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van der Boor SC, van Gemert GJ, Hanssen AEJ, van Waardenburg YM, McCall MBB, Bousema T, de Wilt JHW, Sauerwein RW, Yang ASP. Mid-Liver Stage Arrest of Plasmodium falciparum Schizonts in Primary Porcine Hepatocytes. Front Cell Infect Microbiol 2022; 12:834850. [PMID: 35252038 PMCID: PMC8892583 DOI: 10.3389/fcimb.2022.834850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
During co-evolution Plasmodium parasites and vertebrates went through a process of selection resulting in defined and preferred parasite-host combinations. As such, Plasmodium falciparum (Pf) sporozoites can infect human hepatocytes while seemingly incompatible with host cellular machinery of other species. The compatibility between parasite invasion ligands and their respective human hepatocyte receptors plays a key role in Pf host selectivity. However, it is unclear whether the ability of Pf sporozoites to mature in cross-species infection also plays a role in host tropism. Here we used fresh hepatocytes isolated from porcine livers to study permissiveness to Pf sporozoite invasion and development. We monitored intra-hepatic development via immunofluorescence using anti-HSP70, MSP1, EXP1, and EXP2 antibodies. Our data shows that Pf sporozoites can invade non-human hepatocytes and undergo partial maturation with a significant decrease in schizont numbers between day three and day five. A possible explanation is that Pf sporozoites fail to form a parasitophorous vacuolar membrane (PVM) during invasion. Indeed, the observed aberrant EXP1 and EXP2 staining supports the presence of an atypical PVM. Functions of the PVM include the transport of nutrients, export of waste, and offering a protective barrier against intracellular host effectors. Therefore, an atypical PVM likely results in deficiencies that may detrimentally impact parasite development at multiple levels. In summary, despite successful invasion of porcine hepatocytes, Pf development arrests at mid-stage, possibly due to an inability to mobilize critical nutrients across the PVM. These findings underscore the potential of a porcine liver model for understanding the importance of host factors required for Pf mid-liver stage development.
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Affiliation(s)
- Saskia C. van der Boor
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Alex E. J. Hanssen
- Animal Research Facility, Radboud University Medical Center, Nijmegen, Netherlands
| | - Youri M. van Waardenburg
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Matthew B. B. McCall
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Teun Bousema
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - Robert W. Sauerwein
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
- TropIQ Health Sciences, Nijmegen, Netherlands
| | - Annie S. P. Yang
- Radboudumc Center for Infectious Diseases, Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
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2
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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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3
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Reeder SM, Bah MA, Tursi NJ, Brooks RC, Patel A, Esquivel R, Eaton A, Jhun H, Chu J, Kim K, Xu Z, Zavala F, Weiner DB. Strategic Variants of CSP Delivered as SynDNA Vaccines Demonstrate Heterogeneity of Immunogenicity and Protection from Plasmodium Infection in a Murine Model. Infect Immun 2021; 89:e0072820. [PMID: 34152830 PMCID: PMC8445182 DOI: 10.1128/iai.00728-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 05/27/2021] [Indexed: 11/20/2022] Open
Abstract
Malaria infects millions of people every year, and despite recent advances in controlling disease spread, such as vaccination, it remains a global health concern. The circumsporozoite protein (CSP) has long been acknowledged as a key target in antimalarial immunity. Leveraging the DNA vaccine platform against this formidable pathogen, the following five synthetic DNA vaccines encoding variations of CSP were designed and studied: 3D7, GPI1, ΔGPI, TM, and DD2. Among the single CSP antigen constructs, a range of immunogenicity was observed with ΔGPI generating the most robust immunity. In an intravenous (i.v.) sporozoite challenge, the best protection among vaccinated mice was achieved by ΔGPI, which performed almost as well as the monoclonal antibody 311 (MAb 311) antibody control. Further analyses revealed that ΔGPI develops high-molecular-weight multimers in addition to monomeric CSP. We then compared the immunity generated by ΔGPI versus synDNA mimics for the antimalaria vaccines RTS,S and R21. The anti-CSP antibody responses induced were similar among these three immunogens. T cell responses demonstrated that ΔGPI induced a more focused anti-CSP response. In an infectious mosquito challenge, all three of these constructs generated inhibition of liver-stage infection as well as immunity from blood-stage parasitemia. This study demonstrates that synDNA mimics of complex malaria immunogens can provide substantial protection as can a novel synDNA vaccine ΔGPI.
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Affiliation(s)
- Sophia M. Reeder
- The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Mamadou A. Bah
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Nicholas J. Tursi
- The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Rebekah C. Brooks
- The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Ami Patel
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Rianne Esquivel
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Alison Eaton
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Hugo Jhun
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jacqueline Chu
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Kevin Kim
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Ziyang Xu
- The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Fidel Zavala
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - David B. Weiner
- The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- The Vaccine Center, Wistar Institute, Philadelphia, Pennsylvania, USA
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4
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Chatterjee D, Cockburn IA. The challenges of a circumsporozoite protein-based malaria vaccine. Expert Rev Vaccines 2021; 20:113-125. [PMID: 33554669 DOI: 10.1080/14760584.2021.1874924] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION A safe and effective vaccine will likely be necessary for the control or eradication of malaria which kills 400,000 annually. Our most advanced vaccine candidate to date is RTS,S which is based on the Plasmodium falciparum circumsporozoite protein (PfCSP) of the malaria parasite. However, protection by RTS,S is incomplete and short-lived. AREAS COVERED Here we summarize results from recent clinical trials of RTS,S and critically evaluate recent studies that aim to understand the correlates of protective immunity and why vaccine-induced protection is short-lived. In particular, recent systems serology studies have highlighted a key role for the necessity of inducing functional antibodies. In-depth analyses of immune responses to CSP in both mouse models and vaccinated humans have also highlighted difficulties in generating the maintaining high-quality antibody responses. Finally, in recent years biophysical and structural studies of antibody binding to PfCSP have led to a better understanding of how highly potent antibodies can block infection, which can inform vaccine design. EXPERT OPINION We highlight how both structure-guided vaccine design and a better understanding of the immune response to PfCSP can inform a second generation of PfCSP-based vaccines stimulating a broader range of protective targets within PfCSP.
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Affiliation(s)
- Deepyan Chatterjee
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, the Australian National University, Canberra, Australia
| | - Ian Andrew Cockburn
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, the Australian National University, Canberra, Australia
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5
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Elworth RAL, Diaz C, Yang J, de Figueiredo P, Ternus K, Treangen T. Synthetic DNA and biosecurity: Nuances of predicting pathogenicity and the impetus for novel computational approaches for screening oligonucleotides. PLoS Pathog 2020; 16:e1008649. [PMID: 32760120 PMCID: PMC7410204 DOI: 10.1371/journal.ppat.1008649] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- R. A. Leo Elworth
- Department of Computer Science, Rice University, Houston, Texas, United States of America
| | - Christian Diaz
- Department of Computer Science, Rice University, Houston, Texas, United States of America
| | - Jing Yang
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
- Norman Borlaug Center, Texas A&M University, College Station, Texas, United States of America
| | - Krista Ternus
- Signature Science, LLC, Austin, Texas, United States of America
| | - Todd Treangen
- Department of Computer Science, Rice University, Houston, Texas, United States of America
- * E-mail:
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6
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Jarquín‐Díaz VH, Balard A, Mácová A, Jost J, Roth von Szepesbéla T, Berktold K, Tank S, Kvičerová J, Heitlinger E. Generalist Eimeria species in rodents: Multilocus analyses indicate inadequate resolution of established markers. Ecol Evol 2020; 10:1378-1389. [PMID: 32076521 PMCID: PMC7029063 DOI: 10.1002/ece3.5992] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/13/2019] [Accepted: 12/20/2019] [Indexed: 11/23/2022] Open
Abstract
Intracellular parasites of the genus Eimeria are described as tissue/host-specific. Phylogenetic classification of rodent Eimeria suggested that some species have a broader host range than previously assumed. We explore whether Eimeria spp. infecting house mice are misclassified by the most widely used molecular markers due to a lack of resolution, or whether, instead, these parasite species are indeed infecting multiple host species.With the commonly used markers (18S/COI), we recovered monophyletic clades of E. falciformis and E. vermiformis from Mus that included E. apionodes identified in other rodent host species (Apodemus spp., Myodes glareolus, and Microtus arvalis). A lack of internal resolution in these clades could suggest the existence of a species complex with a wide host range infecting murid and cricetid rodents. We question, however, the power of COI and 18S markers to provide adequate resolution for assessing host specificity. In addition to the rarely used marker ORF470 from the apicoplast genome, we present multilocus genotyping as an alternative approach. Phylogenetic analysis of 35 nuclear markers differentiated E. falciformis from house mice from isolates from Apodemus hosts. Isolates of E. vermiformis from Mus are still found in clusters interspersed with non-Mus isolates, even with this high-resolution data.In conclusion, we show that species-level resolution should not be assumed for COI and 18S markers in coccidia. Host-parasite cospeciation at shallow phylogenetic nodes, as well as contemporary coccidian host ranges more generally, is still open questions that need to be addressed using novel genetic markers with higher resolution.
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Affiliation(s)
- Víctor Hugo Jarquín‐Díaz
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
- Leibniz‐Institut für Zoo‐ und Wildtierforschung (IZW) im Forschungsverbund Berlin e.VBerlinGermany
| | - Alice Balard
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
- Leibniz‐Institut für Zoo‐ und Wildtierforschung (IZW) im Forschungsverbund Berlin e.VBerlinGermany
| | - Anna Mácová
- Department of ParasitologyFaculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Jenny Jost
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
| | - Tabea Roth von Szepesbéla
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
| | - Karin Berktold
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
| | - Steffen Tank
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
| | - Jana Kvičerová
- Department of ParasitologyFaculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Emanuel Heitlinger
- Department of Molecular ParasitologyInstitute for BiologyHumboldt University Berlin (HU)BerlinGermany
- Leibniz‐Institut für Zoo‐ und Wildtierforschung (IZW) im Forschungsverbund Berlin e.VBerlinGermany
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7
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Lin JW, Reid AJ, Cunningham D, Böhme U, Tumwine I, Keller-Mclaughlin S, Sanders M, Berriman M, Langhorne J. Genomic and transcriptomic comparisons of closely related malaria parasites differing in virulence and sequestration pattern. Wellcome Open Res 2018; 3:142. [PMID: 30542666 DOI: 10.12688/wellcomeopenres.14797.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2018] [Indexed: 12/27/2022] Open
Abstract
Background: Malaria parasite species differ greatly in the harm they do to humans. While P. falciparum kills hundreds of thousands per year, P. vivax kills much less often and P. malariae is relatively benign. Strains of the rodent malaria parasite Plasmodium chabaudi show phenotypic variation in virulence during infections of laboratory mice. This make it an excellent species to study genes which may be responsible for this trait. By understanding the mechanisms which underlie differences in virulence we can learn how parasites adapt to their hosts and how we might prevent disease. Methods: Here we present a complete reference genome sequence for a more virulent P. chabaudi strain, PcCB, and perform a detailed comparison with the genome of the less virulent PcAS strain. Results: We found the greatest variation in the subtelomeric regions, in particular amongst the sequences of the pir gene family, which has been associated with virulence and establishment of chronic infection. Despite substantial variation at the sequence level, the repertoire of these genes has been largely maintained, highlighting the requirement for functional conservation as well as diversification in host-parasite interactions. However, a subset of pir genes, previously associated with increased virulence, were more highly expressed in PcCB, suggesting a role for this gene family in virulence differences between strains. We found that core genes involved in red blood cell invasion have been under positive selection and that the more virulent strain has a greater preference for reticulocytes, which has elsewhere been associated with increased virulence. Conclusions: These results provide the basis for a mechanistic understanding of the phenotypic differences between Plasmodium chabaudi strains, which might ultimately be translated into a better understanding of malaria parasites affecting humans.
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Affiliation(s)
- Jing-Wen Lin
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK.,Division of Pediatric Infectious Diseases, Sichuan University and Collaboration Innovation Centre, Chengdu, 610041, China
| | - Adam J Reid
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Deirdre Cunningham
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | - Ulrike Böhme
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Irene Tumwine
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | | | - Mandy Sanders
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Matthew Berriman
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Jean Langhorne
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
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8
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Lin JW, Reid AJ, Cunningham D, Böhme U, Tumwine I, Keller-Mclaughlin S, Sanders M, Berriman M, Langhorne J. Genomic and transcriptomic comparisons of closely related malaria parasites differing in virulence and sequestration pattern. Wellcome Open Res 2018; 3:142. [PMID: 30542666 PMCID: PMC6259598 DOI: 10.12688/wellcomeopenres.14797.2] [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] [Accepted: 11/27/2018] [Indexed: 01/01/2023] Open
Abstract
Background: Malaria parasite species differ greatly in the harm they do to humans. While
P. falciparum kills hundreds of thousands per year,
P. vivax kills much less often and
P. malariae is relatively benign. Strains of the rodent malaria parasite
Plasmodium chabaudi show phenotypic variation in virulence during infections of laboratory mice. This make it an excellent species to study genes which may be responsible for this trait. By understanding the mechanisms which underlie differences in virulence we can learn how parasites adapt to their hosts and how we might prevent disease. Methods: Here we present a complete reference genome sequence for a more virulent
P. chabaudi strain, PcCB, and perform a detailed comparison with the genome of the less virulent PcAS strain. Results: We found the greatest variation in the subtelomeric regions, in particular amongst the sequences of the
pir gene family, which has been associated with virulence and establishment of chronic infection. Despite substantial variation at the sequence level, the repertoire of these genes has been largely maintained, highlighting the requirement for functional conservation as well as diversification in host-parasite interactions. However, a subset of
pir genes, previously associated with increased virulence, were more highly expressed in PcCB, suggesting a role for this gene family in virulence differences between strains. We found that core genes involved in red blood cell invasion have been under positive selection and that the more virulent strain has a greater preference for reticulocytes, which has elsewhere been associated with increased virulence. Conclusions: These results provide the basis for a mechanistic understanding of the phenotypic differences between
Plasmodium chabaudi strains, which might ultimately be translated into a better understanding of malaria parasites affecting humans.
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Affiliation(s)
- Jing-Wen Lin
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK.,Division of Pediatric Infectious Diseases, Sichuan University and Collaboration Innovation Centre, Chengdu, 610041, China
| | - Adam J Reid
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Deirdre Cunningham
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | - Ulrike Böhme
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Irene Tumwine
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | | | - Mandy Sanders
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Matthew Berriman
- Parasites & Microbes, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Jean Langhorne
- Malaria Immunology laboratory, Francis Crick Institute, London, NW1 1AT, UK
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9
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A no film slot blot for the detection of developing P. falciparum oocysts in mosquitoes. PLoS One 2017; 12:e0174229. [PMID: 28430778 PMCID: PMC5400236 DOI: 10.1371/journal.pone.0174229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/05/2017] [Indexed: 11/20/2022] Open
Abstract
Non-microscopy-based assays for sensitive and rapid detection of Plasmodium infection in mosquitoes are needed to allow rapid and high throughput measurement of transmission intensity and malaria control program effectiveness. Here, we report on a modified enhanced chemiluminescence-based slot blot assay for detection of Plasmodium falciparum (Pf) circumsporozite protein (PfCSP) expressed on parasite oocysts developing inside the mosquito midgut. This modified assay has several novel features that include eliminating the need for exposure to autoradiography (AR) film, as well as utilizing a novel high affinity anti-CSP antibody, and optimizing assay procedures resulting in significant reduction in the time required to perform the assay. The chemiluminescent signal for the detection of PfCSP in mosquito samples was captured digitally utilizing the C-Digit blot scanner that, allowed the detection of 0.01 pg of recombinant P. falciparum CSP and as few as 0.02 P. falciparum oocysts in a little over two hours. The earlier ECL-SB detected rCSP and oocysts and took approximately 5 h to perform. Whole mosquito lysates from both high and low prevalence—infected mosquito populations were prepared and evaluated for PfCSP detection on the ECL-SB by both AR film and digital data capture and analysis. There was a 100% agreement between the AR film and the C-Digit scanner methods for PfCSP detection in randomly sampled mosquitoes. This novel “No Film” Slot Blot assay obviates the need for AR film exposure and development and significantly reduces the assay time enabling widespread use in field settings.
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10
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Lauron EJ, Aw Yeang HX, Taffner SM, Sehgal RNM. De novo assembly and transcriptome analysis of Plasmodium gallinaceum identifies the Rh5 interacting protein (ripr), and reveals a lack of EBL and RH gene family diversification. Malar J 2015; 14:296. [PMID: 26243218 PMCID: PMC4524024 DOI: 10.1186/s12936-015-0814-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 07/20/2015] [Indexed: 01/01/2023] Open
Abstract
Background Malaria parasites that infect birds can have narrow or broad host-tropisms. These differences in host specificity make avian malaria a useful model for studying the evolution and transmission of parasite assemblages across geographic ranges. The molecular mechanisms involved in host-specificity and the biology of avian malaria parasites in general are important aspects of malaria pathogenesis that warrant further examination. Here, the transcriptome of the malaria parasite Plasmodium gallinaceum was characterized to investigate the biology and the conservation of genes across various malaria parasite species. Methods The P. gallinaceum transcriptome was annotated and KEGG pathway mapping was performed. The ripr gene and orthologous genes that play critical roles in the purine salvage pathway were identified and characterized using bioinformatics and phylogenetic methods. Results Analysis of the transcriptome sequence database identified essential genes of the purine salvage pathway in P. gallinaceum that shared high sequence similarity to Plasmodium falciparum when compared to other mammalian Plasmodium spp. However, based on the current sequence data, there was a lack of orthologous genes that belonged to the erythrocyte-binding-like (EBL) and reticulocyte-binding-like homologue (RH) family in P. gallinaceum. In addition, an orthologue of the Rh5 interacting protein (ripr) was identified. Conclusions These findings suggest that the pathways involved in parasite red blood cell invasion are significantly different in avian Plasmodium parasites, but critical metabolic pathways are conserved throughout divergent Plasmodium taxa. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0814-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elvin J Lauron
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
| | - Han Xian Aw Yeang
- Rheumatology Division, Washington University School of Medicine, St. Louis, MO, USA.
| | - Samantha M Taffner
- Rheumatology Division, Washington University School of Medicine, St. Louis, MO, USA.
| | - Ravinder N M Sehgal
- Department of Biology, San Francisco State University, San Francisco, CA, USA.
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11
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Reversible Conformational Change in the Plasmodium falciparum Circumsporozoite Protein Masks Its Adhesion Domains. Infect Immun 2015; 83:3771-80. [PMID: 26169272 DOI: 10.1128/iai.02676-14] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 07/02/2015] [Indexed: 11/20/2022] Open
Abstract
The extended rod-like Plasmodium falciparum circumsporozoite protein (CSP) is comprised of three primary domains: a charged N terminus that binds heparan sulfate proteoglycans, a central NANP repeat domain, and a C terminus containing a thrombospondin-like type I repeat (TSR) domain. Only the last two domains are incorporated in RTS,S, the leading malaria vaccine in phase 3 trials that, to date, protects about 50% of vaccinated children against clinical disease. A seroepidemiological study indicated that the N-terminal domain might improve the efficacy of a new CSP vaccine. Using a panel of CSP-specific monoclonal antibodies, well-characterized recombinant CSPs, label-free quantitative proteomics, and in vitro inhibition of sporozoite invasion, we show that native CSP is N-terminally processed in the mosquito host and undergoes a reversible conformational change to mask some epitopes in the N- and C-terminal domains until the sporozoite interacts with the liver hepatocyte. Our findings show the importance of understanding processing and the biophysical change in conformation, possibly due to a mechanical or molecular signal, and may aid in the development of a new CSP vaccine.
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Kumar S, Zheng H, Deng B, Mahajan B, Grabias B, Kozakai Y, Morin MJ, Locke E, Birkett A, Miura K, Long C. A slot blot immunoassay for quantitative detection of Plasmodium falciparum circumsporozoite protein in mosquito midgut oocyst. PLoS One 2014; 9:e115807. [PMID: 25531543 PMCID: PMC4274163 DOI: 10.1371/journal.pone.0115807] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 11/28/2014] [Indexed: 11/19/2022] Open
Abstract
There is still a need for sensitive and reproducible immunoassays for quantitative detection of malarial antigens in preclinical and clinical phases of vaccine development and in epidemiology and surveillance studies, particularly in the vector host. Here we report the results of sensitivity and reproducibility studies for a research-grade, quantitative enhanced chemiluminescent-based slot blot assay (ECL-SB) for detection of both recombinant Plasmodium falciparum circumsporozoite protein (rPfCSP) and native PfCSP from Oocysts (Pf Oocyst) developing in the midguts of Anopheles stephensi mosquitoes. The ECL-SB detects as little as 1.25 pg of rPfCSP (linear range of quantitation 2.5-20 pg; R2 = 0.9505). We also find the earliest detectable expression of native PfCSP in Pf Oocyst by ECL-SB occurs on day 7 post feeding with infected blood meal. The ECL-SB was able to detect approximately as few as 0.5 day 8 Pf Oocysts (linear quantitation range 1-4, R2 = 0.9795) and determined that one Pf Oocyst expressed approximately 2.0 pg (0.5-3 pg) of native PfCSP, suggesting a similar range of detection for recombinant and native forms of Pf CSP. The ECL-SB is highly reproducible; the Coefficient of Variation (CV) for inter-assay variability for rPf CSP and native PfCSP were 1.74% and 1.32%, respectively. The CVs for intra-assay variability performed on three days for rPf CSP were 2.41%, 0.82% and 2% and for native Pf CSP 1.52%, 0.57%, and 1.86%, respectively. In addition, the ECL-SB was comparable to microscopy in determining the P. falciparum prevalence in mosquito populations that distinctly contained either high and low midgut Pf Oocyst burden. In whole mosquito samples, estimations of positivity for P. falciparum in the high and low burden groups were 83.3% and 23.3% by ECL-SB and 85.7% and 27.6% by microscopy. Based on its performance characteristics, ECL-SB could be valuable in vaccine development and to measure the parasite prevalence in mosquitoes and transmission-blocking interventions in endemic areas.
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Affiliation(s)
- Sanjai Kumar
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States of America
- * E-mail:
| | - Hong Zheng
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States of America
| | - Bingbing Deng
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, United States of America
| | - Babita Mahajan
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States of America
| | - Bryan Grabias
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States of America
| | - Yukiko Kozakai
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States of America
| | - Merribeth J. Morin
- Program for Appropriate Technology in Health (PATH) Malaria Vaccine Initiative, Washington, DC 20001, United States of America
| | - Emily Locke
- Program for Appropriate Technology in Health (PATH) Malaria Vaccine Initiative, Washington, DC 20001, United States of America
| | - Ashley Birkett
- Program for Appropriate Technology in Health (PATH) Malaria Vaccine Initiative, Washington, DC 20001, United States of America
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, United States of America
| | - Carole Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, United States of America
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13
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Maturation of Plasmodium falciparum in multiply infected erythrocytes and the potential role in malaria pathogenesis. Parasitol Res 2014; 113:4045-56. [DOI: 10.1007/s00436-014-4073-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 08/05/2014] [Indexed: 10/24/2022]
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14
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Kumar S, Zheng H, Mahajan B, Kozakai Y, Morin M, Locke E. Western blot assay for quantitative and qualitative antigen detection in vaccine development. CURRENT PROTOCOLS IN MICROBIOLOGY 2014; 33:18.4.1-11. [PMID: 24789597 DOI: 10.1002/9780471729259.mc1804s33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Immunological methods for quantitative measurement, antigenic characterization, and monitoring the stability of active immunogenic component(s) are a critical need in the vaccine development process. This unit describes an enhanced chemiluminescence-based western blot for quantitative detection of Plasmodium falciparum circumsporozoite protein (PfCSP), a major malaria candidate vaccine antigen. The most salient features of this assay are its high sensitivity and reproducibility; it can reliably detect ∼5 to 10 pg PfCSP expressed on native parasites or recombinantly expressed in Escherichia coli. Although described for a specific vaccine antigen, this assay should be applicable for any antigen-antibody combination for which relevant detection reagents are available. Detailed stepwise experimental procedures and methods for data acquisition and analysis are described.
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Affiliation(s)
- Sanjai Kumar
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, Maryland
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Pacheco MA, Cranfield M, Cameron K, Escalante AA. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens. Malar J 2013; 12:328. [PMID: 24044371 PMCID: PMC3848613 DOI: 10.1186/1475-2875-12-328] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 09/13/2013] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Plasmodium falciparum shares its most recent common ancestor with parasites found in African apes; these species constitute the so-called Laverania clade. In this investigation, the evolutionary history of Plasmodium lineages found in chimpanzees (Pan troglodytes) was explored. METHODS Here, the remainders of 74 blood samples collected as part of the chimpanzees' routine health examinations were studied. For all positive samples with parasite lineages belonging to the Laverania clade, the complete mitochondrial genome (mtDNA), the gene encoding dihydrofolate reductase-thymidylate synthase (dhfr-ts), the chloroquine resistance transporter (Pfcrt), the circumsporozoite protein (csp), merozoite surface protein 2 (msp2), and the DBL-1 domain from var2CSA were amplified, cloned, and sequenced. Other Plasmodium species were included in the mtDNA, dhfr-ts, and csp analyses. Phylogenetic and evolutionary genetic analyses were performed, including molecular clock analyses on the mtDNA. RESULTS/CONCLUSIONS Nine chimpanzees were malaria positive (12.2%); four of those infections were identified as P. falciparum, two as a Plasmodium reichenowi-like parasite or Plasmodium sp., one as Plasmodium gaboni, and two as Plasmodium malariae. All P. falciparum isolates were resistant to chloroquine indicating that the chimpanzees acquired such infections from humans in recent times. Such findings, however, are not sufficient for implicating chimpanzees as an animal reservoir for P. falciparum.Timing estimates support that the Laverania clade has co-existed with hominids for a long-period of time. The proposed species P. gaboni, Plasmodium billbrayi, and Plasmodium billcollinsi are monophyletic groups supporting that they are indeed different species.An expanded CSP phylogeny is presented, including all the Laverania species and other malarial parasites. Contrasting with other Plasmodium, the Laverania csp exhibits great conservation at the central tandem repeat region. Msp2 and var2CSA, however, show extended recent polymorphism in P. falciparum that likely originated after the P. reichenowi-P. falciparum split. The accumulation of such diversity may indicate adaptation to the human host. These examples support the notion that comparative approaches among P. falciparum and its related species will be of great value in understanding the evolution of proteins that are important in parasite invasion of the human red blood cell, as well as those involved in malaria pathogenesis.
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Affiliation(s)
- M Andreína Pacheco
- Center for Evolutionary Medicine and Informatics, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA.
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Heme-binding properties of heme detoxification protein from Plasmodium falciparum. Biochem Biophys Res Commun 2013; 439:477-80. [PMID: 24025682 DOI: 10.1016/j.bbrc.2013.08.100] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 08/30/2013] [Indexed: 12/15/2022]
Abstract
The heme detoxification protein of the malaria parasite Plasmodium falciparum is involved in the formation of hemozoin, an insoluble crystalline form of heme. Although the disruption of hemozoin formation is the most widely used strategy for controlling the malaria parasite, the heme-binding properties of heme detoxification protein are poorly characterized. In this study, we established a method for the expression and purification of the non-tagged protein and characterized heme-binding properties. The spectroscopic features of non-tagged protein differ from those of the His-tagged protein, suggesting that the artificial tag interferes with the properties of the recombinant protein. The purified recombinant non-tagged heme detoxification protein had two heme-binding sites and exhibited a spectrum typical of heme proteins. A mechanism for hemozoin formation is proposed.
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17
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Kamhi E, Joo EJ, Dordick JS, Linhardt RJ. Glycosaminoglycans in infectious disease. Biol Rev Camb Philos Soc 2013; 88:928-43. [DOI: 10.1111/brv.12034] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 02/07/2013] [Accepted: 02/27/2013] [Indexed: 12/14/2022]
Affiliation(s)
- Eyal Kamhi
- Department of Chemistry and Chemical Biology; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Drughoming Ltd; Rehovot Israel
| | - Eun Ji Joo
- Department of Chemistry and Chemical Biology; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
| | - Jonathan S. Dordick
- Department of Biology; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Department of Biomedical Engineering; Center for Biotechnology & Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
| | - Robert J. Linhardt
- Department of Chemistry and Chemical Biology; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Department of Biology; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
- Department of Biomedical Engineering; Center for Biotechnology & Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180-3590 U.S.A
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18
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Binding activity, structure, and immunogenicity of synthetic peptides derived from Plasmodium falciparum CelTOS and TRSP proteins. Amino Acids 2011; 43:365-78. [PMID: 21952731 DOI: 10.1007/s00726-011-1087-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/30/2011] [Indexed: 01/08/2023]
Abstract
Several sporozoite proteins have been associated with Plasmodium falciparum cell traversal and hepatocyte invasion, including the cell-traversal protein for ookinetes and sporozoites (CelTOS), and thrombospondin-related sporozoite protein (TRSP). CelTOS and TRSP amino acid sequences have been finely mapped to identify regions specifically binding to HeLa and HepG2 cells, respectively. Three high-activity binding peptides (HABPs) were found in CelTOS and one HABP was found in TRSP, all of them having high α-helical structure content. These HABPs' specific binding was sensitive to HeLa and HepG2 cells' pre-treatment with heparinase I and chondroitinase ABC. Despite their similarity at three-dimensional (3D) structural level, TRSP and TRAP HABPs located in the TSR domain did not compete for the same binding sites. CelTOS and TRSP HABPs were used as a template for designing modified sequences to then be assessed in the Aotus monkey experimental model. Antibodies directed against these modified HABPs were able to recognize both the native parasite protein by immunofluorescence assay and the recombinant protein (expressed in Escherichia coli) by Western blot and ELISA assays. The results suggested that these modified HABPs could be promising targets in designing a fully effective, antimalarial vaccine.
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19
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Arévalo-Pinzón G, Curtidor H, Muñoz M, Patarroyo MA, Patarroyo ME. Synthetic peptides from two Pf sporozoite invasion-associated proteins specifically interact with HeLa and HepG2 cells. Peptides 2011; 32:1902-8. [PMID: 21864602 DOI: 10.1016/j.peptides.2011.08.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 08/09/2011] [Accepted: 08/09/2011] [Indexed: 12/17/2022]
Abstract
Two recently described molecules have been associated with sporozoite traversal ability and hepatocyte entry: sporozoite invasion-associated proteins (SIAP)-1 and -2. The HeLa and HepG2 cell binding ability of synthetic peptides spanning the whole SIAP-1 and -2 sequences has been studied in the search for identifying these proteins' functionally active specific regions. Twelve HepG-2 and seventeen HeLa cell high-activity binding peptides (HABPs) have been identified in SIAP-1, 8 of them having high specific binding affinity for both cell lines. Four HepG2 HABPs and two HeLa HABPs have been identified in SIAP-2, one of them interacting with both HeLa and HepG2 cells. SIAP-1 and SIAP-2 HABPs bound specifically and saturably to heparin sulfate and chondroitin sulfate-type membrane receptors on host cells. Circular dichroism assays have shown high α-helix content in SIAP-1 and SIAP-2 HABP secondary structure. Immunofluorescence analysis has revealed that specific peptides against SIAP proteins are highly immunogenic in mice and that anti-SIAP-1 and -2 antibodies recognize the native protein in Plasmodium falciparum sporozoites. Polymorphism studies have shown that a most SIAP-1 and -2 HABPs are conserved among P. falciparum strains. Our results have suggested that SIAP-1 and -2 participate in host-pathogen interactions during cell-traversal and hepatocyte invasion and highlighted the relevance of the ongoing identification and study of potentially new molecules when designing a fully protective antimalarial vaccine.
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20
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Kantele A, Jokiranta TS. Review of cases with the emerging fifth human malaria parasite, Plasmodium knowlesi. Clin Infect Dis 2011; 52:1356-62. [PMID: 21596677 DOI: 10.1093/cid/cir180] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Human malaria has been known to be caused by 4 Plasmodium species, with Plasmodium falciparum causing the most-severe disease. Recently, numerous reports have described human malaria caused by a fifth Plasmodium species, Plasmodium knowlesi, which usually infects macaque monkeys. Hundreds of human cases have been reported from Malaysia, several cases have been reported in other Southeast Asian countries, and a few cases have been reported in travelers visiting these areas. Similarly to P. falciparum, P. knowlesi can cause severe and even fatal cases of disease that are more severe than those caused by the other Plasmodium species. Polymerase chain reaction is of value for diagnosis because P. knowlesi infection is easily misdiagnosed as less dangerous Plasmodium malariae infection with conventional microscopy. P. knowlesi infection should be suspected in patients who are infected with malaria in Southeast Asia. If human-mosquito-human transmission were to occur, the disease could spread to new areas where the mosquito vectors live, such as the popular tourist areas in western India.
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Affiliation(s)
- Anu Kantele
- Division of Infectious Diseases, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland.
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21
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Chattopadhyay R, de la Vega P, Paik SH, Murata Y, Ferguson EW, Richie TL, Ooi GT. Early transcriptional responses of HepG2-A16 liver cells to infection by Plasmodium falciparum sporozoites. J Biol Chem 2011; 286:26396-405. [PMID: 21652718 PMCID: PMC3143603 DOI: 10.1074/jbc.m111.240879] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/01/2011] [Indexed: 11/06/2022] Open
Abstract
Invasion of hepatocytes by Plasmodium sporozoites deposited by Anopheles mosquitoes, and their subsequent transformation into infective merozoites is an obligatory step in the initiation of malaria. Interactions between the sporozoites and hepatocytes lead to a distinct, complex and coordinated cellular and systemic host response. Little is known about host liver cell response to sporozoite invasion, or whether it is primarily adaptive for the parasite, for the host, or for both. Our present study used gene expression profiling of human HepG2-A16 liver cells infected with Plasmodium falciparum sporozoites to understand the host early cellular events and factors influencing parasite infectivity and sporozoite development. Our results show that as early as 30 min following wild-type, non-irradiated sporozoite exposure, the expressions of at least 742 genes was selectively altered. These genes regulate diverse biological functions, such as immune processes, cell adhesion and communications, metabolism pathways, cell cycle regulation, and signal transduction. These functions reflect cellular events consistent with initial host cell defense responses, as well as alterations in host cells to sustain sporozoites growth and survival. Irradiated sporozoites gave very similar gene expression pattern changes, but direct comparative analysis between liver gene expression profiles caused by irradiated and non-irradiated sporozoites identified 29 genes, including glypican-3, that were specifically up-regulated only in irradiated sporozoites. Elucidating the role of this subset of genes may help identify the molecular basis for the irradiated sporozoites inability to develop intrahepatically, and their usefulness as an immunogen for developing protective immunity against pre-erythrocytic stage malaria.
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Affiliation(s)
- Rana Chattopadhyay
- From the Malaria Program, United States Military Malaria Vaccine Program
| | - Patricia de la Vega
- From the Malaria Program, United States Military Malaria Vaccine Program
- Walter Reed Army Institute of Research and
| | - Sun H. Paik
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | - Yoko Murata
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | | | - Thomas L. Richie
- From the Malaria Program, United States Military Malaria Vaccine Program
- the Naval Medical Research Center, Silver Spring, Maryland 20910-7500 and
| | - Guck T. Ooi
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
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Brown A, Higgins MK. Carbohydrate binding molecules in malaria pathology. Curr Opin Struct Biol 2010; 20:560-6. [PMID: 20655195 DOI: 10.1016/j.sbi.2010.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/07/2010] [Accepted: 06/25/2010] [Indexed: 11/27/2022]
Abstract
Interactions between parasite-encoded proteins and host carbohydrate molecules are essential at multiple stages in the life cycle of the malaria-causing parasite, Plasmodium falciparum, and these interactions are targets for the development of therapeutics to treat the disease. Here we review recent structural studies of carbohydrate binding modules that mediate recognition events important for cell invasion and cytoadhesion. In particular we focus on the structures of two molecules; the erythrocyte binding antigen, EBA-175 involved in erythrocyte invasion and the VAR2CSA protein that mediates binding of infected erythrocytes to the placenta. These proteins both use Duffy-binding like (DBL) domains, a Plasmodium specific fold, to bind host carbohydrates, but recent results show that they differ significantly in their architectures and modes of ligand recognition.
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Affiliation(s)
- Alan Brown
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom.
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Amina K, Giuliana G, Prato M. From control to eradication of malaria: the end of being stuck in second gear? ASIAN PAC J TROP MED 2010. [DOI: 10.1016/s1995-7645(10)60101-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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24
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Proteoglycans in host-pathogen interactions: molecular mechanisms and therapeutic implications. Expert Rev Mol Med 2010; 12:e5. [PMID: 20113533 DOI: 10.1017/s1462399409001367] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many microbial pathogens subvert proteoglycans for their adhesion to host tissues, invasion of host cells, infection of neighbouring cells, dissemination into the systemic circulation, and evasion of host defence mechanisms. Where studied, specific virulence factors mediate these proteoglycan-pathogen interactions, which are thus thought to affect the onset, progression and outcome of infection. Proteoglycans are composites of glycosaminoglycan (GAG) chains attached covalently to specific core proteins. Proteoglycans are expressed ubiquitously on the cell surface, in intracellular compartments, and in the extracellular matrix. GAGs mediate the majority of ligand-binding activities of proteoglycans, and many microbial pathogens elaborate cell-surface and secreted factors that interact with GAGs. Some pathogens also modulate the expression and function of proteoglycans through known virulence factors. Several GAG-binding pathogens can no longer attach to and invade host cells whose GAG expression has been reduced by mutagenesis or enzymatic treatment. Furthermore, GAG antagonists have been shown to inhibit microbial attachment and host cell entry in vitro and reduce virulence in vivo. Together, these observations underscore the biological significance of proteoglycan-pathogen interactions in infectious diseases.
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Aquino RS, Lee ES, Park PW. Diverse functions of glycosaminoglycans in infectious diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 93:373-94. [PMID: 20807653 DOI: 10.1016/s1877-1173(10)93016-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Glycosaminoglycans (GAGs) are complex carbohydrates that are expressed ubiquitously and abundantly on the cell surface and in the extracellular matrix (ECM). The extraordinary structural diversity of GAGs enables them to interact with a wide variety of biological molecules. Through these interactions, GAGs modulate various biological processes, such as cell adhesion, proliferation and migration, ECM assembly, tissue repair, coagulation, and immune responses, among many others. Studies during the last several decades have indicated that GAGs also interact with microbial pathogens. GAG-pathogen interactions affect most, if not all, the key steps of microbial pathogenesis, including host cell attachment and invasion, cell-cell transmission, systemic dissemination and infection of secondary organs, and evasion of host defense mechanisms. These observations indicate that GAG-pathogen interactions serve diverse functions that affect the pathogenesis of infectious diseases.
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Affiliation(s)
- Rafael S Aquino
- Children's Hospital, Harvard Medical School, Boston, MA, USA
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Abstract
In this chapter, we outline the tools and techniques available to study the process of host cell invasion by apicomplexan parasites and we provide specific examples of how these methods have been used to further our understanding of apicomplexan invasive mechanisms. Throughout the chapter we focus our discussion on Toxoplasmagondii, because T. gondii is the most experimentally accessible model organism for studying apicomplexan invasion (discussed further in the section, "Toxoplasma as a Model Apicomplexan") and more is known about invasion in T. gondii than in any other apicomplexan.
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HDP-a novel heme detoxification protein from the malaria parasite. PLoS Pathog 2008; 4:e1000053. [PMID: 18437218 PMCID: PMC2291572 DOI: 10.1371/journal.ppat.1000053] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 03/28/2008] [Indexed: 11/19/2022] Open
Abstract
When malaria parasites infect host red blood cells (RBC) and proteolyze hemoglobin, a unique, albeit poorly understood parasite-specific mechanism, detoxifies released heme into hemozoin (Hz). Here, we report the identification and characterization of a novel Plasmodium Heme Detoxification Protein (HDP) that is extremely potent in converting heme into Hz. HDP is functionally conserved across Plasmodium genus and its gene locus could not be disrupted. Once expressed, the parasite utilizes a circuitous "Outbound-Inbound" trafficking route by initially secreting HDP into the cytosol of infected RBC. A subsequent endocytosis of host cytosol (and hemoglobin) delivers HDP to the food vacuole (FV), the site of Hz formation. As Hz formation is critical for survival, involvement of HDP in this process suggests that it could be a malaria drug target.
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28
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Sinnis P, Coppi A, Toida T, Toyoda H, Kinoshita-Toyoda A, Xie J, Kemp MM, Linhardt RJ. Mosquito heparan sulfate and its potential role in malaria infection and transmission. J Biol Chem 2007; 282:25376-84. [PMID: 17597060 PMCID: PMC2121605 DOI: 10.1074/jbc.m704698200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heparan sulfate has been isolated for the first time from the mosquito Anopheles stephensi, a known vector for Plasmodium parasites, the causative agents of malaria. Chondroitin sulfate, but not dermatan sulfate or hyaluronan, was also present in the mosquito. The glycosaminoglycans were isolated, from salivary glands and midguts of the mosquito in quantities sufficient for disaccharide microanalysis. Both of these organs are invaded at different stages of the Plasmodium life cycle. Mosquito heparan sulfate was found to contain the critical trisulfated disaccharide sequence, -->4)beta-D-GlcNS6S(1-->4)-alpha-L-IdoA2S(1-->, that is commonly found in human liver heparan sulfate, which serves as the receptor for apolipoprotein E and is also believed to be responsible for binding to the circumsporozoite protein found on the surface of the Plasmodium sporozoite. The heparan sulfate isolated from the whole mosquito binds to circumsporozoite protein, suggesting a role within the mosquito for infection and transmission of the Plasmodium parasite.
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Affiliation(s)
- Photini Sinnis
- Department of Medical Parasitology, New York University School of Medicine, New York, New York 10010
| | - Alida Coppi
- Department of Medical Parasitology, New York University School of Medicine, New York, New York 10010
| | - Toshihiko Toida
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-33, Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Hidenao Toyoda
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-33, Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Akiko Kinoshita-Toyoda
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-33, Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Jin Xie
- Center for Biocatalysis and Interdisciplinary Studies and Departments of Chemistry, Biology, and Chemical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
| | - Melissa M. Kemp
- Center for Biocatalysis and Interdisciplinary Studies and Departments of Chemistry, Biology, and Chemical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
| | - Robert J. Linhardt
- Center for Biocatalysis and Interdisciplinary Studies and Departments of Chemistry, Biology, and Chemical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
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29
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Garcia JE, Puentes A, Patarroyo ME. Developmental biology of sporozoite-host interactions in Plasmodium falciparum malaria: implications for vaccine design. Clin Microbiol Rev 2006; 19:686-707. [PMID: 17041140 PMCID: PMC1592691 DOI: 10.1128/cmr.00063-05] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum sporozoite infects different types of cells in a mosquito's salivary glands and human epithelial and Kuppfer cells and hepatocytes. These become differentiated later on, transforming themselves into the invasive red blood cell form, the merozoite. The ability of sporozoites to interact with different types of cells requires a wide variety of mechanisms allowing them to survive in both hosts: mobility, receptor-ligand interactions with different cellular receptors, and transformation and development into other invasive parasite forms, which are vitally important for parasite survival. Sporozoite complexity is reflected in the large quantity of proteins that can be expressed. Some of them have been extensively studied, such as CSP, TRAP, STARP, LSA-1, LSA-3, SALSA, SPECT1, SPECT2, MAEBL, and SPATR, due to their importance in infection and their potential use as vaccines. Our work has been focused on the search for the molecular mechanisms of parasite-host cellular receptor-ligand interactions by identifying amino acid sequences and the critical binding residues from these proteins relevant to parasite invasion. Once such sequences have been identified, it will be possible to modify them to induce a strong immune response against P. falciparum in the experimental Aotus monkey model. This all leads towards developing multistage, multicomponent, subunit-based vaccines that will be effective in eradicating or controlling malaria caused by P. falciparum.
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Affiliation(s)
- Javier E Garcia
- Fundacion Instituto de Immunología de Colombia, Carrera 50 #26-00, Bogotá, Colombia
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Warda M, Toida T, Zhang F, Sun P, Munoz E, Xie J, Linhardt RJ. Isolation and characterization of heparan sulfate from various murine tissues. Glycoconj J 2006; 23:555-63. [PMID: 17006646 PMCID: PMC4140570 DOI: 10.1007/s10719-006-7668-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 02/07/2006] [Accepted: 02/08/2006] [Indexed: 11/25/2022]
Abstract
Heparan sulfate (HS), is a proteoglycan (PG) found both in the extracellular matrix and on cell surface. It may represent one of the most biologically important glycoconjugates, playing an essential role in a variety of different events at molecular level. The publication of the mouse genome, and the intensive investigations aimed at understanding the proteome it encodes, has motivated us to initiate studies in mouse glycomics focused on HS. The current study is aimed at determining the quantitative and qualitative organ distribution of HS in mice. HS from brain, eyes, heart, lung, liver, kidney, spleen, intestine and skin was purified from 6-8 week old male and female mice. The recovered yield of HS from these organs is compared with the recovered whole body yield of HS. Structural characterization of the resulting HS relied on disaccharide analysis and (1)H-NMR spectroscopy. Different organs revealed a characteristic HS structure. These data begin to provide a structural understanding of the role of HS in cell-cell interactions, cell signaling and sub-cellular protein trafficking as well as a fundamental understanding of certain aspects of protein-carbohydrate interactions.
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Affiliation(s)
- Mohamad Warda
- Department of Biochemistry- Faculty of Veterinary Medicine, Cairo University
| | | | - Fuming Zhang
- Biotechnology Center and Departments of Chemistry and Chemical Biology, Chemical and Biological Engineering and Biology, Rensselaer Polytechnic Institute
| | - Peilong Sun
- College of Biological and Environmental Engineering, Zhejiang University of Technology
| | - Eva Munoz
- Biotechnology Center and Departments of Chemistry and Chemical Biology, Chemical and Biological Engineering and Biology, Rensselaer Polytechnic Institute
| | - Jin Xie
- Biotechnology Center and Departments of Chemistry and Chemical Biology, Chemical and Biological Engineering and Biology, Rensselaer Polytechnic Institute
| | - Robert J. Linhardt
- Biotechnology Center and Departments of Chemistry and Chemical Biology, Chemical and Biological Engineering and Biology, Rensselaer Polytechnic Institute
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31
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Weedall GD, Preston BMJ, Thomas AW, Sutherland CJ, Conway DJ. Differential evidence of natural selection on two leading sporozoite stage malaria vaccine candidate antigens. Int J Parasitol 2006; 37:77-85. [PMID: 17046771 DOI: 10.1016/j.ijpara.2006.09.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/30/2006] [Accepted: 09/01/2006] [Indexed: 12/01/2022]
Abstract
Experimental malaria vaccines based on two sporozoite stage candidate antigens of Plasmodium falciparum, the circumsporozoite protein (CSP) and thrombospondin-related adhesive protein (TRAP), have undergone clinical trials of efficacy. The relevance of naturally existing polymorphism in these molecules remains unknown. Sequence polymorphism in the genes encoding these antigens was studied in a Gambian population (sample of 48 trap and 44 csp gene sequences) to test for signatures of selection that would result from naturally acquired immunity. Allele frequency distributions were analyzed and compared with data from another population (in Thailand). Patterns of non-synonymous and synonymous polymorphism in P. falciparum and in Plasmodium vivax were compared with divergence from related species. Results indicate that polymorphism in TRAP is under strong selection for amino acid sequence diversity and that allele frequencies are under balancing selection within the Gambian P. falciparum population. There was no such evidence for CSP, calling into question the idea that most polymorphisms in this gene are under immune selection. There was a weak trend for regions known to encode T cell epitopes to have slightly higher indices suggesting balancing selection. Overall, the results predict more allele-specific immunity to TRAP than to CSP and should be considered in design and efficacy testing of vaccine candidates based on these antigens.
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MESH Headings
- Amino Acid Sequence/genetics
- Animals
- Antibody Formation/genetics
- Antibody Formation/immunology
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Child
- Gene Frequency/genetics
- Gene Frequency/immunology
- Genes, Protozoan/genetics
- Genes, Protozoan/immunology
- Humans
- Malaria/genetics
- Malaria/immunology
- Malaria Vaccines/genetics
- Malaria Vaccines/immunology
- Malaria, Falciparum/genetics
- Malaria, Falciparum/immunology
- Malaria, Vivax/genetics
- Malaria, Vivax/immunology
- Plasmodium falciparum/genetics
- Plasmodium falciparum/immunology
- Plasmodium vivax/genetics
- Plasmodium vivax/immunology
- Polymorphism, Genetic/genetics
- Polymorphism, Genetic/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Selection, Genetic
- Species Specificity
- Sporozoites/immunology
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Affiliation(s)
- Gareth D Weedall
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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Tewari R, Rathore D, Crisanti A. Motility and infectivity of Plasmodium berghei sporozoites expressing avian Plasmodium gallinaceum circumsporozoite protein. Cell Microbiol 2006; 7:699-707. [PMID: 15839899 DOI: 10.1111/j.1462-5822.2005.00503.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Avian and rodent malaria sporozoites selectively invade different vertebrate cell types, namely macrophages and hepatocytes, and develop in distantly related vector species. To investigate the role of the circumsporozoite (CS) protein in determining parasite survival in different vector species and vertebrate host cell types, we replaced the endogenous CS protein gene of the rodent malaria parasite Plasmodium berghei with that of the avian parasite P. gallinaceum and control rodent parasite P. yoelii. In anopheline mosquitoes, P. berghei parasites carrying P. gallinaceum and rodent parasite P. yoelii CS protein gene developed into oocysts and sporozoites. Plasmodium gallinaceum CS expressing transgenic sporozoites, although motile, failed to invade mosquito salivary glands and to infect mice, which suggests that motility alone is not sufficient for invasion. Notably, a percentage of infected Anopheles stephensi mosquitoes showed melanotic encapsulation of late stage oocysts. This was not observed in control infections or in A. gambiae infections. These findings shed new light on the role of the CS protein in the interaction of the parasite with both the mosquito vector and the rodent host.
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Affiliation(s)
- Rita Tewari
- Department of Biological Sciences, SAF Building, Imperial College, Imperial College Road, London SW7 2AZ, UK.
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Abstract
Malaria infection is initiated when Plasmodium sporozoites are injected into a host during the bite of an infected mosquito. In the mammal, the sporozoite must rapidly reach an intravacuolar niche within a hepatocyte, where it will generate the parasite stage that invades red blood cells and causes the symptoms of the disease. Herein, we describe our understanding of the way in which sporozoites travel from the site of the mosquito bite to the liver, arrest in the liver, cross the sinusoidal barrier and eventually gain access to hepatocytes. We also highlight some of the recent advances in our understanding of these processes at the molecular level.
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Affiliation(s)
- Patricia Baldacci
- Unité de Biologie et Génétique du Paludisme, Institut Pasteur, Paris, France
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34
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Rathore D, Nagarkatti R, Jani D, Chattopadhyay R, de la Vega P, Kumar S, McCutchan TF. An immunologically cryptic epitope of Plasmodium falciparum circumsporozoite protein facilitates liver cell recognition and induces protective antibodies that block liver cell invasion. J Biol Chem 2005; 280:20524-9. [PMID: 15781464 DOI: 10.1074/jbc.m414254200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Circumsporozoite, a predominant surface protein, is involved in invasion of liver cells by Plasmodium sporozoites, which leads to malaria. We have previously reported that the amino terminus region (amino acids 27-117) of P. falciparum circumsporozoite protein plays a critical role in the invasion of liver cells by the parasite. Here we show that invasion-blocking antibodies are induced by a polypeptide encoding these 91 amino acids, only when it is presented in the absence of the rest of the protein. This suggests that when present in the whole protein, the amino terminus remains immunologically cryptic. A single reactive epitope was identified and mapped to a stretch of 21 amino acids from position 93 to 113. The epitope is configurational in nature, since its recognition was affected by deleting as little as 3 amino acids from either end of the 21-residue peptide. Lysine 104, the only known polymorphic position in the epitope, affected its recognition by the antibodies, and its conversion to leucine in the protein led to a substantial loss of binding activity of the protein to the hepatocytes. This indicated that in the protein, the epitope serves as a binding ligand and facilitates the interaction between sporozoite and hepatic cells. When considered along with the observation that in its native state this motif is immunologically unresponsive, we suggest that hiding functional moieties of the protein from the immune system is an evasion strategy to preserve liver cell binding function and may be of importance in designing anti-sporozoite vaccines.
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Affiliation(s)
- Dharmendar Rathore
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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Abstract
In the year 2003 there was a 17% increase in the number of publications citing work performed using optical biosensor technology compared with the previous year. We collated the 962 total papers for 2003, identified the geographical regions where the work was performed, highlighted the instrument types on which it was carried out, and segregated the papers by biological system. In this overview, we spotlight 13 papers that should be on everyone's 'must read' list for 2003 and provide examples of how to identify and interpret high-quality biosensor data. Although we still find that the literature is replete with poorly performed experiments, over-interpreted results and a general lack of understanding of data analysis, we are optimistic that these shortcomings will be addressed as biosensor technology continues to mature.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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Abstract
Apicomplexan parasites have evolved an efficient mechanism to gain entry into non-phagocytic cells, hence challenging their hosts by the establishment of infection in immuno-privileged tissues. Gliding motility is a prerequisite for the invasive stage of most apicomplexans, allowing them to migrate across tissues, and actively invade and egress host cells. In the late 1960s, detailed morphological studies revealed that motile apicomplexans share an elaborate architecture comprising a subpellicular cytoskeleton and apical organelles. Since 1993, the development of technologies for transient and stable transfection have provided powerful tools with which to identify gene products associated with these structures and organelles, as well as to understand their functions. In combination with access to several parasite genomes, it is now possible to compare and contrast the strategies and molecular machines that have been selectively designed by distinct life stages within a species, or by different apicomplexan species, to optimize infection.
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Affiliation(s)
- Dominique Soldati
- Department of Microbiology and Molecular Medicine, C.M.U. Faculty of Medicine, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland. dominique
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Abstract
Glycosaminoglycans are of critical importance in intercellular communication in organisms. This ubiquitous class of linear polyanions interacts with a wide variety of proteins, including growth factors and chemokines, which regulate important physiological processes. The presence of glycosaminoglycans on cell membranes and in the extracellular matrix also has resulted in their exploitation by infectious pathogens to gain access and entry into animal cells. This Account examines the structural and physical characteristics of these molecules responsible for their interaction with proteins important in cell-cell communication.
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Affiliation(s)
- Robert J Linhardt
- Departments of Chemistry and Chemical Biology, Biology, and Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12210, and Graduate School of Pharmaceutical Sciences, Chiba University, Japan
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