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Bolton JS, MacGill RS, Locke E, Regules JA, Bergmann-Leitner ES. Novel antibody competition binding assay identifies distinct serological profiles associated with protection. Front Immunol 2023; 14:1303446. [PMID: 38152401 PMCID: PMC10752609 DOI: 10.3389/fimmu.2023.1303446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 11/21/2023] [Indexed: 12/29/2023] Open
Abstract
Introduction Pre-erythrocytic malaria vaccines hold the promise of inducing sterile protection thereby preventing the morbidity and mortality associated with Plasmodium infection. The main surface antigen of P. falciparum sporozoites, i.e., the circumsporozoite protein (CSP), has been extensively explored as a target of such vaccines with significant success in recent years. Systematic adjuvant selection, refinements of the immunization regimen, and physical properties of the antigen may all contribute to the potential of increasing the efficacy of CSP-based vaccines. Protection appears to be dependent in large part on CSP antibodies. However due to a knowledge gap related to the exact correlates of immunity, there is a critical need to improve our ability to down select candidates preclinically before entering clinical trials including with controlled human malaria infections (CHMI). Methods We developed a novel multiplex competition assay based on well-characterized monoclonal antibodies (mAbs) that target crucial epitopes across the CSP molecule. This new tool assesses both, quality and epitope-specific concentrations of vaccine-induced antibodies by measuring their equivalency with a panel of well-characterized, CSP-epitope-specific mAbs. Results Applying this method to RTS,S-immune sera from a CHMI trial demonstrated a quantitative epitope-specificity profile of antibody responses that can differentiate between protected vs. nonprotected individuals. Aligning vaccine efficacy with quantitation of the epitope fine specificity results of this equivalency assay reveals the importance of epitope specificity. Discussion The newly developed serological equivalence assay will inform future vaccine design and possibly even adjuvant selection. This methodology can be adapted to other antigens and disease models, when a panel of relevant mAbs exists, and could offer a unique tool for comparing and down-selecting vaccine formulations.
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Affiliation(s)
- Jessica S. Bolton
- Biologics Research & Development, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, United States
| | - Randall S. MacGill
- Center for Vaccine Innovation and Access, PATH, Washington, DC, United States
| | - Emily Locke
- Center for Vaccine Innovation and Access, PATH, Washington, DC, United States
| | - Jason A. Regules
- Biologics Research & Development, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, United States
| | - Elke S. Bergmann-Leitner
- Biologics Research & Development, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, United States
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2
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Jaramillo-Underwood A, Impoinvil D, Sutcliff A, Hamre KES, Joseph V, van den Hoogen L, Lemoine JF, Ashton RA, Chang MA, Existe A, Boncy J, Drakeley C, Stresman G, Druetz T, Eisele T, Rogier E. Factors Associated With Human IgG Antibody Response to Anopheles albimanus Salivary Gland Extract, Artibonite Department, Haiti, 2017. J Infect Dis 2022; 226:1461-1469. [PMID: 35711005 PMCID: PMC10982684 DOI: 10.1093/infdis/jiac245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/14/2022] [Indexed: 11/14/2022] Open
Abstract
Serological data can provide estimates of human exposure to both malaria vector and parasite based on antibody responses. A multiplex bead-based assay was developed to simultaneously detect IgG to Anopheles albimanus salivary gland extract (SGE) and 23 Plasmodium falciparum antigens among 4185 participants enrolled in Artibonite department, Haiti in 2017. Logistic regression adjusted for participant- and site-level covariates and found children under 5 years and 6-15 years old had 3.7- and 5.4-fold increase in odds, respectively, of high anti-SGE IgG compared to participants >15 years. Seropositivity to P. falciparum CSP, Rh2_2030, and SEA-1 antigens was significantly associated with high IgG response against SGE, and participant enrolment at elevations under 200 m was associated with higher anti-SGE IgG levels. The ability to approximate population exposure to malaria vectors through SGE serology data is very dependent by age categories, and SGE antigens can be easily integrated into a multiplex serological assay.
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Affiliation(s)
- Alicia Jaramillo-Underwood
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Daniel Impoinvil
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Alice Sutcliff
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Karen E. S. Hamre
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Lotus van den Hoogen
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jean Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Ruth A. Ashton
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Michelle A. Chang
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Alexandre Existe
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Jacques Boncy
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gillian Stresman
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
- Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, Québec, Canada
| | - Thomas Eisele
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Eric Rogier
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Tursi NJ, Reeder SM, Flores-Garcia Y, Bah MA, Mathis-Torres S, Salgado-Jimenez B, Esquivel R, Xu Z, Chu JD, Humeau L, Patel A, Zavala F, Weiner DB. Engineered DNA-encoded monoclonal antibodies targeting Plasmodium falciparum circumsporozoite protein confer single dose protection in a murine malaria challenge model. Sci Rep 2022; 12:14313. [PMID: 35995959 PMCID: PMC9395511 DOI: 10.1038/s41598-022-18375-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/06/2022] [Indexed: 12/15/2022] Open
Abstract
Novel approaches for malaria prophylaxis remain important. Synthetic DNA-encoded monoclonal antibodies (DMAbs) are a promising approach to generate rapid, direct in vivo host-generated mAbs with potential benefits in production simplicity and distribution coupled with genetic engineering. Here, we explore this approach in a malaria challenge model. We engineered germline-reverted DMAbs based on human mAb clones CIS43, 317, and L9 which target a junctional epitope, major repeat, and minor repeat of the Plasmodium falciparum circumsporozoite protein (CSP) respectively. DMAb variants were encoded into a plasmid vector backbone and their expression and binding profiles were characterized. We demonstrate long-term serological expression of DMAb constructs resulting in in vivo efficacy of CIS43 GL and 317 GL in a rigorous mosquito bite mouse challenge model. Additionally, we engineered an Fc modified variant of CIS43 and L9-based DMAbs to ablate binding to C1q to test the impact of complement-dependent Fc function on challenge outcomes. Complement knockout variant DMAbs demonstrated similar protection to that of WT Fc DMAbs supporting the notion that direct binding to the parasite is sufficient for the protection observed. Further investigation of DMAbs for malaria prophylaxis appears of importance.
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Affiliation(s)
- Nicholas J Tursi
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sophia M Reeder
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yevel Flores-Garcia
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Mamadou A Bah
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
| | - Shamika Mathis-Torres
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Berenice Salgado-Jimenez
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Rianne Esquivel
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
| | - Ziyang Xu
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jacqueline D Chu
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
| | - Laurent Humeau
- Inovio Pharmaceuticals, Plymouth Meeting, PA, 19462, USA
| | - Ami Patel
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA
| | - Fidel Zavala
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - David B Weiner
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, PA, 19104, USA.
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Langowski MD, Khan FA, Savransky S, Brown DR, Balasubramaniyam A, Harrison WB, Zou X, Beck Z, Matyas GR, Regules JA, Miller R, Soisson LA, Batchelor AH, Dutta S. Restricted valency (NPNA) n repeats and junctional epitope-based circumsporozoite protein vaccines against Plasmodium falciparum. NPJ Vaccines 2022; 7:13. [PMID: 35087099 PMCID: PMC8795123 DOI: 10.1038/s41541-022-00430-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 12/14/2021] [Indexed: 12/02/2022] Open
Abstract
The Circumsporozoite Protein (CSP) of Plasmodium falciparum contains an N-terminal region, a conserved Region I (RI), a junctional region, 25-42 copies of major (NPNA) and minor repeats followed by a C-terminal domain. The recently approved malaria vaccine, RTS,S/AS01 contains NPNAx19 and the C-terminal region of CSP. The efficacy of RTS,S against natural infection is low and short-lived, and mapping epitopes of inhibitory monoclonal antibodies may allow for rational improvement of CSP vaccines. Tobacco Mosaic Virus (TMV) was used here to display the junctional epitope (mAb CIS43), Region I (mAb 5D5), NPNAx5, and NPNAx20 epitope of CSP (mAbs 317 and 580). Protection studies in mice revealed that Region I did not elicit protective antibodies, and polyclonal antibodies against the junctional epitope showed equivalent protection to NPNAx5. Combining the junctional and NPNAx5 epitopes reduced immunogenicity and efficacy, and increasing the repeat valency to NPNAx20 did not improve upon NPNAx5. TMV was confirmed as a versatile vaccine platform for displaying small epitopes defined by neutralizing mAbs. We show that polyclonal antibodies against engineered VLPs can recapitulate the binding specificity of the mAbs and immune-focusing by reducing the structural complexity of an epitope may be superior to immune-broadening as a vaccine design approach. Most importantly the junctional and restricted valency NPNA epitopes can be the basis for developing highly effective second-generation malaria vaccine candidates.
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Affiliation(s)
- Mark D Langowski
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Farhat A Khan
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Sofya Savransky
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Dallas R Brown
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Arasu Balasubramaniyam
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - William B Harrison
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Xiaoyan Zou
- Malaria Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - Zoltan Beck
- US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
- Pfizer, 401N Middletown Rd, Pearl River, NY, 10965, USA
| | - Gary R Matyas
- US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Jason A Regules
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Robin Miller
- United States Agency for International Development, Washington, DC, USA
| | | | - Adrian H Batchelor
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Sheetij Dutta
- Structural Vaccinology Lab, Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
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Nateghpour M, Etemadi S, Motevalli Haghi A, Eslami H, Mohebali M, Farivar L. Serological responses to a soluble recombinant circumsporozoite protein-VK210 of Plasmodium vivax (rPvCSP-VK210) among Iranian malaria patients. Eur J Med Res 2021; 26:134. [PMID: 34823591 PMCID: PMC8620637 DOI: 10.1186/s40001-021-00607-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/14/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Circumsporozoite protein (CSP) has a central immune domain that includes short regions of repeating amino acid sequences. This immunodynamic region is an epitope of B cells that can elicit an immune response in human and laboratory animals. The aim of the present study was to express the recombinant PvCSP-VK210 antigen and evaluate it for assaying antibodies obtained during human P. vivax infection by Western blotting and indirect ELISA (enzyme-linked immunosorbent assay). METHOD Genomic DNA of P. vivax was isolated from a blood sample of an Iranian person with vivax malaria, and by PCR, the fragment of the PvCSP-VK210 gene was amplified. The gene fragment was cut after gel purification by BamHI and HindIII enzymes and then cloned into pET28a expression vector. Finally, the recombinant pET28a was transformed into the E. coli BL21 (DE3) as the expression host. In order to produce His-tagged protein, the expression host was cultured in LB medium. The protein was purified by Ni-NTA columns and immobilized metal affinity chromatography, and after confirmation by Western blotting technique, was used as the antigen in the indirect ELISA test. RESULTS The recombinant protein was expressed and purified as a 32-kDa protein. The sensitivity and specificity of the indirect ELISA test with the recombinant PvCSP-VK210 antigen were 61.42% and 97.14%, respectively, based on OD = 0.313. Between the results of the microscopic test and the indirect ELISA test with the recombinant PvCSP-VK210 antigen there was a Kappa coefficient of 0.586. The positive and negative predictive value and validity of the ELISA test with the recombinant PvCSP-VK210 antigen were 95.55%, 71.57%, 79.28%, respectively. CONCLUSION The sensitivity of the indirect ELISA method with the recombinant PvCSP-VK210 antigen was 61.42%, which is the first report from Iran.
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Affiliation(s)
- Mehdi Nateghpour
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Soudabeh Etemadi
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. .,Infectious Disease and Tropical Medicine Research Center, Research Institute of Cellular and Molecular Sciences in Infectious Diseases, Zahedan University of Medical Sciences, Zahedan, Iran. .,Department of Parasitology and Mycology, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran.
| | - Afsaneh Motevalli Haghi
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Hamid Eslami
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Mohebali
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Leila Farivar
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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Sekar V, Rivero A, Pigeault R, Gandon S, Drews A, Ahren D, Hellgren O. Gene regulation of the avian malaria parasite Plasmodium relictum, during the different stages within the mosquito vector. Genomics 2021; 113:2327-2337. [PMID: 34023365 DOI: 10.1016/j.ygeno.2021.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/26/2021] [Accepted: 05/18/2021] [Indexed: 10/21/2022]
Abstract
The malaria parasite Plasmodium relictum is one of the most widespread species of avian malaria. As in the case of its human counterparts, bird Plasmodium undergoes a complex life cycle infecting two hosts: the arthropod vector and the vertebrate host. In this study, we examined transcriptomes of P. relictum (SGS1) during crucial timepoints within its vector, Culex pipiens quinquefasciatus. Differential gene-expression analyses identified genes linked to the parasites life-stages at: i) a few minutes after the blood meal is ingested, ii) during peak oocyst production phase, iii) during peak sporozoite phase and iv) during the late-stages of the infection. A large amount of genes coding for functions linked to host-immune invasion and multifunctional genes was active throughout the infection cycle. One gene associated with a conserved Plasmodium membrane protein with unknown function was upregulated throughout the parasite development in the vector, suggesting an important role in the successful completion of the sporogonic cycle. Gene expression analysis further identified genes, with unknown functions to be significantly differentially expressed during the infection in the vector as well as upregulation of reticulocyte-binding proteins, which raises the possibility of the multifunctionality of these RBPs. We establish the existence of highly stage-specific pathways being overexpressed during the infection. This first study of gene-expression of a non-human Plasmodium species in its vector provides a comprehensive insight into the molecular mechanisms of the common avian malaria parasite P. relictum and provides essential information on the evolutionary diversity in gene regulation of the Plasmodium's vector stages.
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Affiliation(s)
| | - Ana Rivero
- MIVEGEC (CNRS - Université de Montpellier - IRD), 34394 Montpellier, France; CREES (Centre de Recherche en Ecologie et Evolution de la Santé), 34394 Montpellier, France
| | - Romain Pigeault
- Department of Biology, Lund University, Sweden; Department of Ecology and Evolution, CH-1015 Lausanne, Switzerland
| | - Sylvain Gandon
- CEFE (CNRS - Université de Montpellier - Université Paul-Valéry - EPHE - IRD), Montpellier, France
| | - Anna Drews
- MEMEG, Department of Biology, Lund University, Sweden
| | - Dag Ahren
- National Bioinformatics Infrastructure Sweden (NBIS), SciLifeLab, Department of Biology, Lund, Sweden
| | - Olof Hellgren
- MEMEG, Department of Biology, Lund University, Sweden.
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7
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Amelia F, Iyori M, Emran TB, Yamamoto DS, Genshi K, Otsuka H, Onoue Y, Yusuf Y, Islam A, Yoshida S. Down-selecting circumsporozoite protein-based malaria vaccine: A comparison of malaria sporozoite challenge model. Parasite Immunol 2020; 41:e12624. [PMID: 30883819 DOI: 10.1111/pim.12624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/28/2019] [Accepted: 03/08/2019] [Indexed: 12/18/2022]
Abstract
Plasmodium falciparum circumsporozoite protein (PfCSP) is the main target antigen in development of pre-erythrocytic malaria vaccines. To evaluate PfCSP vaccines in animal models, challenge by intravenous sporozoite injection is preferentially used. However, in clinical trials, vaccinated human volunteers are exposed to the bites of malaria-infected mosquitoes. In this study, we down-selected Escherichia coli-produced full-length PfCSP (PfCSP-F) and its three truncated PfCSPs based on their abilities to elicit immune response and protection in mice against two challenge models. We showed that immunization with three doses of PfCSP-F elicited high anti-PfCSP antibody titres and 100% protection against the bites of infected mosquitoes. Meanwhile, three-dose truncated PfCSP induced 60%-70% protection after immunization with each truncated PfCSP. Heterologous prime-boost immunization regimen with adenovirus-PfCSP-F and R32LR greatly induced complete protection against intravenous sporozoite injection. Our results suggest that Abs to both anti-repeat and anti-nonrepeat regions induced by PfCSP-F are required to confer complete protection against challenge by the bites of infected mosquitoes, whereas anti-repeat Abs play an important role in protection against intravenous sporozoite injection. Our findings provide a potential clinical application that PfCSP-F vaccine induces potent Abs capable of neutralizing sporozoites in the dermis inoculated by infected mosquitoes and subsequently sporozoites in the blood circulation.
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Affiliation(s)
- Fitri Amelia
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan.,Department of Chemistry, Universitas Negeri Padang, Padang, Indonesia
| | - Mitsuhiro Iyori
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Talha Bin Emran
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Daisuke S Yamamoto
- Division of Medical Zoology, Department of Infection and Immunity, Jichi Medical University, Shimotsuke, Japan
| | - Kento Genshi
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Hiromu Otsuka
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Yutaro Onoue
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Yenni Yusuf
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Ashekul Islam
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
| | - Shigeto Yoshida
- Laboratory of Vaccinology and Applied Immunology, Kanazawa University School of Pharmacy, Kanazawa, Japan
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Julien JP, Wardemann H. Antibodies against Plasmodium falciparum malaria at the molecular level. Nat Rev Immunol 2019; 19:761-775. [DOI: 10.1038/s41577-019-0209-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2019] [Indexed: 12/11/2022]
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9
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Xu R, Liu Y, Fan R, Liang R, Yue L, Liu S, Su XZ, Li J. Generation and functional characterisation of Plasmodium yoelii csp deletion mutants using a microhomology-based CRISPR/Cas9 method. Int J Parasitol 2019; 49:705-714. [PMID: 31202685 PMCID: PMC10993195 DOI: 10.1016/j.ijpara.2019.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/01/2019] [Accepted: 04/05/2019] [Indexed: 11/24/2022]
Abstract
CRISPR/Cas9 is a powerful genome editing method that has greatly facilitated functional studies in many eukaryotic organisms including malaria parasites. Due to the lack of genes encoding enzymes necessary for the non-homologous end joining DNA repair pathway, genetic manipulation of malaria parasite genomes is generally accomplished through homologous recombination requiring the presence of DNA templates. Recently, an alternative double-strand break repair pathway, microhomology-mediated end joining, was found in the Plasmodium falciparum parasite. Taking advantage of the MMEJ pathway, we developed a MMEJ-based CRISPR/Cas9 (mCRISPR) strategy to efficiently generate multiple mutant parasites simultaneously in genes with repetitive sequences. As a proof of principle, we successfully produced various size mutants in the central repeat region of the Plasmodium yoelii circumsporozoite surface protein without the use of template DNA. Monitoring mixed parasite populations and individual parasites with different sizes of CSP-CRR showed that the CSP-CRR plays a role in the development of mosquito stages, with severe developmental defects in parasites with large deletions in the repeat region. However, the majority of the csp mutant parasite clones grew similarly to the wild type P. yoelii 17XL parasite in mice. This study develops a useful technique to efficiently generate mutant parasites with deletions or insertions, and shows that the CSP-CRR plays a role in parasite development in mosquito.
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Affiliation(s)
- Ruixue Xu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Yanjing Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Ruoxi Fan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Rui Liang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Lixia Yue
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Shengfa Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jian Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
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Cawlfield A, Genito CJ, Beck Z, Bergmann-Leitner ES, Bitzer AA, Soto K, Zou X, Hadiwidjojo SH, Gerbasi RV, Mullins AB, Noe A, Waters NC, Alving CR, Matyas GR, Dutta S. Safety, toxicity and immunogenicity of a malaria vaccine based on the circumsporozoite protein (FMP013) with the adjuvant army liposome formulation containing QS21 (ALFQ). Vaccine 2019; 37:3793-3803. [PMID: 31151801 DOI: 10.1016/j.vaccine.2019.05.059] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 01/21/2023]
Abstract
Antibodies to Circumsporozoite protein (CSP) confer protection against controlled human malaria infection (CHMI) caused by the parasite Plasmodium falciparum. Although CSP is highly immunogenic, it does not induce long lasting protection and efforts to improve CSP-specific immunological memory and duration of protection are underway. We have previously reported that the clinical grade CSP vaccine FMP013 was immunogenic and protective against malaria challenge in mice when combined with the Army Liposomal Formulation adjuvant containing immune modulators 3D-PHAD™ and QS21 (ALFQ). To move forward with clinical evaluation, we now report the safety, toxicity and immunogenicity of clinical grade FMP013 and ALFQ in Rhesus macaques. Three groups of Rhesus (n = 6) received half or full human dose of FMP013 + ALFQ on a 0-1-2 month schedule, which showed mild local site reactions with no hematologic derangements in red blood cell homeostasis, liver function or kidney function. Immunization induced a transient systemic inflammatory response, including elevated white blood cell counts, mild fever, and a few incidences of elevated creatine kinase, receding to normal range by day 7 post vaccination. Optimal immunogenicity in Rhesus was observed using a 1 mL ALFQ + 20 µg FMP013 dose. Doubling the FMP013 antigen dose to 40 µg had no effect while halving the ALFQ adjuvant dose to 0.5 mL lowered immunogenicity. Similar to data generated in mice, FMP013 + ALFQ induced serum antibodies that reacted to all regions of the CSP molecule and a Th1-biased cytokine response in Rhesus. Rhesus antibody response to FMP013 + ALFQ was found to be non-inferior to historical benchmarks including that of RTS,S + AS01 in humans. A four-dose GLP toxicity study in rabbits confirmed no local site reactions and transient systemic inflammation associated with ALFQ adjuvant administration. These safety and immunogenicity data support the clinical progression and testing of FMP013 + ALFQ in a CHMI trial in the near future.
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Affiliation(s)
- Alicia Cawlfield
- Department of Veterinary Medicine, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Christopher J Genito
- Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Zoltan Beck
- Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720A Rockledge Drive, Bethesda, MD 20817, USA
| | - Elke S Bergmann-Leitner
- Flow-cytometeric Center, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Alexis A Bitzer
- Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Kimberly Soto
- Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Xiaoyan Zou
- Malaria Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Sri H Hadiwidjojo
- Malaria Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Robert V Gerbasi
- Malaria Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Anna B Mullins
- Department of Veterinary Medicine, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Amy Noe
- Leidos Life Sciences, 5202 Presidents Court, Suite 110, Fredrick, MD 21703, USA
| | - Norman C Waters
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Carl R Alving
- Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Gary R Matyas
- Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Sheetij Dutta
- Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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11
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Camargo-Ayala PA, Garzón-Ospina D, Moreno-Pérez DA, Ricaurte-Contreras LA, Noya O, Patarroyo MA. On the Evolution and Function of Plasmodium vivax Reticulocyte Binding Surface Antigen ( pvrbsa). Front Genet 2018; 9:372. [PMID: 30250483 PMCID: PMC6139305 DOI: 10.3389/fgene.2018.00372] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/23/2018] [Indexed: 12/28/2022] Open
Abstract
The RBSA protein is encoded by a gene described in Plasmodium species having tropism for reticulocytes. Since this protein is antigenic in natural infections and can bind to target cells, it has been proposed as a potential candidate for an anti-Plasmodium vivax vaccine. However, genetic diversity (a challenge which must be overcome for ensuring fully effective vaccine design) has not been described at this locus. Likewise, the minimum regions mediating specific parasite-host interaction have not been determined. This is why the rbsa gene’s evolutionary history is being here described, as well as the P. vivax rbsa (pvrbsa) genetic diversity and the specific regions mediating parasite adhesion to reticulocytes. Unlike what has previously been reported, rbsa was also present in several parasite species belonging to the monkey-malaria clade; paralogs were also found in Plasmodium parasites invading reticulocytes. The pvrbsa locus had less diversity than other merozoite surface proteins where natural selection and recombination were the main evolutionary forces involved in causing the observed polymorphism. The N-terminal end (PvRBSA-A) was conserved and under functional constraint; consequently, it was expressed as recombinant protein for binding assays. This protein fragment bound to reticulocytes whilst the C-terminus, included in recombinant PvRBSA-B (which was not under functional constraint), did not. Interestingly, two PvRBSA-A-derived peptides were able to inhibit protein binding to reticulocytes. Specific conserved and functionally important peptides within PvRBSA-A could thus be considered when designing a fully-effective vaccine against P. vivax.
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Affiliation(s)
- Paola Andrea Camargo-Ayala
- Department of Molecular Biology and Immunology, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.,Microbiology Postgraduate Programme, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Diego Garzón-Ospina
- Department of Molecular Biology and Immunology, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.,PhD Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Darwin Andrés Moreno-Pérez
- Department of Molecular Biology and Immunology, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.,Livestock Sciences Faculty, Universidad de Ciencias Aplicadas y Ambientales, Bogotá, Colombia
| | | | - Oscar Noya
- Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
| | - Manuel A Patarroyo
- Department of Molecular Biology and Immunology, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
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12
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Marin-Mogollon C, van Pul FJA, Miyazaki S, Imai T, Ramesar J, Salman AM, Winkel BMF, Othman AS, Kroeze H, Chevalley-Maurel S, Reyes-Sandoval A, Roestenberg M, Franke-Fayard B, Janse CJ, Khan SM. Chimeric Plasmodium falciparum parasites expressing Plasmodium vivax circumsporozoite protein fail to produce salivary gland sporozoites. Malar J 2018; 17:288. [PMID: 30092798 PMCID: PMC6085629 DOI: 10.1186/s12936-018-2431-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 07/28/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rodent malaria parasites where the gene encoding circumsporozoite protein (CSP) has been replaced with csp genes from the human malaria parasites, Plasmodium falciparum or Plasmodium vivax, are used as pre-clinical tools to evaluate CSP vaccines in vivo. These chimeric rodent parasites produce sporozoites in Anopheles stephensi mosquitoes that are capable of infecting rodent and human hepatocytes. The availability of chimeric P. falciparum parasites where the pfcsp gene has been replaced by the pvcsp would open up possibilities to test P. vivax CSP vaccines in small scale clinical trials using controlled human malaria infection studies. METHODS Using CRISPR/Cas9 gene editing two chimeric P. falciparum parasites, were generated, where the pfcsp gene has been replaced by either one of the two major pvcsp alleles, VK210 or VK247. In addition, a P. falciparum parasite line that lacks CSP expression was also generated. These parasite lines have been analysed for sporozoite production in An. stephensi mosquitoes. RESULTS The two chimeric Pf-PvCSP lines exhibit normal asexual and sexual blood stage development in vitro and produce sporozoite-containing oocysts in An. stephensi mosquitoes. Expression of the corresponding PvCSP was confirmed in oocyst-derived Pf-PvCSP sporozoites. However, most oocysts degenerate before sporozoite formation and sporozoites were not found in either the mosquito haemocoel or salivary glands. Unlike the chimeric Pf-PvCSP parasites, oocysts of P. falciparum parasites lacking CSP expression do not produce sporozoites. CONCLUSIONS Chimeric P. falciparum parasites expressing P. vivax circumsporozoite protein fail to produce salivary gland sporozoites. Combined, these studies show that while PvCSP can partially complement the function of PfCSP, species-specific features of CSP govern full sporozoite maturation and development in the two human malaria parasites.
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Affiliation(s)
- Catherin Marin-Mogollon
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Fiona J A van Pul
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Shinya Miyazaki
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Takashi Imai
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
- Department of Infectious Diseases and Host Defense, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8510, Japan
| | - Jai Ramesar
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Ahmed M Salman
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, The Henry Welcome Building for Molecular Physiology, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Beatrice M F Winkel
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Ahmad Syibli Othman
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
- Faculty of Health Sciences, Universiti Sultan Zainal Abidin, Terengganu, Malaysia
| | - Hans Kroeze
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Severine Chevalley-Maurel
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Arturo Reyes-Sandoval
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, The Henry Welcome Building for Molecular Physiology, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Blandine Franke-Fayard
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Chris J Janse
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Shahid M Khan
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
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13
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Garzón-Ospina D, Buitrago SP, Ramos AE, Patarroyo MA. Identifying Potential Plasmodium vivax Sporozoite Stage Vaccine Candidates: An Analysis of Genetic Diversity and Natural Selection. Front Genet 2018; 9:10. [PMID: 29422913 PMCID: PMC5788960 DOI: 10.3389/fgene.2018.00010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/09/2018] [Indexed: 11/30/2022] Open
Abstract
Parasite antigen genetic diversity represents a great obstacle when designing a vaccine against malaria caused by Plasmodium vivax. Selecting vaccine candidate antigens has been focused on those fulfilling a role in invasion and which are conserved, thus avoiding specific-allele immune responses. Most antigens described to date belong to the blood stage, thereby blocking parasite development within red blood cells, whilst studying antigens from other stages has been quite restricted. Antigens from different parasite stages are required for developing a completely effective vaccine; thus, pre-erythrocyte stage antigens able to block the first line of infection becoming established should also be taken into account. However, few antigens from this stage have been studied to date. Several P. falciparum sporozoite antigens are involved in invasion. Since 77% of genes are orthologous amongst Plasmodium parasites, P. vivax sporozoite antigen orthologs to those of P. falciparum might be present in its genome. Although these genes might have high genetic diversity, conserved functionally-relevant regions (ideal for vaccine development) could be predicted by comparing genetic diversity patterns and evolutionary rates. This study was thus aimed at searching for putative P. vivax sporozoite genes so as to analyse their genetic diversity for determining their potential as vaccine candidates. Several DNA sequence polymorphism estimators were computed at each locus. The evolutionary force (drift, selection and recombination) drawing the genetic diversity pattern observed was also determined by using tests based on polymorphism frequency spectrum as well as the type of intra- and inter-species substitutions. Likewise, recombination was assessed both indirectly and directly. The results showed that sporozoite genes were more conserved than merozoite genes evaluated to date. Putative domains implied in cell traversal, gliding motility and hepatocyte interaction had a negative selection signal, being conserved amongst different species in the genus. PvP52, PvP36, PvSPATR, PvPLP1, PvMCP1, PvTLP, PvCelTOS, and PvMB2 antigens or functionally restricted regions within them would thus seem promising vaccine candidates and could be used when designing a pre-erythrocyte and/or multi-stage vaccine against P. vivax to avoid allele-specific immune responses that could reduce vaccine efficacy.
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Affiliation(s)
- Diego Garzón-Ospina
- Molecular Biology and Immunology Laboratory, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,PhD Programme in Biomedical and Biological Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Sindy P Buitrago
- Molecular Biology and Immunology Laboratory, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia
| | - Andrea E Ramos
- Molecular Biology and Immunology Laboratory, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia
| | - Manuel A Patarroyo
- Molecular Biology and Immunology Laboratory, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Basic Sciences Department, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
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14
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Sasaki H, Sekiguchi H, Sugiyama M, Ikadai H. Plasmodium berghei Cap93, a novel oocyst capsule-associated protein, plays a role in sporozoite development. Parasit Vectors 2017; 10:399. [PMID: 28841886 PMCID: PMC5574095 DOI: 10.1186/s13071-017-2337-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/16/2017] [Indexed: 11/20/2022] Open
Affiliation(s)
- Hanae Sasaki
- Hokusan Co. Ltd., 27-4, Kitanosato, Kitahiroshima, Hokkaido, 061-111, Japan
| | - Harumi Sekiguchi
- Laboratory of Veterinary Parasitology, School of Veterinary Medicine, Kitasato University, Towada, Aomori, 034-8628, Japan
| | - Makoto Sugiyama
- Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Kitasato University, Towada, Aomori, 034-8628, Japan
| | - Hiromi Ikadai
- Laboratory of Veterinary Parasitology, School of Veterinary Medicine, Kitasato University, Towada, Aomori, 034-8628, Japan.
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15
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Frischknecht F, Matuschewski K. Plasmodium Sporozoite Biology. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a025478. [PMID: 28108531 DOI: 10.1101/cshperspect.a025478] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Plasmodium sporozoite transmission is a critical population bottleneck in parasite life-cycle progression and, hence, a target for prophylactic drugs and vaccines. The recent progress of a candidate antisporozoite subunit vaccine formulation to licensure highlights the importance of sporozoite transmission intervention in the malaria control portfolio. Sporozoites colonize mosquito salivary glands, migrate through the skin, penetrate blood vessels, breach the liver sinusoid, and invade hepatocytes. Understanding the molecular and cellular mechanisms that mediate the remarkable sporozoite journey in the invertebrate vector and the vertebrate host can inform evidence-based next-generation drug development programs and immune intervention strategies.
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Affiliation(s)
- Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School, 69120 Heidelberg, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University Berlin, 10115 Berlin, Germany
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16
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Phares TW, May AD, Genito CJ, Hoyt NA, Khan FA, Porter MD, DeBot M, Waters NC, Saudan P, Dutta S. Rhesus macaque and mouse models for down-selecting circumsporozoite protein based malaria vaccines differ significantly in immunogenicity and functional outcomes. Malar J 2017; 16:115. [PMID: 28288639 PMCID: PMC5347822 DOI: 10.1186/s12936-017-1766-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/28/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Non-human primates, such as the rhesus macaques, are the preferred model for down-selecting human malaria vaccine formulations, but the rhesus model is expensive and does not allow for direct efficacy testing of human malaria vaccines. Transgenic rodent parasites expressing genes of human Plasmodium are now routinely used for efficacy studies of human malaria vaccines. Mice have however rarely predicted success in human malaria trials and there is scepticism whether mouse studies alone are sufficient to move a vaccine candidate into the clinic. METHODS A comparison of immunogenicity, fine-specificity and functional activity of two Alum-adjuvanted Plasmodium falciparum circumsporozoite protein (CSP)-based vaccines was conducted in mouse and rhesus models. One vaccine was a soluble recombinant protein (CSP) and the other was the same CSP covalently conjugated to the Qβ phage particle (Qβ-CSP). RESULTS Mice showed different kinetics of antibody responses and different sensitivity to the NANP-repeat and N-terminal epitopes as compared to rhesus. While mice failed to discern differences between the protective efficacy of CSP versus Qβ-CSP vaccine following direct challenge with transgenic Plasmodium berghei parasites, rhesus serum from the Qβ-CSP-vaccinated animals induced higher in vivo sporozoite neutralization activity. CONCLUSIONS Despite some immunologic parallels between models, these data demonstrate that differences between the immune responses induced in the two models risk conflicting decisions regarding potential vaccine utility in humans. In combination with historical observations, the data presented here suggest that although murine models may be useful for some purposes, non-human primate models may be more likely to predict the human response to investigational vaccines.
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Affiliation(s)
- Timothy W Phares
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Anthony D May
- Division of Veterinary Medicine, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Christopher J Genito
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Nathan A Hoyt
- Division of Veterinary Medicine, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Farhat A Khan
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Michael D Porter
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Margot DeBot
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Norman C Waters
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Philippe Saudan
- Cytos Biotechnology, Wagistrasse 25, 8952, Schlieren, Switzerland
| | - Sheetij Dutta
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA.
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17
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López C, Yepes-Pérez Y, Hincapié-Escobar N, Díaz-Arévalo D, Patarroyo MA. What Is Known about the Immune Response Induced by Plasmodium vivax Malaria Vaccine Candidates? Front Immunol 2017; 8:126. [PMID: 28243235 PMCID: PMC5304258 DOI: 10.3389/fimmu.2017.00126] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 01/25/2017] [Indexed: 12/15/2022] Open
Abstract
Malaria caused by Plasmodium vivax continues being one of the most important infectious diseases around the world; P. vivax is the second most prevalent species and has the greatest geographic distribution. Developing an effective antimalarial vaccine is considered a relevant control strategy in the search for means of preventing the disease. Studying parasite-expressed proteins, which are essential in host cell invasion, has led to identifying the regions recognized by individuals who are naturally exposed to infection. Furthermore, immunogenicity studies have revealed that such regions can trigger a robust immune response that can inhibit sporozoite (hepatic stage) or merozoite (erythrocyte stage) invasion of a host cell and induce protection. This review provides a synthesis of the most important studies to date concerning the antigenicity and immunogenicity of both synthetic peptide and recombinant protein candidates for a vaccine against malaria produced by P. vivax.
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Affiliation(s)
- Carolina López
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC), Bogotá, Colombia; PhD Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Yoelis Yepes-Pérez
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC), Bogotá, Colombia; MSc Programme in Microbiology, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Natalia Hincapié-Escobar
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC) , Bogotá , Colombia
| | - Diana Díaz-Arévalo
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC), Bogotá, Colombia; Universidad de Ciencias Aplicadas y Ambientales (UDCA), Bogotá, Colombia
| | - Manuel A Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC), Bogotá, Colombia; Basic Sciences Department, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
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18
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Janitzek CM, Matondo S, Thrane S, Nielsen MA, Kavishe R, Mwakalinga SB, Theander TG, Salanti A, Sander AF. Bacterial superglue generates a full-length circumsporozoite protein virus-like particle vaccine capable of inducing high and durable antibody responses. Malar J 2016; 15:545. [PMID: 27825348 PMCID: PMC5101663 DOI: 10.1186/s12936-016-1574-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 10/27/2016] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Malaria, caused by Plasmodium falciparum, continues to have a devastating impact on global health, emphasizing the great need for a malaria vaccine. The circumsporozoite protein (CSP) is an attractive target for a malaria vaccine, and forms a major component of RTS,S, the most clinically advanced malaria vaccine. The clinical efficacy of RTS,S has been moderate, yet has demonstrated the viability of a CSP-based malaria vaccine. In this study, a vaccine comprised of the full-length CSP antigen presented on a virus-like particle (VLP) is produced using a split-intein conjugation system (SpyTag/SpyCatcher) and the immunogenicity is tested in mice. METHODS Full-length 3d7 CSP protein was genetically fused at the C-terminus to SpyCatcher. The CSP-SpyCatcher antigen was then covalently attached (via the SpyTag/SpyCatcher interaction) to Acinetobacter phage AP205 VLPs which were modified to display one SpyTag per VLP subunit. To evaluate the VLP-display effect, the immunogenicity of the VLP vaccine was tested in mice and compared to a control vaccine containing AP205 VLPs plus unconjugated CSP. RESULTS Full-length CSP was conjugated at high density (an average of 112 CSP molecules per VLP) to AP205 SpyTag-VLPs. Vaccination of mice with the CSP Spy-VLP vaccine resulted in significantly increased antibody titres over a course of 7 months as compared to the control group (2.6-fold higher at 7 months after immunization). Furthermore, the CSP Spy-VLP vaccine appears to stimulate production of IgG2a antibodies, which has been linked with a more efficient clearing of intracellular parasite infection. CONCLUSION This study demonstrates that the high-density display of CSP on SpyTag-VLPs, significantly increases the level and quality of the vaccine-induced humoral response, compared to a control vaccine consisting of soluble CSP plus AP205 VLPs. The SpyTag-VLP platform utilized in this study constitutes a versatile and rapid method to develop highly immunogenic vaccines. It might serve as a generic tool for the cost-effective development of effective VLP-vaccines, e.g., against malaria.
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Affiliation(s)
- Christoph M Janitzek
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sungwa Matondo
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
| | - Susan Thrane
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Morten A Nielsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Reginald Kavishe
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
| | - Steve B Mwakalinga
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
| | - Thor G Theander
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark.
| | - Adam F Sander
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark.
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Buitrago SP, Garzón-Ospina D, Patarroyo MA. Size polymorphism and low sequence diversity in the locus encoding the Plasmodium vivax rhoptry neck protein 4 (PvRON4) in Colombian isolates. Malar J 2016; 15:501. [PMID: 27756311 PMCID: PMC5069803 DOI: 10.1186/s12936-016-1563-4] [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: 08/24/2016] [Accepted: 10/07/2016] [Indexed: 11/12/2022] Open
Abstract
Background Designing a vaccine against Plasmodium vivax has focused on selecting antigens involved in invasion mechanisms that must have domains with low polymorphism for avoiding allele-specific immune responses. The rhoptry neck protein 4 (RON4) forms part of the tight junction, which is essential in the invasion of hepatocytes and/or erythrocytes; however, little is known about this locus’ genetic diversity. Methods DNA sequences from 73 Colombian clinical isolates from pvron4 gene were analysed for characterizing their genetic diversity; pvron4 haplotype number and distribution, as well as the evolutionary forces determining diversity pattern, were assessed by population genetics and molecular evolutionary approaches. Results ron4 has low genetic diversity in P. vivax at sequence level; however, a variable amount of tandem repeats at the N-terminal region leads to extensive size polymorphism. This region seems to be exposed to the immune system. The central region has a putative esterase/lipase domain which, like the protein’s C-terminal fragment, is highly conserved at intra- and inter-species level. Both regions are under purifying selection. Conclusions pvron4 is the locus having the lowest genetic diversity described to date for P. vivax. The repeat regions in the N-terminal region could be associated with immune evasion mechanisms while the central region and the C-terminal region seem to be under functional or structural constraint. Bearing such results in mind, the PvRON4 central and/or C-terminal portions represent promising candidates when designing a subunit-based vaccine as they are aimed at avoiding an allele-specific immune response, which might limit vaccine efficacy. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1563-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sindy P Buitrago
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia.,Microbiology Postgraduate Program, Universidad Nacional de Colombia, Bogotá D.C., Colombia
| | - Diego Garzón-Ospina
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá D.C., Colombia
| | - Manuel A Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia. .,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá D.C., Colombia.
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Zhao J, Bhanot P, Hu J, Wang Q. A Comprehensive Analysis of Plasmodium Circumsporozoite Protein Binding to Hepatocytes. PLoS One 2016; 11:e0161607. [PMID: 27560376 PMCID: PMC4999272 DOI: 10.1371/journal.pone.0161607] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 08/09/2016] [Indexed: 11/28/2022] Open
Abstract
Circumsporozoite protein (CSP) is the dominant protein on the surface of Plasmodium sporozoites and plays a critical role in the invasion by sporozoites of hepatocytes. Contacts between CSP and heparin sulfate proteoglycans (HSPGs) lead to the attachment of sporozoites to hepatocytes and trigger signaling events in the parasite that promote invasion of hepatocytes. The precise sequence elements in CSP that bind HSPGs have not been identified. We performed a systematic in vitro analysis to dissect the association between Plasmodium falciparum CSP (PfCSP) and hepatocytes. We demonstrate that interactions between PfCSP and heparin or a cultured hepatoma cell line, HepG2, are mediated primarily by a lysine-rich site in the amino terminus of PfCSP. Importantly, the carboxyl terminus of PfCSP facilitates heparin-binding by the amino-terminus but does not interact directly with heparin. These findings provide insights into how CSP recognizes hepatocytes and useful information for further functional studies of CSP.
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Affiliation(s)
- Jinghua Zhao
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin, 300071, China
| | - Purnima Bhanot
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, United States of America
| | - Junjie Hu
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin, 300071, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Qian Wang
- Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, and Tianjin Key Laboratory of Cellular and Molecular Immunology, Tianjin, 300070, China
- * E-mail:
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Human CD8+ T cells mediate protective immunity induced by a human malaria vaccine in human immune system mice. Vaccine 2016; 34:4501-4506. [PMID: 27502569 PMCID: PMC5009892 DOI: 10.1016/j.vaccine.2016.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 06/15/2016] [Accepted: 08/01/2016] [Indexed: 11/30/2022]
Abstract
A number of studies have shown that CD8+ T cells mediate protective anti-malaria immunity in a mouse model. However, whether human CD8+ T cells play a role in protection against malaria remains unknown. We recently established human immune system (HIS) mice harboring functional human CD8+ T cells (HIS-CD8 mice) by transduction with HLA-A∗0201 and certain human cytokines using recombinant adeno-associated virus-based gene transfer technologies. These HIS-CD8 mice mount a potent, antigen-specific HLA-A∗0201-restricted human CD8+ T-cell response upon immunization with a recombinant adenovirus expressing a human malaria antigen, the Plasmodium falciparum circumsporozoite protein (PfCSP), termed AdPfCSP. In the present study, we challenged AdPfCSP-immunized HIS-CD8 mice with transgenic Plasmodium berghei sporozoites expressing full-length PfCSP and found that AdPfCSP-immunized (but not naïve) mice were protected against subsequent malaria challenge. The level of the HLA-A∗0201-restricted, PfCSP-specific human CD8+ T-cell response was closely correlated with the level of malaria protection. Furthermore, depletion of human CD8+ T cells from AdPfCSP-immunized HIS-CD8 mice almost completely abolished the anti-malaria immune response. Taken together, our data show that human CD8+ T cells mediate protective anti-malaria immunity in vivo.
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Development of a Plasmodium berghei transgenic parasite expressing the full-length Plasmodium vivax circumsporozoite VK247 protein for testing vaccine efficacy in a murine model. Malar J 2016; 15:251. [PMID: 27129682 PMCID: PMC4851775 DOI: 10.1186/s12936-016-1297-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/15/2016] [Indexed: 11/30/2022] Open
Abstract
Background The approach of using transgenic rodent malaria parasites to assess the immune system’s response to antigenic targets from a human malaria parasite has been shown to be useful for preclinical evaluation of new vaccine formulations. The transgenic Plasmodium berghei parasite line [PvCSP(VK210)/Pb] generated previously expresses the full-length circumsporozoite protein (CSP) VK210 from Plasmodium vivax. The transgenic parasite expresses one of the two most common alleles of CSP, defined by nine amino acids at the central repeat region of this protein. In the present study, a transgenic P. berghei parasite line [PvCSP(VK247)/Pb] expressing the full-length PvCSP(VK247), which is the alternative common allele, was generated and characterized. Methods The P. berghei expressing full-length PvCSP(VK247) was generated and examined its applicability to CSP-based vaccine research by examining its biological characteristics in mosquitoes and mice. Results Similar to PvCSP(VK210)/Pb, PvCSP(VK247)/Pb developed normally in mosquitoes and produced infectious sporozoites equipped to generate patent infections in mice. Invasion of HepG2 cells by PvCSP(VK247)/Pb sporozoites was inhibited by an anti-PvCSP(VK247) repeat monoclonal antibody (mAb), but not by an anti-PvCSP(VK210) repeat mAb. Conclusions These two transgenic parasites thus far can be used to evaluate the potential efficacy of PvCSP-based vaccine candidates encompassing the two major genetic variants in preclinical trials.
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Khan F, Porter M, Schwenk R, DeBot M, Saudan P, Dutta S. Head-to-Head Comparison of Soluble vs. Qβ VLP Circumsporozoite Protein Vaccines Reveals Selective Enhancement of NANP Repeat Responses. PLoS One 2015; 10:e0142035. [PMID: 26571021 PMCID: PMC4646581 DOI: 10.1371/journal.pone.0142035] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/17/2015] [Indexed: 11/23/2022] Open
Abstract
Circumsporozoite protein (CSP) of Plasmodium falciparum is a promising malaria vaccine target. RTS,S, the most advanced malaria vaccine candidate consists of the central NANP repeat and carboxy-terminal region of CSP displayed on a hepatitis B virus-like particle (VLP). To build upon the success of RTS,S, we produced a near full-length Plasmodium falciparum CSP that also includes the conserved amino-terminal region of CSP. We recently showed that this soluble CSP, combined with a synthetic Toll-like-receptor-4 (TLR4) agonist in stable oil-in-water emulsion (GLA/SE), induces a potent and protective immune response in mice against transgenic parasite challenge. Here we have investigated whether the immunogenicity of soluble CSP could be further augmented by presentation on a VLP. Bacteriophage Qβ VLPs can be readily produced in E.coli, they have a diameter of 25 nm and contain packaged E. coli RNA which serves as a built in adjuvant through the activation of TLR7/8. CSP was chemically conjugated to Qβ and the CSP-Qβ vaccine immunogenicity and efficacy were compared to adjuvanted soluble CSP in the C57Bl/6 mouse model. When formulated with adjuvants lacking a TLR4 agonist (Alum, SE and Montanide) the Qβ-CSP induced higher anti-NANP repeat titers, higher levels of cytophilic IgG2b/c antibodies and a trend towards higher protection against transgenic parasite challenge as compared to soluble CSP formulated in the same adjuvant. The VLP and soluble CSP immunogenicity difference was most pronounced at low antigen dose, and within the CSP molecule, the titers against the NANP repeats were preferentially enhanced by Qβ presentation. While a TLR4 agonist enhanced the immunogenicity of soluble CSP to levels comparable to the VLP vaccine, the TLR4 agonist did not further improve the immunogenicity of the Qβ-CSP vaccine. The data presented here pave the way for further improvement in the Qβ conjugation chemistry and evaluation of both the Qβ-CSP and soluble CSP vaccines in the non-human primate model.
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Affiliation(s)
- Farhat Khan
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States of America
| | - Mike Porter
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States of America
| | - Robert Schwenk
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States of America
| | - Margot DeBot
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States of America
| | - Philippe Saudan
- Cytos Biotechnology, Wagistrasse 25, 8952 Schlieren, Switzerland
| | - Sheetij Dutta
- Structural Vaccinology Laboratory, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States of America
- * E-mail:
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Fong MY, Ahmed MA, Wong SS, Lau YL, Sitam F. Genetic Diversity and Natural Selection of the Plasmodium knowlesi Circumsporozoite Protein Nonrepeat Regions. PLoS One 2015; 10:e0137734. [PMID: 26379157 PMCID: PMC4575020 DOI: 10.1371/journal.pone.0137734] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 08/21/2015] [Indexed: 11/18/2022] Open
Abstract
Background Plasmodium knowlesi is a simian malaria parasite that has been identified to cause malaria in humans. To date, several thousand cases of human knowlesi malaria have been reported around Southeast Asia. Thus far, there is no detailed study on genetic diversity and natural selection of P. knowlesi circumsporozoite protein (CSP), a prominent surface antigen on the sporozoite of the parasite. In the present study, the genetic diversity and natural selection acting on the nonrepeat regions of the gene encoding P. knowlesi CSP were investigated, focusing on the T-cell epitope regions at the C-terminal of the protein. Methods Blood samples from 32 knowlesi malaria patients and 2 wild monkeys (Macaca fascicularis) were used. The CSP of the P. knowlesi isolates was amplified by PCR, cloned into Escherichia coli, and sequenced. The nonrepeat regions of the CSP gene were analysed for genetic diversity, natural selection and haplotypic grouping using MEGA5 and DnaSP version 5.10.00 programmes. A haplotype network was constructed based on the C-terminal (Th2R/Th3R) T-cell epitope regions using the Median-Joining method in the NETWORK version 4.6.1.2 programme. Previously published sequences from other regions (Malaysia Borneo, Singapore) were also included in the analysis. Results A total of 123 P. knowlesi CSP sequences were analysed. Multiple sequence alignment revealed 58 amino acid changes, and 42 novel amino acid haplotypes were identified. Polymorphism was higher in the C-terminal Th2R/Th3R epitope (π = 0.0293, n = 123) region compared to the overall combined nonrepeat regions (π = 0.0120, n = 123). Negative natural selection was observed within the nonrepeat regions of the CSP gene. Within the C-terminal Th2R/Th3R epitope regions, there was evidence of slight positive selection. Based on haplotype network analysis of the Th2R/Th3R regions, five abundant haplotypes were identified. Sharing of haplotypes between humans and macaques were observed. Conclusion This study contributes to the understanding of the type and distribution of naturally occurring polymorphism in the P. knowlesi CSP gene. This study also provides a measurement of the genetic diversity of P. knowlesi and identifies the predominant haplotypes within Malaysia based on the C-terminal Th2R/Th3R regions.
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Affiliation(s)
- Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- * E-mail:
| | - Md Atique Ahmed
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Shen Siang Wong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Frankie Sitam
- Department of Wildlife and National Parks Peninsular Malaysia, Kuala Lumpur, Malaysia
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Niu Q, Marchand J, Yang C, Bonsergent C, Guan G, Yin H, Malandrin L. Rhoptry-associated protein (rap-1) genes in the sheep pathogen Babesia sp. Xinjiang: Multiple transcribed copies differing by 3' end repeated sequences. Vet Parasitol 2015; 211:158-69. [PMID: 26026806 DOI: 10.1016/j.vetpar.2015.04.030] [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: 08/29/2014] [Revised: 04/24/2015] [Accepted: 04/25/2015] [Indexed: 12/11/2022]
Abstract
Sheep babesiosis occurs mainly in tropical and subtropical areas. The sheep parasite Babesia sp. Xinjiang is widespread in China, and our goal is to characterize rap-1 (rhoptry-associated protein 1) gene diversity and expression as a first step of a long term goal aiming at developing a recombinant subunit vaccine. Seven different rap-1a genes were amplified in Babesia sp. Xinjiang, using degenerate primers designed from conserved motifs. Rap-1b and rap-1c gene types could not be identified. In all seven rap-1a genes, the 5' regions exhibited identical sequences over 936 nt, and the 3' regions differed at 28 positions over 147 nt, defining two types of genes designated α and β. The remaining 3' part varied from 72 to 360 nt in length, depending on the gene. This region consists of a succession of two to ten 36 nt repeats, which explains the size differences. Even if the nucleotide sequences varied, 6 repeats encoded the same stretch of amino acids. Transcription of at least four α and two β genes was demonstrated by standard RT-PCR.
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Affiliation(s)
- Qingli Niu
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France; State Key Laboratory of Veterinary Etiological Biology, LVRI, Lanzhou, China.
| | - Jordan Marchand
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France
| | - Congshan Yang
- State Key Laboratory of Veterinary Etiological Biology, LVRI, Lanzhou, China
| | - Claire Bonsergent
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France
| | - Guiquan Guan
- State Key Laboratory of Veterinary Etiological Biology, LVRI, Lanzhou, China
| | - Hong Yin
- State Key Laboratory of Veterinary Etiological Biology, LVRI, Lanzhou, China
| | - Laurence Malandrin
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France
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26
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Ferguson DJP, Balaban AE, Patzewitz EM, Wall RJ, Hopp CS, Poulin B, Mohmmed A, Malhotra P, Coppi A, Sinnis P, Tewari R. The repeat region of the circumsporozoite protein is critical for sporozoite formation and maturation in Plasmodium. PLoS One 2014; 9:e113923. [PMID: 25438048 PMCID: PMC4250072 DOI: 10.1371/journal.pone.0113923] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/31/2014] [Indexed: 11/25/2022] Open
Abstract
The circumsporozoite protein (CSP) is the major surface protein of the sporozoite stage of malaria parasites and has multiple functions as the parasite develops and then migrates from the mosquito midgut to the mammalian liver. The overall structure of CSP is conserved among Plasmodium species, consisting of a species-specific central tandem repeat region flanked by two conserved domains: the NH2-terminus and the thrombospondin repeat (TSR) at the COOH-terminus. Although the central repeat region is an immunodominant B-cell epitope and the basis of the only candidate malaria vaccine in Phase III clinical trials, little is known about its functional role(s). We used the rodent malaria model Plasmodium berghei to investigate the role of the CSP tandem repeat region during sporozoite development. Here we describe two mutant parasite lines, one lacking the tandem repeat region (ΔRep) and the other lacking the NH2-terminus as well as the repeat region (ΔNΔRep). We show that in both mutant lines oocyst formation is unaffected but sporozoite development is defective.
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Affiliation(s)
- David J. P. Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Amanda E. Balaban
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Eva-Maria Patzewitz
- Centre for Genetics and Genomics, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG2 7UH, United Kingdom
| | - Richard J. Wall
- Centre for Genetics and Genomics, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG2 7UH, United Kingdom
| | - Christine S. Hopp
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Benoit Poulin
- Centre for Genetics and Genomics, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG2 7UH, United Kingdom
| | - Asif Mohmmed
- International Centre for Genetic Engineering and Biotechnology, New Delhi-110067, India
| | - Pawan Malhotra
- International Centre for Genetic Engineering and Biotechnology, New Delhi-110067, India
| | - Alida Coppi
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Photini Sinnis
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail: (RT); (PS)
| | - Rita Tewari
- Centre for Genetics and Genomics, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG2 7UH, United Kingdom
- * E-mail: (RT); (PS)
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Schwenk R, DeBot M, Porter M, Nikki J, Rein L, Spaccapelo R, Crisanti A, Wightman PD, Ockenhouse CF, Dutta S. IgG2 antibodies against a clinical grade Plasmodium falciparum CSP vaccine antigen associate with protection against transgenic sporozoite challenge in mice. PLoS One 2014; 9:e111020. [PMID: 25343487 PMCID: PMC4208815 DOI: 10.1371/journal.pone.0111020] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 09/19/2014] [Indexed: 12/26/2022] Open
Abstract
The availability of a highly purified and well characterized circumsporozoite protein (CSP) is essential to improve upon the partial success of recombinant CSP-based malaria vaccine candidates. Soluble, near full-length, Plasmodium falciparum CSP vaccine antigen (CS/D) was produced in E. coli under bio-production conditions that comply with current Good Manufacturing Practices (cGMP). A mouse immunogenicity study was conducted using a stable oil-in-water emulsion (SE) of CS/D in combination with the Toll-Like Receptor 4 (TLR4) agonist Glucopyranosyl Lipid A (GLA/SE), or one of two TLR7/8 agonists: R848 (un-conjugated) or 3M-051 (covalently conjugated). Compared to Alum and SE, GLA/SE induced higher CS/D specific antibody response in Balb/c mice. Subclass analysis showed higher IgG2:IgG1 ratio of GLA/SE induced antibodies as compared to Alum and SE. TLR synergy was not observed when soluble R848 was mixed with GLA/SE. Antibody response of 3M051 formulations in Balb/c was similar to GLA/SE, except for the higher IgG2:IgG1 ratio and a trend towards higher T cell responses in 3M051 containing groups. However, no synergistic enhancement of antibody and T cell response was evident when 3M051 conjugate was mixed with GLA/SE. In C57Bl/6 mice, CS/D adjuvanted with 3M051/SE or GLA/SE induced higher CSP repeat specific titers compared to SE. While, 3M051 induced antibodies had high IgG2c:IgG1 ratio, GLA/SE promoted high levels of both IgG1 and IgG2c. GLA/SE also induced more potent T-cell responses compared to SE in two independent C57/BL6 vaccination studies, suggesting a balanced and productive TH1/TH2 response. GLA and 3M-051 similarly enhanced the protective efficacy of CS/D against challenge with a transgenic P. berghei parasite and most importantly, high levels of cytophilic IgG2 antibodies were associated with protection in this model. Our data indicated that the cGMP-grade, soluble CS/D antigen combined with the TLR4-containing adjuvant GLA/SE warrants further evaluation for protective responses in humans.
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Affiliation(s)
- Robert Schwenk
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Margot DeBot
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Michael Porter
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Jennifer Nikki
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Lisa Rein
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Roberta Spaccapelo
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | | | - Paul D. Wightman
- 3M Drug Delivery Systems, St. Paul, MN, United States of America
| | - Christian F. Ockenhouse
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
- * E-mail:
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28
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Antigenicity and immunogenicity of a novel Plasmodium vivax circumsporozoite derived synthetic vaccine construct. Vaccine 2014; 32:3179-86. [PMID: 24731811 DOI: 10.1016/j.vaccine.2014.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/28/2014] [Accepted: 04/01/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND The circumsporozoite (CS) protein is a major malaria sporozoite surface antigen currently being considered as vaccine candidate. Plasmodium vivax CS (PvCS) protein comprises a dimorphic central repeat fragment flanked by conserved regions that contain functional domains involved in parasite invasion of host cells. The protein amino (N-terminal) flank has a cleavage region (region I), essential for proteolytic processing prior to parasite invasion of liver cells. METHODS We have developed a 131-mer long synthetic polypeptide (LSP) named PvNR1R2 that includes the N-terminal flank and the two natural repeat variant regions known as VK210 and VK247. We studied the natural immune response to this region in human sera from different malaria-endemic areas and its immunogenicity in mice. RESULTS PvNR1R2 was more frequently recognized by sera from Papua New Guinea (PNG) (83%) than by samples from Colombia (24%) when tested by ELISA. The polypeptide formulated in Montanide ISA51 adjuvant elicited strong antibody responses in both C3H and CB6F1 mice strains. Antibodies from immunized mice as well as affinity-purified human IgG reacted with native protein by IFA test. Moreover, mouse immune sera induced strong (90%) in vitro inhibition of sporozoite invasion (ISI) of hepatoma cell lines. CONCLUSIONS These results encourage further studies in non-human primates to confirm the elicitation of sporozoite invasion blocking antibodies, to assess cell mediated immune responses and the protective efficacy of this polypeptide.
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29
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Bauza K, Malinauskas T, Pfander C, Anar B, Jones EY, Billker O, Hill AVS, Reyes-Sandoval A. Efficacy of a Plasmodium vivax malaria vaccine using ChAd63 and modified vaccinia Ankara expressing thrombospondin-related anonymous protein as assessed with transgenic Plasmodium berghei parasites. Infect Immun 2014; 82:1277-86. [PMID: 24379295 PMCID: PMC3957994 DOI: 10.1128/iai.01187-13] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/23/2013] [Indexed: 12/13/2022] Open
Abstract
Plasmodium vivax is the world's most widely distributed malaria parasite and a potential cause of morbidity and mortality for approximately 2.85 billion people living mainly in Southeast Asia and Latin America. Despite this dramatic burden, very few vaccines have been assessed in humans. The clinically relevant vectors modified vaccinia virus Ankara (MVA) and the chimpanzee adenovirus ChAd63 are promising delivery systems for malaria vaccines due to their safety profiles and proven ability to induce protective immune responses against Plasmodium falciparum thrombospondin-related anonymous protein (TRAP) in clinical trials. Here, we describe the development of new recombinant ChAd63 and MVA vectors expressing P. vivax TRAP (PvTRAP) and show their ability to induce high antibody titers and T cell responses in mice. In addition, we report a novel way of assessing the efficacy of new candidate vaccines against P. vivax using a fully infectious transgenic Plasmodium berghei parasite expressing P. vivax TRAP to allow studies of vaccine efficacy and protective mechanisms in rodents. Using this model, we found that both CD8+ T cells and antibodies mediated protection against malaria using virus-vectored vaccines. Our data indicate that ChAd63 and MVA expressing PvTRAP are good preerythrocytic-stage vaccine candidates with potential for future clinical application.
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Affiliation(s)
- Karolis Bauza
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Claudia Pfander
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Burcu Anar
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - E. Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Oliver Billker
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
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Cheng Y, Ito D, Sattabongkot J, Lim CS, Kong DH, Ha KS, Wang B, Tsuboi T, Han ET. Serological responses to a soluble recombinant chimeric Plasmodium vivax circumsporozoite protein in VK210 and VK247 population. Malar J 2013; 12:323. [PMID: 24034268 PMCID: PMC3847697 DOI: 10.1186/1475-2875-12-323] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 09/11/2013] [Indexed: 12/01/2022] Open
Abstract
Background Circumsporozoite protein (CSP) is essential for sporozoite formation and sporozoite invasion into human hepatocyte. Previously, a recombinant P. vivax CSP based on chimeric repeats (rPvCSP-c) representing two major alleles VK210 and VK247 within central region has been designed. Naturally acquired humoral immune responses study show that antigenicity of rPvCSP-c was much higher than that of native strain. However, the serologic reactivity of rPvCSP-c was still unclear in detail. Methods In present study, recognition of rPvCSP-c in vivax malaria typed VK210 and VK247 alleles was assessed. VK210 typed and VK247 typed sera from adult residents reacted specifically with rPvCSP-c using protein array and immunoblot assay. Additionally, anti-rPvCSP-c serum recognized the fixed VK210 and VK247 sporozoites by immunofluorescence assay. Furthermore, statistic analysis was performed for correlational detection. Results The rPvCSP-c reacted with both VK210 typed and VK247 typed P. vivax infected patient sera and anti-rPvCSP-c immune serum also reacted with VK210 and VK247 sporozoite parasites of P. vivax specifically. There was a positive correlation between increased antibody level, age of patients and also associated with pvcsp repeat number, although the level of responses did vary considerably in their reactivity to the rPvCSP-c from negative to very high level within each age group. Conclusions These data confirmed the serologic reactivity of the novel rPvCSP-c in exposed both VK210 and VK247 populations. These results strongly suggested that this recombinant CSP was biologically active and potently immunogenic across major strains and raised the prospect that this protein could be used as serologic marker.
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Affiliation(s)
- Yang Cheng
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, Gangwon-do 200-701, Republic of Korea.
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Wang J, Zhang Y, Zhao YO, Li MWM, Zhang L, Dragovic S, Abraham NM, Fikrig E. Anopheles gambiae circumsporozoite protein-binding protein facilitates plasmodium infection of mosquito salivary glands. J Infect Dis 2013; 208:1161-9. [PMID: 23801601 DOI: 10.1093/infdis/jit284] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Malaria, a mosquito-borne disease caused by Plasmodium species, causes substantial morbidity and mortality throughout the world. Plasmodium sporozoites mature in oocysts formed in the mosquito gut wall and then invade the salivary glands, where they remain until transmitted to the vertebrate host during a mosquito bite. The Plasmodium circumsporozoite protein (CSP) binds to salivary glands and plays a role in the invasion of this organ by sporozoites. We identified an Anopheles salivary gland protein, named CSP-binding protein (CSPBP), that interacts with CSP. Downregulation of CSPBP in mosquito salivary glands inhibited invasion by Plasmodium organisms. In vivo bioassays showed that mosquitoes that were fed blood with CSPBP antibody displayed a 25% and 90% reduction in the parasite load in infected salivary glands 14 and 18 days after the blood meal, respectively. These results suggest that CSPBP is important for the infection of the mosquito salivary gland by Plasmodium organisms and that blocking CSPBP can interfere with the Plasmodium life cycle.
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Affiliation(s)
- Jiuling Wang
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8022, USA
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Transgenic parasites stably expressing full-length Plasmodium falciparum circumsporozoite protein as a model for vaccine down-selection in mice using sterile protection as an endpoint. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:803-10. [PMID: 23536694 DOI: 10.1128/cvi.00066-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Circumsporozoite protein (CSP) of Plasmodium falciparum is a protective human malaria vaccine candidate. There is an urgent need for models that can rapidly down-select novel CSP-based vaccine candidates. In the present study, the mouse-mosquito transmission cycle of a transgenic Plasmodium berghei malaria parasite stably expressing a functional full-length P. falciparum CSP was optimized to consistently produce infective sporozoites for protection studies. A minimal sporozoite challenge dose was established, and protection was defined as the absence of blood-stage parasites 14 days after intravenous challenge. The specificity of protection was confirmed by vaccinating mice with multiple CSP constructs of differing lengths and compositions. Constructs that induced high NANP repeat-specific antibody titers in enzyme-linked immunosorbent assays were protective, and the degree of protection was dependent on the antigen dose. There was a positive correlation between antibody avidity and protection. The antibodies in the protected mice recognized the native CSP on the parasites and showed sporozoite invasion inhibitory activity. Passive transfer of anti-CSP antibodies into naive mice also induced protection. Thus, we have demonstrated the utility of a mouse efficacy model to down-select human CSP-based vaccine formulations.
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