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Arias CF, Acosta FJ, Fernandez-Arias C. Killing the competition: a theoretical framework for liver-stage malaria. Open Biol 2022; 12:210341. [PMID: 35350863 PMCID: PMC8965401 DOI: 10.1098/rsob.210341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The first stage of malaria infections takes place inside the host's hepatocytes. Remarkably, Plasmodium parasites do not infect hepatocytes immediately after reaching the liver. Instead, they migrate through several hepatocytes before infecting their definitive host cells, thus increasing their chances of immune destruction. Considering that malaria can proceed normally without cell traversal, this is indeed a puzzling behaviour. In fact, the role of hepatocyte traversal remains unknown to date, implying that the current understanding of malaria is incomplete. In this work, we hypothesize that the parasites traverse hepatocytes to actively trigger an immune response in the host. This behaviour would be part of a strategy of superinfection exclusion aimed to reduce intraspecific competition during the blood stage of the infection. Based on this hypothesis, we formulate a comprehensive theory of liver-stage malaria that integrates all the available knowledge about the infection. The interest of this new paradigm is not merely theoretical. It highlights major issues in the current empirical approach to the study of Plasmodium and suggests new strategies to fight malaria.
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Affiliation(s)
- Clemente F. Arias
- Centro de Investigaciones Biológicas (CSIC), Madrid, Spain,Grupo Interdisciplinar de Sistemas Complejos de Madrid, Spain
| | | | - Cristina Fernandez-Arias
- Departamento de Inmunología, Universidad Complutense de Madrid, Spain,Instituto de Medicina Molecular, Universidade de Lisboa, Portugal
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2
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Live attenuated vaccines, a favorable strategy to provide long-term immunity against protozoan diseases. Trends Parasitol 2021; 38:316-334. [PMID: 34896016 DOI: 10.1016/j.pt.2021.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 12/25/2022]
Abstract
The control of diseases caused by protozoan parasites is one of the United Nations' Sustainable Development Goals. In recent years much research effort has gone into developing a new generation of live attenuated vaccines (LAVs) against malaria, Chagas disease and leishmaniasis. However, there is a bottleneck related to their biosafety, production, and distribution that slows downs further development. The success of irradiated or genetically attenuated sporozoites against malaria, added to the first LAV against leishmaniasis to be evaluated in clinical trials, is indicative that the drawbacks of LAVs are gradually being overcome. However, whether persistence of LAVs is a prerequisite for sustained long-term immunity remains to be clarified, and the procedures necessary for clinical evaluation of vaccine candidates need to be standardized.
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3
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Reiman JM, Kumar S, Rodriguez IB, Gnidehou S, Ito K, Stanisic DI, Lee M, McPhun V, Majam V, Willemsen NM, Batzloff MR, Raja AI, Dooley B, Hoffman SL, Yanow SK, Good MF. Induction of immunity following vaccination with a chemically attenuated malaria vaccine correlates with persistent antigenic stimulation. Clin Transl Immunology 2018; 7:e1015. [PMID: 29670745 PMCID: PMC5894007 DOI: 10.1002/cti2.1015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 12/12/2022] Open
Abstract
Objectives Blood stage malaria parasites attenuated with seco-cyclopropyl pyrrolo indole (CPI) analogues induce robust immunity in mice to homologous and heterologous malaria parasites and are being considered for the development of a human vaccine. However, it is not understood how attenuated parasites induce immunity. We showed that following vaccination, parasite DNA persisted in blood for several months, raising the possibility that ongoing immune stimulation may be critical. However, parasites were not seen microscopically beyond 24 h postvaccination. We aimed to provide a mechanistic understanding of immune induction. Methods Mice were vaccinated with chemically attenuated Plasmodium chabaudi parasites. PCR and adoptive transfer studies were used to determine the presence of parasites and antigen in vivo. In other experiments, Plasmodium falciparum parasitised red blood cells were attenuated in vitro and RNA and antigen expression studied. Results We show that blood transferred from vaccinated mice into naïve mice activates T cells and induces complete protective immunity in the recipient mice strongly suggesting that there is persistence of parasite antigen postvaccination. This is supported by the presence of parasite RNA in vaccinated mice and both RNA and antigen expression in P. falciparum cultures treated with CPI drugs in vitro. In addition, drugs that block parasite growth also prevent the induction of immunity in vaccinated mice, indicating that some growth of attenuated parasites is required for immune induction. Conclusions Attenuated parasites persist at submicroscopic levels in the blood of mice postvaccination with the ability to activate T cells and induce ongoing protective immune responses.
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Affiliation(s)
- Jennifer M Reiman
- Institute for Glycomics Griffith University Gold Coast QLD Australia
| | - Sanjai Kumar
- Laboratory of Emerging Pathogens Division of Emerging and Transfusion Transmitted Diseases CBER, FDA Rockville MD USA
| | | | | | - Koichi Ito
- Institute for Glycomics Griffith University Gold Coast QLD Australia
| | | | - Moses Lee
- Georgia State University Atlanta GA USA
| | - Virginia McPhun
- Institute for Glycomics Griffith University Gold Coast QLD Australia
| | - Victoria Majam
- Laboratory of Emerging Pathogens Division of Emerging and Transfusion Transmitted Diseases CBER, FDA Rockville MD USA
| | | | | | - Amber I Raja
- Institute for Glycomics Griffith University Gold Coast QLD Australia
| | - Brad Dooley
- Institute for Glycomics Griffith University Gold Coast QLD Australia
| | | | | | - Michael F Good
- Institute for Glycomics Griffith University Gold Coast QLD Australia
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4
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Haeberlein S, Chevalley-Maurel S, Ozir-Fazalalikhan A, Koppejan H, Winkel BMF, Ramesar J, Khan SM, Sauerwein RW, Roestenberg M, Janse CJ, Smits HH, Franke-Fayard B. Protective immunity differs between routes of administration of attenuated malaria parasites independent of parasite liver load. Sci Rep 2017; 7:10372. [PMID: 28871201 PMCID: PMC5583236 DOI: 10.1038/s41598-017-10480-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 08/10/2017] [Indexed: 12/27/2022] Open
Abstract
In humans and murine models of malaria, intradermal immunization (ID-I) with genetically attenuated sporozoites that arrest in liver induces lower protective immunity than intravenous immunization (IV-I). It is unclear whether this difference is caused by fewer sporozoites migrating into the liver or by suboptimal hepatic and injection site-dependent immune responses. We therefore developed a Plasmodium yoelii immunization/boost/challenge model to examine parasite liver loads as well as hepatic and lymph node immune responses in protected and unprotected ID-I and IV-I animals. Despite introducing the same numbers of genetically attenuated parasites in the liver, ID-I resulted in lower sterile protection (53-68%) than IV-I (93-95%). Unprotected mice developed less sporozoite-specific CD8+ and CD4+ effector T-cell responses than protected mice. After immunization, ID-I mice showed more interleukin-10-producing B and T cells in livers and skin-draining lymph nodes, but fewer hepatic CD8 memory T cells and CD8+ dendritic cells compared to IV-I mice. Our results indicate that the lower protection efficacy obtained by intradermal sporozoite administration is not linked to low hepatic parasite numbers as presumed before, but correlates with a shift towards regulatory immune responses. Overcoming these immune suppressive responses is important not only for live-attenuated malaria vaccines but also for other live vaccines administered in the skin.
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Affiliation(s)
- Simone Haeberlein
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.,Institute of Parasitology, Justus-Liebig-University Giessen, Schubertstrasse 81, 35392, Giessen, Germany
| | - Séverine Chevalley-Maurel
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Arifa Ozir-Fazalalikhan
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Hester Koppejan
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Beatrice M F Winkel
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Jai Ramesar
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Shahid M Khan
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Geert-Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.,Department of Infectious Diseases, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Chris J Janse
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Hermelijn H Smits
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Blandine Franke-Fayard
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
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5
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Kreutzfeld O, Müller K, Matuschewski K. Engineering of Genetically Arrested Parasites (GAPs) For a Precision Malaria Vaccine. Front Cell Infect Microbiol 2017; 7:198. [PMID: 28620583 PMCID: PMC5450620 DOI: 10.3389/fcimb.2017.00198] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/04/2017] [Indexed: 01/08/2023] Open
Abstract
Continuous stage conversion and swift changes in the antigenic repertoire in response to acquired immunity are hallmarks of complex eukaryotic pathogens, including Plasmodium species, the causative agents of malaria. Efficient elimination of Plasmodium liver stages prior to blood infection is one of the most promising malaria vaccine strategies. Here, we describe different genetically arrested parasites (GAPs) that have been engineered in Plasmodium berghei, P. yoelii and P. falciparum and compare their vaccine potential. A better understanding of the immunological mechanisms of prime and boost by arrested sporozoites and experimental strategies to enhance vaccine efficacy by further engineering existing GAPs into a more immunogenic form hold promise for continuous improvements of GAP-based vaccines. A critical hurdle for vaccines that elicit long-lasting protection against malaria, such as GAPs, is safety and efficacy in vulnerable populations. Vaccine research should focus on solutions toward turning malaria into a vaccine-preventable disease, which would offer an exciting new path of malaria control.
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Affiliation(s)
- Oriana Kreutzfeld
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Katja Müller
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
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6
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Repetitive live sporozoites inoculation under arteether chemoprophylaxis confers protection against subsequent sporozoite challenge in rodent malaria model. Acta Trop 2016; 158:130-138. [PMID: 26925772 DOI: 10.1016/j.actatropica.2016.02.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 02/14/2016] [Accepted: 02/22/2016] [Indexed: 01/06/2023]
Abstract
Inoculation with live sporozoites under prophylactic antimalarial cover (CPS-immunization) represents an alternate approach to develop sterile, reproducible, and long-term protection against malaria. Here, we have employed arteether (ART), a semi synthetic derivative of artemisinin to explore its potential as a chemoprophylaxis candidate in CPS approach and systematically compared the protective potential of arteether with mefloquine, azithromycin and primaquine. Blood stage patency and quantitative RT-PCR of liver stage parasite load were monitored as primary key end-points for protection against malaria challenge infection. For this purpose, sequential exposures of Plasmodium yoelii sporozoites under prophylactic treatment with arteether (ART), mefloquine (MFQ), azithromycin (AZ) or primaquine (PQ) was conducted in experimental Swiss mice. Our results show that during the first three sequential exposures (1st, 2nd and 3rd challenge) no marked difference in the blood stage patency was observed between control and CPS-ART group. However, delayed patency was recorded following 4th sporozoite challenge and mice enjoyed sterile protection after 5th sporozoite challenge. A similar response was observed in CPS-MFQ group, whereas earlier protection was recorded in CPS-AZ group i.e., after 4th sprozoite challenge. However, mice under PQ cover did not show any protection/delay in patency even after five sequential sporozoite inoculations, possibly due to inhibition of liver stage development. Furthermore, protection acquired by CPS-immunization is stage-specific as the protected mice remained susceptible to challenge with blood stage parasites. In short, the present study demonstrates that sporozoite administration under ART, MFQ or AZ treatment confers strong protection against subsequent sporozoite infection and the acquired response is dependent on the presence of liver stage parasites.
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7
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Pichugin A, Steers N, De La Vega P, Zarling S, Chalom I, Krzych U. TAP-mediated processing of exoerythrocytic antigens is essential for protection induced with radiation-attenuated Plasmodium sporozoites. Eur J Immunol 2016; 46:885-96. [PMID: 26703789 DOI: 10.1002/eji.201545748] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 11/25/2015] [Accepted: 12/18/2015] [Indexed: 02/01/2023]
Abstract
MHC class I dependent CD8(+) T cells are essential for protection induced by radiation-attenuated Plasmodium sporozoites (RAS) in murine malaria models. Apart from the mechanism of activation of CD8(+) T cells specific for the circumsporozoite protein, the major sporozoite antigen (Ag), CD8(+) T cells specific for other exoerythrocytic Ags that have been shown to mediate protection have not been thoroughly investigated. Specifically, mechanisms of processing and presentation of exoerythrocytic Ags, which includes liver stage (LS) Ags, remain poorly understood. We hypothesize that as exogenous proteins, LS Ags are processed by mechanisms involving either the TAP-dependent phagosomal-to-cytosol or TAP-independent vacuolar pathway of cross-presentation. We used TAP-deficient mice to investigate whether LS Ag mediated induction of naïve CD8(+) T cells and their recall during sporozoite challenge occur by the TAP-dependent or TAP-independent pathways. On the basis of functional attributes, CD8(+) T cells were activated via the TAP-independent pathway during immunizations with Plasmodium berghei RAS; however, IFN-γ(+) CD8(+) T cells previously induced by P. berghei RAS in TAP-deficient mice failed to be recalled against sporozoite challenge and the mice became parasitemic. On the basis of these observations, we propose that TAP-associated Ag processing is indispensable for sterile protection induced with P. berghei RAS.
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Affiliation(s)
- Alexander Pichugin
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Nick Steers
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Patricia De La Vega
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Stasya Zarling
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Isaac Chalom
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Urszula Krzych
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
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8
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Abstract
With increasing malaria control and goals of malaria elimination, many endemic areas are transitioning from high-to-low-to-no malaria transmission. Reductions in transmission will impact on the development of naturally acquired immunity to malaria, which develops after repeated exposure to Plasmodium spp. However, it is currently unclear how declining transmission and malaria exposure will affect the development and maintenance of naturally acquired immunity. Here we review the key processes which underpin this knowledge; the amount of Plasmodium spp. exposure required to generate effective immune responses, the longevity of antibody responses and the ability to mount an effective response upon re-exposure through memory responses. Lastly we identify research priorities which will increase our understanding of how changing transmission will impact on malarial immunity.
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9
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Metheni M, Lombès A, Bouillaud F, Batteux F, Langsley G. HIF-1α induction, proliferation and glycolysis of Theileria-infected leukocytes. Cell Microbiol 2015; 17:467-72. [PMID: 25620534 DOI: 10.1111/cmi.12421] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 01/30/2023]
Abstract
Within 2 h of infection by Theileria annulata sporozoites, bovine macrophages display a two- to fourfold increase in transcription of hypoxia inducible factor (HIF-1α). Twenty hours post-invasion sporozoites develop into multi-nucleated macroschizonts that transform the infected macrophage into an immortalized, permanently proliferating, hyper-invasive and disease-causing leukaemia-like cell. Once immortalized Theileria-infected leukocytes can be propagated as cell lines and even though cultivated under normoxic conditions, both infected B cells and macrophages display sustained activation of HIF-1α. Attenuated macrophages used as live vaccines against tropical theileriosis also display HIF-1α activation even though they have lost their tumorigenic phenotype. Here, we review data that ascribes HIF-1α activation to the proliferation status of the infected leukocyte and discuss the possibility that Theileria may have lost its ability to render its host macrophage virulent due to continuous parasite replication in a high Reactive Oxygen Species (ROS) environment. We propose a model where uninfected macrophages have low levels of H2 O2 output, whereas virulent-infected macrophages produce high amounts of H2 O2 . Further increase in H2 O2 output leads to dampening of infected macrophage virulence, a characteristic of disease-resistant macrophages. At the same time exposure to H2 O2 sustains HIF-1α that induces the switch from mitochondrial oxidative phosphorylation to Warburg glycolysis, a metabolic shift that underpins uncontrolled infected macrophage proliferation. We propose that as macroschizonts develop into merozoites and infected macrophage proliferation arrests, HIF-1α levels will decrease and glycolysis will switch back from Warburg to oxidative glycolysis. As Theileria infection transforms its host leukocyte into an aggressive leukaemic-like cell, we propose that manipulating ROS levels, HIF-1α induction and oxidative over Warburg glycolysis could contribute to improved disease control. Finally, as excess amounts of H2 O2 drive virulent Theileria-infected macrophages towards attenuation it highlights how infection-induced pathology and redox balance are intimately linked.
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Affiliation(s)
- Mehdi Metheni
- Inserm U1016, Cnrs UMR8104, Cochin Institute, Paris, France; Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes - Sorbonne Paris Cité, France
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10
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Bertolino P, Bowen DG. Malaria and the liver: immunological hide-and-seek or subversion of immunity from within? Front Microbiol 2015; 6:41. [PMID: 25741320 PMCID: PMC4332352 DOI: 10.3389/fmicb.2015.00041] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/12/2015] [Indexed: 12/28/2022] Open
Abstract
During the pre-erythrocytic asymptomatic phase of malarial infection, sporozoites develop transiently inside less than 100 hepatocytes that subsequently release thousands of merozoites. Killing of these hepatocytes by cytotoxic T cells (CTLs) confers protection to subsequent malarial infection, suggesting that this bottleneck phase in the parasite life cycle can be targeted by vaccination. During natural transmission, although some CTLs are generated in the skin draining lymph nodes, they are unable to eliminate the parasite, suggesting that the liver is important for the sporozoite to escape immune surveillance. The contribution of the organ to this process is unclear. Based on the known ability of several hepatic antigen-presenting cells (APCs) to induce primary activation of CD8 T cells and tolerance, malarial antigens presented by both infected hepatocytes and/or hepatic cross-presenting APCs should result in tolerance. However, our latest model predicts that due to the low frequency of infected hepatocytes, some T cells recognizing sporozoite epitopes with high affinity should differentiate into CTLs. In this review, we discuss two possible models to explain why CTLs generated in the liver and skin draining lymph nodes are unable to eliminate the parasite: (1) sporozoites harness the tolerogenic property of the liver; (2) CTLs are not tolerized but fail to detect infected cells due to sparse infection of hepatocytes and the very short liver stage. We propose that while malaria sporozoites might use the ability of the liver to tolerize both naive and effector cells, they have also developed strategies to decrease the probability of encounter between CTLs and infected liver cells. Thus, we predict that to achieve protection, vaccination strategies should aim to boost intrahepatic activation and/or increase the chance of encounter between sporozoite-specific CTLs and infected hepatocytes.
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Affiliation(s)
- Patrick Bertolino
- Liver Immunology Group, Centenary Institute and AW Morrow Gastroenterology and Liver Centre, University of Sydney and Royal Prince Alfred Hospital Sydney, NSW, Australia
| | - David G Bowen
- Liver Immunology Group, Centenary Institute and AW Morrow Gastroenterology and Liver Centre, University of Sydney and Royal Prince Alfred Hospital Sydney, NSW, Australia
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11
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Datta S, Roy S, Manna M. Therapy with radio-attenuated vaccine in experimental murine visceral leishmaniasis showed enhanced T cell and inducible nitric oxide synthase levels, suppressed tumor growth factor-beta production with higher expression of some signaling molecules. Braz J Infect Dis 2014; 19:36-42. [PMID: 25532783 PMCID: PMC9425217 DOI: 10.1016/j.bjid.2014.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/20/2014] [Accepted: 10/06/2014] [Indexed: 11/15/2022] Open
Abstract
Background Visceral leishmaniasis (VL) or Kala-Azar (KA) is one of the most deadly forms of disease among all neglected tropical diseases. There are no satisfactory drugs or vaccine candidates available for this dreaded disease. Our previous studies showed promising therapeutic and prophylactic efficacy of the live, radio-attenuated parasites through intramuscular (I.M.) and intraperitoneal (I.P.) route in BALB/c mice model. Methods The T-cell proliferation level, the mRNA expression level of inducible nitric oxide synthase (iNOS) and tumor growth factor-beta (TGF-β) genes and finally the phosphorylation levels of phosphoinositide dependent kinase 1 (PDK1), phosphoinositide 3 kinase (PI3K) and p38 mitogen activated protein kinase (p38MAPK) molecules were checked in BALB/c mice model immunized with radio-attenuated Leishmania donovani parasites through I.M. route. Results Higher T-cell proliferation, increased iNOS level, and suppressed TGF-β level were found in treated infected animal groups (100 and 150 Gy) in relation to untreated infected animals. Likewise, phosphorylation levels of PDK1, PI3K and p38MAPK of these two groups were increased when compared to untreated infected controls. Conclusion The clearance of the parasites from treated infected groups of animals may be mediated by the restoration of T-cell due to therapy with radio-attenuated L. donovani parasites. The killing of parasites was mediated by increase in nitric oxide release through PDK1, PI3K and p38MAPK signaling pathways. A lower TGF-β expression has augmented the restored Th1 ambience in the 100 and 150 Gy treated animal groups proving further the efficacy of the candidate vaccine.
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Affiliation(s)
- Sanchita Datta
- Post Graduate Department of Zoology, Barasat Government College, Kolkata, India
| | - Syamal Roy
- Infectious Diseases and Immunology, Indian Institute of Chemical Biology, Kolkata, India
| | - Madhumita Manna
- Post Graduate Department of Zoology, Barasat Government College, Kolkata, India.
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12
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Haussig JM, Burgold J, Hafalla JCR, Matuschewski K, Kooij TWA. Signatures of malaria vaccine efficacy in ageing murine immune memory. Parasite Immunol 2014; 36:199-206. [PMID: 24495208 DOI: 10.1111/pim.12104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 01/27/2014] [Indexed: 02/06/2023]
Abstract
Malaria transmission occurs by mosquito bite. Thereafter, Plasmodium sporozoites specifically invade the liver, where they develop into thousands of merozoites that initiate blood-stage infection and clinical malaria. The pre-erythrocytic phase of a Plasmodium infection is the target of experimental whole-parasite vaccines against malaria. Repeated immunizations with high doses of live, metabolically active sporozoites can induce protracted protection against Plasmodium reinfection. Parasites lacking a Plasmodium-specific apicoplast protein, termed PALM, arrest very late during intrahepatic development just prior to liver merozoite release and can elicit sterile protection with two immunization doses only. In this report, we show in the robust Plasmodium berghei-C57BL/6 model that partial protection extends beyond 1 year after the last immunization. In ageing mice, intracellular cytokine staining of Plasmodium peptide-stimulated intrahepatic CD8+ T cells revealed elevated levels of interferon gamma in vaccinated mice. We conclude that antigen-specific T cells persist in the target organ and are critical signatures of lasting protection. Our data also support the notions that memory T-cell responses generated early in life remain largely intact well into old age and that murine Plasmodium vaccination and infection models are suitable to study the mechanisms of maintenance and efficiency of adaptive immunity during immunosenescence.
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Affiliation(s)
- J M Haussig
- Max Planck Institute for Infection Biology, Parasitology Unit, Berlin, Germany
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13
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Sacks DL. Vaccines against tropical parasitic diseases: a persisting answer to a persisting problem. Nat Immunol 2014; 15:403-5. [PMID: 24747701 PMCID: PMC4814932 DOI: 10.1038/ni.2853] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Live and live-attenuated whole organism vaccines against Plasmodium falciparum malaria and cutaneous leishmaniasis due to Leishmania major remain the most uniformly effective vaccines against human parasitic diseases. These vaccines are discussed in terms of the nature of the T cell populations that mediate the strong and durable localized immunity to these infections, and the requirement for persisting antigen to generate and maintain the protective response. The difficulties in developing subunit vaccines that fulfill this requirement argue that despite their own formidable problems in manufacture and delivery, live and live- attenuated whole organism vaccines against human parasitic diseases should be vigorously pursued.
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Affiliation(s)
- David L Sacks
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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14
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Krzych U, Zarling S, Pichugin A. Memory T cells maintain protracted protection against malaria. Immunol Lett 2014; 161:189-95. [PMID: 24709142 DOI: 10.1016/j.imlet.2014.03.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
Abstract
Immunologic memory is one of the cardinal features of antigen-specific immune responses, and the persistence of memory cells contributes to prophylactic immunizations against infectious agents. Adequately maintained memory T and B cell pools assure a fast, effective and specific response against re-infections. However, many aspects of immunologic memory are still poorly understood, particularly immunologic memory inducible by parasites, for example, Plasmodium spp., the causative agents of malaria. For example, memory responses to Plasmodium antigens amongst residents of malaria endemic areas appear to be either inadequately developed or maintained, because persons who survive episodes of childhood malaria remain vulnerable to intermittent malaria infections. By contrast, multiple exposures of humans and laboratory rodents to radiation-attenuated Plasmodium sporozoites (γ-spz) induce sterile and long-lasting protection against experimental sporozoite challenge. Multifactorial immune mechanisms maintain this protracted and sterile protection. While the presence of memory CD4 T cell subsets has been associated with lasting protection in humans exposed to multiple bites from Anopheles mosquitoes infected with attenuated Plasmodium falciparum, memory CD8 T cells maintain protection induced with Plasmodium yoelii and Plasmodium berghei γ-spz in murine models. In this review, we discuss our observations that show memory CD8 T cells specific for antigens expressed by P. berghei liver stage parasites as an indispensable component for the maintenance of protracted protective immunity against experimental malaria infection; moreover, the provision of an Ag-depot assures a quick recall of memory T cells as IFN-γ-producing effector CD8 T cells and IL-4- producing CD4 T cells that collaborate with B cells for an effective antibody response.
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Affiliation(s)
- Urszula Krzych
- Department of Cellular Immunology, Branch of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States.
| | - Stasya Zarling
- Department of Cellular Immunology, Branch of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States
| | - Alexander Pichugin
- Department of Cellular Immunology, Branch of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, MD 20910, United States
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The whole parasite, pre-erythrocytic stage approach to malaria vaccine development: a review. Curr Opin Infect Dis 2014; 26:420-8. [PMID: 23982233 DOI: 10.1097/qco.0000000000000002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The whole sporozoite (SPZ) vaccine platform provides the only established approach for inducing high-level sustained protective immunity in humans against malaria. We introduce this platform, highlight literature published since 2011, and discuss the challenges of further development. RECENT FINDINGS There are three major approaches to development of a whole parasite vaccine to prevent malaria infection using the SPZ platform: radiation-attenuated sporozoites (irrSPZ), chemoprophylaxis with infectious sporozoites (CPS), and genetically attenuated parasites (GAPs). In all three, SPZ are administered to the vaccinee. All three protect animals against infection when administered by injection with a needle and syringe, and irrSPZ and CPS protect against Plasmodium falciparum malaria in humans when P. falciparum SPZ (PfSPZ) are administered by mosquito bite. Metabolically active, nonreplicating (radiation attenuated) aseptic, purified, cryopreserved PfSPZ (PfSPZ Vaccine), and infectious, aseptic, purified, cryopreserved PfSPZ administered with chemoprophylaxis (PfSPZ-CVac approach) administered by needle and syringe have entered clinical trials. Preliminary data indicate that the PfSPZ Vaccine is safe, well tolerated and highly protective when administered intravenously. SUMMARY With proof-of-concept now established for high-grade protection induced by parenteral administration of a whole sporozoite vaccine, pathways for further development are currently being defined. Demonstration of high-level, durable, cross-strain P. falciparum protection would set the stage for licensure of a vaccine that could lead to dramatic reductions in malaria morbidity and mortality, and eventually elimination of this ancient scourge.
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Stanisic DI, Barry AE, Good MF. Escaping the immune system: How the malaria parasite makes vaccine development a challenge. Trends Parasitol 2013; 29:612-22. [DOI: 10.1016/j.pt.2013.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
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Faber BW, Younis S, Remarque EJ, Rodriguez Garcia R, Riasat V, Walraven V, van der Werff N, van der Eijk M, Cavanagh DR, Holder AA, Thomas AW, Kocken CHM. Diversity covering AMA1-MSP119 fusion proteins as malaria vaccines. Infect Immun 2013; 81:1479-90. [PMID: 23429538 PMCID: PMC3648017 DOI: 10.1128/iai.01267-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/13/2013] [Indexed: 11/20/2022] Open
Abstract
To overcome polymorphism in the malaria vaccine candidate Plasmodium falciparum apical membrane antigen 1 (PfAMA1), fusion protein chimeras comprised of three diversity-covering (DiCo) PfAMA1 molecules (D1, D2, and D3) and two allelic variants of the C-terminal 19-kDa region of merozoite surface protein 1 (MSP119) (variants M1 and M2) were generated. A mixture of fusion proteins (D1M1/D2M2D3) and the D1M1D2M2D3 fusion were compared to a single-unit mixture (D1/D2/D3/M1) in an immunological study in groups of rabbits. Following immunization, titers of antibodies (Abs) against four naturally occurring PfAMA1 alleles were high for all groups, as were growth inhibition assay (GIA) levels against two antigenically distinct laboratory parasite strains. Fusion of AMA1 to MSP119 did not suppress levels of antibodies against the AMA1 component. In addition, the breadth of antibody responses was unaffected. Anti-AMA1 antibodies were largely responsible for parasite growth inhibition, as shown in reversal-of-inhibition experiments by adding competing AMA1 antigen. For all groups, titration of the MSP119 antigen into the GIA led to only a small decrease in parasite inhibition, although titers of antibodies against MSP119 were increased 15-fold for the groups immunized with fusion proteins. GIA with affinity-purified anti-MSP119 antibodies showed that the 50% inhibitory concentrations of the anti-MSP119 antibody preparations were in the same order of magnitude for all animals tested, leading to the conclusion that fusing MSP119 to PfAMA1 leads to a small but significant increase in functional antibody levels. This study shows that combination of multiple vaccine candidates in fusion proteins may lead to improved characteristics of the vaccine.
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Affiliation(s)
- Bart W. Faber
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Sumera Younis
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Edmond J. Remarque
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | | | - Vanessa Riasat
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Vanessa Walraven
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Nicole van der Werff
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Marjolein van der Eijk
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - David R. Cavanagh
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Anthony A. Holder
- Division of Parasitology, MRC National Institute for Medical Research, London, United Kingdom
| | - Alan W. Thomas
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Clemens H. M. Kocken
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
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Zarling S, Berenzon D, Dalai S, Liepinsh D, Steers N, Krzych U. The survival of memory CD8 T cells that is mediated by IL-15 correlates with sustained protection against malaria. THE JOURNAL OF IMMUNOLOGY 2013; 190:5128-41. [PMID: 23589611 DOI: 10.4049/jimmunol.1203396] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ag-specific memory T cell responses elicited by infections or vaccinations are inextricably linked to long-lasting protective immunity. Studies of protective immunity among residents of malaria endemic areas indicate that memory responses to Plasmodium Ags are not adequately developed or maintained, as people who survive episodes of childhood malaria are still vulnerable to either persistent or intermittent malaria infections. In contrast, multiple exposures to radiation-attenuated Plasmodium berghei sporozoites (Pb γ-spz) induce long-lasting protective immunity to experimental sporozoite challenge. We previously demonstrated that sterile protection induced by Pb γ-spz is MHC class I-dependent and CD8 T cells are the key effectors. IFN-γ(+) CD8 T cells that arise in Pb γ-spz-immunized B6 mice are found predominantly in the liver and are sensitive to levels of liver-stage Ag depot and they express CD44(hi)CD62L(lo) markers indicative of effector/effector memory phenotype. The developmentally related central memory CD8 T (TCM) cells express elevated levels of CD122 (IL-15Rβ), which suggests that CD8 TCM cells depend on IL-15 for maintenance. Using IL-15-deficient mice, we demonstrate in this study that although protective immunity is inducible in these mice, protection is short-lived, mainly owing to the inability of CD8 TCM cells to survive in the IL-15-deficient milieu. We present a hypothesis consistent with a model whereby intrahepatic CD8 TCM cells, being maintained by IL-15-mediated survival and basal proliferation, are conscripted into the CD8 effector/effector memory T cell pool during subsequent infections.
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Affiliation(s)
- Stasya Zarling
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
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Mueller I, Galinski MR, Tsuboi T, Arevalo-Herrera M, Collins WE, King CL. Natural acquisition of immunity to Plasmodium vivax: epidemiological observations and potential targets. ADVANCES IN PARASITOLOGY 2013; 81:77-131. [PMID: 23384622 DOI: 10.1016/b978-0-12-407826-0.00003-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Population studies show that individuals acquire immunity to Plasmodium vivax more quickly than Plasmodium falciparum irrespective of overall transmission intensity, resulting in the peak burden of P. vivax malaria in younger age groups. Similarly, actively induced P. vivax infections in malaria therapy patients resulted in faster and generally more strain-transcending acquisition of immunity than P. falciparum infections. The mechanisms behind the more rapid acquisition of immunity to P. vivax are poorly understood. Natural acquired immune responses to P. vivax target both pre-erythrocytic and blood-stage antigens and include humoral and cellular components. To date, only a few studies have investigated the association of these immune responses with protection, with most studies focussing on a few merozoite antigens (such as the Pv Duffy binding protein (PvDBP), the Pv reticulocyte binding proteins (PvRBPs), or the Pv merozoite surface proteins (PvMSP1, 3 & 9)) or the circumsporozoite protein (PvCSP). Naturally acquired transmission-blocking (TB) immunity (TBI) was also found in several populations. Although limited, these data support the premise that developing a multi-stage P. vivax vaccine may be feasible and is worth pursuing.
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Affiliation(s)
- Ivo Mueller
- Walter + Eliza Hall Institute, Infection & Immunity Division, Parkville, Victoria, Australia
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20
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Obeid M, Franetich JF, Lorthiois A, Gego A, Grüner AC, Tefit M, Boucheix C, Snounou G, Mazier D. Skin-draining lymph node priming is sufficient to induce sterile immunity against pre-erythrocytic malaria. EMBO Mol Med 2012; 5:250-63. [PMID: 23255300 PMCID: PMC3569641 DOI: 10.1002/emmm.201201677] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 10/26/2012] [Accepted: 11/09/2012] [Indexed: 12/23/2022] Open
Abstract
The Plasmodium-infected hepatocyte has been considered necessary to prime the immune responses leading to sterile protection after vaccination with attenuated sporozoites. However, it has recently been demonstrated that priming also occurs in the skin. We wished to establish if sterile protection could be obtained in the absence of priming by infected hepatocytes. To this end, we developed a subcutaneous (s.c.) immunization protocol where few, possibly none, of the immunizing irradiated Plasmodium yoelii sporozoites infect hepatocytes, and also used CD81-deficient mice non-permissive to productive hepatocyte infections. We then compared and contrasted the patterns of priming with those obtained by intradermal immunization, where priming occurs in the liver. Using sterile immunity as a primary read-out, we exploited an inhibitor of T-cell migration, transgenic mice with conditional depletion of dendritic cells and adoptive transfers of draining lymph node-derived T cells, to provide evidence that responses leading to sterile immunity can be primed in the skin-draining lymph nodes with little, if any, contribution from the infected hepatocyte.
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Balam S, Romero JF, Bongfen SE, Guillaume P, Corradin G. CSP--a model for in vivo presentation of Plasmodium berghei sporozoite antigens by hepatocytes. PLoS One 2012; 7:e51875. [PMID: 23272182 PMCID: PMC3525584 DOI: 10.1371/journal.pone.0051875] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 11/08/2012] [Indexed: 11/18/2022] Open
Abstract
One target of protective immunity against the Plasmodium liver stage in BALB/c mice is represented by the circumsporozoite protein (CSP), and mainly involves its recognition by IFN-γ producing specific CD8+T-cells. In a previous in vitro study we showed that primary hepatocytes from BALB/c mice process Plasmodium berghei (Pb) CSP (PbCSP) and present CSP-derived peptides to specific H-2kd restricted CD8+T-cells with subsequent killing of the presenting cells. We now extend these observations to an in vivo infection model in which infected hepatocytes and antigen specific T-cell clones are transferred into recipient mice inducing protection from sporozoite (SPZ) challenge. In addition, using a similar protocol, we suggest the capacity of hepatocytes in priming of naïve T-cells to provide protection, as further confirmed by induction of protection after depletion of cross-presenting dendritic cells (DCs) by cytochrome c (cyt c) treatment or using traversal deficient parasites. Our results clearly show that hepatocytes present Plasmodium CSP to specific-primed CD8+T-cells, and could also prime naïve T-cells, leading to protection from infection. These results could contribute to a better understanding of liver stage immune response and design of malaria vaccines.
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Affiliation(s)
- Saidou Balam
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | | | - Silayuv E. Bongfen
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Philippe Guillaume
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Giampietro Corradin
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
- * E-mail:
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Krzych U, Dalai S, Zarling S, Pichugin A. Memory CD8 T cells specific for plasmodia liver-stage antigens maintain protracted protection against malaria. Front Immunol 2012; 3:370. [PMID: 23233854 PMCID: PMC3517952 DOI: 10.3389/fimmu.2012.00370] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 11/20/2012] [Indexed: 01/15/2023] Open
Abstract
Immunologic memory induced by pathogenic agents or vaccinations is inextricably linked to long-lasting protection. Adequately maintained memory T and B cell pools assure a fast, effective, and specific response against re-infections. Studies of immune responses amongst residents of malaria endemic areas suggest that memory responses to Plasmodia antigens appear to be neither adequately developed nor maintained, because persons who survive episodes of childhood malaria remain vulnerable to persistent or intermittent malaria infections. By contrast, multiple exposures of humans and laboratory rodents to radiation-attenuated Plasmodia sporozoites (γ-spz) induces sterile and long-lasting protection against experimental sporozoite challenge. Protection is associated with MHC-class I-dependent CD8 T cells, the key effectors against pre-erythrocytic stage infection. We have adopted the P. berghei γ-spz mouse model to study memory CD8 T cells that are specific for antigens expressed by Pb liver-stage (LS) parasites and are found predominantly in the liver. On the basis of phenotypic and functional characteristics, we have demonstrated that liver CD8 T cells form two subsets: CD44hiCD62LloKLRG-1+CD107+CD127−CD122loCD8 T effector/effector memory (TE/EM) cells that are the dominant IFN-γ producers and CD44hiCD62LhiKLRG-1−CD107−CD127+CD122hiCD8 T central memory (TCM) cells. In this review, we discuss our observations concerning the role of CD8 TE/EM and CD8 TCM cells in the maintenance of protracted protective immunity against experimental malaria infection. Finally, we present a hypothesis consistent with a model whereby intrahepatic CD8 TCM cells, that are maintained in part by LS-Ag depot and by IL-15-mediated survival and homeostatic proliferation, form a reservoir of cells ready for conscription to CD8 TE/EM cells needed to prevent re-infections.
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Affiliation(s)
- Urszula Krzych
- Department of Cellular Immunology, Branch of Military Malaria Vaccine Development, Walter Reed Army Institute of Research Silver Spring, MD, USA
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23
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Immune markers and correlates of protection for vaccine induced immune responses. Vaccine 2012; 30:4907-20. [PMID: 22658928 DOI: 10.1016/j.vaccine.2012.05.049] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/15/2012] [Accepted: 05/19/2012] [Indexed: 12/15/2022]
Abstract
Vaccines have been a major innovation in the history of mankind and still have the potential to address the challenges posed by chronic intracellular infections including tuberculosis, HIV and malaria which are leading causes of high morbidity and mortality across the world. Markers of an appropriate humoral response currently remain the best validated correlates of protective immunity after vaccination. Despite advancements in the field of immunology over the past few decades currently there are, however, no sufficiently validated immune correlates of vaccine induced protection against chronic infections in neither human nor veterinary medicine. Technological and conceptual advancements within cell-mediated immunology have led to a number of new immunological read-outs with the potential to emerge as correlates of vaccine induced protection. For T(H)1 type responses, antigen-specific production of interferon-gamma (IFN-γ) has been promoted as a quantitative marker of protective cell-mediated immune responses over the past couple of decades. More recently, however, evidence from several infections has pointed towards the quality of the immune response, measured through increased levels of antigen-specific polyfunctional T cells capable of producing a triad of relevant cytokines, as a better correlate of sustained protective immunity against this type of infections. Also the possibilities to measure antigen-specific cytotoxic T cells (CTL) during infection or in response to vaccination, through recombinant major histocompatibility complex (MHC) class I tetramers loaded with relevant peptides, has opened a new vista to include CTL responses in the evaluation of protective immune responses. Here, we review different immune markers and new candidates for correlates of a protective vaccine induced immune response against chronic infections and how successful they have been in defining the protective immunity in human and veterinary medicine.
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Douradinha B, van Dijk M, van Gemert GJ, Khan SM, Janse CJ, Waters AP, Sauerwein RW, Luty AJ, Silva-Santos B, Mota MM, Epiphanio S. Immunization with genetically attenuated P52-deficient Plasmodium berghei sporozoites induces a long-lasting effector memory CD8+ T cell response in the liver. JOURNAL OF IMMUNE BASED THERAPIES AND VACCINES 2011; 9:6. [PMID: 22004696 PMCID: PMC3206817 DOI: 10.1186/1476-8518-9-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 10/17/2011] [Indexed: 11/10/2022]
Abstract
Background The induction of sterile immunity and long lasting protection against malaria has been effectively achieved by immunization with sporozoites attenuated by gamma-irradiation or through deletion of genes. For mice immunized with radiation attenuated sporozoites (RAS) it has been shown that intrahepatic effector memory CD8+ T cells are critical for protection. Recent studies have shown that immunization with genetically attenuated parasites (GAP) in mice is also conferred by liver effector memory CD8+ T cells. Findings In this study we analysed effector memory cell responses after immunization of GAP that lack the P52 protein. We demonstrate that immunization with p52-GAP sporozoites also results in a strong increase of effector memory CD8+ T cells, even 6 months after immunization, whereas no specific CD4+ effector T cells response could be detected. In addition, we show that the increase of effector memory CD8+ T cells is specific for the liver and not for the spleen or lymph nodes. Conclusions These results indicate that immunization of mice with P. berghei p52-GAP results in immune responses that are comparable to those induced by RAS or GAP lacking expression of UIS3 or UIS4, with an important role implicated for intrahepatic effector memory CD8+ T cells. The knowledge of the mediators of protective immunity after immunization with different GAP is important for the further development of vaccines consisting of genetically attenuated sporozoites.
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Affiliation(s)
- Bruno Douradinha
- Unidade de Malaria, Instituto de Medicina Molecular, Universidade de Lisboa, Av Professor Egas Moniz, Lisboa, 1649-028, Portugal.
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Epstein JE, Tewari K, Lyke KE, Sim BKL, Billingsley PF, Laurens MB, Gunasekera A, Chakravarty S, James ER, Sedegah M, Richman A, Velmurugan S, Reyes S, Li M, Tucker K, Ahumada A, Ruben AJ, Li T, Stafford R, Eappen AG, Tamminga C, Bennett JW, Ockenhouse CF, Murphy JR, Komisar J, Thomas N, Loyevsky M, Birkett A, Plowe CV, Loucq C, Edelman R, Richie TL, Seder RA, Hoffman SL. Live Attenuated Malaria Vaccine Designed to Protect Through Hepatic CD8+ T Cell Immunity. Science 2011; 334:475-80. [PMID: 21903775 DOI: 10.1126/science.1211548] [Citation(s) in RCA: 392] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- J E Epstein
- U.S. Military Malaria Vaccine Program, Naval Medical Research Center, Silver Spring, MD 20910, USA
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26
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Comparative efficacy of pre-erythrocytic whole organism vaccine strategies against the malaria parasite. Vaccine 2011; 29:7002-8. [DOI: 10.1016/j.vaccine.2011.07.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/08/2011] [Accepted: 07/11/2011] [Indexed: 11/21/2022]
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Valencia SH, Rodríguez DC, Acero DL, Ocampo V, Arévalo-Herrera M. Platform for Plasmodium vivax vaccine discovery and development. Mem Inst Oswaldo Cruz 2011; 106 Suppl 1:179-92. [PMID: 21881773 PMCID: PMC4832982 DOI: 10.1590/s0074-02762011000900023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 06/15/2011] [Indexed: 01/17/2023] Open
Abstract
Plasmodium vivax is the most prevalent malaria parasite on the American continent. It generates a global burden of 80-100 million cases annually and represents a tremendous public health problem, particularly in the American and Asian continents. A malaria vaccine would be considered the most cost-effective measure against this vector-borne disease and it would contribute to a reduction in malaria cases and to eventual eradication. Although significant progress has been achieved in the search for Plasmodium falciparum antigens that could be used in a vaccine, limited progress has been made in the search for P. vivax components that might be eligible for vaccine development. This is primarily due to the lack of in vitro cultures to serve as an antigen source and to inadequate funding. While the most advanced P. falciparum vaccine candidate is currently being tested in Phase III trials in Africa, the most advanced P. vivax candidates have only advanced to Phase I trials. Herein, we describe the overall strategy and progress in P. vivax vaccine research, from antigen discovery to preclinical and clinical development and we discuss the regional potential of Latin America to develop a comprehensive platform for vaccine development.
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Chattopadhyay R, de la Vega P, Paik SH, Murata Y, Ferguson EW, Richie TL, Ooi GT. Early transcriptional responses of HepG2-A16 liver cells to infection by Plasmodium falciparum sporozoites. J Biol Chem 2011; 286:26396-405. [PMID: 21652718 PMCID: PMC3143603 DOI: 10.1074/jbc.m111.240879] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/01/2011] [Indexed: 11/06/2022] Open
Abstract
Invasion of hepatocytes by Plasmodium sporozoites deposited by Anopheles mosquitoes, and their subsequent transformation into infective merozoites is an obligatory step in the initiation of malaria. Interactions between the sporozoites and hepatocytes lead to a distinct, complex and coordinated cellular and systemic host response. Little is known about host liver cell response to sporozoite invasion, or whether it is primarily adaptive for the parasite, for the host, or for both. Our present study used gene expression profiling of human HepG2-A16 liver cells infected with Plasmodium falciparum sporozoites to understand the host early cellular events and factors influencing parasite infectivity and sporozoite development. Our results show that as early as 30 min following wild-type, non-irradiated sporozoite exposure, the expressions of at least 742 genes was selectively altered. These genes regulate diverse biological functions, such as immune processes, cell adhesion and communications, metabolism pathways, cell cycle regulation, and signal transduction. These functions reflect cellular events consistent with initial host cell defense responses, as well as alterations in host cells to sustain sporozoites growth and survival. Irradiated sporozoites gave very similar gene expression pattern changes, but direct comparative analysis between liver gene expression profiles caused by irradiated and non-irradiated sporozoites identified 29 genes, including glypican-3, that were specifically up-regulated only in irradiated sporozoites. Elucidating the role of this subset of genes may help identify the molecular basis for the irradiated sporozoites inability to develop intrahepatically, and their usefulness as an immunogen for developing protective immunity against pre-erythrocytic stage malaria.
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Affiliation(s)
- Rana Chattopadhyay
- From the Malaria Program, United States Military Malaria Vaccine Program
| | - Patricia de la Vega
- From the Malaria Program, United States Military Malaria Vaccine Program
- Walter Reed Army Institute of Research and
| | - Sun H. Paik
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | - Yoko Murata
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | | | - Thomas L. Richie
- From the Malaria Program, United States Military Malaria Vaccine Program
- the Naval Medical Research Center, Silver Spring, Maryland 20910-7500 and
| | - Guck T. Ooi
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
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Abstract
Malaria is a vector-borne infectious disease caused by unicellular parasites of the genus Plasmodium. These obligate intracellular parasites have the unique capacity to infect and replicate within erythrocytes, which are terminally differentiated host cells that lack antigen presentation pathways. Prior to the cyclic erythrocytic infections that cause the characteristic clinical symptoms of malaria, the parasite undergoes an essential and clinically silent expansion phase in the liver. By infecting privileged host cells, employing programs of complex life stage conversions and expressing varying immunodominant antigens, Plasmodium parasites have evolved mechanisms to downmodulate protective immune responses against ongoing and even future infections. Consequently, anti-malaria immunity develops only gradually over many years of repeated and multiple infections in endemic areas. The identification of immune correlates of protection among the abundant non-protective host responses remains a research priority. Understanding the molecular and immunological mechanisms of the crosstalk between the parasite and the host is a prerequisite for the rational discovery and development of a safe, affordable, and protective anti-malaria vaccine.
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Affiliation(s)
- Julius Clemence Hafalla
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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Schwenk RJ, Richie TL. Protective immunity to pre-erythrocytic stage malaria. Trends Parasitol 2011; 27:306-14. [PMID: 21435951 DOI: 10.1016/j.pt.2011.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/14/2011] [Accepted: 02/14/2011] [Indexed: 01/23/2023]
Abstract
The development of a vaccine against malaria is a major research priority given the burden of disease, death and economic loss inflicted upon the tropical world by this parasite. Despite decades of effort, however, a vaccine remains elusive. The best candidate is a subunit vaccine termed RTS,S but this provides only partial protection against clinical disease. This review examines what is known about protective immunity against pre-erythrocytic stage malaria by considering the humoral and T cell-mediated immune responses that are induced by attenuated sporozoites and by the RTS,S vaccine. On the basis of these observations a set of research priorities are defined that are crucial for the development of a vaccine capable of inducing long-lasting and high-grade protection against malaria.
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Affiliation(s)
- Robert J Schwenk
- US Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Division of Malaria Vaccine Development, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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Extreme CD8 T cell requirements for anti-malarial liver-stage immunity following immunization with radiation attenuated sporozoites. PLoS Pathog 2010; 6:e1000998. [PMID: 20657824 PMCID: PMC2904779 DOI: 10.1371/journal.ppat.1000998] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 06/11/2010] [Indexed: 12/02/2022] Open
Abstract
Radiation-attenuated Plasmodium sporozoites (RAS) are the only vaccine shown to induce sterilizing protection against malaria in both humans and rodents. Importantly, these “whole-parasite” vaccines are currently under evaluation in human clinical trials. Studies with inbred mice reveal that RAS-induced CD8 T cells targeting liver-stage parasites are critical for protection. However, the paucity of defined T cell epitopes for these parasites has precluded precise understanding of the specific characteristics of RAS-induced protective CD8 T cell responses. Thus, it is not known whether quantitative or qualitative differences in RAS-induced CD8 T cell responses underlie the relative resistance or susceptibility of immune inbred mice to sporozoite challenge. Moreover, whether extraordinarily large CD8 T cell responses are generated and required for protection following RAS immunization, as has been described for CD8 T cell responses following single-antigen subunit vaccination, remains unknown. Here, we used surrogate T cell activation markers to identify and track whole-parasite, RAS-vaccine-induced effector and memory CD8 T cell responses. Our data show that the differential susceptibility of RAS-immune inbred mouse strains to Plasmodium berghei or P. yoelii sporozoite challenge does not result from host- or parasite-specific decreases in the CD8 T cell response. Moreover, the surrogate activation marker approach allowed us for the first time to evaluate CD8 T cell responses and protective immunity following RAS-immunization in outbred hosts. Importantly, we show that compared to a protective subunit vaccine that elicits a CD8 T cell response to a single epitope, diversifying the targeted antigens through whole-parasite RAS immunization only minimally, if at all, reduced the numerical requirements for memory CD8 T cell-mediated protection. Thus, our studies reveal that extremely high frequencies of RAS-induced memory CD8 T cells are required, but may not suffice, for sterilizing anti-Plasmodial immunity. These data provide new insights into protective CD8 T cell responses elicited by RAS-immunization in genetically diverse hosts, information with relevance to developing attenuated whole-parasite vaccines. Plasmodium infections are a global health crisis resulting in ∼300 million cases of malaria each year and ∼1 million deaths. Radiation-attenuated Plasmodium sporozoites (RAS) are the only vaccines that induce sterilizing anti-malarial immunity in humans. Importantly, “whole parasite” anti-malarial RAS vaccines are currently under evaluation in clinical trials. In rodents, RAS-induced protection is largely mediated by CD8 T cells. However, the quantitative and qualitative characteristics of RAS-induced protective CD8 T cell responses are unknown. Here, we used surrogate markers of T cell activation to reveal the magnitude and kinetics of Plasmodium-specific CD8 T cell responses following RAS-immunization in both inbred and outbred mice. Our data show that, independent of host genetic background, extremely large memory CD8 T cell responses were required, but not always sufficient for sterilizing protection. These data have broad implications for evaluating total T cell responses to attenuated pathogen-vaccines and direct relevance for efforts to translate attenuated whole-Plasmodium vaccines to humans.
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32
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Guilbride DL, Gawlinski P, Guilbride PDL. Why functional pre-erythrocytic and bloodstage malaria vaccines fail: a meta-analysis of fully protective immunizations and novel immunological model. PLoS One 2010; 5:e10685. [PMID: 20502667 PMCID: PMC2873430 DOI: 10.1371/journal.pone.0010685] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 04/16/2010] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Clinically protective malaria vaccines consistently fail to protect adults and children in endemic settings, and at best only partially protect infants. METHODOLOGY/PRINCIPAL FINDINGS We identify and evaluate 1916 immunization studies between 1965-February 2010, and exclude partially or nonprotective results to find 177 completely protective immunization experiments. Detailed reexamination reveals an unexpectedly mundane basis for selective vaccine failure: live malaria parasites in the skin inhibit vaccine function. We next show published molecular and cellular data support a testable, novel model where parasite-host interactions in the skin induce malaria-specific regulatory T cells, and subvert early antigen-specific immunity to parasite-specific immunotolerance. This ensures infection and tolerance to reinfection. Exposure to Plasmodium-infected mosquito bites therefore systematically triggers immunosuppression of endemic vaccine-elicited responses. The extensive vaccine trial data solidly substantiate this model experimentally. CONCLUSIONS/SIGNIFICANCE We conclude skinstage-initiated immunosuppression, unassociated with bloodstage parasites, systematically blocks vaccine function in the field. Our model exposes novel molecular and procedural strategies to significantly and quickly increase protective efficacy in both pipeline and currently ineffective malaria vaccines, and forces fundamental reassessment of central precepts determining vaccine development. This has major implications for accelerated local eliminations of malaria, and significantly increases potential for eradication.
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Cockburn IA, Chen YC, Overstreet MG, Lees JR, van Rooijen N, Farber DL, Zavala F. Prolonged antigen presentation is required for optimal CD8+ T cell responses against malaria liver stage parasites. PLoS Pathog 2010; 6:e1000877. [PMID: 20463809 PMCID: PMC2865532 DOI: 10.1371/journal.ppat.1000877] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 03/25/2010] [Indexed: 11/18/2022] Open
Abstract
Immunization with irradiated sporozoites is currently the most effective vaccination strategy against liver stages of malaria parasites, yet the mechanisms underpinning the success of this approach are unknown. Here we show that the complete development of protective CD8+ T cell responses requires prolonged antigen presentation. Using TCR transgenic cells specific for the malaria circumsporozoite protein, a leading vaccine candidate, we found that sporozoite antigen persists for over 8 weeks after immunization--a remarkable finding since irradiated sporozoites are incapable of replication and do not differentiate beyond early liver stages. Persisting antigen was detected in lymphoid organs and depends on the presence of CD11c+ cells. Prolonged antigen presentation enhanced the magnitude of the CD8+ T cell response in a number of ways. Firstly, reducing the time primed CD8+ T cells were exposed to antigen in vivo severely reduced the final size of the developing memory population. Secondly, fully developed memory cells expanded in previously immunized mice but not when transferred to naïve animals. Finally, persisting antigen was able to prime naïve cells, including recent thymic emigrants, to become functional effector cells capable of eliminating parasites in the liver. Together these data show that the optimal development of protective CD8+ T cell immunity against malaria liver stages is dependent upon the prolonged presentation of sporozoite-derived antigen.
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Affiliation(s)
- Ian A. Cockburn
- Johns Hopkins Malaria Research Institute and Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Yun-Chi Chen
- Johns Hopkins Malaria Research Institute and Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Michael G. Overstreet
- Johns Hopkins Malaria Research Institute and Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jason R. Lees
- Department of Surgery, University of Maryland at Baltimore, Baltimore, Maryland, United States of America
| | - Nico van Rooijen
- Vrije Universiteit, VUMC, Department of Molecular Cell Biology, Faculty of Medicine, Amsterdam, The Netherlands
| | - Donna L. Farber
- Department of Surgery, University of Maryland at Baltimore, Baltimore, Maryland, United States of America
| | - Fidel Zavala
- Johns Hopkins Malaria Research Institute and Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Minimal role for the circumsporozoite protein in the induction of sterile immunity by vaccination with live rodent malaria sporozoites. Infect Immun 2010; 78:2182-8. [PMID: 20194600 DOI: 10.1128/iai.01415-09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Immunization with live Plasmodium sporozoites under chloroquine prophylaxis (Spz plus CQ) induces sterile immunity against sporozoite challenge in rodents and, more importantly, in humans. Full protection is obtained with substantially fewer parasites than with the classic immunization with radiation-attenuated sporozoites. The sterile protection observed comprised a massive reduction in the hepatic parasite load and an additional effect at the blood stage level. Differences in the immune responses induced by the two protocols occur but are as yet little characterized. We have previously demonstrated that in mice immunized with irradiated sporozoites, immune responses against the circumsporozoite protein (CSP), the major component of the sporozoite's surface and the leading malaria vaccine candidate, were not essential for sterile protection. Here, we have employed transgenic Plasmodium berghei parasites in which the endogenous CSP was replaced by that of Plasmodium yoelii, another rodent malaria species, to assess the role of CSP in the sterile protection induced by the Spz-plus-CQ protocol. The data demonstrated that this role was minor because sterile immunity was obtained irrespective of the origin of CSP expressed by the parasites in this model of protection. The immunity was obtained through a single transient exposure of the host to the immunizing parasites (preerythrocytic and erythrocytic), a dose much smaller than that required for immunization with radiation-attenuated sporozoites.
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35
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Vaughan AM, Wang R, Kappe SHI. Genetically engineered, attenuated whole-cell vaccine approaches for malaria. HUMAN VACCINES 2010; 6:107-13. [PMID: 19838068 DOI: 10.4161/hv.6.1.9654] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Malaria remains one of the most significant infectious diseases affecting human populations in developing countries. The quest for an efficacious malaria vaccine has been ongoing for nearly a century with limited success. The identification of malaria parasite antigens focused efforts on the development of subunit vaccines but has so far yielded only one partially efficacious vaccine candidate, RTS/S. The lack of high vaccine efficacy observed to date with subunit vaccine candidates raises doubts that the development of a single antigen or even a multi-antigen malaria subunit vaccine is possible. Fortunately, it has been demonstrated in animal studies and experimental clinical studies that immunizations with live-attenuated sporozoite stages of the malaria parasite confer long lasting, sterile protection against infection, providing a benchmark for vaccine development. These early successful vaccinations with live-attenuated malaria parasites did not however, promote a developmental path forward for such a vaccine approach. The discovery of genetically engineered parasite strains that are fully attenuated during the early asymptomatic liver infection and confer complete sterile protection in animal malaria models support the development of a live attenuated sporozoite vaccine for Plasmodium falciparum and its accelerated safety and efficacy testing in malaria challenge models and in malaria endemic areas.
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36
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Principles of memory CD8 T-cells generation in relation to protective immunity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 684:108-25. [PMID: 20795544 DOI: 10.1007/978-1-4419-6451-9_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Memory T-cell responses are of vital importance in understanding the host's response against pathogens and cancer cells and to begin establishing the correlation of protection against disease. In this review, we discuss our own data in the general context of current knowledge to sketch tentative working principles for the induction of protective T-cell responses by vaccination. We draw attention to quantitative and qualitative aspects of the initial contact with antigen, as well as to the kinetics of events leading to the generation of memory T cells thereafter. Our arguments are based on the current distinction of memory T cells into two lineages: effector memory T cells (T(EM)) and central memory T cells (T(CM)). Our provisional conclusion is that protective T-cell responses correlate positively with the T cells of the central memory phenotype. In proposing a set of working principles to enable protective memory T cells by vaccination we address vaccination both in the context of the immunologically-inexperienced and immunologically-experienced individual, respectively. Finally, we draw attention to the interplay between systemic and local immunity as important factors in determining the success of memory T-cell responses in protecting the individual. We believe that considerations on the immunodynamics of memory induction and maintenance, memory lineage differentiation and their relation to protection may help design strategies to control disease caused by pathogens and cancer.
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37
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Abstract
Immunization with attenuated pre-erythrocytic malaria parasites can confer sterile protection against malaria in humans and rodents, and a single pre-erythrocytic antigen incorporated in a subunit vaccine has substantially reduced clinical Plasmodium falciparum malaria episodes in African infants during phase 2 trials. Building upon this success has been hindered by technical obstacles that limit research on pre-erythrocytic parasites, especially the liver stage (LS) parasites, and by an incomplete understanding of the immune mechanisms that confer protection in humans. Recent improvements in growing and isolating LS parasites have allowed progress in defining the transcriptome and proteome of the LS parasite, although more work remains to be done particularly for the early LS parasite of P. falciparum. Next generation pre-erythrocytic antigens can be assessed and prioritized based on immunization studies in animals, and on models of immunity such as attenuated parasite vaccines that confer sterile protection or naturally acquired LS-specific immune responses that correlate with protection in endemic areas. Although mechanisms of protection in humans remain poorly understood, the availability of a human malaria challenge model for early clinical testing of candidate vaccines is a valuable tool to confirm which immunogens should move forward to larger field trials.
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Affiliation(s)
- C Speake
- Malaria Program, Seattle Biomedical Research Institute, Seattle, WA 98109, USA
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38
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Nemoto Y, Kanai T, Kameyama K, Shinohara T, Sakamoto N, Totsuka T, Okamoto R, Tsuchiya K, Nakamura T, Sudo T, Matsumoto S, Watanabe M. Long-Lived Colitogenic CD4+ Memory T Cells Residing Outside the Intestine Participate in the Perpetuation of Chronic Colitis. THE JOURNAL OF IMMUNOLOGY 2009; 183:5059-68. [DOI: 10.4049/jimmunol.0803684] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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39
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Preerythrocytic, live-attenuated Plasmodium falciparum vaccine candidates by design. Proc Natl Acad Sci U S A 2009; 106:13004-9. [PMID: 19625622 DOI: 10.1073/pnas.0906387106] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Falciparum malaria is initiated when Anopheles mosquitoes transmit the Plasmodium sporozoite stage during a blood meal. Irradiated sporozoites confer sterile protection against subsequent malaria infection in animal models and humans. This level of protection is unmatched by current recombinant malaria vaccines. However, the live-attenuated vaccine approach faces formidable obstacles, including development of accurate, reproducible attenuation techniques. We tested whether Plasmodium falciparum could be attenuated at the early liver stage by genetic engineering. The P. falciparum genetically attenuated parasites (GAPs) harbor individual deletions or simultaneous deletions of the sporozoite-expressed genes P52 and P36. Gene deletions were done by double-cross-over recombination to avoid genetic reversion of the knockout parasites. The gene deletions did not affect parasite replication throughout the erythrocytic cycle, gametocyte production, mosquito infections, and sporozoite production rates. However, the deletions caused parasite developmental arrest during hepatocyte infection. The double-gene deletion line exhibited a more severe intrahepatocytic growth defect compared with the single-gene deletion lines, and it did not persist. This defect was assessed in an in vitro liver-stage growth assay and in a chimeric mouse model harboring human hepatocytes. The strong phenotype of the double knockout GAP justifies its human testing as a whole-organism vaccine candidate using the established sporozoite challenge model. GAPs might provide a safe and reproducible platform to develop an efficacious whole-cell malaria vaccine that prevents infection at the preerythrocytic stage.
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40
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Jobe O, Donofrio G, Sun G, Liepinsh D, Schwenk R, Krzych U. Immunization with radiation-attenuated Plasmodium berghei sporozoites induces liver cCD8alpha+DC that activate CD8+T cells against liver-stage malaria. PLoS One 2009; 4:e5075. [PMID: 19347042 PMCID: PMC2661143 DOI: 10.1371/journal.pone.0005075] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 03/02/2009] [Indexed: 02/07/2023] Open
Abstract
Immunization with radiation (gamma)-attenuated Plasmodia sporozoites (gamma-spz) confers sterile and long-lasting immunity against malaria liver-stage infection. In the P. berghei gamma-spz model, protection is linked to liver CD8+ T cells that express an effector/memory (T(EM)) phenotype, (CD44(hi)CD45RB(lo)CD62L(lo)), and produce IFN-gamma. However, neither the antigen presenting cells (APC) that activate these CD8+ T(EM) cells nor the site of their induction have been fully investigated. Because conventional (c)CD8alpha+ DC (a subset of CD11c+ DC) are considered the major inducers of CD8+ T cells, in this study we focused primarily on cCD8alpha+ DC from livers of mice immunized with Pb gamma-spz and asked whether the cCD8alpha+ DC might be involved in the activation of CD8+ T(EM) cells. We demonstrate that multiple exposures of mice to Pb gamma-spz lead to a progressive and nearly concurrent accumulation in the liver but not the spleen of both the CD11c+NK1.1(-) DC and CD8+ T(EM) cells. Upon adoptive transfer, liver CD11c+NK1.1(-) DC from Pb gamma-spz-immunized mice induced protective immunity against sporozoite challenge. Moreover, in an in vitro system, liver cCD8alpha(+) DC induced naïve CD8+ T cells to express the CD8+ T(EM) phenotype and to secrete IFN-gamma. The in vitro induction of functional CD8+ T(EM) cells by cCD8alpha+ DC was inhibited by anti-MHC class I and anti-IL-12 mAbs. These data suggest that liver cCD8alpha+ DC present liver-stage antigens to activate CD8+ T(EM) cells, the pre-eminent effectors against pre-erythrocytic malaria. These results provide important implications towards a design of anti-malaria vaccines.
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Affiliation(s)
- Ousman Jobe
- Department of Cellular Immunology, Division of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
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41
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Ting LM, Gissot M, Coppi A, Sinnis P, Kim K. Attenuated Plasmodium yoelii lacking purine nucleoside phosphorylase confer protective immunity. Nat Med 2008; 14:954-8. [PMID: 18758447 DOI: 10.1038/nm.1867] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 07/14/2008] [Indexed: 11/09/2022]
Abstract
Malaria continues to devastate sub-Saharan Africa owing to the emergence of drug resistance to established antimalarials and to the lack of an efficacious vaccine. Plasmodium species have a unique streamlined purine pathway in which the dual specificity enzyme purine nucleoside phosphorylase (PNP) functions in both purine recycling and purine salvage. To evaluate the importance of PNP in an in vivo model of malaria, we disrupted PyPNP, the gene encoding PNP in the lethal Plasmodium yoelii YM strain. P. yoelii parasites lacking PNP were attenuated and cleared in mice. Although able to form gametocytes, PNP-deficient parasites did not form oocysts in mosquito midguts and were not transmitted from mosquitoes to mice. Mice given PNP-deficient parasites were immune to subsequent challenge to a lethal inoculum of P. yoelii YM and to challenge from P. yoelii 17XNL, another strain. These in vivo studies with PNP-deficient parasites support purine salvage as a target for antimalarials. They also suggest a strategy for the development of attenuated nontransmissible metabolic mutants as blood-stage malaria vaccine strains.
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Affiliation(s)
- Li-Min Ting
- Department of Medicine and Microbiology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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42
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Ménard R, Heussler V, Yuda M, Nussenzweig V. Plasmodium pre-erythrocytic stages: what's new? Trends Parasitol 2008; 24:564-9. [PMID: 18929511 DOI: 10.1016/j.pt.2008.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 08/14/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
Abstract
The pre-erythrocytic (PE) phase of malaria infection, which extends from injection of sporozoites into the skin to the release of the first generation of merozoites, has traditionally been the 'black box' of the Plasmodium life cycle. However, since the advent of parasite transfection technology 13 years ago, our understanding of the PE phase in cellular and molecular terms has dramatically improved. Here, we review and comment on the major developments in the field in the past five years. Progress has been made in many diverse areas, including identifying and characterizing new proteins of interest, imaging parasites in vivo, understanding better the cell biology of hepatocyte infection and developing new vaccines against PE stages of the parasite.
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Affiliation(s)
- Robert Ménard
- Institut Pasteur, Unité de Biologie et Génétique du Paludisme, 75724 Paris cedex 15, France.
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43
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Langhorne J, Ndungu FM, Sponaas AM, Marsh K. Immunity to malaria: more questions than answers. Nat Immunol 2008; 9:725-32. [PMID: 18563083 DOI: 10.1038/ni.f.205] [Citation(s) in RCA: 621] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Malaria is one of the main health problems facing developing countries today. At present, preventative and treatment strategies are continuously hampered by the issues of the ever-emerging parasite resistance to newly introduced drugs, considerable costs and logistical problems. The main hope for changing this situation would be the development of effective malaria vaccines. An important part of this process is understanding the mechanisms of naturally acquired immunity to malaria. This review will highlight key aspects of immunity to malaria, about which surprisingly little is known and which will prove critical in the search for effective malaria vaccines.
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Affiliation(s)
- Jean Langhorne
- Division of Parasitology, National Institute for Medical Research, London NW7 1AA, UK.
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44
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Tomita T, Kanai T, Fujii T, Nemoto Y, Okamoto R, Tsuchiya K, Totsuka T, Sakamoto N, Watanabe M. Continuous generation of colitogenic CD4+ T cells in persistent colitis. Eur J Immunol 2008; 38:1264-74. [DOI: 10.1002/eji.200737745] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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45
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Bongfen SE, Balam S, Torgler R, Romero JF, Corradin G. Processing of the circumsporozoite protein in infected hepatocytes is not dependent on aspartic proteases. Parasite Immunol 2008; 30:375-8. [PMID: 18444957 DOI: 10.1111/j.1365-3024.2008.01032.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
CD8(+) T cells play a major role in the protective immune response against the liver stage of malaria. It was previously shown that the circumsporozoite protein (CSP) is processed and presented to specific T cells by both traversed and infected hepatocytes, but their respective antigen processing requirements were not completely defined. In the present study, we show that in vitro processing of the Plasmodium berghei CSP by infected mouse primary hepatocytes is exclusively dependent on proteasomes, while aspartic proteases are also needed in the case of traversed hepatocytes.
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Affiliation(s)
- S E Bongfen
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses, Epalinges, Switzerland
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46
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Pinzon-Charry A, Good MF. Malaria vaccines: the case for a whole-organism approach. Expert Opin Biol Ther 2008; 8:441-8. [DOI: 10.1517/14712598.8.4.441] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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47
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Purcell LA, Yanow SK, Lee M, Spithill TW, Rodriguez A. Chemical attenuation of Plasmodium berghei sporozoites induces sterile immunity in mice. Infect Immun 2008; 76:1193-9. [PMID: 18174336 PMCID: PMC2258828 DOI: 10.1128/iai.01399-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 11/16/2007] [Accepted: 12/19/2007] [Indexed: 11/20/2022] Open
Abstract
Radiation and genetic attenuation of Plasmodium sporozoites are two approaches for whole-organism vaccines that protect against malaria. We evaluated chemical attenuation of sporozoites as an alternative vaccine strategy. Sporozoites were treated with the DNA sequence-specific alkylating agent centanamycin, a compound that significantly affects blood stage parasitemia and transmission of murine malaria and also inhibits Plasmodium falciparum growth in vitro. Here we show that treatment of Plasmodium berghei sporozoites with centanamycin impaired parasite function both in vitro and in vivo. The infection of hepatocytes by sporozoites in vitro was significantly reduced, and treated parasites showed arrested liver stage development. Inoculation of mice with sporozoites that were treated in vitro with centanamycin failed to produce blood stage infections. Furthermore, BALB/c and C57BL/6 mice vaccinated with treated sporozoites were protected against subsequent challenge with wild-type sporozoites. Our findings demonstrate that chemically attenuated sporozoites could be a viable alternative for the production of an effective liver stage vaccine for malaria.
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Affiliation(s)
- Lisa A Purcell
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X3V9, Canada
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48
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A combined transcriptome and proteome survey of malaria parasite liver stages. Proc Natl Acad Sci U S A 2008; 105:305-10. [PMID: 18172196 DOI: 10.1073/pnas.0710780104] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For 50 years since their discovery, the malaria parasite liver stages (LS) have been difficult to analyze, impeding their utilization as a critical target for antiinfection vaccines and drugs. We have undertaken a comprehensive transcriptome analysis in combination with a proteomic survey of LS. Green fluorescent protein-tagged Plasmodium yoelii (PyGFP) was used to efficiently isolate LS-infected hepatocytes from the rodent host. Genome-wide LS gene expression was profiled and compared with other parasite life cycle stages. The analysis revealed approximately 2,000 genes active during LS development, and proteomic analysis identified 816 proteins. A subset of proteins appeared to be expressed in LS only. The data revealed exported parasite proteins and LS metabolic pathways including expression of FASII pathway enzymes. The FASII inhibitor hexachlorophene and the antibiotics, tetracycline and rifampicin, that target the apicoplast inhibited LS development, identifying FASII and other pathways localized in the apicoplast as potential drug targets to prevent malaria infection.
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49
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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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Mueller AK, Deckert M, Heiss K, Goetz K, Matuschewski K, Schlüter D. Genetically attenuated Plasmodium berghei liver stages persist and elicit sterile protection primarily via CD8 T cells. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:107-15. [PMID: 17591958 PMCID: PMC1941586 DOI: 10.2353/ajpath.2007.060792] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Live-attenuated Plasmodium liver stages remain the only experimental model that confers complete sterile protection against malaria. Irradiation-attenuated Plasmodium parasites mediate protection primarily by CD8 T cells. In contrast, it is unknown how genetically attenuated liver stage parasites provide protection. Here, we show that immunization with uis3(-) sporozoites does not cause breakthrough infection in T and B-cell-deficient rag1(-/-) and IFN-gamma(-/-) mice. However, protection was abolished in these animals, suggesting a crucial role for adaptive immune responses and interferon-gamma. Although uis3(-) immunization induced Plasmodium-specific antibodies, B- cell-deficient mice immunized with uis3(-) sporozoites were completely protected against wild-type sporozoite challenge infection. T-cell depletion experiments before parasite challenge showed that protection is primarily mediated by CD8 T cells. In good agreement, adoptive transfer of total spleen cells and enriched CD8 T cells from immunized animals conferred sterile protection against malaria transmission to recipient mice, whereas adoptive transfer of CD4 T cells was less protective. Importantly, primaquine treatment completely abolished the uis3(-)-mediated protection, indicating that persistence of uis3(-)-attenuated liver stages is crucial for their protective action. These findings establish the basic immune mechanisms underlying protection induced by genetically attenuated Plasmodium parasites and substantiate their use as vaccines against malaria.
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Affiliation(s)
- Ann-Kristin Mueller
- Department of Parasitology, Heidelberg University School of Medicine, Im Neuenheimer Feld 324, Heidelberg, Germany
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