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Zhang M, Wang Y, Shen HM, Chen SB, Wang TY, Kassegne K, Chen JH. Genetic Diversity and Natural Selection of Plasmodium vivax Merozoite Surface Protein 8 in Global Populations. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2024; 122:105605. [PMID: 38759940 DOI: 10.1016/j.meegid.2024.105605] [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: 11/10/2023] [Revised: 05/09/2024] [Accepted: 05/14/2024] [Indexed: 05/19/2024]
Abstract
Plasmodium vivax Merozoite Surface Protein 8 (PvMSP8) is a promising candidate target for the development of multi-component vaccines. Therefore, determining the genetic variation pattern of Pvmsp8 is essential in providing a reference for the rational design of the P. vivax malaria vaccines. This study delves into the genetic characteristics of the Pvmsp8 gene, specifically focusing on samples from the China-Myanmar border (CMB) region, and contrasts these findings with broader global patterns. The study uncovers that Pvmsp8 exhibits a notable level of conservation across different populations, with limited polymorphisms and relatively low nucleotide diversity (0.00023-0.00120). This conservation contrasts starkly with the high polymorphisms found in other P. vivax antigens such as Pvmsp1. A total of 25 haplotypes and 14 amino acid mutation sites were identified in the global populations, and all mutation sites were confined to non-functional regions. The study also notes that most CMB Pvmsp8 haplotypes are shared among Burmese, Cambodian, Thai, and Vietnamese populations, indicating less geographical variance, but differ notably from those found in Pacific island regions or the Panama. The findings underscore the importance of considering regional genetic diversity in P. vivax when developing targeted malaria vaccines. Non departure from neutral evolution were found by Tajima's D test, however, statistically significant differences were observed between the kn/ks rates. The study's findings are crucial in understanding the evolution and population structure of the Pvmsp8 gene, particularly during regional malaria elimination efforts. The highly conserved nature of Pvmsp8, combined with the lack of mutations in its functional domain, presents it as a promising candidate for developing a broad and effective P. vivax vaccine. This research thus lays a foundation for the rational development of multivalent malaria vaccines targeting this genetically stable antigen.
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Affiliation(s)
- Man Zhang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China
| | - Yue Wang
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou 310013, People's Republic of China
| | - Hai-Mo Shen
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China
| | - Shen-Bo Chen
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China
| | - Tian-Yu Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China
| | - Kokouvi Kassegne
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China; School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China
| | - Jun-Hu Chen
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases; National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai 200025, People's Republic of China; School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou 310013, People's Republic of China; School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China; Hainan Tropical Diseases Research Center (Hainan Sub-Center, Chinese Center for Tropical Diseases Research), Haikou 571199, China.
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Wan Nazri WSM, Ling LY, Wen CF. Detection of Plasmodium knowlesi in whole blood samples with sandwich enzyme-linked immunosorbent assay (ELISA) using rhoptry-associated protein 1 specific polyclonal antibodies. J Vector Borne Dis 2024; 61:203-210. [PMID: 38922654 DOI: 10.4103/jvbd.jvbd_55_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 11/06/2023] [Indexed: 06/27/2024] Open
Abstract
BACKGROUND OBJECTIVES Plasmodium knowlesi, a simian malaria species, is now known to infect humans. Due to disadvantages in the current diagnosis methods, many efforts have been placed into developing new methods to diagnose the disease. This study assessed the ability of the PkRAP-1 sandwich enzyme-linked immunosorbent (ELISA) to detect P knowlesi antigens in whole blood specimens. METHODS Western blot assay was conducted to evaluate the ability of raised mouse and rabbit anti-PkRAP-1 polyclonal antibodies to bind to the native proteins in P. knowlesi lysate. The polyclonal antibodies were then used in sandwich ELISA to detect P. knowlesi. In the sandwich ELISA, mouse and rabbit polyclonal antibodies were used as the capture and detection antibodies, respectively. The limit of detection (LOD) of the assay was determined using P. knowlesi A1H1 culture and purified recombinant PkRAP-1. RESULTS Western blot results showed positive reactions towards the proteins in P. knowlesi lysate. The LOD of the assay from three technical replicates was 0.068% parasitaemia. The assay performance in detecting P. knowlesi was 83% sensitivity and 70% specificity with positive and negative predictive values of 74% and 80%, respectively. The anti-PkRAP-1 polyclonal antibodies did not cross-react with P. falciparum and healthy samples, but P. vivax by detecting all 12 samples. INTERPRETATION CONCLUSION PkRAP-1 has the potential as a biomarker for the development of a new diagnostic tool for P. knowlesi detection. Further studies need to be conducted to establish the full potential of the usage of anti-PkRAP-1 antibodies for P. knowlesi detection.
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Ricaurte-Contreras LA, Lovera A, Moreno-Pérez DA, Bohórquez MD, Suárez CF, Gutiérrez-Vásquez E, Cuy-Chaparro L, Garzón-Ospina D, Patarroyo MA. Two 20-Residue-Long Peptides Derived from Plasmodium vivax Merozoite Surface Protein 10 EGF-Like Domains Are Involved in Binding to Human Reticulocytes. Int J Mol Sci 2021; 22:ijms22041609. [PMID: 33562650 PMCID: PMC7915351 DOI: 10.3390/ijms22041609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/21/2021] [Accepted: 02/02/2021] [Indexed: 11/30/2022] Open
Abstract
Plasmodium parasites’ invasion of their target cells is a complex, multi-step process involving many protein-protein interactions. Little is known about how complex the interaction with target cells is in Plasmodium vivax and few surface molecules related to reticulocytes’ adhesion have been described to date. Natural selection, functional and structural analysis were carried out on the previously described vaccine candidate P. vivax merozoite surface protein 10 (PvMSP10) for evaluating its role during initial contact with target cells. It has been shown here that the recombinant carboxyl terminal region (rPvMSP10-C) bound to adult human reticulocytes but not to normocytes, as validated by two different protein-cell interaction assays. Particularly interesting was the fact that two 20-residue-long regions (388DKEECRCRANYMPDDSVDYF407 and 415KDCSKENGNCDVNAECSIDK434) were able to inhibit rPvMSP10-C binding to reticulocytes and rosette formation using enriched target cells. These peptides were derived from PvMSP10 epidermal growth factor (EGF)-like domains (precisely, from a well-defined electrostatic zone) and consisted of regions having the potential of being B- or T-cell epitopes. These findings provide evidence, for the first time, about the fragments governing PvMSP10 binding to its target cells, thus highlighting the importance of studying them for inclusion in a P. vivax antimalarial vaccine.
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Affiliation(s)
- Laura Alejandra Ricaurte-Contreras
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
- MSc Programme in Microbiology, Universidad Nacional de Colombia, Carrera 45#26-85, Bogotá 111321, Colombia
| | - Andrea Lovera
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Darwin Andrés Moreno-Pérez
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Michel David Bohórquez
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Carlos Fernando Suárez
- Biomathematics Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia;
| | - Elizabeth Gutiérrez-Vásquez
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Laura Cuy-Chaparro
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Diego Garzón-Ospina
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
| | - Manuel Alfonso Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50#26-20, Bogotá 111321, Colombia; (L.A.R.-C.); (A.L.); (D.A.M.-P.); (M.D.B.); (E.G.-V.); (L.C.-C.); (D.G.-O.)
- Health Sciences Division, Main Campus, Universidad Santo Tomás, Carrera 9#51-11, Bogotá 110231, Colombia
- Microbiology Department, Faculty of Medicine, Universidad Nacional de Colombia, Carrera 45#26-85, Bogotá 111321, Colombia
- Correspondence:
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Muh F, Kim N, Nyunt MH, Firdaus ER, Han JH, Hoque MR, Lee SK, Park JH, Moon RW, Lau YL, Kaneko O, Han ET. Cross-species reactivity of antibodies against Plasmodium vivax blood-stage antigens to Plasmodium knowlesi. PLoS Negl Trop Dis 2020; 14:e0008323. [PMID: 32559186 PMCID: PMC7304578 DOI: 10.1371/journal.pntd.0008323] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 04/24/2020] [Indexed: 12/22/2022] Open
Abstract
Malaria is caused by multiple different species of protozoan parasites, and interventions in the pre-elimination phase can lead to drastic changes in the proportion of each species causing malaria. In endemic areas, cross-reactivity may play an important role in the protection and blocking transmission. Thus, successful control of one species could lead to an increase in other parasite species. A few studies have reported cross-reactivity producing cross-immunity, but the extent of cross-reactive, particularly between closely related species, is poorly understood. P. vivax and P. knowlesi are particularly closely related species causing malaria infections in SE Asia, and whilst P. vivax cases are in decline, zoonotic P. knowlesi infections are rising in some areas. In this study, the cross-species reactivity and growth inhibition activity of P. vivax blood-stage antigen-specific antibodies against P. knowlesi parasites were investigated. Bioinformatics analysis, immunofluorescence assay, western blotting, protein microarray, and growth inhibition assay were performed to investigate the cross-reactivity. P. vivax blood-stage antigen-specific antibodies recognized the molecules located on the surface or released from apical organelles of P. knowlesi merozoites. Recombinant P. vivax and P. knowlesi proteins were also recognized by P. knowlesi- and P. vivax-infected patient antibodies, respectively. Immunoglobulin G against P. vivax antigens from both immune animals and human malaria patients inhibited the erythrocyte invasion by P. knowlesi. This study demonstrates that there is extensive cross-reactivity between antibodies against P. vivax to P. knowlesi in the blood stage, and these antibodies can potently inhibit in vitro invasion, highlighting the potential cross-protective immunity in endemic areas. In recent years, malaria initiatives have increasingly shifted focus from achieving malaria control to achieving malaria elimination. However, the interventions used are leading to drastic changes in the proportions of different Plasmodium species causing clinical infection, particularly within Southeast Asia. Little is known about how these different parasite species interact/compete in nature or whether exposure to one species could cause some level of protection against another. We examined cross-reactive antibody responses to key parasite proteins with roles in red blood cell invasion and identified novel cross-species reactivity among the closest of malaria affecting the human population (P. vivax and P. knowlesi). This comprehensive analysis provides evidence that cross-reactive immunity could play an important role in areas where species distributions are perturbed by malaria control measures, and future efforts to identify the specific cross-reactive epitopes involved would be invaluable both to our understanding of malaria immunity and vaccine development.
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Affiliation(s)
- Fauzi Muh
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Namhyeok Kim
- 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
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Mohammad Rafiul Hoque
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Seong-Kyun Lee
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Ji-Hoon Park
- Department of Medical Environmental Biology and Tropical Medicine, 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
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki, Japan
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
- * E-mail:
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Siddiqui G, Proellochs NI, Cooke BM. Identification of essential exported
Plasmodium falciparum
protein kinases in malaria‐infected red blood cells. Br J Haematol 2019; 188:774-783. [DOI: 10.1111/bjh.16219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/31/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Ghizal Siddiqui
- Department of Microbiology Biomedicine Discovery Institute Monash University Clayton Victoria Australia
- Drug Delivery, Disposition and Dynamics Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Nicholas I. Proellochs
- Department of Microbiology Biomedicine Discovery Institute Monash University Clayton Victoria Australia
- Department of Medical Microbiology Radboud University Medical Center Nijmegen the Netherlands
| | - Brian M. Cooke
- Department of Microbiology Biomedicine Discovery Institute Monash University Clayton Victoria Australia
- Australian Institute of Tropical Health and Medicine James Cook University Cairns Queensland Australia
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Parzych EM, Miura K, Ramanathan A, Long CA, Burns JM. Evaluation of a Plasmodium-Specific Carrier Protein To Enhance Production of Recombinant Pfs25, a Leading Transmission-Blocking Vaccine Candidate. Infect Immun 2018; 86:e00486-17. [PMID: 28993460 PMCID: PMC5736822 DOI: 10.1128/iai.00486-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/03/2017] [Indexed: 01/25/2023] Open
Abstract
Challenges with the production and suboptimal immunogenicity of malaria vaccine candidates have slowed the development of a Plasmodium falciparum multiantigen vaccine. Attempting to resolve these issues, we focused on the use of highly immunogenic merozoite surface protein 8 (MSP8) as a vaccine carrier protein. Previously, we showed that a genetic fusion of the C-terminal 19-kDa fragment of merozoite surface protein 1 (MSP119) to P. falciparum MSP8 (PfMSP8) facilitated antigen production and folding and the induction of neutralizing antibodies to conformational B cell epitopes of MSP119 Here, using the PfMSP1/8 construct, we further optimized the recombinant PfMSP8 (rPfMSP8) carrier by the introduction of two cysteine-to-serine substitutions (CΔS) to improve the yield of the monomeric product. We then sought to test the broad applicability of this approach using the transmission-blocking vaccine candidate Pfs25. The production of rPfs25-based vaccines has presented challenges. Antibodies directed against the four highly constrained epidermal growth factor (EGF)-like domains of Pfs25 block sexual-stage development in mosquitoes. The sequence encoding mature Pfs25 was codon harmonized for expression in Escherichia coli We produced a rPfs25-PfMSP8 fusion protein [rPfs25/8(CΔS)] as well as unfused, mature rPfs25. rPfs25 was purified with a modest yield but required the incorporation of refolding protocols to obtain a proper conformation. In comparison, chimeric rPfs25/8(CΔS) was expressed and easily purified, with the Pfs25 domain bearing the proper conformation without renaturation. Both antigens were immunogenic in rabbits, inducing IgG that bound native Pfs25 and exhibited potent transmission-reducing activity. These data further demonstrate the utility of PfMSP8 as a parasite-specific carrier protein to enhance the production of complex malaria vaccine targets.
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Affiliation(s)
- Elizabeth M Parzych
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Kazutoyo Miura
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Aarti Ramanathan
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Carole A Long
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - James M Burns
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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7
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Jackson AP. Gene family phylogeny and the evolution of parasite cell surfaces. Mol Biochem Parasitol 2016; 209:64-75. [DOI: 10.1016/j.molbiopara.2016.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/18/2016] [Accepted: 03/19/2016] [Indexed: 11/30/2022]
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Das S, Hertrich N, Perrin AJ, Withers-Martinez C, Collins CR, Jones ML, Watermeyer JM, Fobes ET, Martin SR, Saibil HR, Wright GJ, Treeck M, Epp C, Blackman MJ. Processing of Plasmodium falciparum Merozoite Surface Protein MSP1 Activates a Spectrin-Binding Function Enabling Parasite Egress from RBCs. Cell Host Microbe 2016; 18:433-44. [PMID: 26468747 PMCID: PMC4608996 DOI: 10.1016/j.chom.2015.09.007] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/17/2015] [Accepted: 09/18/2015] [Indexed: 11/09/2022]
Abstract
The malaria parasite Plasmodium falciparum replicates within erythrocytes, producing progeny merozoites that are released from infected cells via a poorly understood process called egress. The most abundant merozoite surface protein, MSP1, is synthesized as a large precursor that undergoes proteolytic maturation by the parasite protease SUB1 just prior to egress. The function of MSP1 and its processing are unknown. Here we show that SUB1-mediated processing of MSP1 is important for parasite viability. Processing modifies the secondary structure of MSP1 and activates its capacity to bind spectrin, a molecular scaffold protein that is the major component of the host erythrocyte cytoskeleton. Parasites expressing an inefficiently processed MSP1 mutant show delayed egress, and merozoites lacking surface-bound MSP1 display a severe egress defect. Our results indicate that interactions between SUB1-processed merozoite surface MSP1 and the spectrin network of the erythrocyte cytoskeleton facilitate host erythrocyte rupture to enable parasite egress. Merozoite surface protein MSP1 processing is important for P. falciparum viability Proteolytic processing activates MSP1’s heparin and spectrin-binding functions The rate of MSP1 processing governs the kinetics of parasite egress Loss of parasite surface MSP1 results in a severe egress defect
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Affiliation(s)
- Sujaan Das
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK
| | - Nadine Hertrich
- Department für Infektiologie, Parasitologie, Universitätsklinikum Heidelberg, D-69120 Heidelberg, Germany
| | - Abigail J Perrin
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1HH, UK
| | | | - Christine R Collins
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK
| | - Matthew L Jones
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK
| | - Jean M Watermeyer
- Department of Crystallography, Birkbeck College, London, WC1E 7HX, UK
| | - Elmar T Fobes
- Department für Infektiologie, Parasitologie, Universitätsklinikum Heidelberg, D-69120 Heidelberg, Germany
| | - Stephen R Martin
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK
| | - Helen R Saibil
- Department of Crystallography, Birkbeck College, London, WC1E 7HX, UK
| | - Gavin J Wright
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1HH, UK
| | - Moritz Treeck
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK
| | - Christian Epp
- Department für Infektiologie, Parasitologie, Universitätsklinikum Heidelberg, D-69120 Heidelberg, Germany
| | - Michael J Blackman
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, NW7 1AA, UK; Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.
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Burns JM, Miura K, Sullivan J, Long CA, Barnwell JW. Immunogenicity of a chimeric Plasmodium falciparum merozoite surface protein vaccine in Aotus monkeys. Malar J 2016; 15:159. [PMID: 26975721 PMCID: PMC4791798 DOI: 10.1186/s12936-016-1226-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 03/10/2016] [Indexed: 11/23/2022] Open
Abstract
Background The production of properly folded, recombinant sub-unit Plasmodium falciparum malaria vaccine candidates in sufficient quantities is often a challenge. Success in vaccine immunogenicity studies in small animal models does not always predict immunogenicity in non-human primates and/or human subjects. The aim of this study was to assess the immunogenicity of a chimeric blood-stage malaria vaccine in Aotus monkeys. This vaccine candidate includes the neutralizing B cell epitopes of P. falciparum merozoite surface protein 1 (rPfMSP119) genetically linked to a highly immunogenic, well-conserved P. falciparum merozoite surface protein 8 (rPfMSP8 (ΔAsn/Asp)) partner. Methods Aotus nancymaae monkeys were immunized with purified rPfMSP1/8 or rPfMSP8 (ΔAsn/Asp) formulated with Montanide ISA 720 as adjuvant, or with adjuvant alone. Antibody responses to MSP119 and MSP8 domains were measured by ELISA following primary, secondary and tertiary immunizations. The functionality of vaccine-induced antibodies was assessed in a standard P. falciparum blood-stage in vitro growth inhibition assay. Non-parametric tests with corrections for multiple comparisons when appropriate were used to determine the significance of differences in antigen-specific IgG titres and in parasite growth inhibition. Results The chimeric rPfMSP1/8 vaccine was shown to be well tolerated and highly immunogenic with boost-able antibody responses elicited to both PfMSP8 and PfMSP119 domains. Elicited antibodies were highly cross-reactive between FVO and 3D7 alleles of PfMSP119 and potently inhibited the in vitro growth of P. falciparum blood-stage parasites. Conclusions Similar to previous results with inbred and outbred mice and with rabbits, the PfMSP1/8 vaccine was shown to be highly effective in eliciting P. falciparum growth inhibitory antibodies upon immunization of non-human primates. The data support the further assessment of PfMSP1/8 as a component of a multivalent vaccine for use in human subjects. As important, the data indicate that rPfMSP8 (ΔAsn/Asp) can be used as a malaria specific carrier protein to: (1) drive production of antibody responses to neutralizing B cell epitopes of heterologous vaccine candidates and (2) facilitate production of properly folded, recombinant P. falciparum subunit vaccines in high yield.
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Affiliation(s)
- James M Burns
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA, 19129, USA.
| | - Kazutoyo Miura
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - JoAnn Sullivan
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Carole A Long
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA, 19129, USA.,Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - John W Barnwell
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
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10
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Sonaimuthu P, Cheong FW, Chin LC, Mahmud R, Fong MY, Lau YL. Detection of human malaria using recombinant Plasmodium knowlesi merozoire surface protein-1 (MSP-1₁₉) expressed in Escherichia coli. Exp Parasitol 2015; 153:118-22. [PMID: 25812552 DOI: 10.1016/j.exppara.2015.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 03/10/2015] [Accepted: 03/20/2015] [Indexed: 01/30/2023]
Abstract
Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Human infection with Plasmodium knowlesi is widely distributed in Southeast Asia. Merozoite surface protein-1₁₉ (MSP-1₁₉), which plays an important role in protective immunity against asexual blood stage malaria parasites, appears as a leading immunogenic antigen of Plasmodium sp. We evaluated the sensitivity and specificity of recombinant P. knowlesi MSP-1₁₉ (rMSP-1₁₉) for detection of malarial infection. rMSP-1₁₉ was expressed in Escherichia coli expression system and the purified rMSP-1₁₉ was evaluated with malaria, non-malaria and healthy human serum samples (n = 215) in immunoblots. The sensitivity of rMSP-1₁₉ for detection of P. knowlesi, Plasmodium falciparum, Plasmodium vivax and Plasmodium ovale infection was 95.5%, 75.0%, 85.7% and 100%, respectively. rMSP-1₁₉ did not react with all the non-malaria and healthy donor sera, which represents 100% specificity. The rMSP-1₁₉ could be used as a potential antigen in serodiagnosis of malarial infection in humans.
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Affiliation(s)
| | - Fei Wen Cheong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Lit Chein Chin
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Rohela Mahmud
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.
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11
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Amarasinghe S, Kathriarachchi H, Udagama P. Conserved regions of Plasmodium vivax potential vaccine candidate antigens in Sri Lanka: conscious in silico analysis of prospective conformational epitope regions. ASIAN PAC J TROP MED 2014; 7:832-40. [PMID: 25129470 DOI: 10.1016/s1995-7645(14)60146-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/20/2014] [Accepted: 08/22/2014] [Indexed: 10/24/2022] Open
Abstract
OBJECTIVES To do mapping and modeling of conformational B cell epitope regions of highly conserved and protective regions of three merozoitecandidate vaccine proteins of Plasmodium vivax (P. vivax), ie. merozoite purface protein-1 (PvMSP-1), apical membrane antigen -1 domain ∏ (PvAMA1-D∏) and region ∏ of the Duffy binding protein (PvDBP∏), and to analyze the immunogenic properties of these predicted epitopes. METHODS 3-D structures of amino acid haplotypes from Sri Lanka (available in GeneBank) of PvMSP-119 (n=27), PvAMA1-D∏ (n=21) and PvDBP∏ (n=33) were modeled. SEPPA, selected as the best online server was used for conformational epitope predictions, while prediction and modeling of protein structure and properties related to immunogenicity was carried out with Geno3D server, SCRATCH Protein Server, NetSurfP Server and standalonesoftware, Genious 5.4.4. RESULTS SEPPA revealed that regions of predicted conformational epitopes formed 4 clusters in PvMSP-I19, and 3 clusters each in PvAMA1-D∏ and PvDBP∏, all of which displayed a high degree of hydrophilicity, contained solvent exposed residues, displayed high probability of antigenicity and showed positive antigenic propensity values, that indicated high degree of immunogenicity. CONCLUSIONS Findings of this study revealed and confirmed that different parts of the sequences of each of the conserved regions of the three selected potential vaccine candidate antigens of P. vivax are important with regard to conformational epitope prediction that warrants further laboratory experimental investigations in in vivo animal models.
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Affiliation(s)
- Shanika Amarasinghe
- Department of Plant Sciences, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka
| | - Hashendra Kathriarachchi
- Department of Plant Sciences, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka
| | - Preethi Udagama
- Department of Zoology, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka.
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12
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Curd RD, Birdsall B, Kadekoppala M, Ogun SA, Kelly G, Holder AA. The structure of Plasmodium yoelii merozoite surface protein 119, antibody specificity and implications for malaria vaccine design. Open Biol 2014; 4:130091. [PMID: 24403012 PMCID: PMC3909271 DOI: 10.1098/rsob.130091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 12/06/2013] [Indexed: 11/12/2022] Open
Abstract
Merozoite surface protein 1 (MSP1) has been identified as a target antigen for protective immune responses against asexual blood stage malaria, but effective vaccines based on MSP1 have not been developed so far. We have modified the sequence of Plasmodium yoelii MSP119 (the C-terminal region of the molecule) and examined the ability of the variant proteins to bind protective monoclonal antibodies and to induce protection by immunization. In parallel, we examined the structure of the protein and the consequences of the amino acid changes. Naturally occurring sequence polymorphisms reduced the binding of individual protective antibodies, indicating that they contribute to immune evasion, but immunization with these variant proteins still provided protective immunity. One variant that resulted in the localized distortion of a loop close to the N-terminus of MSP119 almost completely ablated protection by immunization, indicating the importance of this region of MSP119 as a target for protective immunity and in vaccine development.
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Affiliation(s)
- Rachel D. Curd
- Divisions of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Berry Birdsall
- Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Madhusudan Kadekoppala
- Divisions of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Solabomi A. Ogun
- Divisions of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Geoffrey Kelly
- NMR Centre, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Anthony A. Holder
- Divisions of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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13
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Persson KEM, Fowkes FJI, McCallum FJ, Gicheru N, Reiling L, Richards JS, Wilson DW, Lopaticki S, Cowman AF, Marsh K, Beeson JG. Erythrocyte-binding antigens of Plasmodium falciparum are targets of human inhibitory antibodies and function to evade naturally acquired immunity. THE JOURNAL OF IMMUNOLOGY 2013; 191:785-94. [PMID: 23776178 DOI: 10.4049/jimmunol.1300444] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Abs that inhibit Plasmodium falciparum invasion of erythrocytes form an important component of human immunity against malaria, but key target Ags are largely unknown. Phenotypic variation by P. falciparum mediates the evasion of inhibitory Abs, contributing to the capacity of P. falciparum to cause repeat and chronic infections. However, Ags involved in mediating immune evasion have not been defined, and studies of the function of human Abs are limited. In this study, we used novel approaches to determine the importance of P. falciparum erythrocyte-binding Ags (EBAs), which are important invasion ligands, as targets of human invasion-inhibitory Abs and define their role in contributing to immune evasion through variation in function. We evaluated the invasion-inhibitory activity of acquired Abs from malaria-exposed children and adults from Kenya, using P. falciparum with disruption of genes encoding EBA140, EBA175, and EBA181, either individually or combined as EBA140/EBA175 or EBA175/EBA181 double knockouts. Our findings provide important new evidence that variation in the expression and function of the EBAs plays an important role in evasion of acquired Abs and that a substantial amount of phenotypic diversity results from variation in expression of different EBAs that contributes to immune evasion by P. falciparum. All three EBAs were identified as important targets of naturally acquired inhibitory Abs demonstrated by differential inhibition of parental parasites greater than EBA knockout lines. This knowledge will help to advance malaria vaccine development and suggests that multiple invasion ligands need to be targeted to overcome the capacity of P. falciparum for immune evasion.
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Affiliation(s)
- Kristina E M Persson
- Karolinska Institutet, Microbiology, Tumor and Cell Biology, 17177 Stockholm, Sweden.
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14
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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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15
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Evaluation of the immunogenicity and vaccine potential of recombinant Plasmodium falciparum merozoite surface protein 8. Infect Immun 2012; 80:2473-84. [PMID: 22585960 DOI: 10.1128/iai.00211-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The C-terminal 19-kDa domain of merozoite surface protein 1 (MSP1₁₉) is the target of protective antibodies but alone is poorly immunogenic. Previously, using the Plasmodium yoelii murine model, we fused P. yoelii MSP1₁₉ (PyMSP1₁₉) with full-length P. yoelii merozoite surface protein 8 (MSP8). Upon immunization, the MSP8-restricted T cell response provided help for the production of high and sustained levels of protective PyMSP1₁₉- and PyMSP8-specific antibodies. Here, we assessed the vaccine potential of MSP8 of the human malaria parasite, Plasmodium falciparum. Distinct from PyMSP8, P. falciparum MSP8 (PfMSP8) contains an N-terminal asparagine and aspartic acid (Asn/Asp)-rich domain whose function is unknown. Comparative analysis of recombinant full-length PfMSP8 and a truncated version devoid of the Asn/Asp-rich domain, PfMSP8(ΔAsn/Asp), showed that both proteins were immunogenic for T cells and B cells. All T cell epitopes utilized mapped within rPfMSP8(ΔAsn/Asp). The dominant B cell epitopes were conformational and common to both rPfMSP8 and rPfMSP8(ΔAsn/Asp). Analysis of native PfMSP8 expression revealed that PfMSP8 is present intracellularly in late schizonts and merozoites. Following invasion, PfMSP8 is found distributed on the surface of ring- and trophozoite-stage parasites. Consistent with a low and/or transient expression of PfMSP8 on the surface of merozoites, PfMSP8-specific rabbit IgG did not inhibit the in vitro growth of P. falciparum blood-stage parasites. These studies suggest that the further development of PfMSP8 as a malaria vaccine component should focus on the use of PfMSP8(ΔAsn/Asp) and its conserved, immunogenic T cell epitopes as a fusion partner for protective domains of poor immunogens, including PfMSP1₁₉.
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16
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Pacheco MA, Elango AP, Rahman AA, Fisher D, Collins WE, Barnwell JW, Escalante AA. Evidence of purifying selection on merozoite surface protein 8 (MSP8) and 10 (MSP10) in Plasmodium spp. INFECTION GENETICS AND EVOLUTION 2012; 12:978-86. [PMID: 22414917 DOI: 10.1016/j.meegid.2012.02.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/16/2012] [Accepted: 02/18/2012] [Indexed: 01/08/2023]
Abstract
Evidence for natural selection, positive or negative, on gene encoding antigens may indicate variation or functional constraints that are immunologically relevant. Most malaria surface antigens with high genetic diversity have been reported to be under positive-diversifying selection. However, antigens with limited genetic variation are usually ignored in terms of the role that natural selection may have in generating such patterns. We investigated orthologous genes encoding two merozoite proteins, MSP8 and MSP10, among several mammalian Plasmodium spp. These antigens, together with MSP1, are among the few MSPs that have two epidermal growth factor-like domains (EGF) at the C-terminal. Those EGF are relatively conserved (low levels of genetic polymorphism) and have been proposed to act as ligands during the invasion of RBCs. We use several evolutionary genetic methods to detect patterns consistent with natural selection acting on MSP8 and MSP10 orthologs in the human parasites Plasmodium falciparum and P. vivax, as well as closely related malarial species found in non-human primates (NHPs). Overall, these antigens have low polymorphism in the human parasites in comparison with the orthologs from other Plasmodium spp. We found that the MSP10 gene polymorphism in P. falciparum only harbor non-synonymous substitutions, a pattern consistent with a gene under positive selection. Evidence of purifying selection was found on the polymorphism observed in both orthologs from P. cynomolgi, a non-human primate parasite closely related to P. vivax, but it was not conclusive in the human parasite. Yet, using phylogenetic base approaches, we found evidence for purifying selection on both MSP8 and MSP10 in the lineage leading to P. vivax. Such antigens evolving under strong functional constraints could become valuable vaccine candidates. We discuss how comparative approaches could allow detecting patterns consistent with negative selection even when there is low polymorphism in the extant populations.
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Affiliation(s)
- M Andreína Pacheco
- Center for Evolutionary Medicine and Informatics, The Biodesign Institute, Arizona State University, Tempe, AZ, United States
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17
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Olivieri A, Collins CR, Hackett F, Withers-Martinez C, Marshall J, Flynn HR, Skehel JM, Blackman MJ. Juxtamembrane shedding of Plasmodium falciparum AMA1 is sequence independent and essential, and helps evade invasion-inhibitory antibodies. PLoS Pathog 2011; 7:e1002448. [PMID: 22194692 PMCID: PMC3240622 DOI: 10.1371/journal.ppat.1002448] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 11/04/2011] [Indexed: 12/16/2022] Open
Abstract
The malarial life cycle involves repeated rounds of intraerythrocytic replication interspersed by host cell rupture which releases merozoites that rapidly invade fresh erythrocytes. Apical membrane antigen-1 (AMA1) is a merozoite protein that plays a critical role in invasion. Antibodies against AMA1 prevent invasion and can protect against malaria in vivo, so AMA1 is of interest as a malaria vaccine candidate. AMA1 is efficiently shed from the invading parasite surface, predominantly through juxtamembrane cleavage by a membrane-bound protease called SUB2, but also by limited intramembrane cleavage. We have investigated the structural requirements for shedding of Plasmodium falciparum AMA1 (PfAMA1), and the consequences of its inhibition. Mutagenesis of the intramembrane cleavage site by targeted homologous recombination abolished intramembrane cleavage with no effect on parasite viability in vitro. Examination of PfSUB2-mediated shedding of episomally-expressed PfAMA1 revealed that the position of cleavage is determined primarily by its distance from the parasite membrane. Certain mutations at the PfSUB2 cleavage site block shedding, and parasites expressing these non-cleavable forms of PfAMA1 on a background of expression of the wild type gene invade and replicate normally in vitro. The non-cleavable PfAMA1 is also functional in invasion. However – in contrast to the intramembrane cleavage site - mutations that block PfSUB2-mediated shedding could not be stably introduced into the genomic pfama1 locus, indicating that some shedding of PfAMA1 by PfSUB2 is essential. Remarkably, parasites expressing shedding-resistant forms of PfAMA1 exhibit enhanced sensitivity to antibody-mediated inhibition of invasion. Drugs that inhibit PfSUB2 activity should block parasite replication and may also enhance the efficacy of vaccines based on AMA1 and other merozoite surface proteins. The malaria parasite invades red blood cells. During invasion several parasite proteins, including a vaccine candidate called PfAMA1, are clipped from the parasite surface. Most of this clipping is performed by an enzyme called PfSUB2, but some also occurs through intramembrane cleavage. The function of this shedding is unknown. We have examined the requirements for shedding of PfAMA1, and the effects of mutations that block shedding. Mutations that block intramembrane cleavage have no effect on the parasite. We then show that PfSUB2 does not recognise a specific amino acid sequence in PfAMA1, but rather cleaves it at a position determined primarily by its distance from the parasite membrane. Certain mutations at the PfSUB2 cleavage site prevent shedding, and parasites expressing non-cleavable PfAMA1 along with unmodified PfAMA1 grow normally. However, these mutations cannot be introduced into the parasite's genome, showing that some shedding by PfSUB2 is essential for parasite survival. Parasites expressing shedding-resistant mutants of PfAMA1 show enhanced sensitivity to invasion-inhibitory antibodies, suggesting that shedding of surface proteins during invasion helps the parasite to evade potentially protective antibodies. Drugs that inhibit PfSUB2 may prevent disease and enhance the efficacy of vaccines based on PfAMA1.
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Affiliation(s)
- Anna Olivieri
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Christine R. Collins
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Fiona Hackett
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | | | - Joshua Marshall
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Helen R. Flynn
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
| | - J. Mark Skehel
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
| | - Michael J. Blackman
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
- * E-mail:
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18
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Chen JH, Jung JW, Wang Y, Ha KS, Lu F, Lim CS, Takeo S, Tsuboi T, Han ET. Immunoproteomics Profiling of Blood Stage Plasmodium vivax Infection by High-Throughput Screening Assays. J Proteome Res 2010; 9:6479-89. [DOI: 10.1021/pr100705g] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Jun-Hu Chen
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Jae-Wan Jung
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Yue Wang
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Kwon-Soo Ha
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Feng Lu
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Chae Seung Lim
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Satoru Takeo
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Takafumi Tsuboi
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
| | - Eun-Taek Han
- Department of Parasitology, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, People’s Republic of China, Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea, Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Republic of Korea, Cell-free Science and
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19
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Protective immune responses elicited by immunization with a chimeric blood-stage malaria vaccine persist but are not boosted by Plasmodium yoelii challenge infection. Vaccine 2010; 28:6876-84. [PMID: 20709001 DOI: 10.1016/j.vaccine.2010.08.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/17/2010] [Accepted: 08/02/2010] [Indexed: 11/20/2022]
Abstract
An efficacious malaria vaccine remains elusive despite concerted efforts. Using the Plasmodium yoelii murine model, we previously reported that immunization with the C-terminal 19 kDa domain of merozoite surface protein 1 (MSP1(19)) fused to full-length MSP8 protected against lethal P. yoelii 17XL, well beyond that achieved by single or combined immunizations with the component antigens. Here, we continue the evaluation of the chimeric PyMSP1/8 vaccine. We show that immunization with rPyMSP1/8 vaccine elicited an MSP8-restricted T cell response that was sufficient to provide help for both PyMSP1(19) and PyMSP8-specific B cells to produce high and sustained levels of protective antibodies. The enhanced efficacy of immunization with rPyMSP1/8, in comparison to a combined formulation of rPyMSP1(42) and rPyMSP8, was not due to improved conformation of protective B cell epitopes in the chimeric molecule. Unexpectedly, rPyMSP1/8 vaccine-induced antibody responses were not boosted by exposure to P. yoelii 17XL infected RBCs. However, rPyMSP1/8 immunized and infected mice mounted robust responses to a diverse set of blood-stage antigens. The data support the further development of an MSP1/8 chimeric vaccine but also suggest that vaccines that prime for responses to a diverse set of parasite proteins will be required to maximize vaccine efficacy.
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20
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Merozoite surface proteins of the malaria parasite: The MSP1 complex and the MSP7 family. Int J Parasitol 2010; 40:1155-61. [PMID: 20451527 DOI: 10.1016/j.ijpara.2010.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/22/2010] [Accepted: 04/26/2010] [Indexed: 11/21/2022]
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21
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Child MA, Epp C, Bujard H, Blackman MJ. Regulated maturation of malaria merozoite surface protein-1 is essential for parasite growth. Mol Microbiol 2010; 78:187-202. [PMID: 20735778 PMCID: PMC2995310 DOI: 10.1111/j.1365-2958.2010.07324.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The malaria parasite Plasmodium falciparum invades erythrocytes where it replicates to produce invasive merozoites, which eventually egress to repeat the cycle. Merozoite surface protein-1 (MSP1), a prime malaria vaccine candidate and one of the most abundant components of the merozoite surface, is implicated in the ligand-receptor interactions leading to invasion. MSP1 is extensively proteolytically modified, first just before egress and then during invasion. These primary and secondary processing events are mediated respectively, by two parasite subtilisin-like proteases, PfSUB1 and PfSUB2, but the function and biological importance of the processing is unknown. Here, we examine the regulation and significance of MSP1 processing. We show that primary processing is ordered, with the primary processing site closest to the C-terminal end of MSP1 being cleaved last, irrespective of polymorphisms throughout the rest of the molecule. Replacement of the secondary processing site, normally refractory to PfSUB1, with a PfSUB1-sensitive site, is deleterious to parasite growth. Our findings show that correct spatiotemporal regulation of MSP1 maturation is crucial for the function of the protein and for maintenance of the parasite asexual blood-stage life cycle.
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Affiliation(s)
- Matthew A Child
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Coppel RL. Vaccinating with the genome: a Sisyphean task? Trends Parasitol 2009; 25:205-12. [PMID: 19359219 DOI: 10.1016/j.pt.2009.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 01/27/2009] [Accepted: 02/09/2009] [Indexed: 11/24/2022]
Abstract
Human trials of subunit vaccines against the asexual blood stage of malaria are yielding disappointing results, supporting the premise that a single recombinant protein will not be particularly efficacious and that additional proteins must be added. The genome sequence of Plasmodium falciparum offers a large number of additional candidates, but which should be chosen? Various criteria have been suggested to rank the additional candidates, but in the absence of even a partially effective asexual-stage vaccine, the criteria remain unvalidated. These issues are discussed here, together with some suggestions as to how the development of an asexual-stage vaccine could be progressed.
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Affiliation(s)
- Ross L Coppel
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
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23
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Koussis K, Withers-Martinez C, Yeoh S, Child M, Hackett F, Knuepfer E, Juliano L, Woehlbier U, Bujard H, Blackman MJ. A multifunctional serine protease primes the malaria parasite for red blood cell invasion. EMBO J 2009; 28:725-35. [PMID: 19214190 PMCID: PMC2647770 DOI: 10.1038/emboj.2009.22] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 01/14/2009] [Indexed: 11/16/2022] Open
Abstract
The malaria parasite Plasmodium falciparum replicates within an intraerythrocytic parasitophorous vacuole (PV). Rupture of the host cell allows release (egress) of daughter merozoites, which invade fresh erythrocytes. We previously showed that a subtilisin-like protease called PfSUB1 regulates egress by being discharged into the PV in the final stages of merozoite development to proteolytically modify the SERA family of papain-like proteins. Here, we report that PfSUB1 has a further role in ‘priming' the merozoite prior to invasion. The major protein complex on the merozoite surface comprises three proteins called merozoite surface protein 1 (MSP1), MSP6 and MSP7. We show that just before egress, all undergo proteolytic maturation by PfSUB1. Inhibition of PfSUB1 activity results in the accumulation of unprocessed MSPs on the merozoite surface, and erythrocyte invasion is significantly reduced. We propose that PfSUB1 is a multifunctional processing protease with an essential role in both egress of the malaria merozoite and remodelling of its surface in preparation for erythrocyte invasion.
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Abstract
In this chapter, we outline the tools and techniques available to study the process of host cell invasion by apicomplexan parasites and we provide specific examples of how these methods have been used to further our understanding of apicomplexan invasive mechanisms. Throughout the chapter we focus our discussion on Toxoplasmagondii, because T. gondii is the most experimentally accessible model organism for studying apicomplexan invasion (discussed further in the section, "Toxoplasma as a Model Apicomplexan") and more is known about invasion in T. gondii than in any other apicomplexan.
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25
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Deletion of the Plasmodium falciparum merozoite surface protein 7 gene impairs parasite invasion of erythrocytes. EUKARYOTIC CELL 2008; 7:2123-32. [PMID: 18820076 DOI: 10.1128/ec.00274-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Merozoite surface proteins have been implicated in the initial attachment to the host red blood cell membrane that begins the process of invasion, an important step in the life cycle of the malaria parasite. In Plasmodium falciparum, merozoite surface proteins include several glycosylphosphatidyl inositol-anchored proteins and peripheral proteins attached to the membrane through protein-protein interactions. The most abundant of these proteins is the merozoite surface protein 1 (MSP1) complex, encoded by at least three genes: msp1, msp6, and msp7. The msp7 gene is part of a six-member multigene family in Plasmodium falciparum. We have disrupted msp7 in the Plasmodium falciparum D10 parasite, as confirmed by Southern hybridization. Immunoblot and indirect immunofluorescence analyses confirmed the MSP7 null phenotype of D10DeltaMSP7 parasites. The synthesis, distribution, and processing of MSP1 were not affected in this parasite line. The level of expression and cellular distribution of the proteins MSP1, MSP3, MSP6, MSP9, and SERA5 remained comparable to those for the parental line. Furthermore, no significant change in the expression of MSP7-related proteins, except for that of MSRP5, was detected at the transcriptional level. The lack of MSP7 was not lethal at the asexual blood stage, but it did impair invasion of erythrocytes by merozoites to a significant degree. Despite this reduction in efficiency, D10DeltaMSP7 parasites did not show any obvious preference for alternate pathways of invasion.
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26
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Gilson PR, O'Donnell RA, Nebl T, Sanders PR, Wickham ME, McElwain TF, de Koning-Ward TF, Crabb BS. MSP1(19) miniproteins can serve as targets for invasion inhibitory antibodies in Plasmodium falciparum provided they contain the correct domains for cell surface trafficking. Mol Microbiol 2008; 68:124-38. [PMID: 18333885 DOI: 10.1111/j.1365-2958.2008.06140.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Antibodies from malaria-exposed individuals can agglutinate merozoites released from Plasmodium schizonts, thereby preventing them from invading new erythrocytes. Merozoite coat proteins attached to the plasma membrane are major targets for host antibodies and are therefore considered important malaria vaccine candidates. Prominent among these is the abundant glycosylphosphatidylinositol (GPI)-anchored merozoite surface protein 1 (MSP1) and particularly its C-terminal fragment (MSP1(19)) comprised of two epidermal growth factor (EGF)-like modules. In this paper, we revisit the role of agglutination and immunity using transgenic fluorescent marker proteins. We describe expression of heterologous MSP1(19)'miniproteins' on the surface of Plasmodium falciparum merozoites. To correctly express these proteins, we determined that GPI-anchoring and the presence of a signal sequence do not allow default export of proteins from the endoplasmic reticulum to merozoite surface and that extra sequence elements are required. The EGFs are insufficient for correct trafficking unless they are fused to additional residues that normally reside upstream of this fragment. Antibodies specifically targeting the surface-expressed miniprotein can inhibit erythrocyte invasion in vitro despite the presence of endogenous MSP1. Using a line expressing a green fluorescent protein-MSP1 fusion protein, we demonstrate that one mode of inhibition by antibodies targeting the MSP1(19) domain is the rapid agglutinating of merozoites prior to erythrocyte attachment.
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Affiliation(s)
- Paul R Gilson
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Vic. 3050, Australia
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27
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de Koning-Ward TF, Drew DR, Chesson JM, Beeson JG, Crabb BS. Truncation of Plasmodium berghei merozoite surface protein 8 does not affect in vivo blood-stage development. Mol Biochem Parasitol 2008; 159:69-72. [DOI: 10.1016/j.molbiopara.2008.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 12/31/2007] [Accepted: 01/25/2008] [Indexed: 11/26/2022]
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28
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Persson KEM, McCallum FJ, Reiling L, Lister NA, Stubbs J, Cowman AF, Marsh K, Beeson JG. Variation in use of erythrocyte invasion pathways by Plasmodium falciparum mediates evasion of human inhibitory antibodies. J Clin Invest 2008; 118:342-51. [PMID: 18064303 DOI: 10.1172/jci32138] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 10/10/2007] [Indexed: 11/17/2022] Open
Abstract
Antibodies that inhibit Plasmodium falciparum invasion of erythrocytes are believed to be an important component of immunity against malaria. During blood-stage infection, P. falciparum can use different pathways for erythrocyte invasion by varying the expression and/or utilization of members of 2 invasion ligand families: the erythrocyte-binding antigens (EBAs) and reticulocyte-binding homologs (PfRhs). Invasion pathways can be broadly classified into 2 groups based on the use of sialic acid (SA) on the erythrocyte surface by parasite ligands. We found that inhibitory antibodies are acquired by malaria-exposed Kenyan children and adults against ligands of SA-dependent and SA-independent invasion pathways, and the ability of antibodies to inhibit erythrocyte invasion depended on the pathway used by P. falciparum isolates. Differential inhibition of P. falciparum lines that varied in their use of specific EBA and PfRh proteins pointed to these ligand families as major targets of inhibitory antibodies. Antibodies against recombinant EBA and PfRh proteins were acquired in an age-associated manner, and inhibitory antibodies against EBA175 appeared prominent among some individuals. These findings suggest that variation in invasion phenotype might have evolved as a mechanism that facilitates immune evasion by P. falciparum and that a broad inhibitory response against multiple ligands may be required for effective immunity.
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Affiliation(s)
- Kristina E M Persson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
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29
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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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30
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Sanders PR, Cantin GT, Greenbaum DC, Gilson PR, Nebl T, Moritz RL, Yates JR, Hodder AN, Crabb BS. Identification of protein complexes in detergent-resistant membranes of Plasmodium falciparum schizonts. Mol Biochem Parasitol 2007; 154:148-57. [PMID: 17553576 DOI: 10.1016/j.molbiopara.2007.04.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/19/2007] [Accepted: 04/20/2007] [Indexed: 11/26/2022]
Abstract
Merozoite surface proteins of the human malaria parasite Plasmodium falciparum are involved in initial contact with target erythrocytes, a process that begins a cascade of events required for successful invasion of these cells. In order to identify complexes that may play a role in invasion we purified detergent-resistant membranes (DRMs), known to be enriched in merozoite surface proteins, and used blue native-polyacrylamide gel electrophoresis (BN-PAGE) to isolate high molecular weight complexes for identification by mass spectrometry. Sixty-two proteins were detected and these mostly belonged to expected DRM proteins classes including GPI-anchored, multi-membrane spanning and rhoptry proteins. Proteins from seven known complexes were identified including MSP-1/7, the low (RAP1/2 and RAP1/3), and high (RhopH1/H2/H3) molecular weight rhoptry complexes, and the invasion motor complex (GAP45/GAP50/myosinA). Remarkably, a large proportion of identified spectra were derived from only 4 proteins: the GPI-anchored proteins MSP-1 and Pf92, the putative GPI-anchored protein Pf113 and RAP-1, the core component of the two RAP complexes. Each of these proteins predominated in high molecular weight species suggesting their aggregation in much larger complexes than anticipated. To demonstrate that the procedure had isolated novel complexes we focussed on MSP-1, which predominated as a distinct species at approximately 500 kDa by BN-PAGE, approximately twice its expected size. Chemical cross-linking supports the existence of a stable MSP-1 oligomer of approximately 500 kDa, probably comprising a highly stable homodimeric species. Our observations also suggests that oligomerization of MSP-1 is likely to occur outside the C-terminal epidermal growth factor (EGF)-like domains. Confirmation of MSP-1 oligomerization, together with the isolation of a number of known complexes by BN-PAGE, makes it highly likely that novel interactions occur amongst members of this proteome.
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Affiliation(s)
- Paul R Sanders
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, Vic 3050, Australia
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31
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Shi Q, Lynch MM, Romero M, Burns JM. Enhanced protection against malaria by a chimeric merozoite surface protein vaccine. Infect Immun 2006; 75:1349-58. [PMID: 17158895 PMCID: PMC1828565 DOI: 10.1128/iai.01467-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 42-kDa processed fragment of Plasmodium falciparum merozoite surface protein 1 (MSP-1(42)) is a prime candidate for a blood-stage malaria vaccine. Merozoite surface protein 8 contains two C-terminal epidermal growth factor (EGF)-like domains that may function similarly to those of MSP-1(42). Immunization with either MSP-1 or MSP-8 induces protection that is mediated primarily by antibodies against conformation-dependent epitopes. In a series of comparative immunogenicity and efficacy studies using the Plasmodium yoelii rodent model, we tested the ability of recombinant P. yoelii MSP-8 (rPyMSP-8) to complement rPyMSP-1-based vaccines. Unlike MSP-1, PyMSP-8-dependent protection required immunization with the full-length protein and was not induced with recombinant antigens that contained only the C-terminal EGF-like domains. Unlike PyMSP-8, the immunogenicity of the PyMSP-1 EGF-like domains was low when present as part of the rPyMSP-1(42) antigen. Immunization with a mixture of rPyMSP-1(42) and rPyMSP-8 further inhibited the antibody response to protective epitopes of rPyMSP-1(42) and did not improve vaccine efficacy. To improve PyMSP-1 immunogenicity, we produced a chimeric antigen containing the EGF-like domains of PyMSP-1 fused to the N terminus of PyMSP-8. Immunization with the chimeric rPyMSP-1/8 antigen induced high and comparable antibody responses against the EGF-like domains of both PyMSP-1 and PyMSP-8. This enhanced MSP-1-specific antibody response and the concurrent targeting of MSP-1 and MSP-8 resulted in improved, nearly complete protection against lethal P. yoelii 17XL malaria. Unexpectedly, immunization with rPyMSP-1/8 failed to protect against challenge infection with reticulocyte-restricted P. yoelii 17X parasites. Overall, these data establish an effective strategy to improve the efficacy of P. falciparum MSP-based vaccines.
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Affiliation(s)
- Qifang Shi
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129
| | - Michelle M. Lynch
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129
| | - Margarita Romero
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129
| | - James M. Burns
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129
- Corresponding author. Mailing address: Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129. Phone: (215) 991-8490. Fax: (215) 848-2271. E-mail:
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32
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Shi Q, Cernetich-Ott A, Lynch MM, Burns JM. Expression, localization, and erythrocyte binding activity of Plasmodium yoelii merozoite surface protein-8. Mol Biochem Parasitol 2006; 149:231-41. [PMID: 16846654 DOI: 10.1016/j.molbiopara.2006.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 06/06/2006] [Accepted: 06/07/2006] [Indexed: 11/28/2022]
Abstract
PyMSP-8 is a member of a family of merozoite surface proteins that have been described in Plasmodium that are characterized by the presence of a glycolipid membrane anchor and 1-2 epidermal growth factor-like domains. Immunization with recombinant PyMSP-8 has also been shown to protect mice against lethal Plasmodium yoelii malaria. In this report, we demonstrate that PyMSP-8 expression is detectable throughout the entire erythrocytic life cycle of P. yoelii 17XL, reaching peak level during trophozoite development. As determined by immunofluorescence, PyMSP-8 co-localizes with PyMSP-1 on the surface of merozoites in segmented schizonts and on the surface of ring stages in newly invaded erythrocytes. PyMSP-8 binds to the surface of uninfected mouse RBCs in a species-dependent manner, suggesting a potential role in merozoite attachment to and/or invasion of erythrocytes. The receptor for PyMSP-8 on RBCs is sensitive to trypsin digestion but is resistant to treatment with chymotrypsin or neuraminidase and is putatively identified as a approximately 105kDa membrane protein. Since PyMSP-8 binds to both mature RBCs as well as reticulocytes, it appears unlikely that the function of PyMSP-8 is restricted to the invasion of normocytes. While proper folding and conformation of PyMSP-8 are important, linear determinants of PyMSP-8 also contribute to erythrocyte binding. Unexpectedly, however, PyMSP-8 specific antibodies that are protective in vivo, do not disrupt the binding of rPyMSP-8 to its receptor on erythrocytes. The data indicate that protective anti-PyMSP-8 antibodies mediate their effect in vivo by an alternate mechanism(s).
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Affiliation(s)
- Qifang Shi
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States
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33
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Gilson PR, Nebl T, Vukcevic D, Moritz RL, Sargeant T, Speed TP, Schofield L, Crabb BS. Identification and stoichiometry of glycosylphosphatidylinositol-anchored membrane proteins of the human malaria parasite Plasmodium falciparum. Mol Cell Proteomics 2006; 5:1286-99. [PMID: 16603573 DOI: 10.1074/mcp.m600035-mcp200] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most proteins that coat the surface of the extracellular forms of the human malaria parasite Plasmodium falciparum are attached to the plasma membrane via glycosylphosphatidylinositol (GPI) anchors. These proteins are exposed to neutralizing antibodies, and several are advanced vaccine candidates. To identify the GPI-anchored proteome of P. falciparum we used a combination of proteomic and computational approaches. Focusing on the clinically relevant blood stage of the life cycle, proteomic analysis of proteins labeled with radioactive glucosamine identified GPI anchoring on 11 proteins (merozoite surface protein (MSP)-1, -2, -4, -5, -10, rhoptry-associated membrane antigen, apical sushi protein, Pf92, Pf38, Pf12, and Pf34). These proteins represent approximately 94% of the GPI-anchored schizont/merozoite proteome and constitute by far the largest validated set of GPI-anchored proteins in this organism. Moreover MSP-1 and MSP-2 were present in similar copy number, and we estimated that together these proteins comprise approximately two-thirds of the total membrane-associated surface coat. This is the first time the stoichiometry of MSPs has been examined. We observed that available software performed poorly in predicting GPI anchoring on P. falciparum proteins where such modification had been validated by proteomics. Therefore, we developed a hidden Markov model (GPI-HMM) trained on P. falciparum sequences and used this to rank all proteins encoded in the completed P. falciparum genome according to their likelihood of being GPI-anchored. GPI-HMM predicted GPI modification on all validated proteins, on several known membrane proteins, and on a number of novel, presumably surface, proteins expressed in the blood, insect, and/or pre-erythrocytic stages of the life cycle. Together this work identified 11 and predicted a further 19 GPI-anchored proteins in P. falciparum.
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Affiliation(s)
- Paul R Gilson
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia
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34
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Abstract
The malaria parasite is the most important member of the Apicomplexa, a large and highly successful phylum of intracellular parasites. Invasion of host cells allows apicomplexan parasites access to a rich source of nutrients in a niche that is largely protected from host defenses. All Apicomplexa adopt a common mode of host-cell entry, but individual species incorporate unique features and utilize a specific set of ligand-receptor interactions. These adhesins ultimately connect to a parasite actin-based motor, which provides the power for invasion. While some Apicomplexa can invade many different host cells, the disease-associated blood-stage form of the malaria parasite is restricted to erythrocytes.
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Affiliation(s)
- Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research, Melbourne 3050, Australia.
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35
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Black CG, Wu T, Wang L, Topolska AE, Coppel RL. MSP8 is a non-essential merozoite surface protein in Plasmodium falciparum. Mol Biochem Parasitol 2005; 144:27-35. [PMID: 16125802 DOI: 10.1016/j.molbiopara.2005.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2005] [Revised: 05/29/2005] [Accepted: 06/05/2005] [Indexed: 10/25/2022]
Abstract
MSP8 is a recently identified merozoite surface protein that shares similar structural features with the leading vaccine candidate MSP1. Both proteins contain two C-terminal epidermal growth factor (EGF)-like domains, a glycosylphosphatidylinositol (GPI) anchor attachment sequence and undergo proteolytic processing. By double recombination, we have disrupted the MSP8 gene in P. falciparum 3D7 parasites, and confirmed integration by southern hybridisation and PCR. Western blot analysis of lysates from asynchronous cultures and isolated merozoites demonstrated the absence of MSP8 in two cloned knockout lines. There was no significant difference in growth rate observed between 3D7 and the cloned DeltaMSP8 lines. Thus, unlike MSP1, MSP8 is not required for asexual stage parasite growth and replication in vitro. Further analysis of the cloned lines showed that loss of MSP8 had no effect on the levels of expression of other merozoite surface proteins including MSP1-5, 7 and 10. Stage-specific immunoblots showed that MSP8 expression commences in late rings and extends throughout the rest of the erythrocytic life cycle in the 3D7 parent line, but is absent from all stages in the DeltaMSP8 transfectants.
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Affiliation(s)
- Casilda G Black
- Department of Microbiology and the Victorian Bioinformatics Consortium, Monash University, Clayton, Vic. 3800, Australia.
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36
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Shi Q, Cernetich A, Daly TM, Galvan G, Vaidya AB, Bergman LW, Burns JM. Alteration in host cell tropism limits the efficacy of immunization with a surface protein of malaria merozoites. Infect Immun 2005; 73:6363-71. [PMID: 16177307 PMCID: PMC1230925 DOI: 10.1128/iai.73.10.6363-6371.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Immunization with Plasmodium yoelii merozoite surface protein-8 (PyMSP-8) has been shown to protect mice against lethal P. yoelii 17XL malaria. Here we demonstrate that PyMSP-8-specific antibodies preferentially suppress P. yoelii 17XL growth in mature erythrocytes compared to growth in reticulocytes and do not suppress the growth of nonlethal P. yoelii 17X, a parasite that primarily replicates in reticulocytes. The protection against normocyte-associated P. yoelii malaria parasites is mediated by antibodies that recognize conformational epitopes of PyMSP-8 that are nonpolymorphic. We examined changes in gene expression in reticulocyte-restricted P. yoelii 17XL parasites that escaped neutralization by PyMSP-8-specific antibodies using P. yoelii DNA microarrays. Of interest, Pymsp-8 gene expression decreased, while the expression of msp-1, msp-7, and several rhoptry protein genes increased. Breakthrough parasites also exhibited increases in the expression of a subset of yir and Pyst-a genes that are predicted to encode polymorphic antigens expressed on the surface of infected erythrocytes. These data suggest that changes in the expression of parasite proteins expressed on the merozoite surface, as well as the surface of infected erythrocytes, may alter host cell tropism and contribute to the ability of malaria parasites to evade merozoite-specific, neutralizing antibodies.
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Affiliation(s)
- Qifang Shi
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA
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37
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O'Donnell RA, Blackman MJ. The role of malaria merozoite proteases in red blood cell invasion. Curr Opin Microbiol 2005; 8:422-7. [PMID: 16019257 DOI: 10.1016/j.mib.2005.06.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 06/22/2005] [Indexed: 11/19/2022]
Abstract
Invasion of red blood cells by the malaria merozoite is an essential step in the life cycle of this obligate intracellular pathogen. The molecular details of invasion are only recently becoming understood, largely through studies in related apicomplexan parasites such as Toxoplasma. Protease activity is required for successful invasion to disengage interactions between parasite adhesins and host cell receptors. Shedding of at least two essential surface proteins from the merozoite is thought to occur continuously during invasion as the parasite moves into the nascent parasitophorous vacuole. This shedding is performed by way of juxtamembrane cleavage and is mediated by a sheddase, which probably belongs to the subtilisin-like superfamily. Recent revelations have shown that transmembrane adhesins that are secreted onto the Toxoplasma tachyzoite surface and capped to its posterior pole are shed by way of cleavage within their transmembrane domains. A family of intramembrane serine proteases called rhomboids have now been identified within Apicomplexa, and one Toxoplasma rhomboid has been localized to the posterior end of the parasite. This supports their role in capping proteolysis. Proteases involved in invasion constitute potential targets for the development of new protease inhibitor-based drugs.
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Affiliation(s)
- Rebecca A O'Donnell
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK
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38
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Drew DR, Sanders PR, Crabb BS. Plasmodium falciparum merozoite surface protein 8 is a ring-stage membrane protein that localizes to the parasitophorous vacuole of infected erythrocytes. Infect Immun 2005; 73:3912-22. [PMID: 15972477 PMCID: PMC1168550 DOI: 10.1128/iai.73.7.3912-3922.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To date, the following seven glycosylphosphatidylinositol (GPI)-anchored merozoite antigens have been described in Plasmodium falciparum: merozoite-associated surface protein 1 (MSP-1), MSP-2, MSP-4, MSP-5, MSP-8, MSP-10, and the rhoptry-associated membrane antigen. Of these, MSP-1, MSP-8, and MSP-10 possess a double epidermal growth factor (EGF)-like domain at the C terminus, and these modules are considered potential targets of protective immunity. In this study, we found that surprisingly, P. falciparum MSP-8 is transcribed and translated in the ring stage and is absent from the surface of merozoites. MSP-8 is the only GPI-anchored protein known to be expressed at this time. It is synthesized as a mature 80-kDa protein which is rapidly processed to a C-terminal 17-kDa species that contains the double EGF module. As determined by a combination of immunofluorescence and membrane purification approaches, it appears likely that MSP-8 initially localizes to the parasite plasma membrane in the ring stage. Although the C-terminal 17-kDa fragment is present in more mature stages, at these times it is found in the food vacuole. We successfully disrupted the MSP-8 gene in P. falciparum, a process that validated the specificity of the antibodies used in this study and also demonstrated that MSP-8 does not play a role essential to maintenance of the erythrocyte cycle. This finding, together with the observation that MSP-8 is exclusively intracellular, casts doubt over the viability of this antigen as a vaccine. However, it is still possible that MSP-8 is involved in an early parasitophorous vacuole function that is significant for pathogenesis in the human host.
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Affiliation(s)
- Damien R Drew
- The Walter & Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3050, Australia
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Carruthers VB, Blackman MJ. A new release on life: emerging concepts in proteolysis and parasite invasion. Mol Microbiol 2005; 55:1617-30. [PMID: 15752188 DOI: 10.1111/j.1365-2958.2005.04483.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell invasion by apicomplexan pathogens such as the malaria parasite and Toxoplasma is accompanied by extensive proteolysis of zoite surface proteins (ZSPs) required for attachment and penetration. Although there is still little known about the proteases involved, a conceptual framework is emerging for the roles of proteolysis in cell invasion. Primary processing of ZSPs, which includes the trimming of terminal peptides or segmentation into multiple fragments, is proposed to activate these adhesive ligands for tight binding to host receptors. Secondary processing, which occurs during penetration, results in the shedding of ZSPs by one of two mechanistically distinct ways, shaving or capping. Resident surface proteins are typically shaved from the surface whereas adhesive ligands mobilized from intracellular secretory vesicles are capped to the posterior end of the parasite before being shed during the final steps of penetration. Intriguingly, recent studies have revealed that ZSPs can be released either by being cleaved adjacent to the membrane anchor or actually within the membrane itself. Mounting evidence suggests that intramembrane cleavage is catalysed by one or more integral membrane serine proteases of the Rhomboid family and we propose that several malaria adhesive ligands may be potential substrates for these enzymes. We also discuss the evidence that the key reason for ZSP shedding during invasion is to break the connection between parasite surface ligands and host receptors. The sequential proteolytic events associated with invasion by pathogenic protozoa may represent vulnerable pathways for the future development of synergistic anti-protozoal therapies.
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Affiliation(s)
- Vern B Carruthers
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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Abstract
The life cycle of the malaria parasite contains three distinct invasive forms, or zoites. For at least two of these--the sporozoite and the blood-stage merozoite--invasion into their respective host cell requires the activity of parasite proteases. This review summarizes the evidence for this, discusses selected well-described proteolytic modifications linked to invasion, and describes recent progress towards identifying the proteases involved.
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Affiliation(s)
- Michael J Blackman
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
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