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Oyen D, Torres JL, Aoto PC, Flores-Garcia Y, Binter Š, Pholcharee T, Carroll S, Reponen S, Wash R, Liang Q, Lemiale F, Locke E, Bradley A, King CR, Emerling D, Kellam P, Zavala F, Ward AB, Wilson IA. Structure and mechanism of monoclonal antibody binding to the junctional epitope of Plasmodium falciparum circumsporozoite protein. PLoS Pathog 2020; 16:e1008373. [PMID: 32150583 PMCID: PMC7082059 DOI: 10.1371/journal.ppat.1008373] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 03/19/2020] [Accepted: 01/31/2020] [Indexed: 11/21/2022] Open
Abstract
Lasting protection has long been a goal for malaria vaccines. The major surface antigen on Plasmodium falciparum sporozoites, the circumsporozoite protein (PfCSP), has been an attractive target for vaccine development and most protective antibodies studied to date interact with the central NANP repeat region of PfCSP. However, it remains unclear what structural and functional characteristics correlate with better protection by one antibody over another. Binding to the junctional region between the N-terminal domain and central NANP repeats has been proposed to result in superior protection: this region initiates with the only NPDP sequence followed immediately by NANP. Here, we isolated antibodies in Kymab mice immunized with full-length recombinant PfCSP and two protective antibodies were selected for further study with reactivity against the junctional region. X-ray and EM structures of two monoclonal antibodies, mAb667 and mAb668, shed light on their differential affinity and specificity for the junctional region. Importantly, these antibodies also bind to the NANP repeat region with equal or better affinity. A comparison with an NANP-only binding antibody (mAb317) revealed roughly similar but statistically distinct levels of protection against sporozoite challenge in mouse liver burden models, suggesting that junctional antibody protection might relate to the ability to also cross-react with the NANP repeat region. Our findings indicate that additional efforts are necessary to isolate a true junctional antibody with no or much reduced affinity to the NANP region to elucidate the role of the junctional epitope in protection. The circumsporozoite protein (CSP) of Plasmodium falciparum malaria has been the foundation for the design of transmission blocking malaria vaccines. To date, the most promising CSP-based vaccine candidate is RTS,S, which consists of the central repeating NANP amino-acid sequence and the C-terminal domain of CSP fused to hepatitis B surface antigen that assembles into virus-like particles. Potential shortcomings of RTS,S includes the lack of other potential CSP epitopes such as the junctional epitope, which is located between the N-terminal domain of CSP and the start of the NANP repeat region. Here, we elicited antibodies against full-length CSP and screened for junctional epitope binding. We then used an array of biophysical techniques to elucidate the nature of the binding and tested the level of two protective antibodies in a mouse challenge model. Although the antibodies were able to bind both junctional and NANP epitopes, the in vivo data showed distinct levels of protection between themselves and also to an NANP-only binder. Our data suggest that their protection ability may be related to the strong cross-reactivity with NANP epitopes. Since all reported junctional antibodies to date have dual-specificity, we suggest that a true junctional binder with no or very low NANP affinity, if one can be found, is essential to evaluate the contribution of the junctional epitope to protection.
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Affiliation(s)
- David Oyen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Jonathan L. Torres
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Phillip C. Aoto
- Department of Pharmacology, University of California at San Diego, La Jolla, California, United States of America
| | - Yevel Flores-Garcia
- Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Špela Binter
- Kymab Ltd., The Bennet Building (B930), Babraham Research Campus, Cambridge, United Kingdom
| | - Tossapol Pholcharee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Sean Carroll
- Atreca Inc., South San Francisco, California, United States of America
| | - Sini Reponen
- Atreca Inc., South San Francisco, California, United States of America
| | - Rachael Wash
- Kymab Ltd., The Bennet Building (B930), Babraham Research Campus, Cambridge, United Kingdom
| | - Qi Liang
- Kymab Ltd., The Bennet Building (B930), Babraham Research Campus, Cambridge, United Kingdom
| | - Franck Lemiale
- PATH’s Malaria Vaccine Initiative, PATH Center for Vaccine Innovation and Access, Washington, United States of America
| | - Emily Locke
- PATH’s Malaria Vaccine Initiative, PATH Center for Vaccine Innovation and Access, Washington, United States of America
| | - Allan Bradley
- Kymab Ltd., The Bennet Building (B930), Babraham Research Campus, Cambridge, United Kingdom
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - C. Richter King
- PATH’s Malaria Vaccine Initiative, PATH Center for Vaccine Innovation and Access, Washington, United States of America
| | - Daniel Emerling
- Atreca Inc., South San Francisco, California, United States of America
| | - Paul Kellam
- Kymab Ltd., The Bennet Building (B930), Babraham Research Campus, Cambridge, United Kingdom
- Department of Infectious Diseases, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Fidel Zavala
- Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Andrew B. Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Ian A. Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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2
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Menzel S, Holland T, Boes A, Spiegel H, Fischer R, Buyel JF. Downstream processing of a plant-derived malaria transmission-blocking vaccine candidate. Protein Expr Purif 2018; 152:122-130. [PMID: 30059744 DOI: 10.1016/j.pep.2018.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 03/15/2018] [Accepted: 07/27/2018] [Indexed: 12/22/2022]
Abstract
Plants as a platform for recombinant protein expression are now economically comparable to well-established systems, such as microbes and mammalian cells, thanks to advantages such as scalability and product safety. However, downstream processing accounts for the majority of the final product costs because plant extracts contain large quantities of host cell proteins (HCPs) that must be removed using elaborate purification strategies. Heat precipitation in planta (blanching) can remove ∼80% of HCPs and thus simplify further purification steps, but this is only possible if the target protein is thermostable. Here we describe a combination of blanching and chromatography to purify the thermostable transmission-blocking malaria vaccine candidate FQS, which was transiently expressed in Nicotiana benthamiana leaves. If the blanching temperature exceeded a critical threshold of ∼75 °C, FQS was no longer recognized by the malaria transmission-blocking monoclonal antibody 4B7. A design-of-experiments approach revealed that reducing the blanching temperature from 80 °C to 70 °C restored antibody binding while still precipitating most HCPs. We also found that blanching inhibited the degradation of FQS in plant extracts, probably due to the thermal inactivation of proteases. We screened hydrophobic interaction chromatography materials using miniature columns and a liquid-handling station. Octyl Sepharose achieved the highest FQS purity during the primary capture step and led to a final purity of ∼72% with 60% recovery via step elution. We found that 30-75% FQS was lost during ultrafiltration/diafiltration, giving a final yield of 9 mg kg-1 plant material after purification based on an initial yield of ∼49 mg kg-1 biomass after blanching.
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Affiliation(s)
- Stephan Menzel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Tanja Holland
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany; Eppendorf AG, Bioprocess Center, Rudolf-Schulten-Str. 5, 52428, Juelich, Germany
| | - Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Rainer Fischer
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Johannes Felix Buyel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany; Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
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3
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Oyen D, Torres JL, Cottrell CA, Richter King C, Wilson IA, Ward AB. Cryo-EM structure of P. falciparum circumsporozoite protein with a vaccine-elicited antibody is stabilized by somatically mutated inter-Fab contacts. Sci Adv 2018; 4:eaau8529. [PMID: 30324137 PMCID: PMC6179375 DOI: 10.1126/sciadv.aau8529] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/07/2018] [Indexed: 05/29/2023]
Abstract
The circumsporozoite protein (CSP) on the surface of Plasmodium falciparum sporozoites is important for parasite development, motility, and host hepatocyte invasion. However, intrinsic disorder of the NANP repeat sequence in the central region of CSP has hindered its structural and functional characterization. Here, the cryo-electron microscopy structure at ~3.4-Å resolution of a recombinant shortened CSP construct with the variable domains (Fabs) of a highly protective monoclonal antibody reveals an extended spiral conformation of the central NANP repeat region surrounded by antibodies. This unusual structure appears to be stabilized and/or induced by interaction with an antibody where contacts between adjacent Fabs are somatically mutated and enhance the interaction. This maturation in non-antigen contact residues may be an effective mechanism for antibodies to target tandem repeat sequences and provide novel insights into malaria vaccine design.
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Affiliation(s)
- David Oyen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jonathan L. Torres
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Christopher A. Cottrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - C. Richter King
- PATH’s Malaria Vaccine Initiative, PATH’s Center for Vaccine Innovation and Access, Washington, DC 20001, USA
| | - Ian A. Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Andrew B. Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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4
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Leow CH, Jones M, Cheng Q, Mahler S, McCarthy J. Production and characterization of specific monoclonal antibodies binding the Plasmodium falciparum diagnostic biomarker, histidine-rich protein 2. Malar J 2014; 13:277. [PMID: 25037150 PMCID: PMC4120728 DOI: 10.1186/1475-2875-13-277] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/30/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Early and accurate diagnosis of Plasmodium falciparum infection is important for providing appropriate treatment to patients with malaria. However, technical limitations of currently available diagnostic tests limit their use in control programs. One possible explanation for the vulnerability of current antibodies used in RDTs is their propensity to degrade at high ambient temperatures. Isolation of new antibodies with better thermal stability represents an appealing approach to improve the performance of RDTs. METHODS In this study, phage display technology was deployed to isolate novel binders by screening a human naïve scFv antibody library against recombinant Plasmodium falciparum histidine rich protein 2 (rPfHRP2). The isolated scFv clones were reformatted to whole IgG and the recombinant mAbs were produced in a mammalian CHO cell expression system. To verify the biological activity of these purified recombinant mAbs, range of functional assays were characterized. RESULTS Two unique clones (D2 and F9) were isolated after five rounds of biopanning. The reformatted and expressed antibodies demonstrated high binding specificity to malaria recombinant PfHRP2 and native proteins. When 5 μg/mL of mAbs applied, mAb C1-13 had the highest sensitivity, with an OD value of 1, the detection achieved 5 ng/mL of rPfHRP2, followed by mAbs D2 and F9 at 10 ng/mL and 100 ng/mL of rPfHRP2, respectively. Although the sensitivity of mAbs D2 and F9 was lower than the control, these recombinant human mAbs have shown better stability compared to mouse mAb C1-13 at various temperatures in DSC and blot assays. In view of epitope mapping, the predominant motif of rPfHRP2 recognized by mAb D2 was AHHAADAHHA, whereas mAb F9 was one amino acid shorter, resulting in AHHAADAHH. mAb F9 had the strongest binding affinity to rPfHRP2 protein, with a KD value of 4.27 × 10(-11) M, followed by control mAb C1-13 at 1.03 × 10(-10) M and mAb D2 at 3.05 × 10(-10) M. CONCLUSIONS Overall, the performance of these mAbs showed comparability to currently available PfHRP2-specific mouse mAb C1-13. The stability of these novel binders indicate that they merit further work to evaluate their utility in the development of new generation point of care diagnosis of malaria.
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MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/isolation & purification
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/isolation & purification
- Antibody Specificity
- Antigen-Antibody Reactions
- Antigens, Protozoan/immunology
- CHO Cells
- Cricetinae
- Cricetulus
- Drug Storage
- Early Diagnosis
- Enzyme-Linked Immunosorbent Assay
- Epitopes/immunology
- Escherichia coli
- Humans
- Immunoglobulin Fragments/genetics
- Immunoglobulin Fragments/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/diagnosis
- Malaria, Falciparum/immunology
- Mice
- Peptide Library
- Plasmodium falciparum/immunology
- Protein Stability
- Protozoan Proteins/immunology
- Recombinant Proteins/immunology
- Sensitivity and Specificity
- Single-Chain Antibodies/genetics
- Single-Chain Antibodies/immunology
- Temperature
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Affiliation(s)
- Chiuan Herng Leow
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
- School of Medicine, University of Queensland, Brisbane, Australia
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia
| | - Martina Jones
- Australian Institute for Bioengineering & Nanotechnology (AIBN), University of Queensland, Brisbane, Australia
| | - Qin Cheng
- Drug Resistance and Diagnostics, Australian Army Malaria Institute, Brisbane, Australia
| | - Stephen Mahler
- Australian Institute for Bioengineering & Nanotechnology (AIBN), University of Queensland, Brisbane, Australia
| | - James McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
- School of Medicine, University of Queensland, Brisbane, Australia
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5
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Chen E, Paing MM, Salinas N, Sim BKL, Tolia NH. Structural and functional basis for inhibition of erythrocyte invasion by antibodies that target Plasmodium falciparum EBA-175. PLoS Pathog 2013; 9:e1003390. [PMID: 23717209 PMCID: PMC3662668 DOI: 10.1371/journal.ppat.1003390] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/15/2013] [Indexed: 02/06/2023] Open
Abstract
Disrupting erythrocyte invasion by Plasmodium falciparum is an attractive approach to combat malaria. P. falciparum EBA-175 (PfEBA-175) engages the host receptor Glycophorin A (GpA) during invasion and is a leading vaccine candidate. Antibodies that recognize PfEBA-175 can prevent parasite growth, although not all antibodies are inhibitory. Here, using x-ray crystallography, small-angle x-ray scattering and functional studies, we report the structural basis and mechanism for inhibition by two PfEBA-175 antibodies. Structures of each antibody in complex with the PfEBA-175 receptor binding domain reveal that the most potent inhibitory antibody, R217, engages critical GpA binding residues and the proposed dimer interface of PfEBA-175. A second weakly inhibitory antibody, R218, binds to an asparagine-rich surface loop. We show that the epitopes identified by structural studies are critical for antibody binding. Together, the structural and mapping studies reveal distinct mechanisms of action, with R217 directly preventing receptor binding while R218 allows for receptor binding. Using a direct receptor binding assay we show R217 directly blocks GpA engagement while R218 does not. Our studies elaborate on the complex interaction between PfEBA-175 and GpA and highlight new approaches to targeting the molecular mechanism of P. falciparum invasion of erythrocytes. The results suggest studies aiming to improve the efficacy of blood-stage vaccines, either by selecting single or combining multiple parasite antigens, should assess the antibody response to defined inhibitory epitopes as well as the response to the whole protein antigen. Finally, this work demonstrates the importance of identifying inhibitory-epitopes and avoiding decoy-epitopes in antibody-based therapies, vaccines and diagnostics. Malaria is a devastating parasitic disease that kills one million people annually. The parasites invade and multiply within red blood cells, leading to the clinical symptoms of malaria. Therefore, preventing red blood cell, entry through vaccines is an attractive approach to controlling the disease. Although widespread efforts to develop a vaccine by identifying and combining critical parasite blood-stage proteins are underway, a protective vaccine for malaria has proved challenging. This is in part because, while parasite proteins have the ability to elicit antibodies that prevent red blood cell invasion, these antibodies are a small proportion compared to the total collection of ineffective antibodies produced. We show an antibody that prevents red blood cell invasion targets regions of the critical parasite protein PfEBA-175 required for red blood cell engagement. We also show that an antibody that does not prevent red blood cell invasion recognizes a region far removed from important functional segments of PfEBA-175. Our work demonstrates that identifying the regions targeted by antibodies, and the mechanisms by which antibodies that prevent invasion function, should drive future vaccine development and studies measuring the effectiveness of current vaccine combinations.
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Affiliation(s)
- Edwin Chen
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - May M. Paing
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Nichole Salinas
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - B. Kim Lee Sim
- Protein Potential, Rockville, Maryland, United States of America
| | - Niraj H. Tolia
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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6
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Vuchelen A, Pardon E, Steyaert J, Gamain B, Loris R, van Nuland NAJ, Ramboarina S. Production, crystallization and X-ray diffraction analysis of two nanobodies against the Duffy binding-like (DBL) domain DBL6ℇ-FCR3 of the Plasmodium falciparum VAR2CSA protein. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:270-4. [PMID: 23519802 PMCID: PMC3606572 DOI: 10.1107/s1744309113001917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/18/2013] [Indexed: 05/14/2024]
Abstract
The VAR2CSA protein has been closely associated with pregnancy-associated malaria and is recognized as the main adhesin exposed on the surface of Plasmodium falciparum-infected erythrocytes. Chondroitin sulfate A was identified as the main host receptor in the placenta. Single-domain heavy-chain camelid antibodies, more commonly called nanobodies, were selected and produced against the DBL6ℇ-FCR3 domain of VAR2CSA. Crystals of two specific nanobodies, Nb2907 and Nb2919, identified as strong binders to DBL6ℇ-FCR3 and the full-length VAR2CSA exposed on the surface of FCR3 P. falciparum-infected erythrocytes, were obtained. Crystals of Nb2907 diffract to 2.45 Å resolution and belong to space group C2 with unit-cell parameters a=136.1, b=78.5, c=103.4 Å, β=118.8°, whereas Nb2919 crystals diffract to 2.15 Å resolution and belong to space group P4₃2₁2 with unit-cell parameters a=b=62.7, c=167.2 Å.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/genetics
- Antibodies, Protozoan/isolation & purification
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Binding Sites
- Camelids, New World/immunology
- Crystallography, X-Ray
- Erythrocytes/parasitology
- Escherichia coli/chemistry
- Escherichia coli/genetics
- Models, Molecular
- Molecular Sequence Data
- Plasmodium falciparum/chemistry
- Plasmodium falciparum/metabolism
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Sequence Alignment
- Sequence Homology, Amino Acid
- Single-Domain Antibodies/chemistry
- Single-Domain Antibodies/genetics
- Single-Domain Antibodies/isolation & purification
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Affiliation(s)
- Anneleen Vuchelen
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Els Pardon
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Benoît Gamain
- Inserm, UMRS665, F-75015 Paris, France
- Université Paris Diderot, F-75013 Paris, France
- Institut National de la Transfusion Sanguine, F-75015 Paris, France
- Laboratoire d’Excellence Gr-Ex, France
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Nico A. J. van Nuland
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Stéphanie Ramboarina
- Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
- Molecular Recognition Unit (MoRe), Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussels, Belgium
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7
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Pizarro JC, Boulot G, Bentley GA, Gómez KA, Hoebeke J, Hontebeyrie M, Levin MJ, Smulski CR. Crystal structure of the complex mAb 17.2 and the C-terminal region of Trypanosoma cruzi P2β protein: implications in cross-reactivity. PLoS Negl Trop Dis 2011; 5:e1375. [PMID: 22069505 PMCID: PMC3206007 DOI: 10.1371/journal.pntd.0001375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 09/11/2011] [Indexed: 01/07/2023] Open
Abstract
Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxyl-terminal end of the ribosomal P2ß protein of Trypanosoma cruzi (TcP2ß). These antibodies, as well as the murine monoclonal antibody (mAb) 17.2, recognize the last 13 amino acids of TcP2ß (called the R13 epitope: EEEDDDMGFGLFD) and are able to cross-react with, and stimulate, the ß1 adrenergic receptor (ß1-AR). Indeed, the mAb 17.2 was able to specifically detect human β1-AR, stably transfected into HEK cells, by flow cytometry and to induce repolarisation abnormalities and first degree atrioventricular conduction block after passive transfer to naïve mice. To study the structural basis of this cross-reactivity, we determined the crystal structure of the Fab region of the mAb 17.2 alone at 2.31 Å resolution and in complex with the R13 peptide at 1.89 Å resolution. We identified as key contact residues on R13 peptide Glu3, Asp6 and Phe9 as was previously shown by alanine scanning. Additionally, we generated a model of human β1-AR to elucidate the interaction with anti-R13 antibodies. These data provide an understanding of the molecular basis of cross-reactive antibodies induced by chronic infection with Trypanosoma cruzi.
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MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/metabolism
- Cross Reactions
- Crystallography, X-Ray
- Female
- Humans
- Immunoglobulin Fab Fragments/chemistry
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Fab Fragments/metabolism
- Mice
- Mice, Inbred BALB C
- Models, Molecular
- Phosphoproteins/chemistry
- Phosphoproteins/immunology
- Phosphoproteins/metabolism
- Protein Binding
- Protein Structure, Quaternary
- Receptors, Adrenergic, beta-1/immunology
- Receptors, Adrenergic, beta-1/metabolism
- Ribosomal Proteins/chemistry
- Ribosomal Proteins/immunology
- Ribosomal Proteins/metabolism
- Trypanosoma cruzi/chemistry
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Affiliation(s)
- Juan Carlos Pizarro
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Ginette Boulot
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Graham A. Bentley
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Karina A. Gómez
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
| | | | | | - Mariano J. Levin
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
| | - Cristian R. Smulski
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
- UPR9021 du CNRS, Strasbourg, France
- * E-mail:
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8
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Stewart L, Gosling R, Griffin J, Gesase S, Campo J, Hashim R, Masika P, Mosha J, Bousema T, Shekalaghe S, Cook J, Corran P, Ghani A, Riley EM, Drakeley C. Rapid assessment of malaria transmission using age-specific sero-conversion rates. PLoS One 2009; 4:e6083. [PMID: 19562032 PMCID: PMC2698122 DOI: 10.1371/journal.pone.0006083] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 05/29/2009] [Indexed: 11/18/2022] Open
Abstract
Background Malaria transmission intensity is a crucial determinant of malarial disease burden and its measurement can help to define health priorities. Rapid, local estimates of transmission are required to focus resources better but current entomological and parasitological methods for estimating transmission intensity are limited in this respect. An alternative is determination of antimalarial antibody age-specific sero-prevalence to estimate sero-conversion rates (SCR), which have been shown to correlate with transmission intensity. This study evaluated SCR generated from samples collected from health facility attendees as a tool for a rapid assessment of malaria transmission intensity. Methodology and Principal Findings The study was conducted in north east Tanzania. Antibodies to Plasmodium falciparum merozoite antigens MSP-119 and AMA-1 were measured by indirect ELISA. Age-specific antibody prevalence was analysed using a catalytic conversion model based on maximum likelihood to generate SCR. A pilot study, conducted near Moshi, found SCRs for AMA-1 were highly comparable between samples collected from individuals in a conventional cross-sectional survey and those collected from attendees at a local health facility. For the main study, 3885 individuals attending village health facilities in Korogwe and Same districts were recruited. Both malaria parasite prevalence and sero-positivity were higher in Korogwe than in Same. MSP-119 and AMA-1 SCR rates for Korogwe villages ranged from 0.03 to 0.06 and 0.07 to 0.21 respectively. In Same district there was evidence of a recent reduction in transmission, with SCR among those born since 1998 [MSP-119 0.002 to 0.008 and AMA-1 0.005 to 0.014 ] being 5 to 10 fold lower than among individuals born prior to 1998 [MSP-119 0.02 to 0.04 and AMA-1 0.04 to 0.13]. Current health facility specific estimates of SCR showed good correlations with malaria incidence rates in infants in a contemporaneous clinical trial (MSP-119 r2 = 0.78, p<0.01 & AMA-1 r2 = 0.91, p<0.001). Conclusions SCRs generated from age-specific anti-malarial antibody prevalence data collected via health facility surveys were robust and credible. Analysis of SCR allowed detection of a recent drop in malaria transmission in line with recent data from other areas in the region. This health facility-based approach represents a potential tool for rapid assessment of recent trends in malaria transmission intensity, generating valuable data for local and national malaria control programs to target, monitor and evaluate their control strategies.
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Affiliation(s)
- Laveta Stewart
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Joint Malaria Programme, Moshi, Tanzania
| | - Roly Gosling
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- KILI-IPTi Project, JMP, Korogwe, Tanzania
| | - Jamie Griffin
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | | | - Joseph Campo
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Joint Malaria Programme, Moshi, Tanzania
| | | | | | | | - Teun Bousema
- Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Seif Shekalaghe
- Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Jackie Cook
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Patrick Corran
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Biotherapeutics Group, NIBSC, South Mimms, Herts, United Kingdom
| | - Azra Ghani
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Eleanor M. Riley
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Joint Malaria Programme, Moshi, Tanzania
- * E-mail:
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9
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Henderson KA, Streltsov VA, Coley AM, Dolezal O, Hudson PJ, Batchelor AH, Gupta A, Bai T, Murphy VJ, Anders RF, Foley M, Nuttall SD. Structure of an IgNAR-AMA1 complex: targeting a conserved hydrophobic cleft broadens malarial strain recognition. Structure 2008; 15:1452-66. [PMID: 17997971 DOI: 10.1016/j.str.2007.09.011] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 08/13/2007] [Accepted: 09/10/2007] [Indexed: 11/18/2022]
Abstract
Apical membrane antigen 1 (AMA1) is essential for invasion of erythrocytes and hepatocytes by Plasmodium parasites and is a leading malarial vaccine candidate. Although conventional antibodies to AMA1 can prevent such invasion, extensive polymorphisms within surface-exposed loops may limit the ability of these AMA1-induced antibodies to protect against all parasite genotypes. Using an AMA1-specific IgNAR single-variable-domain antibody, we performed targeted mutagenesis and selection against AMA1 from three P. falciparum strains. We present cocrystal structures of two antibody-AMA1 complexes which reveal extended IgNAR CDR3 loops penetrating deep into a hydrophobic cleft on the antigen surface and contacting residues conserved across parasite species. Comparison of a series of affinity-enhancing mutations allowed dissection of their relative contributions to binding kinetics and correlation with inhibition of erythrocyte invasion. These findings provide insights into mechanisms of single-domain antibody binding, and may enable design of reagents targeting otherwise cryptic epitopes in pathogen antigens.
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Affiliation(s)
- Kylie A Henderson
- CSIRO Molecular and Health Technologies, 343 Royal Parade, Parkville 3052, Australia
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10
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Gonzalez VDG, Gugliotta LM, Giacomelli CE, Meira GR. Latex of immunodiagnosis for detecting the Chagas disease: II. Chemical coupling of antigen Ag36 onto carboxylated latexes. J Mater Sci Mater Med 2008; 19:789-95. [PMID: 17665133 DOI: 10.1007/s10856-006-0041-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 11/06/2006] [Indexed: 05/16/2023]
Abstract
A novel immunodiagnosis reagent for detecting the Chagas Disease was developed, by chemical coupling of antigen Ag36 of Trypanosoma cruzi onto two (carboxylated and core-shell) latexes. The coupling reactions involved the use of a carbodiimide intermediate. Bovine serum albumin (BSA) was used as a model protein for determining the appropriate conditions for its physical and chemical coupling. BSA showed an increased adsorption onto the base carboxylated latexes, with respect to a PS latex without carboxyl groups. The chemical bonding experiments only involved the carboxylated latexes. With BSA, the final density of covalently bound protein was 2.30 mg/m(2). In addition, around 55% of the total linked protein was chemically coupled, and the reaction was little affected by the pH. With Ag36, the final density of covalently bound protein was 2.44 mg/m(2), around 80% of the total linked protein was chemically coupled, and the chemical coupling was maximum at pH = 5 (i.e., close to the isoelectric point).
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Affiliation(s)
- Verónica D G Gonzalez
- INTEC (Universidad Nacional del Litoral and CONICET), Güemes 3450, Santa Fe, Argentina.
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11
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Sharma B. Structure and mechanism of a transmission blocking vaccine candidate protein Pfs25 from P. falciparum: a molecular modeling and docking study. In Silico Biol 2008; 8:193-206. [PMID: 19032156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Malaria is caused by the protozoan Plasmodium. The parasite Plasmodium completes its life cycle inside two hosts, i. e. human and mosquito. Among all known Plasmodium species, Plasmodium falciparum is known to cause maximum mortality. Various studies done on the mosquito stages of the parasite suggest that the proteins present on the parasite's surface are responsible for its survival under the adverse conditions prevailing in the mosquito midgut. When human blood containing Plasmodium gametocytes enters the mosquito gut, the gametocytes form gametes which then fuse to form zygotes. At this stage two closely related proteins, Pfs25 and Pfs28 are expressed on the surface of the parasite which continue to express up to the young oocyst stage. These proteins present on zygotes, ookinetes and young oocysts of Plasmodium are categorized in P25 and P28 families and are well known malaria vaccine candidate proteins. In this study, we have done sequence analysis, homology modeling and docking studies of a typical member of the P25 family of ookinete surface protein, i.e. Pfs25 from Plasmodium falciparum. We have built a 3D model of Pfs25 based on the X-ray crystallographic structure of Pvs25 from Plasmodium vivax. Also we have modeled the Fv region of the malaria transmission blocking monoclonal antibody 4B7. This antibody is the transmission blocking monoclonal antibody for Pfs25 protein. Pfs25 and 4B7 scFv (single chain variable fragment only) docking results indicate that EGF domain III of the Pfs25 protein interacts with the scFv region of modeled 4B7 antibody forming seven hydrogen bonds out of which six are formed with heavy chain of scFv region. Docking results of Pfs25 with gamma chain of laminin also suggest a possible role of Pfs25 protein in host parasite interaction.
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Affiliation(s)
- Babita Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
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12
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Kim SH, Lee YS, Hwang SY, Bae GW, Nho K, Kang SW, Kwak YG, Moon CS, Han YS, Kim TY, Kho WG. Effects of PEGylated scFv antibodies against Plasmodium vivax duffy binding protein on the biological activity and stability in vitro. J Microbiol Biotechnol 2007; 17:1670-1674. [PMID: 18156783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Duffy binding protein (DBP) plays a critical role in Plasmodium vivax invasion of human red blood cells. We previously reported a single-chain antibody fragment (scFv) that was specific to P. vivax DBP (PvDBP). However, the stabilization and the half-life of scFvs have not been studied. Here, we investigated the effect of PEGylated scFvs on their biological activity and stability in vitro. SDS-PAGE analysis showed that three clones (SFDBII-12, -58, and -92) were formed as dimers (about 70 kDa) with PEGylation. Clone SFDBII-58 gave the highest yield of PEGylated scFv. Binding analysis using BIAcore between DBP and scFv showed that both SFDBII-12 and -58 were decreased approximately by two folds at the level of binding affinity to DBP after PEGylation. However, the SFDBII-92 clone still showed a relatively high level of binding affinity (KD=1.02 x 10(-7) M). Binding inhibition assay showed that PEGylated scFv was still able to competitively bind the PvDBP and play a critical role in inhibiting the interactions between PvDBP protein expressed on the surface of Cos-7 cells and Duffy receptor on the surface of erythrocytes. When both scFvs and their PEGylated counterparts were exposed to trypsin, scFv was completely degraded only after 24 h, whereas 35% of PEGylated scFvs remained intact, maintaining their stability against the proteolytic attack of trypsin until 72 h. Taken together, these results suggest that the PEGylated scFvs retain their stability against proteolytic enzymes in vivo, with no significant loss in their binding affinity to target antigen, DBP.
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Affiliation(s)
- So-Hee Kim
- Department of Malariology, Paik Institute for Clinical Research, Inje University College of Medicine, Busan, Korea
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13
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Voigt J, Woestemeyer J, Frank R. The chaotrope-soluble glycoprotein GP2 is a precursor of the insoluble glycoprotein framework of the Chlamydomonas cell wall. J Biol Chem 2007; 282:30381-92. [PMID: 17673458 DOI: 10.1074/jbc.m701673200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The cell wall of the unicellular green alga Chlamydomonas reinhardtii consists of an insoluble, hydroxyproline-rich glycoprotein framework and several chaotrope-soluble, hydroxyproline-containing glycoproteins. Up to now, there have been no data concerning the amino acid sequences of the hydroxyproline-containing polypeptides of the insoluble wall fraction. Matrix-assisted laser desorption ionization time-of-flight analyses of peptides released from the insoluble cell wall fraction by trypsin treatment revealed the presence of 14 peptide fragments that could be attributed to non-glycosylated domains of the chaotrope-soluble cell wall glycoprotein GP2. However, these peptides cover only 15% of the GP2 polypeptide backbone. Considerably more information concerning the presence of GP2 in the insoluble cell wall fraction was obtained by an immunochemical approach. For this purpose, 407 overlapping pentadecapeptides covering the whole known amino acid sequence of GP2 were chemically synthesized and probed with a polyclonal antibody raised against the deglycosylated, insoluble cell wall fraction. This particular antibody reacted with 297 of the 407 GP2-derived peptides. The peptides that were recognized by this antibody are distributed over the whole known GP2 sequence. The epitopes recognized by polyclonal antibodies raised against the 64- and 45-kDa constituents purified from the deglycosylation products of the insoluble cell wall fraction are also distributed over the whole GP2 backbone, although the corresponding antigens are considerably smaller than GP2. The significance of the latter results for the structure of the insoluble cell wall fraction is discussed.
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Affiliation(s)
- Jürgen Voigt
- Institute for Biochemistry, University of Leipzig, Johannisallee 30, D-04103 Leipzig, Germany.
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14
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Villard V, Agak GW, Frank G, Jafarshad A, Servis C, Nébié I, Sirima SB, Felger I, Arevalo-Herrera M, Herrera S, Heitz F, Bäcker V, Druilhe P, Kajava AV, Corradin G. Rapid identification of malaria vaccine candidates based on alpha-helical coiled coil protein motif. PLoS One 2007; 2:e645. [PMID: 17653272 PMCID: PMC1920550 DOI: 10.1371/journal.pone.0000645] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 06/15/2007] [Indexed: 11/18/2022] Open
Abstract
To identify malaria antigens for vaccine development, we selected alpha-helical coiled coil domains of proteins predicted to be present in the parasite erythrocytic stage. The corresponding synthetic peptides are expected to mimic structurally "native" epitopes. Indeed the 95 chemically synthesized peptides were all specifically recognized by human immune sera, though at various prevalence. Peptide specific antibodies were obtained both by affinity-purification from malaria immune sera and by immunization of mice. These antibodies did not show significant cross reactions, i.e., they were specific for the original peptide, reacted with native parasite proteins in infected erythrocytes and several were active in inhibiting in vitro parasite growth. Circular dichroism studies indicated that the selected peptides assumed partial or high alpha-helical content. Thus, we demonstrate that the bioinformatics/chemical synthesis approach described here can lead to the rapid identification of molecules which target biologically active antibodies, thus identifying suitable vaccine candidates. This strategy can be, in principle, extended to vaccine discovery in a wide range of other pathogens.
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Affiliation(s)
- Viviane Villard
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - George W. Agak
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Géraldine Frank
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | | | - Catherine Servis
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Issa Nébié
- Centre National de Recherche et Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Sodiomon B. Sirima
- Centre National de Recherche et Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | | | | | - Frederic Heitz
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | - Volker Bäcker
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | | | | | - Giampietro Corradin
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
- * To whom correspondence should be addressed. E-mail:
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15
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Autore F, Melchiorre S, Kleinjung J, Morgan WD, Fraternali F. Interaction of malaria parasite-inhibitory antibodies with the merozoite surface protein MSP1(19) by computational docking. Proteins 2007; 66:513-27. [PMID: 17173281 DOI: 10.1002/prot.21212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Merozoite surface protein 1 (MSP1) of the malaria parasite Plasmodium falciparum is an important vaccine candidate antigen. Antibodies specific for the C-terminal maturation product, MSP1(19), have been shown to inhibit erythrocyte invasion and parasite growth. Specific monoclonal antibodies react with conformational epitopes contained within the two EGF-like domains that constitute the antigen MSP1(19). To gain greater insight into the inhibitory process, the authors selected two strongly inhibitory antibodies (designated 12.8 and 12.10) and modeled their structures by homology. Computational docking was used to generate antigen-antibody complexes and a selection filter based on NMR data was applied to obtain plausible models. Molecular Dynamics simulations of the selected complexes were performed to evaluate the role of specific side chains in the binding. Favorable complexes were obtained that complement the NMR data in defining specific binding sites. These models can provide valuable guidelines for future experimental work that is devoted to the understanding of the action mechanism of invasion-inhibitory antibodies.
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Affiliation(s)
- Flavia Autore
- Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, Complesso Universitario Monte Sant'Angelo, via Cinthia, 80126, Naples, Italy
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16
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Chang CD, Cheng KY, Jiang LX, Salbilla VA, Haller AS, Yem AW, Bryant JD, Kirchhoff LV, Leiby DA, Schochetman G, Shah DO. Evaluation of a prototype Trypanosoma cruzi antibody assay with recombinant antigens on a fully automated chemiluminescence analyzer for blood donor screening. Transfusion 2006; 46:1737-44. [PMID: 17002630 DOI: 10.1111/j.1537-2995.2006.00965.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Chagas disease is caused by Trypanosoma cruzi, a protozoan parasite that can be transmitted by transfusion. The diagnosis of chronic T. cruzi infection is generally made by detecting specific antibodies that bind to parasite antigens. The aim of this study was to assess the sensitivity and specificity of a new serologic assay for antibodies to T. cruzi on a fully automated analyzer (PRISM, Abbott Laboratories). STUDY DESIGN AND METHODS A prototype chemiluminescent immunoassay based on chimeric recombinant antigens and run on the automated PRISM system was developed for detecting antibodies to T. cruzi in human serum and plasma. Assay specificity was evaluated by testing samples from random blood donors and from a diverse group of specimens from persons with diseases or conditions often associated with false-positive reactions in T. cruzi assays. Sensitivity was determined by testing 377 geographically diverse T. cruzi antibody-positive specimens. RESULTS Six of 7911 samples (0.08%) from random donors were repeatedly reactive in the prototype PRISM Chagas assay. One of these was reactive in three other tests, including the radioimmune precipitation assay and was presumed to be a true positive. Hence, the specificity was 99.94 percent (7905/7910) in the negative donor group studied. All 377 T. cruzi antibody-positive specimens were positive in the prototype assay and thus the sensitivity was 100 percent. CONCLUSION The results obtained to date, in terms of sensitivity as well as specificity, strongly suggest that the PRISM Chagas assay should function well as a tool for screening blood for serologic evidence of T. cruzi infection.
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Affiliation(s)
- Chi-Deu Chang
- Emerging Pathogens R&D, Abbott Diagnostics Division, Abbott Laboratories, Abbott Park, Illinois 60064, USA
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17
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Abstract
The restructuring of chromatin precedes tightly regulated events such as DNA transcription, replication, and repair. One type of chromatin remodeling involves the covalent modification of nucleosomes by histone acetyltransferase (HAT) complexes. The observation that apicidin exerts antiprotozoal activity by targeting a histone deacetyltransferase has prompted our search for more components of the histone modifying machinery in parasitic protozoa. We have previously identified GNAT family HATs in the opportunistic pathogen Toxoplasma gondii and now describe the first MYST (named for members MOZ, Ybf2/Sas3, Sas2, and Tip60) family HATs in apicomplexa (TgMYST-A and -B). The TgMYST-A genomic locus is singular and generates a approximately 3.5-kb transcript that can encode two proteins of 411 or 471 amino acids. TgMYST-B mRNA is approximately 7.0 kb and encodes a second MYST homologue. In addition to the canonical MYST HAT catalytic domain, both TgMYST-A and -B possess an atypical C2HC zinc finger and a chromodomain. Recombinant TgMYST-A exhibits a predilection to acetylate histone H4 in vitro at lysines 5, 8, 12, and 16. Antibody generated to TgMYST-A reveals that both the long and short (predominant) versions are present in the nucleus and are also plentiful in the cytoplasm. Moreover, both TgMYST-A forms are far more abundant in rapidly replicating parasites (tachyzoites) than encysted parasites (bradyzoites). A bioinformatics survey of the Toxoplasma genome reveals numerous homologues known to operate in native MYST complexes. The characterization of TgMYST HATs represents another important step toward understanding the regulation of gene expression in pathogenic protozoa and provides evolutionary insight into how these processes operate in eukaryotic cells in general.
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Affiliation(s)
- Aaron T Smith
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Medical Sciences Building Room A-525, Indianapolis, IN 46202-5120, USA
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18
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Taguchi T, Arakaki A, Takeyama H, Haraguchi S, Yoshino M, Kaneko M, Ishimori Y, Matsunaga T. Detection ofCryptosporidium parvum oocysts using a microfluidic device equipped with the SUS micromesh and FITC-labeled antibody. Biotechnol Bioeng 2006; 96:272-80. [PMID: 16917954 DOI: 10.1002/bit.21104] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Development of a microfluidic device equipped with micromesh for detection of Cryptosporidium parvum oocyst was reported. A micromesh consisting of 10 x 10 cavities was microfabricated on the stainless steel plate by laser ablation. Each cavity size, approximately 2.7 microm in diameter, was adopted to capture a single C. parvum oocyst. Under negative pressure operation, suspensions containing microbeads or C. parvum oocysts flowed into the microchannel. Due to strong non-specific adsorption of microbeads onto the PDMS microchannel surface during sample injection, the surface was treated with air plasma, followed by treatment with 1% sodium dodecyl sulfate (SDS) solution. This process reduced the non-specific adsorption of microbeads on the microchannel to 10% or less in comparison to a non-treated microchannel. This microfluidic device equipped with the SUS micromesh was further applied for the capture of C. parvum oocysts. Trapped C. parvum oocysts were visualized by staining with FITC-labeled anti-C. parvum oocyst antibody on a micromesh and counted under fluoroscopic observation. The result obtained by our method was consistent with that obtained by direct immunofluorescence assay coupled with immunomagnetic separation (DFA-IMS) method, indicating that the SUS micromesh is useful for counting of C. parvum oocysts. The newly designed microfluidic device exploits a geometry that allowed for the entrapment of oocysts on the micromesh while providing the rapid introduction of a series of reagents and washes through the microfluidic structure. Our data indicate that this microfluidic device is useful for high-throughput counting of C. parvum oocysts from tap water sample.
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Affiliation(s)
- Tomoyuki Taguchi
- Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
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19
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Jouin H, Garraud O, Longacre S, Baleux F, Mercereau-Puijalon O, Milon G. Human antibodies to the polymorphic block 2 domain of the Plasmodium falciparum merozoite surface protein 1 (MSP-1) exhibit a highly skewed, peptide-specific light chain distribution. Immunol Cell Biol 2005; 83:392-5. [PMID: 16033534 DOI: 10.1111/j.1440-1711.2005.01343.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antibodies to polymorphic block 2 of the Plasmodium falciparum merozoite surface protein 1 (MSP-1) present a paradoxical association with acquired protection against clinical malaria, while showing restricted and fixed specificity, reminiscent of antigenic sin. We report here that these antibodies present a highly imbalanced, peptide-specific light chain distribution. This was not observed with several other parasite-derived peptides or antigens. These data point to a skewed immune response to MSP-1 block 2 that is constrained both in specificity and chain usage. This is the first report of a biased response to polymorphic epitopes of a surface antigen in malaria parasites.
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Affiliation(s)
- Hélène Jouin
- Parasite Molecular Immunology Unit, CNRS URA 2581, Pasteur Institute, Paris, France.
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20
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Morgan WD, Frenkiel TA, Lock MJ, Grainger M, Holder AA. Precise epitope mapping of malaria parasite inhibitory antibodies by TROSY NMR cross-saturation. Biochemistry 2005; 44:518-23. [PMID: 15641776 DOI: 10.1021/bi0482957] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have applied NMR cross-saturation with TROSY detection to the problem of precisely mapping conformational epitopes on complete protein antigen molecules. We have investigated complexes of the Fab fragments of two antibodies that have parasite inhibitory activity, bound to the important malaria vaccine candidate antigen, Plasmodium falciparum MSP1(19). The results indicate remarkable overlap between these epitopes for inhibitory antibodies, and will provide a basis for theoretical modeling of the antibody-antigen interface.
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Affiliation(s)
- William D Morgan
- Division of Parasitology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.
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21
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Itabashi T, Terasaki T, Asai H. Novel nuclear and cytoplasmic proteins detected by anti-Zoothamnium arbuscula (Protozoa) spasmin 1 antibody in mammalian cells are dependent on the cell cycle. J Biochem 2005; 136:651-7. [PMID: 15632305 DOI: 10.1093/jb/mvh173] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spasmin is a calcium-binding protein that is the major component of calcium-induced contractile filaments, called spasmoneme, found in vorticellid ciliates. Such filaments have not been observed in any organisms other than green algae. To determine whether calcium-induced contractile filaments resembling spasmoneme are present in higher eukaryotes, we performed immunofluorescence imaging of an anti-Zoothamnium arbuscula (protozoa, ciliophora) spasmin 1 polyclonal antibody in HeLa cells. In the cytoplasm, ubiquitous antigens seemed to be co-localized with microtubules at interphase, but not throughout mitosis. In the nucleus, areas linked to the nuclear envelope contained a number of hot spots. These regions were unclear during condensation of the replicated chromosomes, but became clearly visible again at cytokinesis. Immunoblotting analysis identified localized antigens during different phases of the cell cycle, including a 68/71 kDa cytoplasmic protein and a 55 kDa nuclear protein in interphase, and a 55/70 kDa protein in mitosis. The anti-spasmin 1 antibody recognized antigens in both hamster kidney BHK21 cells and Human lung cancer A-549 cells. These results suggest that novel spasmin-like proteins could be common in mammalian cells.
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Affiliation(s)
- Takeshi Itabashi
- Major in Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, Tokyo, 169-8555, Japan.
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22
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Abstract
BACKGROUND Microsporidia are obligate intracellular protozoan parasites that emerged as major opportunistic pathogens in humans since the onset of the AIDS pandemic. In the present study, we investigated whether FCM is a useful method for the quantitation of intracellular microsporidian spores in cultured cells. METHODS Microsporidia (Encephalitozoon cuniculi) were grown in cell cultures and various cell-lines were coincubated with microsporidian spores at different multiplicities of infection, as well as for different periods of time. After permeabilization of the cells, intracellular spores were stained with a polyclonal anti-E. cuniculi serum and a FITC-labeled secondary antibody. Stained cells were analyzed on a flow cytometer and results were compared with those of fluorescence microscopy. RESULTS Noninfected cells showed a lower fluorescence, while the relative fluorescence observed for infected cells was significantly higher. The cell population with the more intense fluorescence, representing cells with internalized microsporidian spores, increased with the multiplicity of infection as well as over time. Results of FCM and fluorescence microscopy were in excellent agreement for all experiments. CONCLUSIONS We have developed a flow cytometric assay to detect and quantify cells with intracellular microsporidian spores. This method is easy to use, highly reproducible, and should be useful for future research.
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Affiliation(s)
- Caspar Franzen
- Department of Internal Medicine I, University of Regensburg, Regensburg, Germany.
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23
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Saxena AK, Singh K, Long CA, Garboczi DN. Preparation, crystallization and preliminary X-ray analysis of a complex between the Plasmodium vivax sexual stage 25 kDa protein Pvs25 and a malaria transmission-blocking antibody Fab fragment. Acta Crystallogr D Biol Crystallogr 2004; 60:2054-7. [PMID: 15502325 DOI: 10.1107/s0907444904021584] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 09/01/2004] [Indexed: 11/10/2022]
Abstract
The Plasmodium vivax sexual stage 25 kDa protein Pvs25, located on the surface of the ookinete form of the parasite, is a vaccine candidate designed to elicit immunity that blocks the transmission of malaria by mosquitoes. The 2A8 murine monoclonal antibody directed against recombinant Pvs25 prevents the formation of P. vivax oocysts in mosquitoes fed in the laboratory. The complex between recombinant Pvs25 and the Fab fragment of 2A8 forms crystals that diffract X-rays to 3.5 A. Two native data sets, A and B, have been collected from crystals of the Pvs25-Fab complex. Both crystals belong to space group P2(1), with unit-cell parameters of a = 86.3, b = 61.7, c = 142.7 A, beta = 101.7 degrees for data set A and a = 86.8, b = 61.0, c = 149.3 A, beta = 104.3 degrees for data set B, and contain two complex molecules per asymmetric unit. Efforts are under way to reveal the structure of the Pvs25-Fab complex by molecular replacement. The three-dimensional structure of the Pvs25-Fab complex will provide an understanding of the interaction between Pvs25 and the 2A8 antibody that inhibits ookinete development in the mosquito and should aid in the development of transmission-blocking vaccines against P. vivax malaria.
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Affiliation(s)
- Ajay K Saxena
- Structural Biology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Twinbrook II, 12441 Parklawn Drive, Rockville, Maryland 20852, USA
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24
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Dekker C, Uthaipibull C, Calder LJ, Lock M, Grainger M, Morgan WD, Dodson GG, Holder AA. Inhibitory and neutral antibodies to Plasmodium falciparum MSP119 form ring structures with their antigen. Mol Biochem Parasitol 2004; 137:143-9. [PMID: 15279960 DOI: 10.1016/j.molbiopara.2004.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Revised: 05/15/2004] [Accepted: 05/17/2004] [Indexed: 10/26/2022]
Abstract
Blood-stage malaria vaccine candidates include surface proteins of the merozoite. Antibodies to these proteins may either block essential steps during invasion or render the merozoite susceptible to phagocytosis or complement-mediated degradation. Structural information on merozoite surface proteins complexed to antibodies provides crucial information for knowledge-based vaccine design. The major merozoite surface protein MSP1 is an abundant surface molecule in Plasmodium falciparum. Only a subset of antibodies against MSP119 inhibits invasion (inhibitory antibodies), whereas other antibodies binding to MSP119 have no effect on invasion (neutral antibodies). Here we report on the complex of MSP119 with both inhibitory monoclonal antibody 12.10 and neutral monoclonal antibody 2F10. The complexes were established using both whole IgG's and Fab fragments, and analysed by dynamic light scattering, electron microscopy and analytical ultra centrifugation. Specific ring structures were formed in the ternary complex with the two antibodies, providing direct evidence of non-overlapping epitopes on MSP119. Mutational studies also indicated that the epitopes of the inhibitory and neutral antibodies are spatially remote.
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MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/metabolism
- Antigen-Antibody Complex/chemistry
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- DNA Mutational Analysis
- Epitope Mapping
- Epitopes/genetics
- Epitopes/immunology
- Merozoite Surface Protein 1/chemistry
- Merozoite Surface Protein 1/immunology
- Merozoite Surface Protein 1/metabolism
- Microscopy, Electron
- Models, Molecular
- Plasmodium falciparum/immunology
- Protein Binding
- Protein Conformation
- Protein Structure, Quaternary
- Ultracentrifugation
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Affiliation(s)
- Carien Dekker
- Division of Parasitology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK.
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25
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Nuttall SD, Humberstone KS, Krishnan UV, Carmichael JA, Doughty L, Hattarki M, Coley AM, Casey JL, Anders RF, Foley M, Irving RA, Hudson PJ. Selection and affinity maturation of IgNAR variable domains targeting Plasmodium falciparum AMA1. Proteins 2004; 55:187-97. [PMID: 14997552 DOI: 10.1002/prot.20005] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The new antigen receptor (IgNAR) is an antibody unique to sharks and consists of a disulphide-bonded dimer of two protein chains, each containing a single variable and five constant domains. The individual variable (V(NAR)) domains bind antigen independently, and are candidates for the smallest antibody-based immune recognition units. We have previously produced a library of V(NAR) domains with extensive variability in the CDR1 and CDR3 loops displayed on the surface of bacteriophage. Now, to test the efficacy of this library, and further explore the dynamics of V(NAR) antigen binding we have performed selection experiments against an infectious disease target, the malarial Apical Membrane Antigen-1 (AMA1) from Plasmodium falciparum. Two related V(NAR) clones were selected, characterized by long (16- and 18-residue) CDR3 loops. These recombinant V(NAR)s could be harvested at yields approaching 5mg/L of monomeric protein from the E. coli periplasm, and bound AMA1 with nanomolar affinities (K(D)= approximately 2 x 10(-7) M). One clone, designated 12Y-2, was affinity-matured by error prone PCR, resulting in several variants with mutations mapping to the CDR1 and CDR3 loops. The best of these variants showed approximately 10-fold enhanced affinity over 12Y-2 and was Plasmodium falciparum strain-specific. Importantly, we demonstrated that this monovalent V(NAR) co-localized with rabbit anti-AMA1 antisera on the surface of malarial parasites and thus may have utility in diagnostic applications.
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Affiliation(s)
- Stewart D Nuttall
- CSIRO Health Sciences and Nutrition, Parkville, Victoria, Australia.
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26
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Pleass RJ, Ogun SA, McGuinness DH, van de Winkel JGJ, Holder AA, Woof JM. Novel antimalarial antibodies highlight the importance of the antibody Fc region in mediating protection. Blood 2003; 102:4424-30. [PMID: 12855589 DOI: 10.1182/blood-2003-02-0583] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parasite drug resistance and difficulties in developing effective vaccines have precipitated the search for alternative therapies for malaria. The success of passive immunization suggests that immunoglobulin (Ig)-based therapies are effective. To further explore the mechanism(s) by which antibody mediates its protective effect, we generated human chimeric IgG1 and IgA1 and a single-chain diabody specific for the C-terminal 19-kDa region of Plasmodium yoelii merozoite surface protein 1 (MSP119), a major target of protective immune responses. These novel human reagents triggered in vitro phagocytosis of merozoites but, unlike their parental mouse IgG2b, failed to protect against parasite challenge in vivo. Therefore, the Fc region appears critical for mediating protection in vivo, at least for this MSP119 epitope. Such antibodies may serve as prototype therapeutic agents, and as useful tools in the development of in vitro neutralization assays with Plasmodium parasites.
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Affiliation(s)
- Richard J Pleass
- School of Biology, University Park, Nottingham, NG7 2RD, United Kingdom.
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27
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Pizarro JC, Chitarra V, Verger D, Holm I, Pêtres S, Dartevelle S, Nato F, Longacre S, Bentley GA. Crystal structure of a Fab complex formed with PfMSP1-19, the C-terminal fragment of merozoite surface protein 1 from Plasmodium falciparum: a malaria vaccine candidate. J Mol Biol 2003; 328:1091-103. [PMID: 12729744 DOI: 10.1016/s0022-2836(03)00376-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Merozoite surface protein 1 (MSP1) is the major protein component on the surface of the merozoite, the erythrocyte-invasive form of the malaria parasite Plasmodium. Present in all species of Plasmodium, it undergoes two distinct proteolytic maturation steps during the course of merozoite development that are essential for invasion of the erythrocyte. Antibodies specific for the C-terminal maturation product, MSP1-19, can inhibit erythrocyte invasion and parasite growth. This polypeptide is therefore considered to be one of the more promising malaria vaccine candidates. We describe here the crystal structure of recombinant MSP1-19 from P.falciparum (PfMSP1-19), the most virulent species of the parasite in humans, as a complex with the Fab fragment of the monoclonal antibody G17.12. This antibody recognises a discontinuous epitope comprising 13 residues on the first epidermal growth factor (EGF)-like domain of PfMSP1-19. Although G17.12 was raised against the recombinant antigen expressed in an insect cell/baculovirus system, it binds uniformly to the surface of merozoites from the late schizont stage, showing that the cognate epitope is exposed on the naturally occurring MSP1 polypeptide complex. Although the epitope includes residues that have been mapped to regions recognised by invasion-inhibiting antibodies studied by other workers, G17.12 does not inhibit erythrocyte invasion or MSP1 processing.
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Affiliation(s)
- J C Pizarro
- Unité d'Immunologie Structurale (CNRS URA 2185), Département de Biologie Structurale et Chimie, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris, cedex 15, France
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28
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Lozano JM, Alba MP, Vanegas M, Silva Y, Torres-Castellanos JL, Patarroyo ME. MSP-1 malaria pseudopeptide analogs: biological and immunological significance and three-dimensional structure. Biol Chem 2003; 384:71-82. [PMID: 12674501 DOI: 10.1515/bc.2003.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Merozoite Surface Protein-1 (MSP-1) has been considered as a malaria vaccine candidate. It is processed during the Plasmodium falciparum invasion process of red blood cells (RBCs). A conserved MSP-1 C-terminal peptide was identified as a high-activity erythrocyte-binding peptide (HAEBP) termed 1585. Since conserved HAEBPs are neither antigenic nor immunogenic we decided to assess the significance of a single peptide bond replacement in 1585. Thus, two pseudopeptides were obtained by introducing a Y[CH2-NH] reduced amide isoster into the 1585 critical binding motif. The pseudopeptides bound to different HLA-DR alleles, suggesting that backbone modifications affect MHC-II binding patterns. Pseudopeptide-antibodies inhibit in vitro parasite RBC invasion by recognizing MSP-1. Each pseudopeptide-induced antibody shows distinct recognition patterns. 1H-NMR studies demonstrated that isoster bonds modulate the pseudopeptides' structure and thus their immunological properties, therefore representing a possible subunit malaria vaccine component.
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Affiliation(s)
- José Manuel Lozano
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia
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29
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Abstract
Adult Schistosoma mansoni parasites live in the bloodstream of their vertebrate hosts where they consume red blood cells. Hemoglobin, released from the ingested red blood cells, is degraded by a variety of parasite proteases, including Sm31 (cathepsin B) and Sm32 (schistosome legumain). In this study the localization pattern of the Sm31 and Sm32 enzymes in cercariae (the infectious life cycle stage) was examined. Antibodies generated against recombinant Sm31 and Sm32 recognize their respective proteins in Western blots of soluble parasite extracts. Highest levels are seen in adult female extracts, whereas the level of both proteins is below detection in cercarial extracts. However, in fixed, whole cercariae, both proteins are seen in the cecum and protonephridia. In the cecum, the staining pattern has a granular appearance, suggesting that the proteins are packaged in vesicles. In the protonephridial system, Sm31 and Sm32 are detected in all 8 flame cells in the cercarial body and in both flame cells in the cercarial tail. The distribution of the 2 proteins differs in the flame cells. Examination of immunostained cercariae using laser scanning confocal microscopy shows that whereas Sm31 is located in the tubule cell, Sm32 is found in both the tubule cell and its adjoining cap cell. These findings suggest that the proteins are involved in the proposed excretory and osmoregulatory roles of flame cells.
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Affiliation(s)
- P J Skelly
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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30
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Abstract
In Trypanosoma brucei, uptake of host transferrin is mediated by a heterodimeric, glycosylphosphatidylinositol-anchored receptor derived from the 2 expression site-associated genes 6 and 7 (ESAG6 and ESAG7). By using specific antibodies, it is shown here that T. evansi, a trypanosome species transmitted mechanically by biting flies, also expresses a transferrin receptor composed of ESAG6 and ESAG7. The cellular uptake of transferrin in T. evansi is completely inhibited with anti-T. brucei (ESAG6/7 heterodimer) antibodies. The demonstration of a functional ESAG6/7 transferrin receptor in T. evansi supports further its close relationship to T. brucei.
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Affiliation(s)
- M Kabiri
- Abteilung Parasitologie, Hygiene-Institut der Ruprecht-Karls-Universität, Heidelberg, Germany
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31
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Hough VC, Greenman J, Paget TA. Generation of anti-Giardia antibodies by bacteriophage antibody display. Dis Markers 2001; 16:91-3. [PMID: 11360834 PMCID: PMC3850809 DOI: 10.1155/2000/713940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- V C Hough
- University of Hull, Department of Biological Sciences, Hardy Building, Cottingham Road, Hull HU6 7RX, UK.
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32
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Silvestrini F, Alano P, Williams JL. Commitment to the production of male and female gametocytes in the human malaria parasite Plasmodium falciparum. Parasitology 2000; 121 Pt 5:465-71. [PMID: 11128797 DOI: 10.1017/s0031182099006691] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Commitment to the production of female and male gametocytes was studied in the NF54 line of the human malaria parasite Plasmodium falciparum. The development of sibling parasites derived from individual schizonts was followed, and 2 antisera against the female gametocyte-specific protein Pfg377 and the male gametocyte-specific protein alpha-tubulin II were used to determine the sex of sibling gametocytes. The experiment showed that individual cohorts of sibling gametocytes were stained in a mutually exclusive fashion by only one or the other antiserum, indicating that individual schizonts committed to yield sexual parasite progeny produce gametocytes of the same sex. This work suggests that in P. falciparum commitment to sexual differentiation occurs prior to schizont maturation, at the same moment when the sex of the resulting gametocytes is determined.
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Affiliation(s)
- F Silvestrini
- Laboratorio di Biologia Cellulare, Istituto Superiore di Sanità, Rome, Italy
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33
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Bohidar HB, Bhakat P, Sharma J, Saxena A. Anomalous colloidal stability of protein coated polystyrene latex beads studied by small angle light scattering. Int J Biol Macromol 2000; 27:111-6. [PMID: 10771060 DOI: 10.1016/s0141-8130(00)00113-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Results of small angle laser light scattering experiments carried out on polystyrene latex beads coated with lysate of Plasmodium falciparum (Pf) antigen (Ag) and human seropositive sera (10:1 ratio) are reported for various NaCl concentrations (0-300 mM). The protein coated beads showed time-dependent coagulation. The normalised intensity of scattered light I(s)(t)/I(0) showed I(s)(t)/I(0)=1+(Gammat)(delta) behaviour with the coagulation rate, Gamma and exponent, delta showing anomalous dependence on NaCl concentration. The coagulation rate exhibited strong increase up to NaCl concentration of 50 mM, above this and up to 300 mM the coagulation rate was found to remain independent of NaCl concentration yielding non-DLVO behaviour. The same was true for delta which increased from 1.04+/-0.06 to 6.94+/-0.07 as NaCl concentration was raised from 0 to 50 mM. Above 50 mM it remained constant with delta=6.94+/-0.07. Results are discussed through Smoluchowski aggregation kinetics and theoretical construction of interparticle interaction potentials relevant to our problem.
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Affiliation(s)
- H B Bohidar
- Department of Biomedical Engineering, Indian Institute of Technology, New Delhi, India.
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34
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Ferguson DJ, Jacobs D, Saman E, Dubremetz JF, Wright SE. In vivo expression and distribution of dense granule protein 7 (GRA7) in the exoenteric (tachyzoite, bradyzoite) and enteric (coccidian) forms of Toxoplasma gondii. Parasitology 1999; 119 ( Pt 3):259-65. [PMID: 10503251 DOI: 10.1017/s0031182099004692] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The in vivo expression and distribution of the dense granule protein GRA7 was examined in both the exoenteric (tachyzoite and bradyzoite) and enteric (coccidian) forms of Toxoplasma gondii by immunocytochemistry. There was strong staining of GRA7 in granules within all the infectious stages (tachyzoite, bradyzoite, merozoite and sporozoite). During tachyzoite development, GRA7 was secreted and was associated with the parasitophorous vacuole. In contrast, although there was staining of granules within the bradyzoites of more mature cysts, there appeared to be little staining of the tissue cyst wall or host cell. The apparent stage-specific variation in secretion of GRA7 between tachyzoites and bradyzoites was confirmed by double labelling using stage-specific markers (SAG1 and BAG1). In the enteric forms in the cat gut there was strong labelling of the PV containing early asexual and sexual stages and staining of a few granules in the apical cytoplasm of the merozoite. The positive enteric staining pattern differentiates GRA7 from the other GRA proteins (GRA1-6) which were absent in the merozoites and enteric stages. The staining pattern of GRA7 with strong staining during tachyzoite and enteric development and reduced staining in the tissue cysts is similar to that seen for NTPases. The function of GRA7 is unknown but it is unique among the dense granule proteins in being expressed in all the infectious forms of T. gondii which would point to a basic role in the vacuolar adaptations required for active parasite development.
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MESH Headings
- Animals
- Antibodies, Monoclonal
- Antibodies, Protozoan/chemistry
- Antigens, Protozoan
- Brain/parasitology
- Brain/pathology
- Cat Diseases/parasitology
- Cats
- Gene Expression Regulation
- Immunohistochemistry
- Intestinal Diseases, Parasitic/parasitology
- Intestinal Diseases, Parasitic/veterinary
- Intestine, Small/parasitology
- Intestine, Small/pathology
- Mice
- Mice, Inbred BALB C
- Microscopy, Fluorescence/veterinary
- Protozoan Proteins/biosynthesis
- Protozoan Proteins/genetics
- Toxoplasma/genetics
- Toxoplasmosis, Animal/parasitology
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Affiliation(s)
- D J Ferguson
- Nuffield Department of Pathology, Oxford University, John Radcliffe Hospital, UK.
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35
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Tachibana H, Cheng XJ, Watanabe K, Takekoshi M, Maeda F, Aotsuka S, Kaneda Y, Takeuchi T, Ihara S. Preparation of recombinant human monoclonal antibody Fab fragments specific for Entamoeba histolytica. Clin Diagn Lab Immunol 1999; 6:383-7. [PMID: 10225840 PMCID: PMC103727 DOI: 10.1128/cdli.6.3.383-387.1999] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Genes coding for human antibody Fab fragments specific for Entamoeba histolytica were cloned and expressed in Escherichia coli. Lymphocytes were separated from the peripheral blood of a patient with an amebic liver abscess. Poly(A)+ RNA was isolated from the lymphocytes, and then genes coding for the light chain and Fd region of the heavy chain were amplified by a reverse transcriptase PCR. The amplified DNA fragments were ligated with a plasmid vector and were introduced into Escherichia coli. Three thousand colonies were screened for the production of antibodies to E. histolytica HM-1:IMSS by an indirect fluorescence-antibody (IFA) test. Lysates from five Escherichia coli clones were positive. Analysis of the DNA sequences of the five clones showed that three of the five heavy-chain sequences and four of the five light-chain sequences differed from each other. When the reactivities of the Escherichia coli lysates to nine reference strains of E. histolytica were examined by the IFA test, three Fab fragments with different DNA sequences were found to react with all nine strains and another Fab fragment was found to react with seven strains. None of the four human monoclonal antibody Fab fragments reacted with Entamoeba dispar reference strains or with other enteric protozoan parasites. These results indicate that the bacterial expression system reported here is effective for the production of human monoclonal antibodies specific for E. histolytica. The recombinant human monoclonal antibody Fab fragments may be applicable for distinguishing E. histolytica from E. dispar and for use in the serodiagnosis of amebiasis.
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Affiliation(s)
- H Tachibana
- Departments of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
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36
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Bryant MS, Lee RP, Lester RJ, Whittington RJ. Anti-immunoglobulin antisera used in an ELISA to detect antibodies in barramundi Lates calcarifer to Cryptocaryon irritans. Dis Aquat Organ 1999; 36:21-28. [PMID: 10349549 DOI: 10.3354/dao036021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Immunoglobulins (Ig) in serum from barramundi vaccinated with bovine serum albumin (BSA) were purified by ammonium sulphate precipitation and affinity chromatography using BSA as the ligand. The BSA-binding activity of eluted putative Ig fractions was assessed by enzyme-linked immunosorbent assay (ELISA) before being pooled and characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Double affinity purification did not improve the purity of the Ig preparation compared to single affinity purification. Barramundi Ig were injected into sheep to produce anti-Ig antisera which were assessed in an indirect ELISA as the secondary antibody to detect serum Ig in barramundi vaccinated with Cryptocaryon irritans theronts. Affinity-purified Ig induced a more specific reagent for use as secondary antibody in ELISA than did normal whole-barramundi sera. The heavy (H) chain of barramundi Ig had an apparent molecular weight of 70 kDa while that of the light (L) chain was 27 kDa in SDS-PAGE studies. Under non-reducing conditions 2 putative populations of Ig were identified, at 768 and 210 kDa. The N-terminal sequence of the barramundi Ig H chain showed 78% homology with channel catfish Ictalurus punctatus Ig H chain sequence.
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Affiliation(s)
- M S Bryant
- Department of Parasitology, University of Queensland, Brisbane, Australia.
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37
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Mnaimneh S, Geffard M, Veyret B, Vincendeau P. Detection of nitrosylated epitopes in Trypanosoma brucei gambiense by polyclonal and monoclonal anti-conjugated-NO-cysteine antibodies. C R Acad Sci III 1999; 322:311-22. [PMID: 10216803 DOI: 10.1016/s0764-4469(99)80067-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Activated macrophages with the Calmette/Guérin bacillus (BCG) have a cytotoxic/cytostatic effect on the extracellular parasite, Trypanosoma brucei gambiense. This effect was inhibited when the NO-synthase inhibitor NG-monomethyl-L-arginine (NMMA; 0.5 mM) was added to the culture media. Using an immunocytochemical method with rabbit polyclonal or mouse monoclonal antibodies directed against conjugated nitroso-epitopes (anti-conjugated-NO-cysteine), nitrosylated antigens were visualized in fixed trypanosomes. These results suggest that NO was synthesized by the activated macrophages and that it reacted with some parasitic proteins containing cysteine. The release of NO bound to parasitic proteins may cause the killing of trypanosomes. The immunoreactivity was positive when the trypanosomes were obtained from the supernatant of the BCG-activated macrophages that contains BSA (4 mg/mL). In contrast, the parasites cocultured with non-activated macrophages remained completely viable, and, the immunoreactivity was completely negative.
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Affiliation(s)
- S Mnaimneh
- Laboratoire de physique des interactions ondes-matières, UMR 5501, CNRS, Talence, France.
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38
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Rhalem A, Sahibi H, Guessous-Idrissi N, Lasri S, Natami A, Riyad M, Berrag B. Immune response against Leishmania antigens in dogs naturally and experimentally infected with Leishmania infantum. Vet Parasitol 1999; 81:173-84. [PMID: 10190861 DOI: 10.1016/s0304-4017(98)00240-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Cell-mediated and humoral immune response in naturally and experimentally infected dogs was studied using crude and pure antigens. Both types of infections induced severe signs of visceral disease, but the symptoms observed in natural infections were more pronounced than in experimental infections. In addition, asymptomatic infections were not observed in experimentally infected animals. Disease evolution in laboratory infections was rapid and an increase in antibody titer to crude parasite antigen was correlated with the appearance and aggravation of clinical symptoms. Peripheral blood lymphocyte proliferation to crude antigen and pure gp63 was observed early following experimental infection, but was abolished once the infected dogs began to exhibit clinical signs. A similar pattern was observed in naturally infected dogs. Serum from all patent dogs showed high antibody titers to rK39 in enzyme-linked immunosorbent assays (ELISA), and reacted by western blotting with several antigens, 12 to 120 KDa, including gp63 and gp70. In the case of asymptomatic dogs. antibody titers to crude antigen were low and only a few antigens were identified by western blotting. None of the pure proteins examined, gp63, gp70, and rK39 were recognized by western blotting or ELISA. However, asymptomatic dogs exhibited specific lymphocyte proliferation to both crude antigen and the potential vaccine candidate gp63.
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Affiliation(s)
- A Rhalem
- Département de Parasitologie et Maladies Parasitaires, Institut Agronomique et Veterinaire Hassan II, Rabat-Instituts, Morocco
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39
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Abstract
The expression and activity of topoisomerase I (PfTopoI) has been examined during the intraerythrocytic stages of the Plasmodium falciparum life cycle. The promoter is inactive during the early ring stage and becomes active only during the later trophozoite and schizont stages. The PfTOP1 transcript starts to accumulate in the trophozoite stage parasite, decreasing again in the schizont stage. Using both stage-specific Western analysis and immunofluorescent assays we show that PfTopoI is present at low levels in rings and accumulates to approximately equal levels in the trophozoite and schizont stages. Experiments to determine the activity of PfTopoI, using a topoisomerase I relaxation assay, show that there is a low level of PfTopoI activity in both ring and trophozoite stages, but activity increases dramatically in the schizont stage. The PfTopoI activity can be inhibited by treatment with specific antiserum and by the type I topoisomerase-specific inhibitor camptothecin.
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MESH Headings
- Animals
- Antibodies, Protozoan/chemistry
- Blotting, Northern
- Blotting, Western
- Camptothecin/pharmacology
- DNA Topoisomerases, Type I/genetics
- DNA Topoisomerases, Type I/metabolism
- DNA, Protozoan/chemistry
- Electrophoresis, Agar Gel
- Electrophoresis, Polyacrylamide Gel
- Enzyme Inhibitors/pharmacology
- Fluorescent Antibody Technique
- Gene Expression Regulation, Enzymologic
- Malaria, Falciparum/enzymology
- Malaria, Falciparum/parasitology
- Nucleic Acid Hybridization
- Plasmodium falciparum/drug effects
- Plasmodium falciparum/enzymology
- Plasmodium falciparum/genetics
- Promoter Regions, Genetic/physiology
- Rabbits
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Affiliation(s)
- K Tosh
- Institute of Cell and Molecular Biology, University of Edinburgh, United Kingdom
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40
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Tachibana H, Takekoshi M, Cheng XJ, Maeda F, Aotsuka S, Ihara S. Bacterial expression of a neutralizing mouse monoclonal antibody Fab fragment to a 150-kilodalton surface antigen of Entamoeba histolytica. Am J Trop Med Hyg 1999; 60:35-40. [PMID: 9988319 DOI: 10.4269/ajtmh.1999.60.1.9988319] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A mouse monoclonal antibody (MAb) (EH3015, IgG1 with a K light chain) prepared by hybridoma technology recognizes a 150-kD surface antigen of Entamoeba histolytica and inhibits adherence and cytotoxicity of the ameba to mammalian cells. The genes encoding the light chain and the Fd region of the heavy chain of the MAb were cloned and expressed in Escherichia coli. The plasmid used was designed for the expression of Fab with a hexa-histidine tag in the periplasmic space. Recombinant Fab fragments were purified and analyzed by an indirect immunofluorescence antibody test and Western immunoblot. The specificity of the recombinant Fab fragment was comparable with the parent whole IgG. In addition, the Fab fragments significantly inhibited the adherence of E. histolytica to erythrocytes. These results suggest that the production of a neutralizing MAb in Escherichia coli is practical and efficient with this expression system.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/biosynthesis
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/immunology
- Antibodies, Protozoan/biosynthesis
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/genetics
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/immunology
- Antigens, Surface/immunology
- Base Sequence
- Blotting, Western
- Cell Adhesion/immunology
- Cloning, Molecular
- DNA, Complementary/chemistry
- Electrophoresis, Polyacrylamide Gel
- Entamoeba histolytica/immunology
- Escherichia coli/genetics
- Fluorescent Antibody Technique, Indirect
- Gene Expression Regulation, Bacterial
- Hybridomas
- Immunoglobulin Fab Fragments/biosynthesis
- Immunoglobulin Fab Fragments/chemistry
- Immunoglobulin Fab Fragments/genetics
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Heavy Chains/biosynthesis
- Immunoglobulin Heavy Chains/chemistry
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/immunology
- Immunoglobulin kappa-Chains/biosynthesis
- Immunoglobulin kappa-Chains/chemistry
- Immunoglobulin kappa-Chains/genetics
- Immunoglobulin kappa-Chains/immunology
- Mice
- Molecular Sequence Data
- RNA, Messenger/genetics
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- H Tachibana
- Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa, Japan
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41
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Abstract
The leishmanin skin test was used to detect Leishmania-specific cellular immunity in asymptomatic dogs from an endemic region of visceral leishmaniosis. The test was safe since no clinical signs of intolerance to leishmanin were detected during 1 month, in 14 dogs after inoculations of 3 x 10(8) promastigotes/ml. In another group of four dogs no cross reactivity was found after inoculations of a PPD which demonstrated the specificity of the test. In the same group of animals, repeatability was assessed by repeated inoculations of leishmanin at 1-5-month intervals and the threshold of sensitivity was the concentration of 3 x 10(6) promastigotes/ml. Secondly, we applied the test in a dog population that live in an endemic region of visceral leishmaniosis and found a significant increase in Leishmania-infected dogs after the application of this test in the field.
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Affiliation(s)
- L Cardoso
- Departamento de Higiene e Sanidade, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal
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42
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Hui GS, Hashimoto CN. Pathways for potentiation of immunogenicity during adjuvant-assisted immunizations with Plasmodium falciparum major merozoite surface protein 1. Infect Immun 1998; 66:5329-36. [PMID: 9784540 PMCID: PMC108666 DOI: 10.1128/iai.66.11.5329-5336.1998] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vaccine adjuvants exert critical and unique influences on the quality of immune responses induced during active immunizations. We investigated the mechanisms of action of immunological adjuvants in terms of their requirements for cytokine-mediated pathways for adjuvanticity. Antibody responses potentiated by several adjuvants to a Plasmodium falciparum MSP1-19 (C-terminal 19-kDa processing fragment of MSP1) vaccine were studied in gamma interferon (IFN-gamma) or interleukin (IL-4) knockout mice. The levels of anti-MSP1-19 antibodies and the induction of Th1- and Th2-type antibodies were analyzed. Results revealed a spectrum of requirements for cytokine-mediated pathways in the potentiation of immunogenicity, and such requirements were influenced by interactions among individual components of the adjuvant formulations. One adjuvant strictly depended on IFN-gamma to induce appreciable levels of anti-MSP1-19 antibodies, while some formulations required IFN-gamma only for the induction of Th1-type antibodies. Other formulations induced exclusively Th2-type antibodies and were not affected by IFN-gamma knockout. There were three patterns of requirements for IL-4 by various adjuvants in the induction of Th2-type anti-MSP1-19 antibodies. Moreover, the induction of Th1-type anti-MSP1-19 antibodies by adjuvants showed two distinct patterns of regulation by IL-4. The utilization of an IL-4 regulated pathway(s) for the induction of Th2-type antibodies by the same adjuvant differed between mouse strains, suggesting that animal species variability in responses to vaccine adjuvants may be due, at least in part, to differences in the utilization of immune system pathways by an adjuvant among animal hosts.
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Affiliation(s)
- G S Hui
- Department of Tropical Medicine, University of Hawaii, Honolulu, Hawaii 96816, USA.
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43
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Abstract
Clinical neosporosis was diagnosed in a 2-month-old Pit Bull Terrier from Italy. Neospora caninum tachyzoites were found in semitendinosus muscle with myositis. The diagnosis was confirmed by immunohistochemical staining with anti-N. caninum specific antibodies. This is the first report of systemic neosporosis in dogs from Italy.
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Affiliation(s)
- P Pasquali
- Facolta' di Medicina Veterinaria, Istituto di Parassitologia, Universita' degli Studi di Perugia, Italy.
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44
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Soares H, Cyrne L, Casalou C, Ehmann B, Rodrigues-Pousada C. The third member of the Tetrahymena CCT subunit gene family, TpCCT alpha, encodes a component of the hetero-oligomeric chaperonin complex. Biochem J 1997; 326 ( Pt 1):21-9. [PMID: 9337846 PMCID: PMC1218632 DOI: 10.1042/bj3260021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The sequence of a third member of the Tetrahymena pyriformis chaperonin CCT ('chaperonin containing TCP1') subunit gene family is presented. This gene, designated TpCCT alpha, is the orthologue of the mouse chaperonin gene TCP1/CCT alpha. To characterize the CCT complex in this ciliate, we have produced polyclonal antibodies against synthetic peptides based on C-terminal sequences deduced from the primary sequences of the TpCCT alpha, TpCCT gamma and TpCCT eta subunits. We have also used polyclonal antibodies produced against recombinant yeast CCT alpha and CCT beta subunits. Using these antibodies, we show that Tetrahymena cells contain a hetero-oligomeric CCT chaperonin comprising at least seven distinct subunits. Three of these were assigned to specific TpCCT genes, whereas a fourth was recognized by the polyclonal antibody against yeast CCT beta, suggesting that this gene is also present in the ciliate. The CCT complex also contains other unidentified proteins that were recognized by the polyclonal antibody UM-1, raised against the putative ATP binding domain of the chaperonin proteins. TpCCT alpha gene expression was shown in exponentially growing cells and cells regenerating their cilia for different periods to have a similar pattern to the previously identified genes TpCCT gamma and TpCCT eta, and also to tubulin genes.
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Affiliation(s)
- H Soares
- Laboratório de Genética Molecular, Instituto Gulbenkian de Ciência, Oeiras, Portugal
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45
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Wilson DR, Wirtz RA, Finlay BB. Recognition of phage-expressed peptides containing Asx-Pro sequences by monoclonal antibodies produced against Plasmodium falciparum circumsporozoite protein. Protein Eng 1997; 10:531-40. [PMID: 9215571 DOI: 10.1093/protein/10.5.531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The immunodominant region of the Plasmodium falciparum circumsporozoite protein is comprised mainly of a series of tetrapeptide repeats that can, depending on the starting cadence chosen, be described as (NANP)n, (ANPN)n, (NPNA)n or (PNAN)n in one-letter amino acid code. Data from several studies suggest that the NPNA cadence alone is structurally correct, in that each NPNA tetrapeptide effectively forms a structural unit initiated by an Asx-Pro turn. To explore this idea further and to assess the immunological relevance of peptide conformation as it relates to the cadence of these tetrapeptide repeats, we used ELISA to compare the abilities of monoclonal antibodies (MAbs) produced against P. falciparum sporozoites to recognize repeat-related heptapeptides expressed on the surface of filamentous bacteriophage. Having included representatives of both NANP and NPNA cadences and other peptides in which the number and location of Asx-Pro sequences varied, we provide evidence that Asx-Pro sequences play an important role in peptide conformation and antibody recognition, that peptide conformation is influenced by the cadence of the tetrapeptide repeats and that peptide conformation is important to the abilities of these MAbs to recognize their epitopes.
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Affiliation(s)
- D R Wilson
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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46
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Doury JC, Goasdoue JL, Tolou H, Martelloni M, Bonnefoy S, Mercereau-Puijalon O. Characterisation of the binding sites of monoclonal antibodies reacting with the Plasmodium falciparum rhoptry protein RhopH3. Mol Biochem Parasitol 1997; 85:149-59. [PMID: 9106189 DOI: 10.1016/s0166-6851(96)02819-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Twenty one mouse monoclonal antibodies reacting or cross-reacting with the Plasmodium falciparum RhopH3 protein reacted with Ag44, a recombinant antigen expressing the 134 C-terminal RhopH3 residues. Using overlapping peptides scanning this region, two major binding sites were identified. The first one, recognised by eight anti-RhopH3 and seven cross-reacting mAbs, was mapped to the sequence Thr Asp Asn Thr Tyr or Thr Asp Asn Thr Tyr Lys (aa 823-828), depending on the support used for synthesis. Binding specificity and affinity were investigated for a subset of four mAbs reacting with this epitope, including one growth inhibitory mAb. Systematic replacements showed that the various mAbs had similar requirements. The inhibitory mAb presented a higher affinity for this sequence and bound to the adjacent sequence, Tyr Lys Glu Met Glu Leu (aa 827-832). A 2nd binding site, located around residue 850, was recognised by two anti-RhopH3 mAbs, which reacted exclusively with the 110 kDa RhopH3 polypeptide, unlike the other mAbs, which reacted with the 110 and 105 kDa RhopH3 antigens. This suggested that the 105 kDa RhopH3 polypeptide derives from the 110 kDa by C-terminal processing. Experimental evidence substantiating this conclusion was provided by the observation that antisera raised to peptides located upstream of the putative cleavage site reacted with both the 110 kDa and 105 kDa polypeptides, whereas antisera raised to the 45 C-terminal amino acids of RhopH3 reacted exclusively with the larger, 110 kDa product. The biological significance of this processing is discussed.
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Affiliation(s)
- J C Doury
- Institut de Médecine Tropicale, Service de Santé des Armées, Marseille Armées, France
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47
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Bossus M, BenMohamed L, Londono A, Barbier B, Tartar A, Druilhe P, Gras-Masse H, Mohammed L. Improved detection of human antibodies to a Plasmodium antigen using a peptide modified with Aib residues. J Pept Sci 1997; 3:47-53. [PMID: 9230470 DOI: 10.1002/(sici)1099-1387(199701)3:1<47::aid-psc80>3.0.co;2-v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A 17-mer sequence was selected as a model to study the influence of modifications of terminal ends both on the conformational of a peptide and on its antigenicity towards naturally developing antibodies. This sequence corresponded to a tandemly repeated motif, found in a long repetitive region, with high helical propensity, of a Plasmodium falciparum liver-stage antigen (LSA-1), immunogenic in man. Our model peptide was synthesized with ionizable or non-ionizable ends, or modified in both extremities by introduction of the helix-promoting residue alpha-aminoisobutyric acid (Aib). Helical contribution, absent in the 17 amino-acid sequence possessing ionizable ends, was detectable when non-ionizable ends were introduced, and dramatically increased in the Aib-modified analogue. The presence of ionizable ends totally abolished reactivity towards human sera, otherwise detectable with the peptide possessing non-ionizable ends. While modification by Aib residues was neither detrimental nor beneficial to antigenicity in solution, it clearly resulted in an improved sensitivity of the specific antibody detection when used as solid-phase antigen in ELISA.
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Affiliation(s)
- M Bossus
- Service de chimie des biomolécules, URA CNRS 1309, Institut Pasteur de Lille, France
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48
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Abstract
An antibody reactive with cholesterol sulphate (CS) was characterized in human sera by ELISA, erythrocyte and liposome absorption. This antibody was found evenly distributed between the IgA and IgM classes, and whilst this was present at low titres in the serum of 16% of healthy individuals studied, it was significantly elevated in 78% of Trypanosoma cruzi-infected subjects. No association was found between antibody levels and the degree of myocardial damage. No significant difference in immunoreactivity was found between healthy and chagasic subjects using dehydro-epiandrosterone sulphate and pregnenolone sulphate and cholesterol, ergosterol, lanosterol, stigmastanol, beta-stigmasterol, pregnenolone, prednisolone and dehydroepiandrosterone as antigens, suggesting that in chagasic sera the whole sterol molecule is important for optimal antibody binding. CS-reactive antibodies were easily purified by absorption either with CS-bearing liposomes or with dextran sulphate gel and further elution with 1.5 M NaCl. The optimal pH of CS-antibody interaction was 4.0 with 85% binding at pH 7.0. Polylysine strongly decreased the binding of these antibodies to the corresponding antigen. Furthermore, these antibodies were strongly absorbed by rabbit and guinea pig erythrocyte but not by rat or human erythrocyte. In contrast with anti-sulphatide antibodies, no significant increase in CS-reactive antibodies was found in dilated cardiomyopathies. Whilst CS itself was not detected in T. cruzi lipid extracts, there is an unidentified sulphated sterol, which migrates close to standard CS and which strongly binds chagasic but not control sera. This latter sterol might be acting in chagasic patients as a powerful antigen, triggering specific autoantibody production.
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Affiliation(s)
- J L Avila
- Instituto de Biomedicina, Caracas, Venezuela
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49
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Gross U, Bormuth H, Gaissmaier C, Dittrich C, Krenn V, Bohne W, Ferguson DJ. Monoclonal rat antibodies directed against Toxoplasma gondii suitable for studying tachyzoite-bradyzoite interconversion in vivo. Clin Diagn Lab Immunol 1995; 2:542-8. [PMID: 8548532 PMCID: PMC170197 DOI: 10.1128/cdli.2.5.542-548.1995] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We previously reported the in vitro analysis of stage differentiation of Toxoplasma gondii in murine bone marrow-derived macrophages. The purpose of this study was to generate monoclonal rat antibodies that might be suitable for investigating tachyzoite-bradyzoite interconversion in vivo with the murine model. Immunization of Fischer rats with cysts of T. gondii NTE resulted in the generation of seven monoclonal antibodies of the immunoglobulin G2a, G2b, or M isotype, which were further characterized by the immunoblot technique, immunofluorescence assay, immunohistology, and immunoelectron microscopy. Immunoblots demonstrated specific reactivity of five monoclonal antibodies with proteins with molecular masses of 40, 52, 55, 60, 64, 65, and 115 kDa. One antibody (CC2) appeared to recognize a differently expressed antigen depending on the parasite stage, reacting with a 40-kDa molecule in tachyzoites and a 115-kDa antigen in bradyzoites and oocysts. Several other monoclonal antibodies were shown to be stage specific and to react in immunofluorescence assays or in immunoblots with either tachyzoites or bradyzoites. Kinetics of stage conversion in vitro could be monitored by immunofluorescence with two of these monoclonal antibodies. Preliminary immunohistological investigations of tissue sections from infected mice demonstrated the possible usefulness of these monoclonal antibodies for future in vivo studies on stage differentiation of T. gondii in the murine system.
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MESH Headings
- Animals
- Antibodies, Monoclonal/biosynthesis
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/classification
- Antibodies, Protozoan/biosynthesis
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/classification
- Antigen-Antibody Reactions
- Antigens, Protozoan/analysis
- Fluorescent Antibody Technique, Indirect
- Immunoblotting
- Immunoglobulin Isotypes/analysis
- Immunohistochemistry
- Kinetics
- Mice
- Mice, Inbred CBA
- Rats
- Species Specificity
- Toxoplasma/growth & development
- Toxoplasma/immunology
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/parasitology
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Affiliation(s)
- U Gross
- Institute of Hygiene and Microbiology, University of Würzburg, Germany
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50
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Porter KR, Liang L, Long GW, Bangs MJ, Anthony R, Andersen EM, Hayes CG. Evidence for anti-Plasmodium falciparum antibodies that cross-react with human T-lymphotropic virus type I proteins in a population in Irian Jaya, Indonesia. Clin Diagn Lab Immunol 1994; 1:11-5. [PMID: 7496910 PMCID: PMC368188 DOI: 10.1128/cdli.1.1.11-15.1994] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This study was performed to demonstrate the presence of anti-Plasmodium falciparum antibodies in a population living in Irian Jaya, Indonesia that cross-react with human T-lymphotropic virus type I (HTLV-I) proteins. Serum samples from 63 volunteers living in Oksibil, a secluded highland valley in Irian Jaya, were tested for anti-P. falciparum antibodies by an immunofluorescence assay and for anti-HTLV-I antibodies by an enzyme immunoassay (EIA). All samples were positive for anti-P. falciparum antibodies at titers of > or = 1:256. Twenty-four samples were reactive by EIA for HTLV-I, and of these, 23 were tested by western blotting (immunoblotting). Five of the 23 samples were classified as western blot positive and 18 were classified as western blot indeterminate. In competitive blocking assays with malaria proteins, western blot immunoreactivity to all HTLV-I Gag proteins was either reduced or eliminated. Significant reductions in the HTLV-I EIA optical density values of the Oksibil sera occurred when the sera were competitively blocked with the malaria antigens. The optical density values of HTLV-I-positive control sera showed no significant change. Competitive blocking with HTLV-I antigens produced reductions in the optical density values of both the Oksibil sera and the HTLV-I-positive control sera. These data suggest that in this population, anti-P. falciparum antibodies are cross-reactive with HTLV-I proteins in the western blot and EIA tests.
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Affiliation(s)
- K R Porter
- Infectious Diseases Threat Assessment Program, Naval Medical Research Institute, Bethesda, Maryland 20852, USA
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