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Chia WN, Goh YS, Rénia L. Novel approaches to identify protective malaria vaccine candidates. Front Microbiol 2014; 5:586. [PMID: 25452745 PMCID: PMC4233905 DOI: 10.3389/fmicb.2014.00586] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 12/17/2022] Open
Abstract
Efforts to develop vaccines against malaria have been the focus of substantial research activities for decades. Several categories of candidate vaccines are currently being developed for protection against malaria, based on antigens corresponding to the pre-erythrocytic, blood stage, or sexual stages of the parasite. Long lasting sterile protection from Plasmodium falciparum sporozoite challenge has been observed in human following vaccination with whole parasite formulations, clearly demonstrating that a protective immune response targeting predominantly the pre-erythrocytic stages can develop against malaria. However, most of vaccine candidates currently being investigated, which are mostly subunits vaccines, have not been able to induce substantial (>50%) protection thus far. This is due to the fact that the antigens responsible for protection against the different parasite stages are still yet to be known and relevant correlates of protection have remained elusive. For a vaccine to be developed in a timely manner, novel approaches are required. In this article, we review the novel approaches that have been developed to identify the antigens for the development of an effective malaria vaccine.
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Affiliation(s)
- Wan Ni Chia
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore ; Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore, Singapore
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore ; Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore, Singapore
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Lu F, Li J, Wang B, Cheng Y, Kong DH, Cui L, Ha KS, Sattabongkot J, Tsuboi T, Han ET. Profiling the humoral immune responses to Plasmodium vivax infection and identification of candidate immunogenic rhoptry-associated membrane antigen (RAMA). J Proteomics 2014; 102:66-82. [PMID: 24607491 DOI: 10.1016/j.jprot.2014.02.029] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/05/2014] [Accepted: 02/23/2014] [Indexed: 11/17/2022]
Abstract
UNLABELLED Completion of sequencing of the Plasmodium vivax genome and transcriptome offers the chance to identify antigens among >5000 candidate proteins. To identify those P. vivax proteins that are immunogenic, a total of 152 candidate proteins (160 fragments) were expressed using a wheat germ cell-free system. The results of Western blot analysis showed that 92.5% (148/160) of the targets were expressed, and 96.6% (143/148) were in a soluble form with 67.7% of solubility rate. The proteins were screened by protein arrays with sera from 22 vivax malaria patients and 10 healthy individuals to confirm their immune profile, and 44 (27.5%, 44/160) highly reactive P. vivax antigens were identified. Overall, 5 candidates (rhoptry-associated membrane antigen [RAMA], Pv-fam-a and -b, EXP-1 and hypothetical protein PVX_084775) showed a positive reaction with >80% of patient sera, and 21 candidates with 50% to 80%. More than 23% of the highly immunoreactive proteins were hypothetical proteins, described for the first time in this study. One of the top immunogenic proteins, RAMA, was characterized and confirmed to be a serological marker of recent exposure to P. vivax infection. These novel immunoproteomes should greatly facilitate the identification of promising novel malaria antigens and may warrant further study. BIOLOGICAL SIGNIFICANCE The establishment of high-throughput cloning and expression systems has permitted the construction of protein arrays for proteome-wide study of Plasmodium vivax. In this study, high-throughput screening assays have been applied to investigate blood stage-specific immune proteomes from P. vivax. We identified 44 antigenic proteins from the 152 putative candidates, more than 23% of which were hypothetical proteins described for the first time in this study. In addition, PvRAMA was characterized further and confirmed to be a serological marker of exposure to infections. The expression of one-third of the selected antigenic genes were shifted between P. vivax and Plasmodium falciparum, suggesting that these genes may represent important factors associated with P. vivax selectivity for young erythrocytes and/or with immune evasion. These novel immune proteomes of the P. vivax blood stage provide a baseline for further prospective serological marker studies in malaria. These methods could be used to determine immunodominant candidate antigens from the P. vivax genome.
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Affiliation(s)
- Feng Lu
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea; Jiangsu Institute of Parasitic Diseases, Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Wuxi, Jiangsu, People's Republic of China
| | - Jian Li
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea; Jiangsu Institute of Parasitic Diseases, Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Wuxi, Jiangsu, People's Republic of China
| | - Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Yang Cheng
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Deok-Hoon Kong
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Liwang Cui
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea.
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Butler NS, Schmidt NW, Vaughan AM, Aly AS, Kappe SHI, Harty JT. Superior antimalarial immunity after vaccination with late liver stage-arresting genetically attenuated parasites. Cell Host Microbe 2011; 9:451-62. [PMID: 21669394 DOI: 10.1016/j.chom.2011.05.008] [Citation(s) in RCA: 182] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 04/20/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
While subunit vaccines have shown partial efficacy in clinical trials, radiation-attenuated sporozoites (RAS) remain the "gold standard" for sterilizing protection against Plasmodium infection in human vaccinees. The variability in immunogenicity and replication introduced by the extensive, random DNA damage necessary to generate RAS could be overcome by genetically attenuated parasites (GAP) designed via gene deletion to arrest at defined points during liver-stage development. Here, we demonstrate the principle that late liver stage-arresting GAP induce larger and broader CD8 T cell responses that provide superior protection in inbred and outbred mice compared to RAS or early-arresting GAP immunizations. Late liver stage-arresting GAP also engender high levels of cross-stage and cross-species protection and complete protection when administered by translationally relevant intradermal or subcutaneous routes. Collectively, our results underscore the potential utility of late liver stage-arresting GAP as broadly protective next-generation live-attenuated malaria vaccines and support their potential as a powerful model for identifying antigens to generate cross-stage protection.
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Affiliation(s)
- Noah S Butler
- Department of Microbiology, University of Iowa, 3-512 Bowen Science Building, Iowa City, IA 52242, USA
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Belnoue E, Voza T, Costa FTM, Grüner AC, Mauduit M, Rosa DS, Depinay N, Kayibanda M, Vigário AM, Mazier D, Snounou G, Sinnis P, Rénia L. Vaccination with live Plasmodium yoelii blood stage parasites under chloroquine cover induces cross-stage immunity against malaria liver stage. THE JOURNAL OF IMMUNOLOGY 2009; 181:8552-8. [PMID: 19050274 DOI: 10.4049/jimmunol.181.12.8552] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Immunity to malaria has long been thought to be stage-specific. In this study we show that immunization of BALB/c mice with live erythrocytes infected with nonlethal strains of Plasmodium yoelii under curative chloroquine cover conferred protection not only against challenge by blood stage parasites but also against sporozoite challenge. This cross-stage protection was dose-dependent and long lasting. CD4(+) and CD8(+) T cells inhibited malaria liver but not blood stage. Their effect was mediated partially by IFN-gamma, and was completely dependent of NO. Abs against both pre-erythrocytic and blood parasites were elicited and were essential for protection against blood stage and liver stage parasites. Our results suggest that Ags shared by liver and blood stage parasites can be the foundation for a malaria vaccine that would provide effective protection against both pre-erythrocytic and erythrocytic asexual parasites found in the mammalian host.
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Affiliation(s)
- Elodie Belnoue
- Department of Immunology, Centre National de la Recherche Scientifique, Institut Cochin, Université Paris Descartes, Paris, France
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Proteomic profiling of Plasmodium sporozoite maturation identifies new proteins essential for parasite development and infectivity. PLoS Pathog 2008; 4:e1000195. [PMID: 18974882 PMCID: PMC2570797 DOI: 10.1371/journal.ppat.1000195] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 10/09/2008] [Indexed: 12/12/2022] Open
Abstract
Plasmodium falciparum sporozoites that develop and mature inside an Anopheles mosquito initiate a malaria infection in humans. Here we report the first proteomic comparison of different parasite stages from the mosquito—early and late oocysts containing midgut sporozoites, and the mature, infectious salivary gland sporozoites. Despite the morphological similarity between midgut and salivary gland sporozoites, their proteomes are markedly different, in agreement with their increase in hepatocyte infectivity. The different sporozoite proteomes contain a large number of stage specific proteins whose annotation suggest an involvement in sporozoite maturation, motility, infection of the human host and associated metabolic adjustments. Analyses of proteins identified in the P. falciparum sporozoite proteomes by orthologous gene disruption in the rodent malaria parasite, P. berghei, revealed three previously uncharacterized Plasmodium proteins that appear to be essential for sporozoite development at distinct points of maturation in the mosquito. This study sheds light on the development and maturation of the malaria parasite in an Anopheles mosquito and also identifies proteins that may be essential for sporozoite infectivity to humans. Human malaria is caused by Plasmodium falciparum, a unicellular protozoan parasite that is transmitted by Anopheles mosquitoes. An infectious mosquito injects saliva containing sporozoite forms of the parasite and these then migrate from the skin to the liver, where they establish an infection. Many intervention strategies are currently focused on preventing the establishment of infection by sporozoites. Clearly, an understanding of the biology of the sporozoite is essential for developing new intervention strategies. Sporozoites are produced within the oocyst, located on the outside wall of the mosquito midgut, and migrate after release from the oocysts to the salivary glands where they are stored as mature infectious forms. Comparison of the proteomes of sporozoites derived from either the oocyst or from the salivary gland reveals remarkable differences in the protein content of these stages despite their similar morphology. The changes in protein content reflect the very specific preparations the sporozoites make in order to establish an infection of the liver. Analysis of the function of several previously uncharacterized, conserved proteins revealed proteins essential for sporozoite development at distinct points of their maturation.
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Patarroyo ME, Cifuentes G, Rodríguez R. Structural characterisation of sporozoite components for a multistage, multi-epitope, anti-malarial vaccine. Int J Biochem Cell Biol 2008; 40:543-57. [DOI: 10.1016/j.biocel.2007.09.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 09/21/2007] [Accepted: 09/25/2007] [Indexed: 11/30/2022]
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Adisa A, Frankland S, Rug M, Jackson K, Maier AG, Walsh P, Lithgow T, Klonis N, Gilson PR, Cowman AF, Tilley L. Re-assessing the locations of components of the classical vesicle-mediated trafficking machinery in transfected Plasmodium falciparum. Int J Parasitol 2007; 37:1127-41. [PMID: 17428488 DOI: 10.1016/j.ijpara.2007.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 02/15/2007] [Accepted: 02/16/2007] [Indexed: 11/16/2022]
Abstract
The malaria parasite, Plasmodium falciparum, exports proteins beyond the confines of its own plasma membrane, however there is debate regarding the machinery used for these trafficking events. We have generated transgenic parasites expressing chimeric proteins and used immunofluorescence studies to determine the locations of plasmodial homologues of the COPII component, Sar1p, and the Golgi-docking protein, Bet3p. The P. falciparum Sar1p (PfSar1p) chimeras bind to the endoplasmic reticulum surface and define a network of membranes wrapped around parasite nuclei. As the parasite matures, the endomembrane systems of individual merozoites remain interconnected until very late in schizogony. Antibodies raised against plasmodial Bet3p recognise two foci of reactivity in early parasite stages that increase in number as the parasite matures. Some of the P. falciparum Bet3p (PfBet3p) compartments are juxtaposed to compartments defined by the cis Golgi marker, PfGRASP, while others are distributed through the cytoplasm. The compartments defined by the trans Golgi marker, PfRab6, are separate, suggesting that the Golgi is dispersed. Bet3p-green fluorescent protein (GFP) is partly associated with punctate structures but a substantial population diffuses freely in the parasite cytoplasm. By contrast, yeast Bet3p is very tightly associated with immobile structures. This study challenges the view that the COPII complex and the Golgi apparatus are exported into the infected erythrocyte cytoplasm.
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Affiliation(s)
- Akinola Adisa
- Department of Biochemistry, La Trobe University, Melbourne 3086, Vic., Australia
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Sinnis P, Coppi A. A long and winding road: the Plasmodium sporozoite's journey in the mammalian host. Parasitol Int 2007; 56:171-8. [PMID: 17513164 PMCID: PMC1995443 DOI: 10.1016/j.parint.2007.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Accepted: 04/17/2007] [Indexed: 11/21/2022]
Abstract
The Plasmodium sporozoite, the infectious stage of the malaria parasite, makes a remarkable journey in its mammalian host. Here we review our current knowledge of the molecular and cellular basis of this journey, which begins in the skin and ends in the hepatocyte.
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Affiliation(s)
- Photini Sinnis
- Department of Medical Parasitology, New York University School of Medicine, 341 East 25th Street, New York, NY 10010, United States.
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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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Abstract
Malaria infection is initiated when Plasmodium sporozoites are injected into a host during the bite of an infected mosquito. In the mammal, the sporozoite must rapidly reach an intravacuolar niche within a hepatocyte, where it will generate the parasite stage that invades red blood cells and causes the symptoms of the disease. Herein, we describe our understanding of the way in which sporozoites travel from the site of the mosquito bite to the liver, arrest in the liver, cross the sinusoidal barrier and eventually gain access to hepatocytes. We also highlight some of the recent advances in our understanding of these processes at the molecular level.
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Affiliation(s)
- Patricia Baldacci
- Unité de Biologie et Génétique du Paludisme, Institut Pasteur, Paris, France
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Bozdech Z, Llinás M, Pulliam BL, Wong ED, Zhu J, DeRisi JL. The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum. PLoS Biol 2003; 1:E5. [PMID: 12929205 PMCID: PMC176545 DOI: 10.1371/journal.pbio.0000005] [Citation(s) in RCA: 1164] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Accepted: 07/25/2003] [Indexed: 01/27/2023] Open
Abstract
Plasmodium falciparum is the causative agent of the most burdensome form of human malaria, affecting 200-300 million individuals per year worldwide. The recently sequenced genome of P. falciparum revealed over 5,400 genes, of which 60% encode proteins of unknown function. Insights into the biochemical function and regulation of these genes will provide the foundation for future drug and vaccine development efforts toward eradication of this disease. By analyzing the complete asexual intraerythrocytic developmental cycle (IDC) transcriptome of the HB3 strain of P. falciparum, we demonstrate that at least 60% of the genome is transcriptionally active during this stage. Our data demonstrate that this parasite has evolved an extremely specialized mode of transcriptional regulation that produces a continuous cascade of gene expression, beginning with genes corresponding to general cellular processes, such as protein synthesis, and ending with Plasmodium-specific functionalities, such as genes involved in erythrocyte invasion. The data reveal that genes contiguous along the chromosomes are rarely coregulated, while transcription from the plastid genome is highly coregulated and likely polycistronic. Comparative genomic hybridization between HB3 and the reference genome strain (3D7) was used to distinguish between genes not expressed during the IDC and genes not detected because of possible sequence variations. Genomic differences between these strains were found almost exclusively in the highly antigenic subtelomeric regions of chromosomes. The simple cascade of gene regulation that directs the asexual development of P. falciparum is unprecedented in eukaryotic biology. The transcriptome of the IDC resembles a "just-in-time" manufacturing process whereby induction of any given gene occurs once per cycle and only at a time when it is required. These data provide to our knowledge the first comprehensive view of the timing of transcription throughout the intraerythrocytic development of P. falciparum and provide a resource for the identification of new chemotherapeutic and vaccine candidates.
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Affiliation(s)
- Zbynek Bozdech
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Manuel Llinás
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Brian Lee Pulliam
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Edith D Wong
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Jingchun Zhu
- 2Department of Biological and Medical Informatics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Joseph L DeRisi
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
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Abstract
Sporozoites are the most versatile of the invasive stages of the Plasmodium life cycle. During their passage within the mosquito vector and the vertebrate host, sporozoites display diverse behaviors, including gliding locomotion and invasion of, migration through and egress from target cells. At the end of the journey, sporozoites invade hepatocytes and transform into exoerythrocytic stages, marking the transition from the pre-erythrocytic to the erythrocytic part of the life cycle. This article discusses recent work, mostly done with rodent malaria parasites, that has contributed to a better understanding of the sporozoites' complex biology and which has opened up new avenues for future sporozoite research.
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Affiliation(s)
- Stefan H I Kappe
- Michael Heidelberger Division, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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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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Kaviratne M, Khan SM, Jarra W, Preiser PR. Small variant STEVOR antigen is uniquely located within Maurer's clefts in Plasmodium falciparum-infected red blood cells. EUKARYOTIC CELL 2002; 1:926-35. [PMID: 12477793 PMCID: PMC138759 DOI: 10.1128/ec.1.6.926-935.2002] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Malaria parasite antigens encoded by multigene families are important factors in virulence and in disease pathology. In Plasmodium falciparum, the virulence factor PfEMP-1 is encoded by the var multigene family and is exposed at the infected erythrocyte surface. PfEMP-1 is clonally variant, allowing the parasite to evade host immunity. The recently identified P. falciparum stevor multigene family and its products also have the potential to be involved in similar important aspects of host-parasite interactions. Here, we show tightly regulated stage-specific transcription of stevor occurring over just a few hours of the asexual parasite life cycle. Only a subset of stevor genes are transcribed in parasite populations maintained in cultures and in single micromanipulated parasites. Antibodies against STEVOR recognize proteins of the expected size (approximately 37 kDa) and localize STEVOR in Maurer's clefts, unique membranous structures located in the cytoplasm of infected erythrocytes. The fact that the timing of stevor expression and the location of STEVOR are clearly distinct from those of other parasite variant antigens suggests that this gene family may have a novel role in P. falciparum biology.
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Affiliation(s)
- M Kaviratne
- Division of Parasitology, National Institute for Medical Research, London, United Kingdom
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Carvalho LJM, Daniel-Ribeiro CT, Goto H. Malaria vaccine: candidate antigens, mechanisms, constraints and prospects. Scand J Immunol 2002; 56:327-43. [PMID: 12234254 DOI: 10.1046/j.1365-3083.2002.01160.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
More than 30 years after the first report of successful vaccination against malaria using radiation-attenuated sporozoites, an effective malaria vaccine is not yet available. However, field and experimental data indicate that it can be developed. An astonishing amount of data has accumulated concerning parasite biology, host-parasite interactions, immunity and escape mechanisms, targets and modulators of immune responses. Nevertheless, so far this knowledge has not been enough to make us understand how to properly manipulate the whole system to build an effective vaccine. In this article, we describe candidate antigens, mechanisms, targets and trials performed with potential malaria vaccines and discuss the approaches, in vivo and in vitro models, constraints and how technologies such as DNA vaccination, genomics/proteomics and reverse immunogenetics are providing exciting results and opening new doors to make malaria vaccine a reality.
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Affiliation(s)
- L J M Carvalho
- Department of Immunology, WHO Collaborating Centre for Research and Training in the Immunology of Parasitic Diseases, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
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