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Asghari A, Nourmohammadi H, Majidiani H, Shariatzadeh SA, Shams M, Montazeri F. In silico analysis and prediction of immunogenic epitopes for pre-erythrocytic proteins of the deadly Plasmodium falciparum. INFECTION GENETICS AND EVOLUTION 2021; 93:104985. [PMID: 34214673 DOI: 10.1016/j.meegid.2021.104985] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 06/23/2021] [Accepted: 06/27/2021] [Indexed: 12/18/2022]
Abstract
Malaria is the deadliest parasitic disease in tropical and subtropical areas around the world, with considerable morbidity and mortality, particularly due to the life-threatening Plasmodium falciparum. The present in silico investigation was performed to reveal the biophysical characteristics and immunogenic epitopes of the six pre-erythrocytic proteins of the P. falciparum using comprehensive immunoinformatics approaches. For this aim, different web servers were employed to predict subcellular localization, antigenicity, allergenicity, solubility, physico-chemical properties, post-translational modification sites (PTMs), the presence of signal peptide and transmembrane domains. Moreover, the secondary and tertiary structures of the proteins were revealed followed by refinement and validations. Finally, NetCTL server was used to predict cytotoxic T-lymphocyte (CTL) epitopes, followed by subsequent screening in terms of antigenicity and immunogenicity. Also, IEDB server was utilized to predict helper T-lymphocyte (HTL) epitopes, followed by screening regarding interferon gamma induction and population coverage. These proteins showed appropriate antigenicity, abundant PTMs as well as many CTL and HTL epitopes, which could be directed for future vaccination studies in the context of multi-epitope vaccine design.
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Affiliation(s)
- Ali Asghari
- Department of Medical Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hassan Nourmohammadi
- Department of Internal Medicine, Shahid Mostafa Khomeini Hospital, Ilam University of Medical Sciences, Ilam, Iran; Zoonotic Diseases Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Hamidreza Majidiani
- Zoonotic Diseases Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Seyyed Ali Shariatzadeh
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran; Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.
| | - Morteza Shams
- Zoonotic Diseases Research Center, Ilam University of Medical Sciences, Ilam, Iran; Student Research Committee, Ilam University of Medical Sciences, Ilam, Iran.
| | - Fattaneh Montazeri
- Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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Moita D, Nunes-Cabaço H, Mendes AM, Prudêncio M. A guide to investigating immune responses elicited by whole-sporozoite pre-erythrocytic vaccines against malaria. FEBS J 2021; 289:3335-3359. [PMID: 33993649 DOI: 10.1111/febs.16016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/19/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022]
Abstract
In the last few decades, considerable efforts have been made toward the development of efficient vaccines against malaria. Whole-sporozoite (Wsp) vaccines, which induce efficient immune responses against the pre-erythrocytic (PE) stages (sporozoites and liver forms) of Plasmodium parasites, the causative agents of malaria, are among the most promising immunization strategies tested until present. Several Wsp PE vaccination approaches are currently under evaluation in the clinic, including radiation- or genetically-attenuated Plasmodium sporozoites, live parasites combined with chemoprophylaxis, or genetically modified rodent Plasmodium parasites. In addition to the assessment of their protective efficacy, clinical trials of Wsp PE vaccine candidates inevitably involve the thorough investigation of the immune responses elicited by vaccination, as well as the identification of correlates of protection. Here, we review the main methodologies employed to dissect the humoral and cellular immune responses observed in the context of Wsp PE vaccine clinical trials and discuss future strategies to further deepen the knowledge generated by these studies, providing a toolbox for the in-depth analysis of vaccine-induced immunogenicity.
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Affiliation(s)
- Diana Moita
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - Helena Nunes-Cabaço
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - António M Mendes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - Miguel Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
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Novel insights from the Plasmodium falciparum sporozoite-specific proteome by probabilistic integration of 26 studies. PLoS Comput Biol 2021; 17:e1008067. [PMID: 33930021 PMCID: PMC8115857 DOI: 10.1371/journal.pcbi.1008067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 05/12/2021] [Accepted: 04/06/2021] [Indexed: 11/19/2022] Open
Abstract
Plasmodium species, the causative agent of malaria, have a complex life cycle involving two hosts. The sporozoite life stage is characterized by an extended phase in the mosquito salivary glands followed by free movement and rapid invasion of hepatocytes in the human host. This transmission stage has been the subject of many transcriptomics and proteomics studies and is also targeted by the most advanced malaria vaccine. We applied Bayesian data integration to determine which proteins are not only present in sporozoites but are also specific to that stage. Transcriptomic and proteomic Plasmodium data sets from 26 studies were weighted for how representative they are for sporozoites, based on a carefully assembled gold standard for Plasmodium falciparum (Pf) proteins known to be present or absent during the sporozoite life stage. Of 5418 Pf genes for which expression data were available at the RNA level or at the protein level, 975 were identified as enriched in sporozoites and 90 specific to them. We show that Pf sporozoites are enriched for proteins involved in type II fatty acid synthesis in the apicoplast and GPI anchor synthesis, but otherwise appear metabolically relatively inactive in the salivary glands of mosquitos. Newly annotated hypothetical sporozoite-specific and sporozoite-enriched proteins highlight sporozoite-specific functions. They include PF3D7_0104100 that we identified to be homologous to the prominin family, which in human has been related to a quiescent state of cancer cells. We document high levels of genetic variability for sporozoite proteins, specifically for sporozoite-specific proteins that elicit antibodies in the human host. Nevertheless, we can identify nine relatively well-conserved sporozoite proteins that elicit antibodies and that together can serve as markers for previous exposure. Our understanding of sporozoite biology benefits from identifying key pathways that are enriched during this life stage. This work can guide studies of molecular mechanisms underlying sporozoite biology and potential well-conserved targets for marker and drug development. When a person is bitten by an infectious malaria mosquito, sporozoites are injected into the skin with mosquito saliva. These sporozoites then travel to the liver, invade hepatocytes and multiply before the onset of the symptom-causing blood stage of malaria. By integrating published data, we contrast sporozoite protein expression with other life stages to filter out the unique features of sporozoites that help us understand this stage. We used a “guideline” that we derived from the literature on individual proteins so that we knew which proteins should be present or absent at the sporozoite stage, allowing us to weigh 26 data sets for their relevance to sporozoites. Among the newly discovered sporozoite-specific genes are candidates for fatty acid synthesis while others might play a role keeping the sporozoites in an inactive state in the mosquito salivary glands. Furthermore, we show that most sporozoite-specific proteins are genetically more variable than non-sporozoite proteins. We identify a set of conserved sporozoite proteins against which antibodies can serve as markers of recent exposure to sporozoites or that can serve as vaccine candidates. Our predictions of sporozoite-specific proteins and the assignment of previously unknown functions give new insights into the biology of this life stage.
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Bettencourt P. Current Challenges in the Identification of Pre-Erythrocytic Malaria Vaccine Candidate Antigens. Front Immunol 2020; 11:190. [PMID: 32153565 PMCID: PMC7046804 DOI: 10.3389/fimmu.2020.00190] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/24/2020] [Indexed: 12/27/2022] Open
Abstract
Plasmodium spp.-infected mosquitos inject sporozoites into the skin of a mammalian host during a blood meal. These enter the host's circulatory system and establish an infection in the liver. After a silent metamorphosis, merozoites invade the blood leading to the symptomatic and transmissible stages of malaria. The silent pre-erythrocytic malaria stage represents a bottleneck in the disease which is ideal to block progression to clinical malaria, through chemotherapeutic and immunoprophylactic interventions. RTS,S/AS01, the only malaria vaccine close to licensure, although with poor efficacy, blocks the sporozoite invasion mainly through the action of antibodies against the CSP protein, a major component of the pellicle of the sporozoite. Strikingly, sterile protection against malaria can be obtained through immunization with radiation-attenuated sporozoites, genetically attenuated sporozoites or through chemoprophylaxis with infectious sporozoites in animals and humans, but the deployability of sporozoite-based live vaccines pose tremendous challenges. The protection induced by sporozoites occurs in the pre-erythrocytic stages and is mediated mainly by antibodies against the sporozoite and CD8+ T cells against peptides presented by MHC class I molecules in infected hepatocytes. Thus, the identification of malaria antigens expressed in the sporozoite and liver-stage may provide new vaccine candidates to be included, alone or in combination, as recombinant protein-based, virus-like particles or sub-unit virally-vectored vaccines. Here I review the efforts being made to identify Plasmodium falciparum antigens expressed during liver-stage with focus on the development of parasite, hepatocyte, mouse models, and resulting rate of infection in order to identify new vaccine candidates and to improve the efficacy of the current vaccines. Finally, I propose new approaches for the identification of liver-stage antigens based on immunopeptidomics.
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Heide J, Vaughan KC, Sette A, Jacobs T, Schulze Zur Wiesch J. Comprehensive Review of Human Plasmodium falciparum-Specific CD8+ T Cell Epitopes. Front Immunol 2019; 10:397. [PMID: 30949162 PMCID: PMC6438266 DOI: 10.3389/fimmu.2019.00397] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/15/2019] [Indexed: 12/16/2022] Open
Abstract
Control of malaria is an important global health issue and there is still an urgent need for the development of an effective prophylactic vaccine. Multiple studies have provided strong evidence that Plasmodium falciparum-specific MHC class I-restricted CD8+ T cells are important for sterile protection against Plasmodium falciparum infection. Here, we present an interactive epitope map of all P. falciparum-specific CD8+ T cell epitopes published to date, based on a comprehensive data base (IEDB), and literature search. The majority of the described P. falciparum-specific CD8+ T cells were directed against the antigens CSP, TRAP, AMA1, and LSA1. Notably, most of the epitopes were discovered in vaccine trials conducted with malaria-naïve volunteers. Only few immunological studies of P. falciparum-specific CD8+ T cell epitopes detected in patients suffering from acute malaria or in people living in malaria endemic areas have been published. Further detailed immunological mappings of P. falciparum-specific epitopes of a broader range of P. falciparum proteins in different settings and with different disease status are needed to gain a more comprehensive understanding of the role of CD8+ T cell responses for protection, and to better guide vaccine design and to study their efficacy.
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Affiliation(s)
- Janna Heide
- Infectious Diseases Unit, I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany
| | - Kerrie C Vaughan
- Division of Vaccine Discovery, La Jolla Institute for Immunology, La Jolla, CA, United States
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Immunology, La Jolla, CA, United States.,Department of Medicine, Division of Infectious Diseases, University of California, San Diego (UCSD), La Jolla, CA, United States
| | - Thomas Jacobs
- Protozoa Immunology, Bernhard-Nocht-Institute of Tropical Medicine, Hamburg, Germany
| | - Julian Schulze Zur Wiesch
- Infectious Diseases Unit, I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany
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Tuju J, Kamuyu G, Murungi LM, Osier FHA. Vaccine candidate discovery for the next generation of malaria vaccines. Immunology 2017; 152:195-206. [PMID: 28646586 PMCID: PMC5588761 DOI: 10.1111/imm.12780] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 12/21/2022] Open
Abstract
Although epidemiological observations, IgG passive transfer studies and experimental infections in humans all support the feasibility of developing highly effective malaria vaccines, the precise antigens that induce protective immunity remain uncertain. Here, we review the methodologies applied to vaccine candidate discovery for Plasmodium falciparum malaria from the pre- to post-genomic era. Probing of genomic and cDNA libraries with antibodies of defined specificities or functional activity predominated the former, whereas reverse vaccinology encompassing high throughput in silico analyses of genomic, transcriptomic or proteomic parasite data sets is the mainstay of the latter. Antibody-guided vaccine design spanned both eras but currently benefits from technological advances facilitating high-throughput screening and downstream applications. We make the case that although we have exponentially increased our ability to identify numerous potential vaccine candidates in a relatively short space of time, a significant bottleneck remains in their validation and prioritization for evaluation in clinical trials. Longitudinal cohort studies provide supportive evidence but results are often conflicting between studies. Demonstration of antigen-specific antibody function is valuable but the relative importance of one mechanism over another with regards to protection remains undetermined. Animal models offer useful insights but may not accurately reflect human disease. Challenge studies in humans are preferable but prohibitively expensive. In the absence of reliable correlates of protection, suitable animal models or a better understanding of the mechanisms underlying protective immunity in humans, vaccine candidate discovery per se may not be sufficient to provide the paradigm shift necessary to develop the next generation of highly effective subunit malaria vaccines.
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Affiliation(s)
- James Tuju
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Department of BiochemistryPwani UniversityKilifiKenya
| | - Gathoni Kamuyu
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Linda M. Murungi
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Faith H. A. Osier
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Centre for Infectious DiseasesHeidelberg University HospitalHeidelbergGermany
- Department of Biomedical SciencesPwani UniversityKilifiKenya
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Singh SP, Srivastava D, Mishra BN. Genome-wide identification of novel vaccine candidates for Plasmodium falciparum malaria using integrative bioinformatics approaches. 3 Biotech 2017; 7:318. [PMID: 28955615 DOI: 10.1007/s13205-017-0947-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 09/05/2017] [Indexed: 12/12/2022] Open
Abstract
In spite of decades of malaria research and clinical trials, a fully effective and long-lasting preventive vaccine remains elusive. In the present study, 5370 proteins of Plasmodium falciparum genome were screened for the presence of signal peptide/anchor and GPI anchor motifs. Out of 45 screened surface-associated proteins, 22 were consensually predicted as antigens and had no orthologs in human and mouse except circumsporozoite protein (PF3D7_0304600). Among 22 proteins, 19 were identified as new antigens. In the next step, a total of 4944 peptides were predicted as CD8+ T cell epitopes from 22 probable antigens. Of these, the highest scoring 262 epitopes from each antigen were taken for optimization study in the malaria-endemic regions which covered a broad human population (~93.95%). The predicted epitope 13ILFYFFLWV21 of antigen 6-cysteine (PF3D7_1346800) was binding to the HLA-A*0201 allele with the highest fraction (26%) of immunogenicity in the target populations of North-East Asia, South-East Asia, and sub-Saharan Africa. Therefore, these epitopes are proposed to be favored in vaccine designs against malaria.
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Affiliation(s)
- Satarudra Prakash Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh (Lucknow Campus), Lucknow, 226028 India
| | - Deeksha Srivastava
- Institute of Engineering and Technology, Dr. A.P.J. Abdul Kalam Technical University (Formerly Known as U.P. Technical University), Lucknow, 226021 India
| | - Bhartendu Nath Mishra
- Institute of Engineering and Technology, Dr. A.P.J. Abdul Kalam Technical University (Formerly Known as U.P. Technical University), Lucknow, 226021 India
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Druilhe P, Sabchareon A, Bouharoun-Tayoun H, Oeuvray C, Perignon JL. In vivo veritas: lessons from immunoglobulin-transfer experiments in malaria patients. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2016. [DOI: 10.1080/00034983.1997.11813238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Stone BC, Kas A, Billman ZP, Fuller DH, Fuller JT, Shendure J, Murphy SC. Complex Minigene Library Vaccination for Discovery of Pre-Erythrocytic Plasmodium T Cell Antigens. PLoS One 2016; 11:e0153449. [PMID: 27070430 PMCID: PMC4829254 DOI: 10.1371/journal.pone.0153449] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/30/2016] [Indexed: 01/15/2023] Open
Abstract
Development of a subunit vaccine targeting liver-stage Plasmodium parasites requires the identification of antigens capable of inducing protective T cell responses. However, traditional methods of antigen identification are incapable of evaluating T cell responses against large numbers of proteins expressed by these parasites. This bottleneck has limited development of subunit vaccines against Plasmodium and other complex intracellular pathogens. To address this bottleneck, we are developing a synthetic minigene technology for multi-antigen DNA vaccines. In an initial test of this approach, pools of long (150 bp) antigen-encoding oligonucleotides were synthesized and recombined into vectors by ligation-independent cloning to produce two DNA minigene library vaccines. Each vaccine encoded peptides derived from 36 (vaccine 1) and 53 (vaccine 2) secreted or transmembrane pre-erythrocytic P. yoelii proteins. BALB/cj mice were vaccinated three times with a single vaccine by biolistic particle delivery (gene gun) and screened for interferon-γ-producing T cell responses by ELISPOT. Library vaccination induced responses against four novel antigens. Naïve mice exposed to radiation-attenuated sporozoites mounted a response against only one of the four novel targets (PyMDH, malate dehydrogenase). The response to PyMDH could not be recalled by additional homologous sporozoite immunizations but could be partially recalled by heterologous cross-species sporozoite exposure. Vaccination against the dominant PyMDH epitope by DNA priming and recombinant Listeria boosting did not protect against sporozoite challenge. Improvements in library design and delivery, combined with methods promoting an increase in screening sensitivity, may enable complex minigene screening to serve as a high-throughput system for discovery of novel T cell antigens.
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Affiliation(s)
- Brad C. Stone
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- * E-mail: (BCS); (SCM)
| | - Arnold Kas
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Zachary P. Billman
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Deborah H. Fuller
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - James T. Fuller
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Sean C. Murphy
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Seattle Malaria Clinical Trials Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Human Challenge Center, Center for Infectious Disease Research, Seattle, Washington, United States of America
- * E-mail: (BCS); (SCM)
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Aguiar JC, Bolton J, Wanga J, Sacci JB, Iriko H, Mazeika JK, Han ET, Limbach K, Patterson NB, Sedegah M, Cruz AM, Tsuboi T, Hoffman SL, Carucci D, Hollingdale MR, Villasante ED, Richie TL. Discovery of Novel Plasmodium falciparum Pre-Erythrocytic Antigens for Vaccine Development. PLoS One 2015; 10:e0136109. [PMID: 26292257 PMCID: PMC4546230 DOI: 10.1371/journal.pone.0136109] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 07/29/2015] [Indexed: 02/07/2023] Open
Abstract
Background Nearly 100% protection against malaria infection can be achieved in humans by immunization with P. falciparum radiation-attenuated sporozoites (RAS). Although it is thought that protection is mediated by T cell and antibody responses, only a few of the many pre-erythrocytic (sporozoite and liver stage) antigens that are targeted by these responses have been identified. Methodology Twenty seven P. falciparum pre-erythrocytic antigens were selected using bioinformatics analysis and expression databases and were expressed in a wheat germ cell-free protein expression system. Recombinant proteins were recognized by plasma from RAS-immunized subjects, and 21 induced detectable antibody responses in mice and rabbit and sera from these immunized animals were used to characterize these antigens. All 21 proteins localized to the sporozoite: five localized to the surface, seven localized to the micronemes, cytoplasm, endoplasmic reticulum or nucleus, two localized to the surface and cytoplasm, and seven remain undetermined. PBMC from RAS-immunized volunteers elicited positive ex vivo or cultured ELISpot responses against peptides from 20 of the 21 antigens. Conclusions These T cell and antibody responses support our approach of using reagents from RAS-immunized subjects to screen potential vaccine antigens, and have led to the identification of a panel of novel P. falciparum antigens. These results provide evidence to further evaluate these antigens as vaccine candidates. Trial Registration ClinicalTrials.gov NCT00870987 ClinicalTrials.gov NCT00392015
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Affiliation(s)
- Joao C. Aguiar
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- Camris International, Bethesda, MD 20814, United States of America
- * E-mail:
| | - Jessica Bolton
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, United States of America
| | - Joyce Wanga
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- Technical Resources International, Inc., Bethesda, MD 20817, United States of America
| | - John B. Sacci
- Department of Microbiology and Immunology, The University of Maryland School of Medicine, Baltimore, MD 21201, United States of America
| | - Hideyuki Iriko
- Department of International Health, Kobe University Graduate School of Health Science, Kobe 654-0142, Japan
| | - Julie K. Mazeika
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- EMD Millipore Corporation, North Andover, MA 01845, United States of America
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea
| | - Keith Limbach
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, United States of America
| | - Noelle B. Patterson
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, United States of America
| | - Martha Sedegah
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
| | - Ann-Marie Cruz
- PATH Malaria Vaccine Initiative, Washington, DC 20001, United States of America
| | - Takafumi Tsuboi
- Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Stephen L. Hoffman
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
| | - Daniel Carucci
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
| | - Michael R. Hollingdale
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, United States of America
| | - Eileen D. Villasante
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
| | - Thomas L. Richie
- Malaria Department, Naval Medical Research Center, Silver Spring, MD 20910, United States of America
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SSP3 is a novel Plasmodium yoelii sporozoite surface protein with a role in gliding motility. Infect Immun 2014; 82:4643-53. [PMID: 25156733 DOI: 10.1128/iai.01800-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Plasmodium sporozoites develop within oocysts in the mosquito midgut wall and then migrate to the salivary glands. After transmission, they embark on a complex journey to the mammalian liver, where they infect hepatocytes. Proteins on the sporozoite surface likely mediate multiple steps of this journey, yet only a few sporozoite surface proteins have been described. Here, we characterize a novel, conserved sporozoite surface protein (SSP3) in the rodent malaria parasite Plasmodium yoelii. SSP3 is a putative type I transmembrane protein unique to Plasmodium. By using epitope tagging and SSP3-specific antibodies in conjunction with immunofluorescence microscopy, we showed that SSP3 is expressed in mosquito midgut oocyst sporozoites, exhibiting an intracellular localization. In sporozoites derived from the mosquito salivary glands, however, SSP3 localized predominantly to the sporozoite surface as determined by immunoelectron microscopy. However, the ectodomain of SSP3 appeared to be inaccessible to antibodies in nonpermeabilized salivary gland sporozoites. Antibody-induced shedding of the major surface protein circumsporozoite protein (CSP) exposed the SSP3 ectodomain to antibodies in some sporozoites. Targeted deletion of SSP3 adversely affected in vitro sporozoite gliding motility, which, surprisingly, impacted neither their cell traversal capacity, host cell invasion in vitro, nor infectivity in vivo. Together, these data reveal a previously unappreciated complexity of the Plasmodium sporozoite surface proteome and the roles of surface proteins in distinct biological activities of sporozoites.
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Sheehy SH, Spencer AJ, Douglas AD, Sim BKL, Longley RJ, Edwards NJ, Poulton ID, Kimani D, Williams AR, Anagnostou NA, Roberts R, Kerridge S, Voysey M, James ER, Billingsley PF, Gunasekera A, Lawrie AM, Hoffman SL, Hill AVS. Optimising Controlled Human Malaria Infection Studies Using Cryopreserved P. falciparum Parasites Administered by Needle and Syringe. PLoS One 2013; 8:e65960. [PMID: 23823332 PMCID: PMC3688861 DOI: 10.1371/journal.pone.0065960] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 04/29/2013] [Indexed: 11/18/2022] Open
Abstract
Background Controlled human malaria infection (CHMI) studies have become a routine tool to evaluate efficacy of candidate anti-malarial drugs and vaccines. To date, CHMI trials have mostly been conducted using the bite of infected mosquitoes, restricting the number of trial sites that can perform CHMI studies. Aseptic, cryopreserved P. falciparum sporozoites (PfSPZ Challenge) provide a potentially more accurate, reproducible and practical alternative, allowing a known number of sporozoites to be administered simply by injection. Methodology We sought to assess the infectivity of PfSPZ Challenge administered in different dosing regimens to malaria-naive healthy adults (n = 18). Six participants received 2,500 sporozoites intradermally (ID), six received 2,500 sporozoites intramuscularly (IM) and six received 25,000 sporozoites IM. Findings Five out of six participants receiving 2,500 sporozoites ID, 3/6 participants receiving 2,500 sporozoites IM and 6/6 participants receiving 25,000 sporozoites IM were successfully infected. The median time to diagnosis was 13.2, 17.8 and 12.7 days for 2,500 sporozoites ID, 2,500 sporozoites IM and 25,000 sporozoites IM respectively (Kaplan Meier method; p = 0.024 log rank test). Conclusions 2,500 sporozoites ID and 25,000 sporozoites IM have similar infectivities. Given the dose response in infectivity seen with IM administration, further work should evaluate increasing doses of PfSPZ Challenge IM to identify a dosing regimen that reliably infects 100% of participants. Trial Registration ClinicalTrials.gov NCT01465048
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Affiliation(s)
- Susanne H. Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | | | | | - B. Kim Lee Sim
- Sanaria Inc., Rockville, Maryland, United States of America
| | - Rhea J. Longley
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Nick J. Edwards
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Ian D. Poulton
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Domtila Kimani
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Andrew R. Williams
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Nicholas A. Anagnostou
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Rachel Roberts
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Simon Kerridge
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Merryn Voysey
- Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom
| | - Eric R. James
- Sanaria Inc., Rockville, Maryland, United States of America
| | | | | | - Alison M. Lawrie
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Adrian V. S. Hill
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
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Offeddu V, Thathy V, Marsh K, Matuschewski K. Naturally acquired immune responses against Plasmodium falciparum sporozoites and liver infection. Int J Parasitol 2012; 42:535-48. [DOI: 10.1016/j.ijpara.2012.03.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/18/2012] [Accepted: 03/24/2012] [Indexed: 10/28/2022]
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Porter DW, Thompson FM, Berthoud TK, Hutchings CL, Andrews L, Biswas S, Poulton I, Prieur E, Correa S, Rowland R, Lang T, Williams J, Gilbert SC, Sinden RE, Todryk S, Hill AVS. A human Phase I/IIa malaria challenge trial of a polyprotein malaria vaccine. Vaccine 2011; 29:7514-22. [PMID: 21501642 PMCID: PMC3195259 DOI: 10.1016/j.vaccine.2011.03.083] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 02/12/2011] [Accepted: 03/22/2011] [Indexed: 11/30/2022]
Abstract
We examined the safety, immunogenicity and efficacy of a prime-boost vaccination regime involving two poxvirus malaria subunit vaccines, FP9-PP and MVA-PP, expressing the same polyprotein consisting of six pre-erythrocytic antigens from Plasmodium falciparum. Following safety assessment of single doses, 15 volunteers received a heterologous prime-boost vaccination regime and underwent malaria sporozoite challenge. The vaccines were safe but interferon-γ ELISPOT responses were low compared to other poxvirus vectors, despite targeting multiple antigens. There was no vaccine efficacy as measured by delay in time to parasitaemia. A number of possible explanations are discussed, including the very large insert size of the polyprotein transgene.
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Affiliation(s)
- David W Porter
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Oxford, OX3 7LJ, UK.
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15
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Suwancharoen C, Putaporntip C, Rungruang T, Jongwutiwes S. Naturally acquired IgG antibodies against the C-terminal part of Plasmodium falciparum sporozoite threonine–asparagine-rich protein in a low endemic area. Parasitol Res 2011; 109:315-20. [DOI: 10.1007/s00436-011-2257-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 01/14/2011] [Indexed: 10/18/2022]
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Bermúdez A, Alba MP, Vanegas M, Patarroyo ME. 3D structure determination of STARP peptides implicated in P. falciparum invasion of hepatic cells. Vaccine 2010; 28:4989-96. [PMID: 20580741 DOI: 10.1016/j.vaccine.2010.05.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/17/2010] [Accepted: 05/07/2010] [Indexed: 10/19/2022]
Abstract
To block the different stages of Plasmodium falciparum invasion into human hepatocytes and red blood cells, we have focused on those proteins belonging to the pre-erythrocytic stage. One of these proteins is Sporozoite Threonine and Asparagine Rich Protein (STARP), which is a ligand used by P. falciparum parasites to bind Hepatic cells (HepG2). Previous studies on this protein identified two conserved peptides binding with high activity to HepG2 cells (namely 20546 and 20570) with corresponding critical hepatic-cell binding residues and determined an important role for these two peptides in the invasion process. This study shows the results of immunization trials in Aotus monkeys with native STARP peptides and analogues modified in critical hepatic-cell binding residues. The results show that native peptides are not immunogenic but can induce high-antibody titers when their critical residues are replaced by other with similar volume and mass but different polarity. Nuclear Magnetic Resonance ((1)H NMR) studies revealed that native peptides (non-immunogenic) displayed shorter alpha-helical regions compared to their highly immunogenic modified analogues. Binding assays with HLA-DRbeta1* molecules showed that 20546 modified peptides inducing high-antibody titers (24972, 24320 and 24486) bound to HLA-DRbeta1*0301 molecules, while the 20570 modified analogue (24322) bound to HLA-DRbeta1*0101. The results support including these high-immunogenic STARP-derived modified peptides as pre-erythrocytic candidates to be included in the design of a synthetic antimalarial vaccine.
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Affiliation(s)
- Adriana Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Colombia
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17
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A prospective analysis of the Ab response to Plasmodium falciparum before and after a malaria season by protein microarray. Proc Natl Acad Sci U S A 2010; 107:6958-63. [PMID: 20351286 DOI: 10.1073/pnas.1001323107] [Citation(s) in RCA: 327] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Abs are central to malaria immunity, which is only acquired after years of exposure to Plasmodium falciparum (Pf). Despite the enormous worldwide burden of malaria, the targets of protective Abs and the basis of their inefficient acquisition are unknown. Addressing these knowledge gaps could accelerate malaria vaccine development. To this end, we developed a protein microarray containing approximately 23% of the Pf 5,400-protein proteome and used this array to probe plasma from 220 individuals between the ages of 2-10 years and 18-25 years in Mali before and after the 6-month malaria season. Episodes of malaria were detected by passive surveillance over the 8-month study period. Ab reactivity to Pf proteins rose dramatically in children during the malaria season; however, most of this response appeared to be short-lived based on cross-sectional analysis before the malaria season, which revealed only modest incremental increases in Ab reactivity with age. Ab reactivities to 49 Pf proteins measured before the malaria season were significantly higher in 8-10-year-old children who were infected with Pf during the malaria season but did not experience malaria (n = 12) vs. those who experienced malaria (n = 29). This analysis also provided insight into patterns of Ab reactivity against Pf proteins based on the life cycle stage at which proteins are expressed, subcellular location, and other proteomic features. This approach, if validated in larger studies and in other epidemiological settings, could prove to be a useful strategy for better understanding fundamental properties of the human immune response to Pf and for identifying previously undescribed vaccine targets.
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18
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Mackinnon MJ, Li J, Mok S, Kortok MM, Marsh K, Preiser PR, Bozdech Z. Comparative transcriptional and genomic analysis of Plasmodium falciparum field isolates. PLoS Pathog 2009; 5:e1000644. [PMID: 19898609 PMCID: PMC2764095 DOI: 10.1371/journal.ppat.1000644] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 10/05/2009] [Indexed: 11/18/2022] Open
Abstract
Mechanisms for differential regulation of gene expression may underlie much of the phenotypic variation and adaptability of malaria parasites. Here we describe transcriptional variation among culture-adapted field isolates of Plasmodium falciparum, the species responsible for most malarial disease. It was found that genes coding for parasite protein export into the red cell cytosol and onto its surface, and genes coding for sexual stage proteins involved in parasite transmission are up-regulated in field isolates compared with long-term laboratory isolates. Much of this variability was associated with the loss of small or large chromosomal segments, or other forms of gene copy number variation that are prevalent in the P. falciparum genome (copy number variants, CNVs). Expression levels of genes inside these segments were correlated to that of genes outside and adjacent to the segment boundaries, and this association declined with distance from the CNV boundary. This observation could not be explained by copy number variation in these adjacent genes. This suggests a local-acting regulatory role for CNVs in transcription of neighboring genes and helps explain the chromosomal clustering that we observed here. Transcriptional co-regulation of physical clusters of adaptive genes may provide a way for the parasite to readily adapt to its highly heterogeneous and strongly selective environment.
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19
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Nguyen TV, Sacci JB, de la Vega P, John CC, James AA, Kang AS. Characterization of immunoglobulin G antibodies to Plasmodium falciparum sporozoite surface antigen MB2 in malaria exposed individuals. Malar J 2009; 8:235. [PMID: 19852802 PMCID: PMC2772840 DOI: 10.1186/1475-2875-8-235] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 10/23/2009] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND MB2 protein is a sporozoite surface antigen on the human malaria parasite Plasmodium falciparum. MB2 was identified by screening a P. falciparum sporozoite cDNA expression library using immune sera from a protected donor immunized via the bites of P. falciparum-infected irradiated mosquitoes. It is not known whether natural exposure to P. falciparum also induces the anti-MB2 response and if this response differs from that in protected individuals immunized via the bites of P. falciparum infected irradiated mosquitoes. The anti-MB2 antibody response may be part of a robust protective response against the sporozoite. METHODS Fragments of polypeptide regions of MB2 were constructed as recombinant fusions sandwiched between glutathione S-transferase and a hexa histidine tag for bacterial expression. The hexa histidine tag affinity purified proteins were used to immunize rabbits and the polyclonal sera evaluated in an in vitro inhibition of sporozoite invasion assay. The proteins were also used in immunoblots with sera from a limited number of donors immunized via the bites of P. falciparum infected irradiated mosquitoes and plasma and serum obtained from naturally exposed individuals in Kenya. RESULTS Rabbit polyclonal antibodies targeting the non-repeat region of the basic domain of MB2 inhibited sporozoites entry into HepG2-A16 cells in vitro. Analysis of serum from five human volunteers that were immunized via the bites of P. falciparum infected irradiated mosquitoes that developed immunity and were completely protected against subsequent challenge with non-irradiated parasite also had detectable levels of antibody against MB2 basic domain. In contrast, in three volunteers not protected, anti-MB2 antibodies were below the level of detection. Sera from protected volunteers preferentially recognized a non-repeat region of the basic domain of MB2, whereas plasma from naturally-infected individuals also had antibodies that recognize regions of MB2 that contain a repeat motif in immunoblots. Sequence analysis of eleven field isolates and four laboratory strains showed that these antigenic regions of the basic domain of the MB2 gene are highly conserved in parasites obtained from different parts of the world. Moreover, anti-MB2 antibodies also were detected in the plasma of 83% of the individuals living in a malaria endemic area of Kenya (n = 41). CONCLUSION A preliminary analysis of the human humoral response against MB2 indicates that it may be an additional highly conserved target for immune intervention at the pre-erythrocytic stage of P. falciparum life cycle.
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Affiliation(s)
- Thanh V Nguyen
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
- NeoGenomics California, 6 Morgan, Suite 150, Irvine, CA 92618, USA
| | - John B Sacci
- Department of Microbiology and Immunology, University of Maryland, School of Medicine, Room 324 660 W Redwood Street, Baltimore, MD 21201, USA
| | - Patricia de la Vega
- Department of Microbiology and Immunology, University of Maryland, School of Medicine, Room 324 660 W Redwood Street, Baltimore, MD 21201, USA
- Department of Cell Mediated Immunity, Division of Malaria Vaccine Development, US Military Malaria Vaccine Program, Walter Reed Army Institute of Research, USA
| | - Chandy C John
- Global Pediatrics Program and Division of Pediatric Infectious Diseases, University of MN Medical School, 420 Delaware Street, SE, MMC #296, 850-Mayo, Minneapolis, MN 55455, USA
| | - Anthony A James
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-3900, USA
| | - Angray S Kang
- The School of Life Sciences, Department of Molecular and Applied Biosciences, University of Westminster, 115 New Cavendish Street, London, W1W 6UW, UK
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Tall A, Sokhna C, Perraut R, Fontenille D, Marrama L, Ly AB, Sarr FD, Toure A, Trape JF, Spiegel A, Rogier C, Druilhe P. Assessment of the relative success of sporozoite inoculations in individuals exposed to moderate seasonal transmission. Malar J 2009; 8:161. [PMID: 19604389 PMCID: PMC2717115 DOI: 10.1186/1475-2875-8-161] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 07/15/2009] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The time necessary for malaria parasite to re-appear in the blood following treatment (re-infection time) is an indirect method for evaluating the immune defences operating against pre-erythrocytic and early erythrocytic malaria stages. Few longitudinal data are available in populations in whom malaria transmission level had also been measured. METHODS One hundred and ten individuals from the village of Ndiop (Senegal), aged between one and 72 years, were cured of malaria by quinine (25 mg/day oral Quinimax in three equal daily doses, for seven days). Thereafter, thick blood films were examined to detect the reappearance of Plasmodium falciparum every week, for 11 weeks after treatment. Malaria transmission was simultaneously measured weekly by night collection of biting mosquitoes. RESULTS Malaria transmission was on average 15.3 infective bites per person during the 77 days follow up. The median reappearance time for the whole study population was 46.8 days, whereas individuals would have received an average one infective bite every 5 days. At the end of the follow-up, after 77 days, 103 of the 110 individuals (93.6%; CI 95% [89.0-98.2]) had been re-infected with P. falciparum. The median reappearance time ('re-positivation') was longer in subjects with patent parasitaemia at enrolment than in parasitologically-negative individuals (58 days vs. 45.9; p = 0.03) and in adults > 30 years than in younger subjects (58.6 days vs. 42.7; p = 0.0002). In a multivariate Cox PH model controlling for the sickle cell trait, G6PD deficiency and the type of habitat, the presence of parasitaemia at enrolment and age >/= 30 years were independently predictive of a reduced risk of re-infection (PH = 0.5 [95% CI: 0.3-0.9] and 0.4; [95% CI: 0.2-0.6] respectively). CONCLUSION Results indicate the existence of a substantial resistance to sporozoites inoculations, but which was ultimately overcome in almost every individual after 2 1/2 months of natural challenges. Such a study design and the results obtained suggest that, despite a small sample size, this approach can contribute to assess the impact of intervention methods, such as the efficacy vector-control measures or of malaria pre-erythrocytic stages vaccines.
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Affiliation(s)
- Adama Tall
- Unité d'Epidémiologie, Institut Pasteur de Dakar, B.P. 220 Dakar, Sénégal.
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21
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Doolan DL, Mu Y, Unal B, Sundaresh S, Hirst S, Valdez C, Randall A, Molina D, Liang X, Freilich DA, Oloo JA, Blair PL, Aguiar JC, Baldi P, Davies DH, Felgner PL. Profiling humoral immune responses to P. falciparum infection with protein microarrays. Proteomics 2009; 8:4680-94. [PMID: 18937256 DOI: 10.1002/pmic.200800194] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A complete description of the serological response following exposure of humans to complex pathogens is lacking and approaches suitable for accomplishing this are limited. Here we report, using malaria as a model, a method which elucidates the profile of antibodies that develop after natural or experimental infection or after vaccination with attenuated organisms, and which identifies immunoreactive antigens of interest for vaccine development or other applications. Expression vectors encoding 250 Plasmodium falciparum (Pf) proteins were generated by PCR/recombination cloning; the proteins were individually expressed with >90% efficiency in Escherichia coli cell-free in vitro transcription and translation reactions, and printed directly without purification onto microarray slides. The protein microarrays were probed with human sera from one of four groups which differed in immune status: sterile immunity or no immunity against experimental challenge following vaccination with radiation-attenuated Pf sporozoites, partial immunity acquired by natural exposure, and no previous exposure to Pf. Overall, 72 highly reactive Pf antigens were identified. Proteomic features associated with immunoreactivity were identified. Importantly, antibody profiles were distinct for each donor group. Information obtained from such analyses will facilitate identifying antigens for vaccine development, dissecting the molecular basis of immunity, monitoring the outcome of whole-organism vaccine trials, and identifying immune correlates of protection.
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22
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Jongwutiwes S, Putaporntip C, Karnchaisri K, Seethamchai S, Hongsrimuang T, Kanbara H. Positive selection on the Plasmodium falciparum sporozoite threonine-asparagine-rich protein: analysis of isolates mainly from low endemic areas. Gene 2008; 410:139-46. [PMID: 18201845 DOI: 10.1016/j.gene.2007.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 11/22/2007] [Accepted: 12/11/2007] [Indexed: 11/17/2022]
Abstract
The sporozoite threonine-asparagine-rich protein (STARP) of Plasmodium falciparum is an attractive target for a pre-erythrocytic stage malaria vaccine because both naturally acquired and experimentally induced anti-STARP antibodies can block sporozoite invasion of hepatocytes. To explore the extent of sequence variation, we surveyed nucleotide polymorphism across the entire gene, encompassing 2 exons and an intron, of 124 P. falciparum-infected blood samples from Thailand and 10 from 4 other endemic areas. In total 24 haplotypes were identified despite low-level nucleotide diversity at this locus. The mean number of nonsynonymous substitutions per nonsynonymous site (d(N)) significantly exceeded that of synonymous substitutions per synonymous site (d(S)), suggesting that the STARP gene has evolved under positive selection, probably from host immune pressure. The preponderance of conservative amino acid exchanges and a strongly biased T-nucleotide toward the third position of codons in repeat arrays have reflected simultaneous constraints on this molecule, probably from its respective unknown function and nucleotide composition. Sequence conservation in the STARP locus among clinical isolates from different disease endemic areas would not compromise vaccine incorporation.
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Affiliation(s)
- Somchai Jongwutiwes
- Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
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Li F, Sonbuchner L, Kyes SA, Epp C, Deitsch KW. Nuclear non-coding RNAs are transcribed from the centromeres of Plasmodium falciparum and are associated with centromeric chromatin. J Biol Chem 2007; 283:5692-8. [PMID: 18165241 DOI: 10.1074/jbc.m707344200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-coding RNAs (ncRNAs) play an important role in a variety of nuclear processes, including genetic imprinting, RNA interference-mediated transcriptional repression, and dosage compensation. These transcripts are thought to influence chromosome organization and, in some cases, gene expression by directing the assembly of specific chromatin modifications to targeted regions of the genome. In the malaria parasite Plasmodium falciparum, little is known about the regulation of nuclear organization or gene expression, although a notable scarcity of identifiable transcription factors encoded in its genome has led to speculation that this organism may be unusually reliant on chromatin modifications as a mechanism for regulating gene expression. To study the mechanisms that regulate chromatin structure in malaria parasites, we examined the role of ncRNAs in the assembly of chromatin at the centromeres of P. falciparum. We show that centromeric regions within the Plasmodium genome contain bidirectional promoter activity driving the expression of short ncRNAs that are localized within the nucleus and appear to associate with the centromeres themselves, strongly suggesting that they are central characters in the maintenance and function of centromeric chromatin. These observations support the hypothesis that ncRNAs play an important role in the proper organizational assembly of chromatin in P. falciparum, perhaps compensating for a lack of both regulatory transcription factors and RNA interference machinery.
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Affiliation(s)
- Felomena Li
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021, USA
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Druilhe P, Barnwell JW. Pre-erythrocytic stage malaria vaccines: time for a change in path. Curr Opin Microbiol 2007; 10:371-8. [PMID: 17709281 DOI: 10.1016/j.mib.2007.07.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 07/25/2007] [Indexed: 11/17/2022]
Abstract
Vaccines against the pre-erythrocytic stages of malaria hold the greatest promise as an effective intervention tool against malaria, as shown by immunization with radiation-attenuated sporozoites over four decades ago. To date, however, the development of subunit vaccines, while generating high expectations and investment, has not lived up at all to the promise. This path has been characterized by insufficient research into both identification of key defense mechanisms in humans and the discovery of better antigens, focusing rather on a technological race of how to present mainly a single antigen. The lack of success has also led, perhaps from desperation, to a revival of the live attenuated sporozoite approach, handicapped, however, by major bottlenecks in production, safety, and regulatory issues. It should now be clear that the field can no longer continue to succeed in mice and fail in the clinic. We advocate here in favor of a third option, relying on an understanding of the basis of attenuated sporozoite immunity in humans, to provide leads to the discovery of critical immunogens and the use of models with validated relevance to the human situation in order to rationalize and renew the promise of pre-erythrocytic subunit vaccines.
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Affiliation(s)
- Pierre Druilhe
- Biomedical Parasitology Unit, Department of Parasitology & Mycology, Pasteur Institute, Paris, France.
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25
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Garcia JE, Puentes A, Patarroyo ME. Developmental biology of sporozoite-host interactions in Plasmodium falciparum malaria: implications for vaccine design. Clin Microbiol Rev 2006; 19:686-707. [PMID: 17041140 PMCID: PMC1592691 DOI: 10.1128/cmr.00063-05] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum sporozoite infects different types of cells in a mosquito's salivary glands and human epithelial and Kuppfer cells and hepatocytes. These become differentiated later on, transforming themselves into the invasive red blood cell form, the merozoite. The ability of sporozoites to interact with different types of cells requires a wide variety of mechanisms allowing them to survive in both hosts: mobility, receptor-ligand interactions with different cellular receptors, and transformation and development into other invasive parasite forms, which are vitally important for parasite survival. Sporozoite complexity is reflected in the large quantity of proteins that can be expressed. Some of them have been extensively studied, such as CSP, TRAP, STARP, LSA-1, LSA-3, SALSA, SPECT1, SPECT2, MAEBL, and SPATR, due to their importance in infection and their potential use as vaccines. Our work has been focused on the search for the molecular mechanisms of parasite-host cellular receptor-ligand interactions by identifying amino acid sequences and the critical binding residues from these proteins relevant to parasite invasion. Once such sequences have been identified, it will be possible to modify them to induce a strong immune response against P. falciparum in the experimental Aotus monkey model. This all leads towards developing multistage, multicomponent, subunit-based vaccines that will be effective in eradicating or controlling malaria caused by P. falciparum.
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Affiliation(s)
- Javier E Garcia
- Fundacion Instituto de Immunología de Colombia, Carrera 50 #26-00, Bogotá, Colombia
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Sacci JB, Ribeiro JMC, Huang F, Alam U, Russell JA, Blair PL, Witney A, Carucci DJ, Azad AF, Aguiar JC. Transcriptional analysis of in vivo Plasmodium yoelii liver stage gene expression. Mol Biochem Parasitol 2005; 142:177-83. [PMID: 15876462 DOI: 10.1016/j.molbiopara.2005.03.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Revised: 03/07/2005] [Accepted: 03/31/2005] [Indexed: 11/18/2022]
Abstract
The transcriptional repertoire of the in vivo liver stage of Plasmodium has remained largely unidentified and seemingly not amenable to traditional molecular analysis because of the small number of parasites and large number of uninfected hepatocytes. We have overcome this obstruction by utilizing laser capture microdissection to provide a high quality source of parasite mRNA for the construction of a liver stage cDNA library. Sequencing and annotation of this library demonstrated expression of 623 different Plasmodium yoelii genes during development in the hepatocyte. Of these genes, 25% appear to be unique to the liver stage. This is the first comprehensive analysis of in vivo gene expression undertaken for the liver stage of P. yoelii, and provides insights into the differential expression of P. yoelii genes during this critical stage of development.
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Affiliation(s)
- John B Sacci
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA.
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BenMohamed L, Thomas A, Druilhe P. Long-term multiepitopic cytotoxic-T-lymphocyte responses induced in chimpanzees by combinations of Plasmodium falciparum liver-stage peptides and lipopeptides. Infect Immun 2004; 72:4376-84. [PMID: 15271893 PMCID: PMC470687 DOI: 10.1128/iai.72.8.4376-4384.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Preclinical immunogenicity studies of 12 malaria peptides, selected from four Plasmodium falciparum antigens (Ags), namely, LSA1, LSA3, SALSA, and STARP, that are expressed at the pre-erythrocytic (sporozoite and liver) stages of the human parasite were carried out in chimpanzees. To strengthen their immunogenicity, six of these synthetic peptides were modified by the C-terminal addition of a single palmitoyl chain (lipopeptides) and delivered without adjuvant, whereas the remaining six unmodified peptides were emulsified and delivered by using Montanide ISA51 adjuvant. We have previously reported that these peptides and lipopeptides induce high B-cell and CD4(+)-T-helper responses in chimpanzees. In this report, we show their ability to induce multiepitopic and long-lasting antigen-specific CD8(+) cytotoxic-T-lymphocyte (CTL) responses. The magnitude, consistency, and memory of CTL responses generated by LSA3 peptides point to the strong immunogenicity of this liver-stage Ag. These findings support the screening strategy used to select the four P. falciparum pre-erythrocytic Ags and emphasize their valuable immunogenic properties. The successful immunization of nonhuman primates with combinations of corresponding peptides in a mineral oil emulsion (ISA51) and lipopeptides in saline provide a vaccine formulation that can be tested in humans.
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Affiliation(s)
- Lbachir BenMohamed
- Unité de Parasitologie Bio-Médicale, Institut Pasteur, 75015 Paris, France
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28
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Prieur E, Gilbert SC, Schneider J, Moore AC, Sheu EG, Goonetilleke N, Robson KJH, Hill AVS. A Plasmodium falciparum candidate vaccine based on a six-antigen polyprotein encoded by recombinant poxviruses. Proc Natl Acad Sci U S A 2003; 101:290-5. [PMID: 14694197 PMCID: PMC314178 DOI: 10.1073/pnas.0307158101] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To generate broadly protective T cell responses more similar to those acquired after vaccination with radiation-attenuated Plasmodium falciparum sporozoites, we have constructed candidate subunit malaria vaccines expressing six preerythrocytic antigens linked together to produce a 3240-aa-long polyprotein (L3SEPTL). This polyprotein was expressed by a plasmid DNA vaccine vector (DNA) and by two attenuated poxvirus vectors, modified vaccinia virus Ankara (MVA) and fowlpox virus of the FP9 strain. MVAL3SEPTL boosted anti-thrombospondin-related adhesive protein (anti-TRAP) and anti-liver stage antigen 1 (anti-LSA1) CD8(+) T cell responses when primed by single antigen TRAP- or LSA1-expressing DNAs, respectively, but not by DNA-L3SEPTL. However, prime boost regimes involving two heterologous viral vectors expressing L3SEPTL induced a strong cellular response directed against an LSA1 peptide located in the C-terminal region of the polyprotein. Peptide-specific T cells secreted IFN-gamma and were cytotoxic. IFN-gamma-secreting T cells specific for each of the six antigens were induced after vaccination with L3SEPTL, supporting the use of polyprotein inserts to induce multispecific T cells against P. falciparum. The use of polyprotein constructs in nonreplicating poxviruses should broaden the target antigen range of vaccine-induced immunity and increase the number of potential epitopes available for immunogenetically diverse human populations.
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Affiliation(s)
- Eric Prieur
- Weatherall Institute of Molecular Medicine and Cellular Immunology, Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
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29
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Chauhan VS, Bhardwaj D. Current status of malaria vaccine development. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2003; 84:143-82. [PMID: 12934936 DOI: 10.1007/3-540-36488-9_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
There is an urgent need to develop an effective vaccine against malaria--a disease that has approximately 10% of the world population at risk of infection at any given time. The economic burden this disease puts on the medico-social set-up of countries in Sub-Saharan Africa and South East Asia is phenomenal. Increasing drug resistance and failure of vector control strategies have necessitated the search for a suitable vaccine that could be integrated into the extended program of immunization for countries in the endemic regions. Malaria vaccine development has seen a surge of activity in the last decade or so owing largely to the advances made in the fields of genetic engineering and biotechnology. This revolution has brought sweeping changes in the understanding of the biology of the parasite and has helped formulate newer more effective strategies to combat the disease. Latest developments in the field of malaria vaccine development will be discussed in this chapter.
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Affiliation(s)
- Virander Singh Chauhan
- Malaria Research Group, International Center for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India.
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30
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López R, Garcia J, Puentes A, Curtidor H, Ocampo M, Vera R, Rodriguez LE, Suarez J, Urquiza M, Rodríguez AL, Reyes CA, Granados CG, Patarroyo ME. Identification of specific Hep G2 cell binding regions in Plasmodium falciparum sporozoite-threonine-asparagine-rich protein (STARP). Vaccine 2003; 21:2404-11. [PMID: 12744871 DOI: 10.1016/s0264-410x(03)00063-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It has been demonstrated that Plasmodium falciparum sporozoite threonine-asparagine-rich protein (PfSTARP) is located on the sporozoite surface. This protein's non-overlapping consecutive peptides were synthesised and tested in Hep G2 cell binding assays. Twelve high activity binding peptides (HABPs) were identified in the resulting 31 peptides. Three were found in 5' non-repeat region (amino acids 41-80). Peptides 20546 (41VIKHNRFLSEYQSNFLGGGY(60)), 20547 (61SAALKLVNSKKSGTNVNVTKY(80)) and 20548 (81NSENTNTNNNIPESSSTYTN(100)) were located in the conserved amino terminal region, as well as peptide 20548 which shared the sequence with the M region (amino acids 85-134). Six HABPs were located in region 10 (Rp10) (STDNNNTKTI). HABPs 20569 (501TSDDELNKDSCDYSEEKENI(520)) and 20570 (521KSMINAYLDKLDLETVRKIH(40)) were found in 3' non-repeat region. All these HABPs showed saturable binding and presented dissociation constants between 18 and 219 nM. The number of binding sites per Hep G2 cell ranged from 45000 to 370000. High binding peptides' critical amino acids involved in Hep G2 cell binding were determined by competition binding assays. SDS-PAGE results showed that both peptides 20570 and 20547 had at least two different sets of 44 and 38 kDa HABP receptors on Hep G2 cells. Specific modification of peptide 20546 and 20570 critical binding residues rendered these peptides immunogenic in Aotus monkeys, inducing high antibody titres against sporozoites, as assessed by IFA.
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Affiliation(s)
- Ramsés López
- Fundación Instituto de Inmunología de Colombia (FIDIC), Universidad Nacional de Colombia, Carrera 50 No 26-00, Bogotá, Colombia
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31
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Kyes SA, Christodoulou Z, Raza A, Horrocks P, Pinches R, Rowe JA, Newbold CI. A well-conserved Plasmodium falciparum var gene shows an unusual stage-specific transcript pattern. Mol Microbiol 2003; 48:1339-48. [PMID: 12787360 PMCID: PMC2869446 DOI: 10.1046/j.1365-2958.2003.03505.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The var multicopy gene family encodes Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) variant antigens, which, through their ability to adhere to a variety of host receptors, are thought to be important virulence factors. The predominant expression of a single cytoadherent PfEMP1 type on an infected red blood cell, and the switching between different PfEMP1 types to evade host protective antibody responses, are processes thought to be controlled at the transcriptional level. Contradictory data have been published on the timing of var gene transcription. Reverse transcription-polymerase chain reaction (RT-PCR) data suggested that transcription of the predominant var gene occurs in the later (pigmented trophozoite) stages, whereas Northern blot data indicated such transcripts only in early (ring) stages. We investigated this discrepancy by Northern blot, with probes covering a diverse var gene repertoire. We confirm that almost all var transcript types were detected only in ring stages. However, one type, the well-conserved varCSA transcript, was present constitutively in different laboratory parasites and does not appear to undergo antigenic variation. Although varCSA has been shown to encode a chondroitin sulphate A (CSA)-binding PfEMP1, we find that the presence of full-length varCSA transcripts does not correlate with the CSA-binding phenotype.
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Affiliation(s)
- Sue A Kyes
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, Headington, Oxford OX3 9DS, UK.
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32
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García JE, Puentes A, López R, Vera R, Suárez J, Rodríguez L, Curtidor H, Ocampo M, Tovar D, Forero M, Bermudez A, Cortés J, Urquiza M, Patarroyo ME. Peptides of the liver stage antigen-1 (LSA-1) of Plasmodium falciparum bind to human hepatocytes. Peptides 2003; 24:647-57. [PMID: 12895649 DOI: 10.1016/s0196-9781(03)00135-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Synthetic peptides from the liver stage antigen-1 (LSA-1) antigen sequence were used in HepG2 cell and erythrocyte binding assays to identify regions that could be involved in parasite invasion. LSA-1 protein peptides 20630 ((21)INGKIIKNSEKDEIIKSNLRY(40)), 20637 ((157)KEKLQGQQSDSEQERRAY(173)), 20638 ((174)KEKLQEQQSDLEQERLAY(190)) and 20639 (191KEKLQEQQSDLEQERRAY(207)) had high binding activity in HepG2 assays. Were located in immunogenic regions; peptide cell binding was saturable. Peptide 20630 bound specifically to 48kDa HepG2 membrane surface protein. LSA-1 peptides 20630 ((21)INGKIIKNSEKDEIIKSNLRY(40)) and 20633 ((81)DKELTMSNVKNVSQTNFKSLY(100)) showed specific erythrocyte binding activity and inhibited merozoite invasion of erythrocytes in vitro. A monkey serum prepared against LSA-1 20630 peptide analog (CGINGKNIKNAEKPMIIKSNLRGC) inhibited merozoite invasion in vitro. The data suggest LSA-1 "High Activity Binding Peptides" could play a possible role in hepatic cell invasion as well as merozoite invasion of erythrocytes.
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Affiliation(s)
- Javier E García
- Fundación Instituto de Inmunologi;a de Colombia, Universidad Nacional de Colombia, Bogotá, Colombia
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33
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Lobo CA, Rodriguez M, Hou G, Perkins M, Oskov Y, Lustigman S. Characterization of PfRhop148, a novel rhoptry protein of Plasmodium falciparum. Mol Biochem Parasitol 2003; 128:59-65. [PMID: 12706797 DOI: 10.1016/s0166-6851(03)00050-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Rhoptries are apical organelles which play an important role in erythrocytic invasion. A Plasmodium falciparum cDNA clone, coding for a novel rhoptry protein PfRhop148, was obtained by antibody screening of a library. The deduced amino acid sequence consists of 1262 amino acids and is highly rich in Asn (22%). The Asn residues are distributed in clusters and in multiple units of repeats. Analysis of specific RNA transcript and protein showed that PfRhop148 was synthesized at around 21 h post-invasion. IFA and immunoelectron microscopic analyses revealed a rhoptry localization for the protein. The role of this protein in invasion and its relationship to the RhopH complex is now under further investigation.
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Affiliation(s)
- Cheryl-Ann Lobo
- Department of Molecular Parasitology, The Lindsley Kimball Research Institute, New York Blood Center, 310 E 67th St, New York, NY 10021, USA.
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34
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Grüner AC, Snounou G, Brahimi K, Letourneur F, Rénia L, Druilhe P. Pre-erythrocytic antigens of Plasmodium falciparum: from rags to riches? Trends Parasitol 2003; 19:74-8. [PMID: 12586475 DOI: 10.1016/s1471-4922(02)00067-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A growing number of Plasmodium genomes have joined the sequencing treadmill, and the genome of Plasmodium falciparum has recently been published. Most malaria vaccinologists will soon be confronted by a bewildering array of new potential antigens from the recently completed genome of this parasite. However, for those aiming to target the pre-erythrocytic stages of the hepatic parasite, the wait might be long. In the absence of readily available materials and specific reagents, the selection of pre-erythrocytic antigens from raw sequence data is likely to prove difficult. Here, current knowledge of pre-erythrocytic antigens is updated in the light of recent results, and the post-genomic prospects of completing the antigenic repertoire of these immunologically important and intriguing stages is discussed.
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Affiliation(s)
- Anne Charlotte Grüner
- Unité de Parasitologie Biomédicale, Institut Pasteur, 25 Rue du Dr Roux, 75724 Paris Cedex 15, France
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35
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Abstract
The complex life cycle of malaria parasites requires significant changes in gene expression as the parasites move from vector to host and back to the vector. Although recognised as an important vaccine and drug target, the liver stage parasite has remained difficult to study. One of the major impediments in identifying parasite gene expression at the liver stage has remained the large number of uninfected hepatocytes relative to the number of infected hepatocytes in the liver after sporozoite inoculation. This article describes several of the approaches that have been utilised to overcome this difficulty in rodent models of malaria. While significant progress has been made to identify genes that are expressed during liver stage parasite development, a great deal more work remains to be done.
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Affiliation(s)
- John B Sacci
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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36
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Gilbert SC, Schneider J, Hannan CM, Hu JT, Plebanski M, Sinden R, Hill AVS. Enhanced CD8 T cell immunogenicity and protective efficacy in a mouse malaria model using a recombinant adenoviral vaccine in heterologous prime-boost immunisation regimes. Vaccine 2002; 20:1039-45. [PMID: 11803063 DOI: 10.1016/s0264-410x(01)00450-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recombinant replication-defective adenovirus expressing the CS gene from Plasmodium berghei (Ad-PbCS) was found to induce a strong CD8(+) T cell response after intra-dermal or -muscular immunisation. Boosting of an adenovirus-primed immune response with the replication-impaired poxvirus, modified vaccinia virus Ankara (MVA) led to enhanced immunogenicity and substantial protective efficacy. The recombinant adenoviral vaccine was capable of boosting to protective levels a CD8(+) T cell response primed by either a plasmid DNA vaccine, a recombinant Ty virus-like particle vaccine or recombinant MVA each expressing the same epitope or antigen. Complete protective efficacy after intradermal immunisation was observed with the adenovirus prime-MVA boost regime. This study identifies recombinant replication-defective adenovirus as an alternative to recombinant replication-defective poxviruses as boosting agents for the induction of strong protective CD8(+) T cell responses.
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Affiliation(s)
- Sarah C Gilbert
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, OX3 7BN, Oxford, UK.
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37
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Abstract
Many pathogens that either rely on an insect vector to complete their life cycle (e.g., Trypanosoma spp. and Borrelia spp.) or exist in a unique ecological niche where transmission from host to host is sporadic (e.g., Neisseria spp.) have evolved strategies to maintain infection of their mammalian hosts for long periods of time in order to ensure their survival. Because they have to survive in the face of a fully functional immune system, a common feature of many of these organisms is their development of sophisticated strategies for immune evasion. For the above organisms and for malaria parasites of the genus Plasmodium, a common theme is the ability to undergo clonal antigenic variation. In all cases, surface molecules that are important targets of the humoral immune response are encoded in the genome as multicopy, nonallelic gene families. Antigenic variation is accomplished by the successive expression of members of these gene families that show little or no immunological cross-reactivity. In the case of malaria parasites, however, some of the molecules that undergo antigenic variation are also major virulence factors, adding an additional level of complication to the host-parasite interaction. In this review, we cover the history of antigenic variation in malaria and then summarize the more recent data with particular emphasis on Plasmodium falciparum, the etiological agent of the most severe form of human malaria.
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Affiliation(s)
- S Kyes
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, Headington, Oxford OX3 9DS United Kingdom.
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38
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Kappe SH, Gardner MJ, Brown SM, Ross J, Matuschewski K, Ribeiro JM, Adams JH, Quackenbush J, Cho J, Carucci DJ, Hoffman SL, Nussenzweig V. Exploring the transcriptome of the malaria sporozoite stage. Proc Natl Acad Sci U S A 2001; 98:9895-900. [PMID: 11493695 PMCID: PMC55549 DOI: 10.1073/pnas.171185198] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2001] [Indexed: 11/18/2022] Open
Abstract
Most studies of gene expression in Plasmodium have been concerned with asexual and/or sexual erythrocytic stages. Identification and cloning of genes expressed in the preerythrocytic stages lag far behind. We have constructed a high quality cDNA library of the Plasmodium sporozoite stage by using the rodent malaria parasite P. yoelii, an important model for malaria vaccine development. The technical obstacles associated with limited amounts of RNA material were overcome by PCR-amplifying the transcriptome before cloning. Contamination with mosquito RNA was negligible. Generation of 1,972 expressed sequence tags (EST) resulted in a total of 1,547 unique sequences, allowing insight into sporozoite gene expression. The circumsporozoite protein (CS) and the sporozoite surface protein 2 (SSP2) are well represented in the data set. A BLASTX search with all tags of the nonredundant protein database gave only 161 unique significant matches (P(N) < or = 10(-4)), whereas 1,386 of the unique sequences represented novel sporozoite-expressed genes. We identified ESTs for three proteins that may be involved in host cell invasion and documented their expression in sporozoites. These data should facilitate our understanding of the preerythrocytic Plasmodium life cycle stages and the development of preerythrocytic vaccines.
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Affiliation(s)
- S H Kappe
- Michael Heidelberger Division, Department of Pathology, Kaplan Cancer Center, New York University School of Medicine, New York, NY 10016, USA.
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39
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Brahimi K, Badell E, Sauzet JP, BenMohamed L, Daubersies P, Guérin-Marchand C, Snounou G, Druilhe P. Human antibodies against Plasmodium falciparum liver-stage antigen 3 cross-react with Plasmodium yoelii preerythrocytic-stage epitopes and inhibit sporozoite invasion in vitro and in vivo. Infect Immun 2001; 69:3845-52. [PMID: 11349050 PMCID: PMC98406 DOI: 10.1128/iai.69.6.3845-3952.2001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum liver-stage antigen 3 (LSA3), a recently identified preerythrocytic antigen, induces protection against malaria in chimpanzees. Using antibodies from individuals with hyperimmunity to malaria affinity purified on recombinant or synthetic polypeptides of LSA3, we identified four non-cross-reactive B-cell epitopes in Plasmodium yoelii preerythrocytic stages. On sporozoites the P. yoelii protein detected has a molecular mass similar to that of LSA3. T-cell epitopes cross-reacting with P. yoelii were also demonstrated using peripheral blood lymphocytes from LSA3-immunized chimpanzees. In contrast, no cross-reactive epitopes were found in Plasmodium berghei. LSA3-specific human antibodies exerted up to 100% inhibition of in vitro invasion of P. yoelii sporozoites into mouse hepatocytes. This strong in vitro activity was reproduced in vivo by passive transfer of LSA3 antibodies. These results indicate that the homologous epitopes may be biologically functional and suggest that P. yoelii could be used as a model to assess the antisporozoite activity of anti-LSA3 antibodies.
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Affiliation(s)
- K Brahimi
- Laboratoire de Parasitologie Biomédicale, Institut Pasteur, 75015 Paris Cedex 15, France
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40
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Nguyen TV, Fujioka H, Kang AS, Rogers WO, Fidock DA, James AA. Stage-dependent localization of a novel gene product of the malaria parasite, Plasmodium falciparum. J Biol Chem 2001; 276:26724-31. [PMID: 11371568 DOI: 10.1074/jbc.m103375200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel Plasmodium falciparum gene, MB2, was identified by screening a sporozoite cDNA library with the serum of a human volunteer protected experimentally by the bites of P. falciparum-infected and irradiated mosquitoes. The single-exon, single-copy MB2 gene is predicted to encode a protein with an M(r) of 187,000. The MB2 protein has an amino-terminal basic domain, a central acidic domain, and a carboxyl-terminal domain with similarity to the GTP-binding domain of the prokaryotic translation initiation factor 2. MB2 is expressed in sporozoites, the liver, and blood-stage parasites and gametocytes. The MB2 protein is distributed as a approximately 120-kDa moiety on the surface of sporozoites and is imported into the nucleus of blood-stage parasites as a approximately 66-kDa species. Proteolytic processing is favored as the mechanism regulating the distinct subcellular localization of the MB2 protein. This differential localization provides multiple opportunities to exploit the MB2 gene product as a vaccine or therapeutic target.
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Affiliation(s)
- T V Nguyen
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA
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41
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Grüner AC, Brahimi K, Eling W, Konings R, Meis J, Aikawa M, Daubersies P, Guérin-Marchand C, Mellouk S, Snounou G, Druilhe P. The Plasmodium falciparum knob-associated PfEMP3 antigen is also expressed at pre-erythrocytic stages and induces antibodies which inhibit sporozoite invasion. Mol Biochem Parasitol 2001; 112:253-61. [PMID: 11223132 DOI: 10.1016/s0166-6851(00)00373-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The expression of the pfemp3 gene and the corresponding PfEMP3 knob-associated protein in the pre-erythrocytic stages of Plasmodium falciparum was demonstrated by RT-PCR, Western blots, IFAT and IEM. The antigen was found on the surface of the sporozoite and in the cytoplasm of mature hepatic stage parasites. Immunological cross-reactivity was observed with sporozoites from the rodent malaria parasites Plasmodium yoelii yoelii and Plasmodium berghei and was exploited to assess a potential role of this protein at the pre-erythrocytic stages. Specific antibodies from immune individuals were found to inhibit P. yoelii yoelii and P. berghei sporozoite invasion of primary hepatocyte cultures. PfEMP3 should now be added to the small list of proteins expressed at the pre-erythrocytic stages of P. falciparum, and its vaccine potential now deserves to be investigated.
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MESH Headings
- Animals
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- Antigens, Protozoan/ultrastructure
- Blotting, Western
- Cloning, Molecular
- Conserved Sequence
- Cross Reactions/immunology
- Epitopes/immunology
- Erythrocytes/parasitology
- Fluorescent Antibody Technique, Indirect
- Gene Expression Regulation, Developmental
- Hepatocytes/parasitology
- Humans
- Immune Sera/immunology
- Malaria/immunology
- Malaria/parasitology
- Membrane Proteins/genetics
- Membrane Proteins/immunology
- Membrane Proteins/metabolism
- Membrane Proteins/ultrastructure
- Microscopy, Immunoelectron
- Plasmodium/immunology
- Plasmodium falciparum/genetics
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Plasmodium falciparum/metabolism
- Protozoan Proteins
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- Recombinant Proteins
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Affiliation(s)
- A C Grüner
- Unité de Parasitologie Biomédicale, Institut Pasteur, 25 and 28 Rue du Dr. Roux, Paris Cedex 15, 75724, France
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42
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González JM, Peter K, Esposito F, Nebié I, Tiercy JM, Bonelo A, Arévalo-Herrera M, Valmori D, Romero P, Herrera S, Corradin G, López JA. HLA-A*0201 restricted CD8+ T-lymphocyte responses to malaria: identification of new Plasmodium falciparum epitopes by IFN-gamma ELISPOT. Parasite Immunol 2000; 22:501-14. [PMID: 11012976 DOI: 10.1046/j.1365-3024.2000.00331.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of antigen specific CD8+ T-lymphocytes in mediating protection against sporozoite-induced malaria has been well established in murine models. In humans, indirect evidence has accumulated suggesting a similar protective role for antigen-specific CD8+ T-lymphocytes. Nevertheless, the low frequency of circulating specific cells together with the lack of sensitive methods to quantify them has hampered the direct assessment of their function. Using a combination of short-term cell culture and IFN-gamma ELISPOT, we studied CD8+ T-lymphocyte responses to a panel of HLA-A*0201 binding peptides. In addition to confirming the response to already described epitopes, we also identified five new CD8+ T-lymphocyte epitopes. These epitopes are presented in pre-erythrocytic stages gene products of Plasmodium falciparum 7G8 strain and correspond to the following protein segments: circumsporozoite (CS) 64-72, 104-113, 299-308 and 403-411; liver stage antigen (LSA-1) repeat region; sporozoite surface protein 2 or thrombospondin related anonymous protein (SSP2/TRAP) 78-88 and 504-513. Four of these peptides are conserved amongst all published sequences of P. falciparum strains. We conclude that the modified IFN-gamma ELISPOT assay is a sensitive technique to monitor antigen-specific CD8+ T-lymphocyte responses in human malaria which may help in the improvement and assessment of the efficacy of malaria subunit vaccines.
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Affiliation(s)
- J M González
- Instituto de Inmunología del Valle, Universidad del Valle, Cali, Colombia
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Benmohamed L, Thomas A, Bossus M, Brahimi K, Wubben J, Gras-Masse H, Druilhe P. High immunogenicity in chimpanzees of peptides and lipopeptides derived from four new Plasmodium falciparum pre-erythrocytic molecules. Vaccine 2000; 18:2843-55. [PMID: 10812228 DOI: 10.1016/s0264-410x(00)00068-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have investigated the immunogenicity in chimpanzees of twelve synthetic peptides derived from four new Plasmodium falciparum molecules expressed at pre-erythrocytic stages of the human malaria parasite. These parasite molecules were initially selected through their ability to be recognized by stage restricted human antibodies. Twelve 20- to 41-mer peptides representing potential human B- or T-cell epitopes were selected from these proteins, and synthesized. Six of these were modified by a C-terminal lipidic chain in order to re-inforce their immunogenicity. Strong B- and T-helper cell responses were induced in chimpanzees by lipopeptides injected without adjuvant and by peptides in Montanide. All twelve peptides induced CD4(+) T-cell proliferative responses, as well as the secretion of IFN-gamma (some of them at very high levels) and eleven peptides induced antibody responses. The immune responses elicited in this way were reactive with native parasite proteins, as shown by recall studies with sporozoite stage proteins, and proved to be long-lasting (up to 10 months after immunization). Our results support the strategy employed to select these four new malarial antigens and the corresponding peptides, and suggest that the immunizing formulations are both efficient and clinically acceptable.
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Affiliation(s)
- L Benmohamed
- Unité de Parasitologie Bio-Médicale, Institut Pasteur, Paris, France
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Zhang K, Fujioka H, Aikawa M, Kumar N. Plasmodium falciparum: detection of a novel asparagine-rich protein on the surface of sporozoite. Exp Parasitol 1999; 93:1-6. [PMID: 10464033 DOI: 10.1006/expr.1999.4435] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We had previously cloned and characterized a gene for a novel asparagine-rich protein from P. falciparum (PfARP), a target of natural human immune response. The antibodies to PfARP were localized to the surface of parasitized red blood cells and reacted with intracellular components in all erythrocytic asexual and sexual stages of the parasite. We here describe reactivity of antibodies against this novel PfARP on the surface of mosquito stage sporozoite of P. falciparum by indirect immunofluorescence assay and immunoelectron microscopy, the latter revealing a highly periodic punctate pattern of distribution of PfARP on the surface of sporozoite. These results suggest a possibility that PfARP might represent yet another sporozoite surface protein.
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Affiliation(s)
- K Zhang
- Department of Molecular Microbiology and Immunology, School of Hygiene and Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, Maryland 21205, USA
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45
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Abstract
Malaria infection of the host cells requires host-parasite recognition events mediated by adhesion and signaling molecules. Recent development of systems for stable transformation and targeted integration of exogenous DNA in malaria parasites provides a powerful tool to study the structure and function of Plasmodium attachment motifs, and their role in infection and disease.
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Affiliation(s)
- R L Coppel
- Department of Microbiology, Monash University, Clayton, Victoria 3168, Australia
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46
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Chen Q, Fernandez V, Sundström A, Schlichtherle M, Datta S, Hagblom P, Wahlgren M. Developmental selection of var gene expression in Plasmodium falciparum. Nature 1998; 394:392-5. [PMID: 9690477 DOI: 10.1038/28660] [Citation(s) in RCA: 370] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The protozoan Plasmodium falciparum causes lethal malaria. Adhesion of erythrocytes infected with P. falciparum to vascular endothelium and to uninfected red blood cells (rosetting) may be involved in the pathogenesis of severe malaria. The binding is mediated by the antigenically variant erythrocyte-membrane-protein-1 (PfEMP-1), which is encoded by members of the P. falciparum var gene family. The control of expression and switching of var genes seems to lack resemblance to mechanisms operating in variant gene families of other microbial pathogens. Here we show that multiple, distinct var gene transcripts (about 24 or more) can be detected by reverse transcription and polymerase chain reaction in bulk cultures of the rosetting parasite FCR3S1.2, despite the adhesive homogeneity of the cultures. We also detected several var transcripts in single erythrocytes infected with a ring-stage parasite of FCR3S1.2, and found that different var genes are transcribed simultaneously from several chromosomes in the same cell. In contrast, we detected only one var transcript, FCR3S1.2 var-1, which encodes the rosetting PfEMP-1 protein, in individual rosette-adhesive trophozoite-infected cells, and we found only one PfEMP-1 type at the erythrocyte surface by labelling with 125iodine and immunoprecipitation. We conclude that a single P. falciparum parasite simultaneously transcribes multiple var genes but, through a developmentally regulated process, selects only one PfEMP-1 to reach the surface of the host cell.
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Affiliation(s)
- Q Chen
- Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden
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47
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Perlaza BL, Arévalo-Herrera M, Brahimi K, Quintero G, Palomino JC, Gras-Masse H, Tartar A, Druilhe P, Herrera S. Immunogenicity of four Plasmodium falciparum preerythrocytic antigens in Aotus lemurinus monkeys. Infect Immun 1998; 66:3423-8. [PMID: 9632616 PMCID: PMC108363 DOI: 10.1128/iai.66.7.3423-3428.1998] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aotus lemurinus monkeys were immunized with pools of either lipid-tailed peptides injected in PBS or peptides in Montanide ISA-51, all derived from four Plasmodium falciparum pre-erythrocytic antigens, namely, LSA1, LSA3, SALSA, and STARP. These formulations were well tolerated. Their immunogenicity was demonstrated by the induction of both B- and T-cell responses to most of the peptides studied (of the 12, 10 induced antibody production, 9 induced T-cell proliferative responses, and all 12 induced gamma interferon secretion). Immune responses proved to be long lasting, since some were still detectable 210 days after immunization. Of particular importance is the fact that B- and T-cell responses elicited in this way by synthetic peptides were specific for native parasite proteins on P. falciparum sporozoites and liver stage parasites.
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Affiliation(s)
- B L Perlaza
- Instituto de Inmunologia, Universidad del Valle, AA 2188 Cali, Colombia
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48
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de Vries E, Stam JG, Zijlstra NM, Overdulve JP. Sequence diversity in the intron, flanking sequences and coding region of the DNA polymerase alpha gene of Plasmodium falciparum. Mol Biochem Parasitol 1998; 93:139-42. [PMID: 9662036 DOI: 10.1016/s0166-6851(98)00019-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- E de Vries
- Institute of Infectious Diseases and Immunology, Department of Parasitology and Tropical Veterinary Medicine, Utrecht University, The Netherlands.
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49
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Fidock DA, Pasquetto V, Gras H, Badell E, Eling W, Ballou WR, Belghiti J, Tartar A, Druilhe P. Plasmodium falciparum sporozoite invasion is inhibited by naturally acquired or experimentally induced polyclonal antibodies to the STARP antigen. Eur J Immunol 1997; 27:2502-13. [PMID: 9368603 DOI: 10.1002/eji.1830271007] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Antibody(Ab)-mediated inhibition of sporozoite invasion of hepatocytes is a mechanism that has been clearly demonstrated to act upon Plasmodium falciparum pre-erythrocytic stages in humans. Consequently we have analyzed the Ab response to a recently identified P. falciparum sporozoite surface protein, STARP, in malaria-exposed individuals and tested the inhibitory effect of these Ab upon hepatocyte invasion in vitro. STARP-specific IgG were detected in 90 and 61% of sera from regions where individuals were exposed to 100 and 1-5 infectious bites per year, respectively. These IgG were predominantly of the cytophilic IgG1 or IgG3 type. STARP and the major sporozoite surface protein, CS, elicited equivalent IgG levels in adults. When affinity purified from either African immune sera or the serum of an individual experimentally protected by irradiated sporozoite immunization, STARP-specific Ab prevented up to 90% of sporozoites from invading human hepatocytes. The dose-dependent and reproducible inhibition was more pronounced than that observed with human CS-specific Ab affinity purified under identical conditions. Substantial reduction of sporozoite invasion was also observed with Ab induced by artificial immunization with recombinant STARP protein and reactive with the native protein. Taken together with recent findings of human cytotoxic T lymphocytes specific for this antigen, these results promote the interest of studying the efficacy of STARP as a target for immune effector mechanisms operating upon pre-erythrocytic stages.
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Affiliation(s)
- D A Fidock
- Laboratoire de Parasitologie Bio-Médicale, Institut Pasteur, Paris, France
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50
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BenMohamed L, Gras-Masse H, Tartar A, Daubersies P, Brahimi K, Bossus M, Thomas A, Druilhe P. Lipopeptide immunization without adjuvant induces potent and long-lasting B, T helper, and cytotoxic T lymphocyte responses against a malaria liver stage antigen in mice and chimpanzees. Eur J Immunol 1997; 27:1242-53. [PMID: 9174617 DOI: 10.1002/eji.1830270528] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have employed a 26-amino-acid synthetic peptide based on Plasmodium falciparum liver stage antigen-3 to evaluate improvements in immunogenicity mediated by the inclusion of a simple lipid-conjugated amino acid during peptide synthesis. Comparative immunization by the peptide in Freund's adjuvant or by the lipopeptide in saline shows that the addition of a palmitoyl chain can dramatically increase T helper (Th) cell responses in a wide range of major histocompatibility complex (MHC) class II haplotypes, to the extent that responses were induced in mice otherwise unable to respond to the non-modified peptide injected with Freund's adjuvant, and that the increased immunogenicity of the lipopeptide led to high and longer lasting antibody production (studied up to 8 months). B and T cell responses induced by the lipopeptide were reactive with native parasite protein epitopes, and a lipopeptide longer than ten amino acids was endogenously processed to associate with MHC class I and elicit cytotoxic T lymphocyte (CTL) responses. Finally, the lipopeptide was safe and highly immunogenic in chimpanzees, whose immune system is very similar to that of humans. Our results suggest that relatively large synthetic peptides, carefully chosen from pertinent areas of proteins and incorporating a simple palmitoyl-lysine, can induce not only CTL, but also strong Th and antibody responses in genetically diverse populations. Lipopeptides engineered in this way are simple to produce and purify under GMP conditions, they are well tolerated by apes, and with the enhanced immunogenicity without the need for adjuvant that we report here, they offer a quick and relatively low-cost route to provide material for human malaria vaccination trials.
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MESH Headings
- Adjuvants, Immunologic/pharmacology
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/biosynthesis
- Antibodies, Protozoan/drug effects
- Antigens, Protozoan/immunology
- B-Lymphocytes/immunology
- Conserved Sequence
- Lipoproteins/chemistry
- Lipoproteins/immunology
- Lipoproteins/pharmacology
- Liver/immunology
- Liver/parasitology
- Lymphocyte Activation/drug effects
- Malaria, Falciparum/immunology
- Malaria, Falciparum/prevention & control
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Molecular Sequence Data
- Palmitic Acid/pharmacology
- Pan troglodytes
- Peptides/chemistry
- Peptides/immunology
- Peptides/pharmacology
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Protozoan Proteins/immunology
- Protozoan Vaccines/immunology
- Sequence Analysis
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Helper-Inducer/immunology
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Affiliation(s)
- L BenMohamed
- Laboratoire de Parasitologie, Bio-Médicale, Institut Pasteur, Paris, France
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