparum infections. The mechanisms behind the more rapid acquisition of immunity to P. vivax are poorly understood. Natural acquired immune responses to P. vivax target both pre-erythrocytic and blood-stage antigens and include humoral and cellular components. To date, only a few studies have investigated the association of these immune responses with protection, with most studies focussing on a few merozoite antigens (such as the Pv Duffy binding protein (PvDBP), the Pv reticulocyte binding proteins (PvRBPs), or the Pv merozoite surface proteins (PvMSP1, 3 & 9)) or the circumsporozoite protein (PvCSP). Naturally acquired transmission-blocking (TB) immunity (TBI) was also found in several populations. Although limited, these data support the premise that developing a multi-stage P. vivax vaccine may be feasible and is worth pursuing.
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Affiliation(s)
- Ivo Mueller
- Walter + Eliza Hall Institute, Infection & Immunity Division, Parkville, Victoria, Australia
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Genetic diversity and natural selection of Duffy binding protein of Plasmodium vivax Korean isolates. Acta Trop 2013; 125:67-74. [PMID: 23031445 DOI: 10.1016/j.actatropica.2012.09.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 09/19/2012] [Accepted: 09/22/2012] [Indexed: 11/23/2022]
Abstract
Plasmodium vivax Duffy binding protein (PvDBP) is a micronemal type I membrane protein that plays an essential role in erythrocyte invasion of merozoites. PvDBP is a prime blood stage vaccine candidate antigen against P. vivax, but its polymorphic nature represents a major obstacle to the successful design of a protective vaccine against vivax malaria. In this study, we analyzed the genetic polymorphism and natural selection at the N-terminal cysteine-rich region of PvDBP (PvDBPII) among 70 P. vivax isolates collected from Korean patients during 2005-2010. Seventeen single nucleotide polymorphisms (SNP), which resulted in 14 non-synonymous and 3 synonymous mutations, were found in PvDBPII among the Korean P. vivax isolates. Sequence analyses revealed that 13 different PvDBPII haplotypes, which were clustered into 3 distinct clades, were identified in Korean P. vivax isolates. The difference between the rates of nonsynomyous and synonymous mutations suggested that the region has evolved under natural selection. High selective pressure preferentially acted on regions identified or predicted to be B- and T-cell epitopes and MHC binding regions of PvDBPII. Recombination may also contribute to genetic diversity of PvDBPII. Our results suggest that PvDBPII of Korean P. vivax isolates display a limited genetic polymorphism and are under selective pressure. These results have significant implications for understanding the nature of the P. vivax population circulating in Korea and provide useful information for development of malaria vaccines based on this antigen.
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Ntumngia FB, King CL, Adams JH. Finding the sweet spots of inhibition: understanding the targets of a functional antibody against Plasmodium vivax Duffy binding protein. Int J Parasitol 2012; 42:1055-62. [PMID: 23068913 DOI: 10.1016/j.ijpara.2012.09.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 09/11/2012] [Accepted: 09/14/2012] [Indexed: 11/26/2022]
Abstract
Plasmodium vivax Duffy binding protein region II (DBPII) is an essential ligand for reticulocyte invasion, thereby making this molecule an attractive vaccine candidate against asexual blood-stage P. vivax. Similar to other Plasmodium blood-stage vaccine candidates, strain-specific immunity due to DBPII allelic variation may complicate vaccine efficacy. Targeting immune responses to more conserved epitopes that are potential targets of strain-transcending neutralising immunity is necessary to avoid induction of strain-specific responses to dominant variant epitopes. In this article, we focus on different approaches to optimise the design of DBP immunogenicity to target conserved epitopes, which is important for developing a broadly effective vaccine against P. vivax.
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Affiliation(s)
- Francis B Ntumngia
- Department of Global Health, University of South Florida, Tampa, FL, USA
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13
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Molina DM, Finney OC, Arevalo-Herrera M, Herrera S, Felgner PL, Gardner MJ, Liang X, Wang R. Plasmodium vivax pre-erythrocytic-stage antigen discovery: exploiting naturally acquired humoral responses. Am J Trop Med Hyg 2012; 87:460-9. [PMID: 22826492 DOI: 10.4269/ajtmh.2012.12-0222] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The development of pre-erythrocytic Plasmodium vivax vaccines is hindered by the lack of in vitro culture systems or experimental rodent models. To help bypass these roadblocks, we exploited the fact that naturally exposed Fy- individuals who lack the Duffy blood antigen (Fy) receptor are less likely to develop blood-stage infections; therefore, they preferentially develop immune responses to pre-erythrocytic-stage parasites, whereas Fy+ individuals experience both liver- and blood-stage infections and develop immune responses to both pre-erythrocytic and erythrocytic parasites. We screened 60 endemic sera from P. vivax-exposed Fy+ or Fy- donors against a protein microarray containing 91 P. vivax proteins with P. falciparum orthologs that were up-regulated in sporozoites. Antibodies against 10 P. vivax antigens were identified in sera from P. vivax-exposed individuals but not unexposed controls. This technology has promising implications in the discovery of potential vaccine candidates against P. vivax malaria.
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Bei AK, Duraisingh MT. Functional analysis of erythrocyte determinants of Plasmodium infection. Int J Parasitol 2012; 42:575-82. [PMID: 22726752 DOI: 10.1016/j.ijpara.2012.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 03/14/2012] [Accepted: 03/14/2012] [Indexed: 11/18/2022]
Abstract
The Plasmodium falciparum parasite is an obligate intracellular pathogen whose invasion and remodelling of the human erythrocyte results in the clinical manifestations of malarial disease. The functional analysis of erythrocyte determinants of invasion and growth is a relatively unexplored frontier in malaria research, encompassing studies of natural variation of the erythrocyte, as well as genomic, biochemical and chemical biological and transgenic approaches. These studies have allowed the functional analysis of the erythrocyte in vitro, resulting in the discovery of critical erythrocyte determinants of Plasmodium infection. Here, we will focus on the varied approaches used for the study of the erythrocyte in Plasmodium infection, with a particular emphasis on erythrocyte invasion.
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Affiliation(s)
- Amy K Bei
- Harvard School of Public Health, 665, Huntington Avenue, Building 1, Room 715, Boston, MA 02115, USA
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15
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Age-dependent IgG subclass responses to Plasmodium falciparum EBA-175 are differentially associated with incidence of malaria in Mozambican children. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 19:157-66. [PMID: 22169088 DOI: 10.1128/cvi.05523-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Plasmodium falciparum blood-stage antigens such as merozoite surface protein 1 (MSP-1), apical membrane antigen 1 (AMA-1), and the 175-kDa erythrocyte binding antigen (EBA-175) are considered important targets of naturally acquired immunity to malaria. However, it is not clear whether antibodies to these antigens are effectors in protection against clinical disease or mere markers of exposure. In the context of a randomized, placebo-controlled trial of intermittent preventive treatment in infants conducted between 2002 and 2004, antibody responses to Plasmodium falciparum blood-stage antigens in a cohort of 302 Mozambican children were evaluated by immunofluorescence antibody test and enzyme-linked immunosorbent assay at 5, 9, 12, and 24 months of age. We found that IgG subclass responses to EBA-175 were differentially associated with the incidence of malaria in the follow-up period. A double amount of cytophilic IgG1 or IgG3 was associated with a significant decrease in the incidence of malaria (incidence rate ratio [IRR] = 0.49, 95% confidence interval [CI] = 0.25 to 0.97, and P = 0.026 and IRR = 0.44, CI = 0.19 to 0.98, and P = 0.037, respectively), while a double amount of noncytophilic IgG4 was significantly correlated with an increased incidence of malaria (IRR = 3.07, CI = 1.08 to 8.78, P = 0.020). No significant associations between antibodies to the 19-kDa fragment of MSP-1 (MSP-1(19)) or AMA-1 and incidence of malaria were found. Age, previous episodes of malaria, present infection, and neighborhood of residence were the main factors influencing levels of antibodies to all merozoite antigens. Deeper understanding of the acquisition of antibodies against vaccine target antigens in early infancy is crucial for the rational development and deployment of malaria control tools in this vulnerable population.
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Srivastava A, Singh S, Dhawan S, Mahmood Alam M, Mohmmed A, Chitnis CE. Localization of apical sushi protein in Plasmodium falciparum merozoites. Mol Biochem Parasitol 2010; 174:66-9. [PMID: 20540969 DOI: 10.1016/j.molbiopara.2010.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 06/01/2010] [Accepted: 06/02/2010] [Indexed: 10/19/2022]
Abstract
Plasmodium falciparum belongs to the Apicomplexan group of parasites and is characterised by presence of specialized secretory organelles at the apical end. These apical organelles, referred to as microneme and rhoptries, contain proteins that play important roles during host cell invasion by mediating specific functions such as initial attachment, apical reorientation and junction formation. Recently, a protein referred to as P. falciparum apical sushi protein (PfASP), which is expressed at late schizont stage, was localized to micronemes of P. falciparum merozoites. In the present study, we have used indirect immunofluorescence assays and immunoelectron microscopy to demonstrate that PfASP is localized in the neck of rhoptries and not in micronemes as previously described.
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Affiliation(s)
- Anand Srivastava
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India
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Murphy SC, Hiller NL, Harrison T, Lomasney JW, Mohandas N, Haldar K. Lipid rafts and malaria parasite infection of erythrocytes (Review). Mol Membr Biol 2009; 23:81-8. [PMID: 16611583 DOI: 10.1080/09687860500473440] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Infection of human erythrocytes by the malarial parasite, Plasmodium falciparum, results in complex membrane sorting and signaling events in the mature erythrocyte. These events appear to rely heavily on proteins resident in erythrocyte lipid rafts. Over the past five years, we and others have undertaken a comprehensive characterization of major proteins present in erythrocyte detergent-resistant membrane lipid rafts and determined which of these proteins traffic to the host-derived membrane that bounds the intraerythrocytic parasite. The data suggest that raft association is necessary but not sufficient for vacuolar recruitment, and that there is likely a mechanism of active uptake of a subset of erythrocyte detergent-resistant membrane proteins. Of the ten internalized proteins, few have been evaluated for a role in malarial entry. The beta(2)-adrenergic receptor and heterotrimeric G protein G(s) signaling pathway proteins regulate invasion. The implications of these differences are discussed. In addition, the latter finding indicates that erythrocytes possess important signaling pathways. These signaling cascades may have important influences on in vivo malarial infection, as well as on erythrocyte membrane flexibility and adhesiveness in sickle cell anemia. With respect to malarial infection, host signaling components alone are not sufficient to induce formation of the malarial vacuole. Parasite proteins are likely to have a major role in making the intraerythrocytic environment conducive for vacuole formation. Such interactions should be the focus of future efforts to understand malarial infection of erythrocytes since host- and parasite-targeted interventions are urgently needed to combat this terrible disease.
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Affiliation(s)
- Sean C Murphy
- Department of Pathology and Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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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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Haldar K, Mohandas N. Malaria, erythrocytic infection, and anemia. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2009; 2009:87-93. [PMID: 20008186 PMCID: PMC2933134 DOI: 10.1182/asheducation-2009.1.87] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Malaria is a major world health problem. It results from infection of parasites belonging to the genus Plasmodium. Plasmodium falciparum and Plasmodium vivax cause the major human malarias, with P falciparum being the more virulent. During their blood stages of infection, both P falciparum and P vivax induce anemia. Severe malarial anemia caused by P falciparum is responsible for approximately a third of the deaths associated with disease. Malarial anemia appears to be multi-factorial. It involves increased removal of circulating erythrocytes as well as decreased production of erythrocytes in the bone marrow. The molecular mechanisms underlying malarial anemia are largely unknown. Over the last five years, malaria parasite ligands have been investigated for their remodeling of erythrocytes and possible roles in destruction of mature erythrocytes. Polymorphisms in cytokines have been associated with susceptibility to severe malarial anemia: these cytokines and malaria "toxins" likely function by perturbing erythropoiesis. Finally a number of co-infections increase susceptibility to malarial anemia, likely because they exacerbate inflammation caused by malaria. Because of the complexities involved, the study of severe malarial anemia may need a "systems approach" to yield comprehensive understanding of defects in both erythropoiesis and immunity associated with disease. New and emerging tools such as (i) mathematical modeling of the dynamics of host control of malarial infection, (ii) ex vivo perfusion of human spleen to measure both infected and uninfected erythrocyte retention, and (iii) in vitro development of erythroid progenitors to dissect responsiveness to cytokine imbalance or malaria toxins, may be especially useful to develop integrated mechanistic insights and therapies to control this major and fatal disease pathology.
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Affiliation(s)
- Kasturi Haldar
- Center for Rare and Neglected Diseases, University of Notre Dame, South Bend, IN, USA.
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Alam MT, Bora H, Singh N, Sharma YD. High immunogenecity and erythrocyte-binding activity in the tryptophan-rich domain (TRD) of the 74-kDa Plasmodium vivax alanine-tryptophan-rich antigen (PvATRAg74). Vaccine 2008; 26:3787-94. [DOI: 10.1016/j.vaccine.2008.05.059] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Accepted: 05/12/2008] [Indexed: 11/25/2022]
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Mphande FA, Ribacke U, Kaneko O, Kironde F, Winter G, Wahlgren M. SURFIN4.1, a schizont-merozoite associated protein in the SURFIN family of Plasmodium falciparum. Malar J 2008; 7:116. [PMID: 18593471 PMCID: PMC2515329 DOI: 10.1186/1475-2875-7-116] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 07/01/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In its effort to survive the human immune system, Plasmodium falciparum uses several parasite-derived antigens most of which are expressed at the surface of the parasitized red blood cells (pRBCs). Recently SURFINs, a new family of antigens encoded by the surf multi-gene family, has been reported. One member of the family, SURFIN4.2, was found present both at the pRBC-surface and at the merozoite apex. METHODS The presence of a second SURFIN member, SURFIN4.1 (PFD0100c, PFD0105c) is reported here. Bioinformatic tools were used to study the structure of the surf4.1 gene. To investigate the expression of surf genes PCR and real-time quantitative PCR (Rt-QPCR) were employed and Northern and Western blots were used to confirm the size of the surf4.1 gene and the SURFIN4.1 protein respectively. Localization of SURFIN4.1 was determined using immunofluorescence assays. RESULTS The surf4.1 gene was found present in one copy by Rt-QPCR in some parasites (3D7AH1, 3D7S8, 7G8) whereas six copies of the gene were identified in FCR3 and FCR3S1.2. surf4.1 was found transcribed in the late asexual stages of the parasite beginning approximately 32 hours post invasion and throughout the schizont stages with the level of transcription peaking at late schizogony. The levels of transcript correlated with the number of gene copies in FCR3 and 3D7S8. surf4.1 was found to encode a polypeptide of approximately Mw 258 kDa (SURFIN4.1) present within the parasitophorous vacuole (PV), around free merozoites as merozoite-associated material, but not at the pRBC-surface. Despite multiple surf4.1 gene copies in some parasites this was not reflected in the levels of SURFIN4.1 polypeptide. CONCLUSION SURFIN4.1 is a member of the SURFINs, present in the PV and on the released merozoite. The results suggest different SURFINs to be expressed at different locations in the parasite and at distinct time-points during the intra-erythrocytic cycle.
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Affiliation(s)
- Fingani A Mphande
- Department of Microbiology, Tumor and Cell Biology (MTC) Karolinska Institutet and Swedish Institute for Infectious Disease Control, Nobel's väg 16, Box 280, SE-171 77, Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology (MTC) Karolinska Institutet and Swedish Institute for Infectious Disease Control, Nobel's väg 16, Box 280, SE-171 77, Stockholm, Sweden
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Fred Kironde
- Department of Biochemistry, Makerere University, Kampala, Uganda
| | - Gerhard Winter
- Department of Microbiology, Tumor and Cell Biology (MTC) Karolinska Institutet and Swedish Institute for Infectious Disease Control, Nobel's väg 16, Box 280, SE-171 77, Stockholm, Sweden
- Department of General Practice, Flinders University, Adelaide, Australia
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC) Karolinska Institutet and Swedish Institute for Infectious Disease Control, Nobel's väg 16, Box 280, SE-171 77, Stockholm, Sweden
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Impact of intermittent preventive treatment with sulfadoxine-pyrimethamine on antibody responses to erythrocytic-stage Plasmodium falciparum antigens in infants in Mozambique. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2008; 15:1282-91. [PMID: 18495848 DOI: 10.1128/cvi.00044-08] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We evaluated the impact of intermittent preventive treatment in infants (IPTi) with sulfadoxine-pyrimethamine (SP), which was given at ages 3, 4, and 9 months through the Expanded Program on Immunization (EPI), on the development of antibody responses to Plasmodium falciparum in Mozambique. Immunoglobulin M (IgM) and IgG subclass antibodies specific to whole asexual parasites and to recombinant MSP-1(19), AMA-1, and EBA-175 were measured at ages 5, 9, 12, and 24 months for 302 children by immunofluorescence antibody tests and by enzyme-linked immunosorbent assays. Antibody responses did not significantly differ between children receiving IPTi with SP and those receiving a placebo at any time point measured, with the exception of the responses of IgG and IgG1 to AMA-1 and/or MSP-1(19), which were significantly higher in the SP-treated group than in the placebo group at ages 5, 9, and/or 24 months. IPTi with SP given through the EPI reduces the frequency of malarial illness while allowing the development of naturally acquired antibody responses to P. falciparum antigens.
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Sherman IW. References. ADVANCES IN PARASITOLOGY 2008. [DOI: 10.1016/s0065-308x(08)00430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Targeting the Plasmodium vivax Duffy-binding protein. Trends Parasitol 2007; 24:29-34. [PMID: 18023618 DOI: 10.1016/j.pt.2007.10.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 08/10/2007] [Accepted: 10/01/2007] [Indexed: 11/17/2022]
Abstract
Plasmodium vivax requires interaction with the Duffy antigen receptor for chemokines (DARC) to enable its invasion of human erythrocytes. Interaction with DARC is mediated by the P. vivax Duffy-binding protein (PvDBP) and is essential for junction formation, which is a key step in the invasion process. The receptor-binding domain of PvDBP maps to a conserved cysteine-rich region, referred to as region II (PvRII). Here, we review data on the interaction of PvRII with DARC and explore the potential of targeting this crucial receptor-ligand interaction to develop new intervention strategies against P. vivax.
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Withers-Martinez C, Haire LF, Hackett F, Walker PA, Howell SA, Smerdon SJ, Dodson GG, Blackman MJ. Malarial EBA-175 region VI crystallographic structure reveals a KIX-like binding interface. J Mol Biol 2007; 375:773-81. [PMID: 18036613 DOI: 10.1016/j.jmb.2007.10.071] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2007] [Revised: 10/26/2007] [Accepted: 10/26/2007] [Indexed: 10/22/2022]
Abstract
The malaria parasite proliferates in the bloodstream of its vertebrate host by invading and replicating within erythrocytes. To achieve successful invasion, a number of discrete and essential events need to take place at the parasite-host cell interface. Erythrocyte-binding antigen 175 (EBA-175) is a member of a family of Plasmodium falciparum erythrocyte-binding proteins involved in the formation of a tight junction, a necessary step in invasion. Here we present the crystal structure of EBA-175 region VI (rVI), a cysteine-rich domain that is highly conserved within the protein family and is essential for EBA-175 trafficking. The structure was solved by selenomethionine single-wavelength anomalous dispersion at 1.8 A resolution. It reveals a homodimer, containing in each subunit a compact five-alpha-helix core that is stabilized by four conserved disulfide bridges. rVI adopts a novel fold that is likely conserved across the protein family, indicating a conserved function. It shows no similarity to the Duffy-binding-like domains of EBA-175 involved in erythrocyte binding, indicating a distinct role. Remarkably, rVI possesses structural features related to the KIX-binding domain of the coactivator CREB-binding protein, supporting the binding and trafficking roles that have been ascribed to it and providing a rational basis for further experimental investigation of its function.
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Garcia Y, Puentes A, Curtidor H, Cifuentes G, Reyes C, Barreto J, Moreno A, Patarroyo ME. Identifying Merozoite Surface Protein 4 and Merozoite Surface Protein 7 Plasmodium falciparum Protein Family Members Specifically Binding to Human Erythrocytes Suggests a New Malarial Parasite-Redundant Survival Mechanism. J Med Chem 2007; 50:5665-75. [DOI: 10.1021/jm070773z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yesid Garcia
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Alvaro Puentes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Hernando Curtidor
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Claudia Reyes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Jose Barreto
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Armando Moreno
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
| | - Manuel E. Patarroyo
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, Bogotá D.C., Colombia, South America, and Universidad Nacional de Colombia Bogotá, Bogotá D.C., Colombia, South America
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Ghosh K, Ghosh K. Pathogenesis of anemia in malaria: a concise review. Parasitol Res 2007; 101:1463-9. [PMID: 17874326 DOI: 10.1007/s00436-007-0742-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 08/21/2007] [Indexed: 10/22/2022]
Abstract
Anemia is a common complication in malarial infection, although the consequences are more pronounced with Plasmodium falciparum malaria (Ghosh, Indian J Hematol Blood Tranfus 21(53):128-130, 2003). Anemia in this infection is caused by a variety of pathophysiologic mechanisms, and in areas where malaria infection is endemic, co-morbidities like other parasitic infestations, iron, folate and Vitamin B12 deficiency, deficiency of other nutrients, and anemia, which is aggravated by anti-malarial drugs both through immune and non-immune mechanisms, are important considerations. In different endemic areas, beta-thalassemia, alpha-thalassemia, Hb S, Hb E, G6PD deficiency, or ovalocytosis in different proportions interact with this infection. Finally, aberrant immune response to repeated or chronic falciparum malarial infection may produce tropical splenomegaly syndrome, a proportion of which show clonal proliferation of B lymphocytes. Cooperation between chronic malarial infection and infection with E-B virus infection in producing Burkitt's lymphoma is well known. In this review, the fascinating and multifaceted pathophysiolgoy of malarial anemia has been discussed.
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Affiliation(s)
- Kanjaksha Ghosh
- Institute of Immunohaematology (ICMR), 13th Floor, KEM Hospital Campus, Parel, Mumbai 400 012, India.
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28
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Herrera S, Corradin G, Arévalo-Herrera M. An update on the search for a Plasmodium vivax vaccine. Trends Parasitol 2007; 23:122-8. [PMID: 17258937 DOI: 10.1016/j.pt.2007.01.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 11/09/2006] [Accepted: 01/17/2007] [Indexed: 11/27/2022]
Abstract
Although Plasmodium falciparum is the leading cause of morbidity and mortality due to malaria worldwide, nearly 2.5 billion people, mostly outside Africa, are also at risk from malaria caused by Plasmodium vivax infection. Currently, almost all efforts to develop a malaria vaccine have focused on P. falciparum. For example, there are 23 P. falciparum vaccine candidates undergoing advanced clinical studies and only two P. vivax vaccine candidates being tested in preliminary (Phase I) clinical trials, with few others being assessed in preclinical studies. More investment and a greater effort toward the development of P. vivax vaccine components for a multi-species vaccine are required. This is mainly because of the wide geographical coexistence of both parasite species but also because of increasing drug resistance, recent observations of severe and lethal P. vivax cases and relapsing parasite behaviour. Availability of the P. vivax genome has contributed to antigen discovery but new means to test vaccines in future trials remain to be designed.
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Affiliation(s)
- Sócrates Herrera
- Malaria Vaccine and Drug Development Center, AA 26020, Cali, Colombia; Immunology Institute, Universidad del Valle, AA 25574, Cali, Colombia.
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Thompson J, Fernandez-Reyes D, Sharling L, Moore SG, Eling WM, Kyes SA, Newbold CI, Kafatos FC, Janse CJ, Waters AP. Plasmodium cysteine repeat modular proteins 1-4: complex proteins with roles throughout the malaria parasite life cycle. Cell Microbiol 2007; 9:1466-80. [PMID: 17253978 DOI: 10.1111/j.1462-5822.2006.00885.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Cysteine Repeat Modular Proteins (PCRMP1-4) of Plasmodium, are encoded by a small gene family that is conserved in malaria and other Apicomplexan parasites. They are very large, predicted surface proteins with multipass transmembrane domains containing motifs that are conserved within families of cysteine-rich, predicted surface proteins in a range of unicellular eukaryotes, and a unique combination of protein-binding motifs, including a >100 kDa cysteine-rich modular region, an epidermal growth factor-like domain and a Kringle domain. PCRMP1 and 2 are expressed in life cycle stages in both the mosquito and vertebrate. They colocalize with PfEMP1 (P. falciparum Erythrocyte Membrane Antigen-1) during its export from P. falciparum blood-stage parasites and are exposed on the surface of haemolymph- and salivary gland-sporozoites in the mosquito, consistent with a role in host tissue targeting and invasion. Gene disruption of pcrmp1 and 2 in the rodent malaria model, P. berghei, demonstrated that both are essential for transmission of the parasite from the mosquito to the mouse and has established their discrete and important roles in sporozoite targeting to the mosquito salivary gland. The unprecedented expression pattern and structural features of the PCRMPs thus suggest a variety of roles mediating host-parasite interactions throughout the parasite life cycle.
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Affiliation(s)
- Joanne Thompson
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK.
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30
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Pattnaik P, Shakri AR, Singh S, Goel S, Mukherjee P, Chitnis CE. Immunogenicity of a recombinant malaria vaccine based on receptor binding domain of Plasmodium falciparum EBA-175. Vaccine 2007; 25:806-13. [PMID: 17045706 DOI: 10.1016/j.vaccine.2006.09.048] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 09/07/2006] [Accepted: 09/12/2006] [Indexed: 11/15/2022]
Abstract
Malaria parasites require specific receptor-ligand interactions to invade host erythrocytes. The 175 kDa Plasmodium falciparum erythrocyte binding antigen (EBA-175) binds sialic acid residues on glycophorin A to mediate erythrocyte invasion. The amino-terminal, conserved, cysteine-rich region of EBA-175, referred to as F2, contains receptor-binding sites. We propose to develop a recombinant malaria vaccine based on region F2. Recombinant P. falciparum region F2 (PfF2) was expressed in Escherichia coli, purified from inclusion bodies under denaturing conditions by metal affinity chromatography, renatured by oxidative refolding and purified further by ion-exchange and gel filtration chromatography. Recombinant PfF2 was characterized and shown to be pure, homogeneous and functionally active in that it binds human erythrocytes with specificity. The immunogenicity of recombinant PfF2 formulated with three human compatible adjuvants, namely, Montanide ISA720, AS02A and alum was tested in mice. All the formulations tested elicited high titer antibodies that block erythrocyte invasion in vitro. The AS02 formulation yielded sera with the highest end-point ELISA titers followed by Montanide ISA720 and alum. Analysis of cellular immune responses indicated that all formulations resulted in significant splenocyte proliferation. Analysis of cytokines secreted by proliferating splenocytes indicated that all the adjuvant formulations tested induced Th1 type responses. These results suggest that recombinant PfF2 formulated with human compatible adjuvants is immunogenic and can elicit high titer invasion inhibitory antibodies providing support for further clinical development of this promising vaccine candidate.
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Affiliation(s)
- Priyabrata Pattnaik
- Malaria Group, International Centre for Genetic Engineering and Biotechnology, P.O. Box 10504, Aruna Asaf Ali Marg, New Delhi 110067, India
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31
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Uneke CJ. Plasmodium falciparum malaria and ABO blood group: is there any relationship? Parasitol Res 2006; 100:759-65. [PMID: 17047997 DOI: 10.1007/s00436-006-0342-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2006] [Accepted: 09/11/2006] [Indexed: 10/24/2022]
Abstract
There is increasing evidence that Plasmodium falciparum malaria is influenced by ABO blood group but the extent of association between both is yet to be well defined. Studies that investigated association between P. falciparum malaria and ABO blood group were identified using MEDLINE search and were systematically reviewed. There were apparent discrepancies and contradictions in the studies as some reported significant association between both while others observed no significant association. This outcome may reflect the complex interaction between P. falciparum malaria and the host immune responses. However, findings from all studies reviewed suggested that individuals of blood group O are relatively resistant to severe disease caused by P. falciparum infection. It was established that parasitized erythrocytes form rosettes more readily with red blood cells (RBCs) of A, B, or AB groups than with blood group O and this parasite-triggered RBC rosette formation is associated with the severity of clinical disease and with the development of cerebral malaria. Differences in rosetting ability were based on the P. falciparum strain-specific preference of rosetting with non-O blood groups and not only a phenomenon of laboratory-propagated strains, but also exist in wild clinical isolates from all major malarious areas of the world.
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Affiliation(s)
- C J Uneke
- Department of Medical Microbiology, Faculty of Clinical Medicine, Ebonyi State University, Abakaliki, PMB 053, Nigeria.
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Verra F, Chokejindachai W, Weedall GD, Polley SD, Mwangi TW, Marsh K, Conway DJ. Contrasting signatures of selection on the Plasmodium falciparum erythrocyte binding antigen gene family. Mol Biochem Parasitol 2006; 149:182-90. [PMID: 16837078 DOI: 10.1016/j.molbiopara.2006.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 05/12/2006] [Accepted: 05/30/2006] [Indexed: 10/24/2022]
Abstract
Erythrocyte binding antigens of Plasmodium falciparum are involved in erythrocyte invasion, and may be targets of acquired immunity. Of the five eba genes, protein products have been detected for eba-175, eba-181 and eba-140, but not for psieba-165 or ebl-1, providing opportunity for comparative analysis of genetic variation to identify selection. Region II of each of these genes was sequenced from a cross-sectional sample of parasites in an endemic Kenyan population, and the frequency distributions of polymorphisms analysed. A positive value of Tajima's D was observed for eba-175 (D=1.13) indicating an excess of intermediate frequency polymorphisms, while all other genes had negative values, the most negative being ebl-1 (D=-2.35) followed by psieba-165 (D=-1.79). The eba-175 and ebl-1 genes were then studied in a sample of parasites from Thailand, for which a positive Tajima's D value was again observed for eba-175 (D=1.79), and a negative value for ebl-1 (D=-1.85). This indicates that eba-175 is under balancing selection in each population, in strong contrast to the other members of the gene family, particularly ebl-1 and psieba-165 that may have been under recent directional selection. Population expansion simulations were performed under a neutral model, further supporting the departures from neutrality of these genes.
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Affiliation(s)
- Federica Verra
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
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Abstract
The clinical manifestations of Plasmodium falciparum malaria are directly linked to the blood stage of the parasite life cycle. At the blood stage, the circulating merozoites invade erythrocytes via a specific invasion pathway often identified with its dependence or independence on sialic acid residues of the host receptor. The invasion process involves multiple receptor-ligand interactions that mediate a complex series of events in a period of approximately 1 min. Although the mechanism by which merozoites invade erythrocytes is not fully understood, recent advances have put a new perspective on the importance of developing a multivalent blood stage-malaria vaccine. In this review, we highlight the role of currently identified host invasion receptors in blood-stage malaria.
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Affiliation(s)
- S S Oh
- Division of Cell Biology, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, 736 Cambridge Street, Boston, MA 02135, USA
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Russell C, Mercereau-Puijalon O, Le Scanf C, Steward M, Arnot DE. Further definition of PfEMP-1 DBL-1alpha domains mediating rosetting adhesion of Plasmodium falciparum. Mol Biochem Parasitol 2005; 144:109-13. [PMID: 16122820 DOI: 10.1016/j.molbiopara.2005.06.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 06/22/2005] [Accepted: 06/29/2005] [Indexed: 11/25/2022]
Affiliation(s)
- Clare Russell
- Institute of Immunology and Infection Research, Division of Biological Sciences, Ashworth Laboratory, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JT, UK
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Valbuena J, Vera R, Puentes A, Ocampo M, Garcia J, Curtidor H, Lopez R, Rodriguez L, Rosas J, Cortes J, Forero M, Pinto M, Patarroyo ME. P. falciparum pro-histoaspartic protease (proHAP) protein peptides bind specifically to erythrocytes and inhibit the invasion process in vitro. Biol Chem 2005; 386:361-7. [PMID: 15899698 DOI: 10.1515/bc.2005.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Plasmodium falciparum histoaspartic protease (HAP) is an active enzyme involved in haemoglobin degradation. HAP is expressed as an inactive 51-kDa zymogen and is cleaved into an active 37-kDa enzyme. It has been proposed that this kind of protease might be implicated in the parasite's invasion of erythrocytes; however, this protein's role during invasion has still to be determined. Synthetic peptides derived from the HAP precursor (proHAP) were tested in erythrocyte binding assays to identify their possible function in the invasion process. Two proHAP high-activity binding peptides (HABPs) specifically bound to erythrocytes; these peptides were numbered 30609 (101LKNYIKESVKLFNKGLTKKS120) and 30610 (121YLGSEFDNVELKDLANVLSF140 ). The binding of these two peptides was saturable, presenting nanomolar affinity constants. These peptides interacted with 26- and 45-kDa proteins on the erythrocyte surface; the nature of these receptor sites was studied in peptide binding assays using enzyme-treated erythrocytes. The HABPs showed greater than 90% merozoite invasion inhibition in in vitro assays. Goat serum containing proHAP polymeric peptide antibodies inhibited parasite invasion in vitro .
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Affiliation(s)
- John Valbuena
- Fundacion Instituto de Inmunologia de Colombia (FIDIC), Cra 50 26-00, Bogotá, Colombia.
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Vera-Bravo R, Valbuena JJ, Ocampo M, Garcia JE, Rodriguez LE, Puentes A, Lopez R, Curtidor H, Torres E, Trujillo M, Tovar DR, Patarroyo MA, Patarroyo ME. Amino terminal peptides from the Plasmodium falciparum EBA-181/JESEBL protein bind specifically to erythrocytes and inhibit in vitro merozoite invasion. Biochimie 2005; 87:425-36. [PMID: 15820749 DOI: 10.1016/j.biochi.2005.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 01/13/2005] [Indexed: 11/21/2022]
Abstract
Several EBA-175 paralogues (EBA-140, EBA-165, EBA-175, EBA-181, and EBL-1) have been described among the Plasmodium falciparum malaria parasite proteins, which are important in the red blood cell (RBC) invasion process. EBA-181/JESEBL is a 181 kDa protein expressed in the late schizont stage and located in the micronemes; it belongs to the Plasmodium Duffy binding-like family and is able to interact with the erythrocyte surface. Here, we describe the synthesis of 78, 20-mer synthetic peptides derived from the reported EBA-181/JESEBL sequence and their ability to bind RBCs in receptor-ligand assays. Five peptides (numbered 30030, 30031, 30045, 30051, and 30060) displayed high specific binding to erythrocytes; their equilibrium binding parameters were then determined. These peptides interacted with 53 and 33 kDa receptor proteins on the erythrocyte surface, this binding being altered when RBCs were pretreated with enzymes. They were able to inhibit P. falciparum merozoite invasion of RBCs when tested in in vitro assays. According to these results, these five EBA-181/JESEBL high specific erythrocyte binding peptides, as well as the entire protein, were seen to be involved in the molecular machinery used by the parasite for invading RBCs. They are thus suggested as potential candidates in designing a multi-sub-unit vaccine able to combat the P. falciparum malaria parasite.
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Affiliation(s)
- Ricardo Vera-Bravo
- Fundacion Instituto de Inmunologia de Colombia and Universidad Nacional de Colombia, Bogotá, Colombia.
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de Brevern AG, Wong H, Tournamille C, Colin Y, Le Van Kim C, Etchebest C. A structural model of a seven-transmembrane helix receptor: The Duffy antigen/receptor for chemokine (DARC). Biochim Biophys Acta Gen Subj 2005; 1724:288-306. [PMID: 16046070 DOI: 10.1016/j.bbagen.2005.05.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 05/13/2005] [Accepted: 05/16/2005] [Indexed: 01/28/2023]
Abstract
The Duffy antigen/receptor for chemokine (DARC) is an erythrocyte receptor for malaria parasites (Plasmodium vivax and Plasmodium knowlesi) and for chemokines. In contrast to other chemokine receptors, DARC is a promiscuous receptor that binds chemokines of both CC and CXC classes. The four extracellular domains (ECDs) of DARC are essential for its interaction with chemokines, whilst the first (ECD1) is sufficient for the interaction with malaria erythrocyte-binding protein. In this study, we elaborate and analyze structural models of the DARC. The construction of the 3D models is based on a comparative modeling process and on the use of many procedures to predict transmembrane segments and to detect far homologous proteins with known structures. Threading, ab initio, secondary structure and Protein Blocks approaches are used to build a very large number of models. The conformational exploration of the ECDs is performed with simulated annealing. The second and fourth ECDs are strongly constrained. On the contrary, the ECD1 is highly flexible, but seems composed of three consecutive regions: a small beta-sheet, a linker region and a structured loop. The chosen structural models encompass most of the biochemical features and reflect the known experimental data. They may be used to analyze functional interaction properties.
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Affiliation(s)
- A G de Brevern
- Equipe de Bioinformatique Génomique et Moléculaire (EBGM), INSERM U 726, Université Denis DIDEROT-Paris 7, case 7113, 2, place Jussieu, 75251 Paris, France.
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Bharara R, Singh S, Pattnaik P, Chitnis CE, Sharma A. Structural analogs of sialic acid interfere with the binding of erythrocyte binding antigen-175 to glycophorin A, an interaction crucial for erythrocyte invasion by Plasmodium falciparum. Mol Biochem Parasitol 2005; 138:123-9. [PMID: 15500923 DOI: 10.1016/j.molbiopara.2004.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Accepted: 07/31/2004] [Indexed: 12/16/2022]
Abstract
Plasmodium falciparum causes the most virulent form of malaria and remains a major worldwide health problem. The erythrocytic development of P. falciparum relies on parasite invasion of host erythrocytes, a process mediated in part by the interaction of erythrocyte binding antigen 175 (EBA-175) with the erythrocyte receptor glycophorin A (GA). The binding domain of EBA-175 that interacts with glycophorin A is a approximately 330 residues module called F2. Several studies have shown that F2 recognizes both sialic acids and the protein backbone on glycophorin A. Here, we have developed ELISA-based quantitative F2-GA binding assays. We also performed a series of competitive inhibition assays to block the F2-GA interaction using a variety of sialic acid analogs. Our data show that both 2,3-didehydro-2-deoxy-N-acetyl neuraminic acid (DANA) and 3'-N-acetyl neuraminyl-N-acetyl lactosamine are excellent inhibitors of the F2-GA interaction. Moderate levels of inhibition were also observed with monomers or oligomers of N-acetyl neuraminic acid (sialic acid). Furthermore, we show that DANA is able to significantly inhibit the invasion of erythrocytes by P. falciparum. Together, our ELISA-based binding assays and in vitro inhibition of erythrocyte invasion data suggest that small variations in the structures of DANA and related inhibitors can result in even more potent invasion inhibitory activities. Our studies provide a platform for the development of high potency inhibitors of the F2-GA interaction using high throughput drug discovery technologies. Such compounds may form part of inhibitor cocktails, which aim to block invasion of erythrocytes by P. falciparum.
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Affiliation(s)
- Ritica Bharara
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, P.O. Box 10504, Aruna Asaf Ali Marg, New Delhi 110067, India
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Singh AP, Ozwara H, Kocken CHM, Puri SK, Thomas AW, Chitnis CE. Targeted deletion ofPlasmodium knowlesiDuffy binding protein confirms its role in junction formation during invasion. Mol Microbiol 2005; 55:1925-34. [PMID: 15752210 DOI: 10.1111/j.1365-2958.2005.04523.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Red cell invasion by Plasmodium merozoites involves multiple steps such as attachment, apical reorientation, junction formation and entry into a parasitophorous vacuole. These steps are mediated by specific molecular interactions. P. vivax and the simian parasite P. knowlesi require interaction with the Duffy blood group antigen to invade human erythrocytes. P. vivax and P. knowlesi Duffy binding proteins (PvDBP and PkDBP), which bind the Duffy antigen during invasion, share regions of sequence homology and belong to a family of erythrocyte binding proteins (EBPs). By deletion of the gene that encodes PkDBP, we demonstrate that interaction of PkDBP with the Duffy antigen is absolutely necessary for invasion of human erythrocytes by P. knowlesi. Electron microscopy studies reveal that PkDBP knockout parasites are unable to form a junction with human erythrocytes. The interaction of PkDBP with the Duffy antigen is thus necessary for the critical step of junction formation during invasion. These studies provide support for development of intervention strategies that target EBPs to inhibit junction formation and block erythrocyte invasion by malaria parasites.
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Affiliation(s)
- Agam P Singh
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Choe H, Moore MJ, Owens CM, Wright PL, Vasilieva N, Li W, Singh AP, Shakri R, Chitnis CE, Farzan M. Sulphated tyrosines mediate association of chemokines and Plasmodium vivax Duffy binding protein with the Duffy antigen/receptor for chemokines (DARC). Mol Microbiol 2005; 55:1413-22. [PMID: 15720550 DOI: 10.1111/j.1365-2958.2004.04478.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Plasmodium vivax is one of four Plasmodium species that cause human malaria. P. vivax and a related simian malaria parasite, Plasmodium knowlesi, invade erythrocytes by binding the Duffy antigen/receptor for chemokines (DARC) through their respective Duffy binding proteins. Here we show that tyrosines 30 and 41 of DARC are modified by addition of sulphate groups, and that the sulphated tyrosine 41 is essential for association of the Duffy binding proteins of P. vivax (PvDBP) and P. knowlesi (PkDaBP) with DARC-expressing cells. These sulphated tyrosines also participate in the association of DARC with each of its four known chemokine ligands. Alteration of tyrosine 41 to phenylalanine interferes with MCP-1, RANTES and MGSA association with DARC, but not with that of IL8. In contrast, alteration of tyrosine 30 to phenylalanine interferes with the association of IL8 with DARC. A soluble sulphated amino-terminal domain of DARC, but not one modified to phenylalanine at residue 41, can be used to block the association of PvDBP and PkDaBP with red blood cells, with an IC50 of approximately 5 nM. These data are consistent with a role for tyrosine sulphation in the association of many or most chemokines with their receptors, and identify a key molecular determinant of erythrocyte invasion by P. vivax.
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Affiliation(s)
- Hyeryun Choe
- Perlmutter Laboratory, Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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Hans D, Pattnaik P, Bhattacharyya A, Shakri AR, Yazdani SS, Sharma M, Choe H, Farzan M, Chitnis CE. Mapping binding residues in the Plasmodium vivax domain that binds Duffy antigen during red cell invasion. Mol Microbiol 2005; 55:1423-34. [PMID: 15720551 DOI: 10.1111/j.1365-2958.2005.04484.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Summary Plasmodium vivax depends on interaction with the Duffy antigen/receptor for chemokines (DARC) for invasion of human erythrocytes. The 140 kDa P. vivax Duffy-binding protein (PvDBP) mediates interaction with DARC. The receptor-binding domain of PvDBP maps to its N-terminal, cysteine-rich region, region II (PvRII), which contains approximately 300 amino acid residues including 12 conserved cysteines. Using surface plasmon resonance, we show that binding of PvRII to DARC is a high-affinity interaction with a binding constant (K(D)) of 8.7 nM. The minimal binding domain of PvRII has been previously mapped to a central 170-amino-acid stretch that includes cysteines 5-8. Here, we have used site-directed mutagenesis and quantitative binding assays to map amino acid residues within PvRII that make contact with DARC. Of the seven alanine replacement mutations that had an effect on binding, five were mutations in hydrophobic residues suggesting that hydrophobic interactions play a major role in the interaction of PvDBP with DARC. Genetic diversity studies have shown that six of the seven binding residues identified in PvRII are conserved in P. vivax field isolates, which provides support for their role in interaction with DARC.
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Affiliation(s)
- Dhiraj Hans
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India
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Mayor A, Bir N, Sawhney R, Singh S, Pattnaik P, Singh SK, Sharma A, Chitnis CE. Receptor-binding residues lie in central regions of Duffy-binding-like domains involved in red cell invasion and cytoadherence by malaria parasites. Blood 2004; 105:2557-63. [PMID: 15345591 DOI: 10.1182/blood-2004-05-1722] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythrocyte invasion by malaria parasites and cytoadherence of Plasmodium falciparum-infected erythrocytes to host capillaries are 2 key pathogenic mechanisms in malaria. The receptor-binding domains of erythrocyte-binding proteins (EBPs) such as Plasmodium falciparum EBA-175, which mediate invasion, and P falciparum erythrocyte membrane protein 1 (PfEMP-1) family members, which are encoded by var genes and mediate cytoadherence, have been mapped to conserved cysteine-rich domains referred to as Duffy-binding-like (DBL) domains. Here, we have mapped regions within DBL domains from EBPs and PfEMP-1 that contain receptor-binding residues. Using biochemical and molecular methods we demonstrate that the receptor-binding residues of parasite ligands that bind sialic acid on glycophorin A for invasion as well as complement receptor-1 and chondroitin sulfate A for cytoadherence map to central regions of DBL domains. In contrast, binding to intercellular adhesion molecule 1 (ICAM-1) requires both the central and terminal regions of DBLbetaC2 domains. Determination of functional regions within DBL domains is the first step toward understanding the structure-function bases for their interaction with diverse host receptors.
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Affiliation(s)
- Alfredo Mayor
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), PO Box 10504, Aruna Asaf Ali Marg, New Delhi 110067, India
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Valbuena JJ, Bravo RV, Ocampo M, Lopez R, Rodriguez LE, Curtidor H, Puentes A, Garcia JE, Tovar D, Gomez J, Leiton J, Patarroyo ME. Identifying Plasmodium falciparum EBA-175 homologue sequences that specifically bind to human erythrocytes. Biochem Biophys Res Commun 2004; 321:835-44. [PMID: 15358103 DOI: 10.1016/j.bbrc.2004.07.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Indexed: 10/26/2022]
Abstract
Erythrocyte binding antigen-160 (EBA-160) protein is a Plasmodium falciparum antigen homologue from the erythrocyte binding protein family (EBP). It has been shown that the EBP family plays a role in parasite binding to the erythrocyte surface. The EBA-160 sequence has been chemically synthesised in seventy 20-mer sequential peptides covering the entire 3D7 protein strain, each of which was tested in erythrocyte binding assays to identify possible EBA-160 functional regions. Five EBA-160 high activity binding peptides (HABPs) specifically binding to erythrocytes with high affinity were identified. Dissociation constants lay between 200 and 460 nM and Hill coefficients between 1.5 and 2.3. Erythrocyte membrane protein binding peptide cross-linking assays using SDS-PAGE showed that these peptides bound specifically to 12, 28, and 44 kDa erythrocyte membrane proteins. The nature of these receptor sites was studied in peptide binding assays using enzyme-treated erythrocytes. HABPs were able to block merozoite in vitro invasion of erythrocytes. HABPs' potential as anti-malarial vaccine candidates is also discussed.
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Affiliation(s)
- John Jairo Valbuena
- Fundacion Instituto de Inmunologia de Colombia, Universidad Nacional de Colombia, Colombia.
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Han HJ, Park SG, Kim SH, Hwang SY, Han J, Traicoff J, Kho WG, Chung JY. Epidermal growth factor-like motifs 1 and 2 of Plasmodium vivax merozoite surface protein 1 are critical domains in erythrocyte invasion. Biochem Biophys Res Commun 2004; 320:563-70. [PMID: 15219866 DOI: 10.1016/j.bbrc.2004.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Indexed: 11/22/2022]
Abstract
Plasmodium vivax merozoite surface protein 1 (PvMSP1) is believed to be important in erythrocyte invasion. However, the detailed mechanism of PvMSP1-mediated invasion has been unclear. We demonstrate that the C-terminal 19 kDa domain (PvMSP119) of PvMSP1, the 42-kDa fragment of PvMSP1 is further cleaved to a 33 kDa N-terminal polypeptide and a 19 kDa C-terminal fragment in a secondary processing step, is a critical domain in the binding between parasite ligand and erythrocyte receptor. Also, its cytoadherence was successfully blocked by naturally acquired immunity, was partially sensitive to neuraminidase and trypsin. When expressed separately epidermal growth factor (EGF)-like motifs 1 and 2, subunits of the PvMSP119, mediated 64% and 66% of the erythrocyte-binding activity, respectively, relative to their expression together as a single intact ligand domain. These results suggest that the EGF-like motifs 1 and 2 of PvMSP119 function as a core-binding portion in the attachment of PvMSP1 to erythrocytes.
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Affiliation(s)
- Hye-Jin Han
- Department of Microbiology, Inje University College of Medicine, Busan 614-735, South Korea
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Cramer JP, Mockenhaupt FP, Möhl I, Dittrich S, Dietz E, Otchwemah RN, Ehrhardt S, Bienzle U, Jelinek T. Allelic dimorphism of the erythrocyte binding antigen-175 (eba-175) gene of Plasmodium falciparum and severe malaria: Significant association of the C-segment with fatal outcome in Ghanaian children. Malar J 2004; 3:11. [PMID: 15140262 PMCID: PMC420250 DOI: 10.1186/1475-2875-3-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Accepted: 05/12/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The erythrocyte binding antigen-175 (EBA-175) on Plasmodium falciparum merozoites mediates sialic acid dependent binding to glycophorin A on host erythrocytes and, therefore, plays a crucial role in cell invasion. Dimorphic allele segments have been found in its encoding gene with a 342 bp segment present in FCR-3 strains (F-segment) and a 423 bp segment in CAMP strains (C-segment). Possible associations of the dimorphism with severe malaria have been analysed in a case-control study in northern Ghana. METHODS Blood samples of 289 children with severe malaria and 289 matched parasitaemic but asymptomatic controls were screened for eba-175 F- and C-segments by nested polymerase chain reaction. RESULTS In children with severe malaria, prevalences of F-, C- and mixed F-/C-segments were 70%, 19%, and 11%, respectively. The C-segment was found more frequently in severe malaria cases whereas mixed infections were more common in controls. Infection with strains harbouring the C-segment significantly increased the risk of fatal outcome. CONCLUSION The results show that the C-segment is associated with fatal outcome in children with severe malaria in northern Ghana, suggesting that it may contribute to the virulence of the parasite.
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Affiliation(s)
| | | | - Ingo Möhl
- Berlin Institute of Tropical Medicine, Berlin, Germany
| | | | - Ekkehardt Dietz
- Institute for International Health Sciences, Humboldt University, Berlin, Germany
| | - Rowland N Otchwemah
- School of Medicine and Health Sciences, University of Development Studies, Tamale, Ghana
| | - Stephan Ehrhardt
- Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
| | | | - Tomas Jelinek
- Berlin Institute of Tropical Medicine, Berlin, Germany
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Ocampo M, Curtidor H, Vera R, Valbuena JJ, Rodríguez LE, Puentes A, López R, García JE, Tovar D, Pacheco P, Navarro MA, Patarroyo ME. MAEBL Plasmodium falciparum protein peptides bind specifically to erythrocytes and inhibit in vitro merozoite invasion. Biochem Biophys Res Commun 2004; 315:319-29. [PMID: 14766210 DOI: 10.1016/j.bbrc.2004.01.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2004] [Indexed: 11/29/2022]
Abstract
MAEBL is an erythrocyte binding protein located in the rhoptries and on the surface of mature merozoites, being expressed at the beginning of schizogony. The structure of MAEBL originally isolated from rodent malaria parasites suggested a molecule likely to be involved in invasion. We thus became interested in identifying possible MAEBL functional regions. Synthetic peptides spanning the MAEBL sequence were tested in erythrocyte binding assays to identify such possible MAEBL functional regions. Nine high activity binding peptides (HABPs) were identified: two were found in the M1 domain, one was found between the M1 and M2 regions, five in the erythrocyte binding domain (M2), and one in the protein's repeat region. The results showed that peptide binding was saturable; some HABPs inhibited in vitro merozoite invasion and specifically bound to a 33kDa protein on red blood cell membrane. HABPs' possible function in merozoite invasion of erythrocytes is also discussed.
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Affiliation(s)
- Marisol Ocampo
- Fundación Instituto de Inmunologia de Colombia, Universidad Nacional de Colombia, Avda. Calle 26 No. 50-00, Bogotá, Colombia.
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Cole-Tobian J, King CL. Diversity and natural selection in Plasmodium vivax Duffy binding protein gene. Mol Biochem Parasitol 2003; 127:121-32. [PMID: 12672521 DOI: 10.1016/s0166-6851(02)00327-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Plasmodium vivax Duffy binding protein (DBP) binds to the Duffy blood group antigen on the surface of erythrocytes and is essential for invasion. Natural immunity develops to this protein making it an important vaccine candidate. Genetic diversity within and between populations was compared in 100 dbp sequences from isolates obtained from Papua New Guinea, Colombia, and South Korea. The cysteine-rich region II, that contains the binding domain, has the highest diversity compared to the rest of the dbp gene and appears to be under strong selective pressure based on statistical tests comparing rates of non-synonymous (K(n)) to synonymous mutations (K(s)) among P. vivax isolates and to those of closely related species. By contrast, meiotic recombination was not found to be significant for maintaining genetic diversity. A comparison of the patterns of nucleotide diversity within dbpII to that of genes encoding homologous erythrocyte binding proteins of Plasmodium knowlesi predict critical binding residues juxtaposed to polymorphic B- and T-cell epitopes. Phylogenic analysis and measurement of nucleotide diversity between and within the different geographic populations support emergence of distinct allelic families suggestive of divergent selection of alleles between populations. Development of a P. vivax DBP-based vaccine must take into account regions of high diversity within the molecule and alleles that show distinct geographic differences.
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Affiliation(s)
- Jennifer Cole-Tobian
- Center for Global Health and Diseases at Case Western Reserve University School of Medicine and Veteran's Affairs Medical Center, 2109 Adelbert Rd, Rm W137, Cleveland, OH 44106-4983, USA
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Baum J, Thomas AW, Conway DJ. Evidence for diversifying selection on erythrocyte-binding antigens of Plasmodium falciparum and P. vivax. Genetics 2003; 163:1327-36. [PMID: 12702678 PMCID: PMC1462517 DOI: 10.1093/genetics/163.4.1327] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Malaria parasite antigens involved in erythrocyte invasion are primary vaccine candidates. The erythrocyte-binding antigen 175K (EBA-175) of Plasmodium falciparum binds to glycophorin A on the human erythrocyte surface via an N-terminal cysteine-rich region (termed region II) and is a target of antibody responses. A survey of polymorphism in a malaria-endemic population shows that nucleotide alleles in eba-175 region II occur at more intermediate frequencies than expected under neutrality, but polymorphisms in the homologous domains of two closely related genes, eba-140 (encoding a second erythrocyte-binding protein) and psieba-165 (a putative pseudogene), show an opposite trend. McDonald-Kreitman tests employing interspecific comparison with the orthologous genes in P. reichenowi (a closely related parasite of chimpanzees) reveal a significant excess of nonsynonymous polymorphism in P. falciparum eba-175 but not in eba-140. An analysis of the Duffy-binding protein gene, encoding a major erythrocyte-binding antigen in the other common human malaria parasite P. vivax, also reveals a significant excess of nonsynonymous polymorphisms when compared with divergence from its ortholog in P. knowlesi (a closely related parasite of macaques). The results suggest that EBA-175 in P. falciparum and DBP in P. vivax are both under diversifying selection from acquired human immune responses.
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Affiliation(s)
- Jake Baum
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom.
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Black CG, Wang L, Wu T, Coppel RL. Apical location of a novel EGF-like domain-containing protein of Plasmodium falciparum. Mol Biochem Parasitol 2003; 127:59-68. [PMID: 12615336 DOI: 10.1016/s0166-6851(02)00308-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using bioinformatics analyses of the unfinished malaria genome sequence, we have identified a novel protein of Plasmodium falciparum that contains two epidermal growth factor (EGF)-like domains near the C-terminus of the protein. The sequence contains a single open reading frame of 1572bp with the potential to encode a protein of 524 residues containing hydrophobic regions at the extreme N- and C-termini which appear to represent signal peptide and glycosylphosphatidylinositol (GPI)-attachment sites, respectively. RT-PCR analysis has confirmed that the novel gene is transcribed in asexual stages of P. falciparum. Antibodies to the EGF-like domains of the novel protein are highly specific and do not cross-react with the EGF-like domains of MSP1, MSP4, MSP5 or MSP8 expressed as GST fusion proteins. Antisera to the C-terminal fragments react with two bands of 80 and 36kDa in P. falciparum parasite lysates whereas antisera to the most N-terminal fusion protein only recognises the 80kDa band, suggesting that the novel protein may undergo processing in a similar way to MSP1 and MSP8, but with fewer cleavage events. Immunoblot analysis of stage-specific parasite samples reveals that the protein is present in trophozoites, schizonts and in isolated merozoites. The protein partitions in the detergent-enriched phase after Triton X-114 fractionation and is localised to the surfaces of trophozoites, schizonts and free merozoites in an apical distribution. Based on the accepted nomenclature in the field we now designate this protein MSP10. We have shown that the MSP10 fusion proteins are in a conformation that can be recognised by human immune sera and that there is very limited sequence diversity in an approximately lkb region of MSP10, encompassing the two EGF-like domains. A sequence similar to MSP10 can be identified in the available P. yoelii genomic sequence, offering the possibility of ascertaining whether this novel protein can induce host protective responses in an in vivo model.
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Affiliation(s)
- Casilda G Black
- Department of Microbiology and the Victorian Bioinformatics Consortium, P.O. Box 53, Monash University, 3800 Victoria, Australia.
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Abstract
Plasmodium falciparum malaria remains as one of the most devastating global health problems of today. It is estimated that around 150 million individuals get the disease every year and of these 2-3 million die from it. Our knowledge of the mechanisms underlying the pathology has expanded greatly over the last decades, but many aspects of the molecular biology, immunology and epidemiology that govern the pathogenesis and spread of this parasite are still unclear. As new insights are gained we are also revealing a challenging biological complexity. Piecing this information together is the key to vaccine development and production of new antimalarial drugs.
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Affiliation(s)
- Andreas Heddini
- Microbiology and Tumor Biology Center, Karolinska Institutet and Swedish Institute for Infectious Disease Control, Stockholm, Sweden.
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