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Nicholas J, De SL, Thawornpan P, Brashear AM, Kolli SK, Subramani PA, Barnes SJ, Cui L, Chootong P, Ntumngia FB, Adams JH. Preliminary characterization of Plasmodium vivax sporozoite antigens as pre-erythrocytic vaccine candidates. PLoS Negl Trop Dis 2023; 17:e0011598. [PMID: 37703302 PMCID: PMC10519608 DOI: 10.1371/journal.pntd.0011598] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 09/25/2023] [Accepted: 08/15/2023] [Indexed: 09/15/2023] Open
Abstract
Plasmodium vivax pre-erythrocytic (PE) vaccine research has lagged far behind efforts to develop Plasmodium falciparum vaccines. There is a critical gap in our knowledge of PE antigen targets that can induce functionally inhibitory neutralizing antibody responses. To overcome this gap and guide the selection of potential PE vaccine candidates, we considered key characteristics such as surface exposure, essentiality to infectivity and liver stage development, expression as recombinant proteins, and functional immunogenicity. Selected P. vivax sporozoite antigens were surface sporozoite protein 3 (SSP3), sporozoite microneme protein essential for cell traversal (SPECT1), sporozoite surface protein essential for liver-stage development (SPELD), and M2 domain of MAEBL. Sequence analysis revealed little variation occurred in putative B-cell and T-cell epitopes of the PE candidates. Each antigen was tested for expression as refolded recombinant proteins using an established bacterial expression platform and only SPELD failed. The successfully expressed antigens were immunogenic in vaccinated laboratory mice and were positively reactive with serum antibodies of P. vivax-exposed residents living in an endemic region in Thailand. Vaccine immune antisera were tested for reactivity to native sporozoite proteins and for their potential vaccine efficacy using an in vitro inhibition of liver stage development assay in primary human hepatocytes quantified on day 6 post-infection by high content imaging analysis. The anti-PE sera produced significant inhibition of P. vivax sporozoite invasion and liver stage development. This report provides an initial characterization of potential new PE candidates for a future P. vivax vaccine.
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Affiliation(s)
- Justin Nicholas
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Sai Lata De
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Pongsakorn Thawornpan
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
| | - Awtum M. Brashear
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Surendra Kumar Kolli
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Pradeep Annamalai Subramani
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Samantha J. Barnes
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Liwang Cui
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Patchanee Chootong
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
| | - Francis Babila Ntumngia
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - John H. Adams
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, United States of America
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2
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Vigdorovich V, Patel H, Watson A, Raappana A, Reynolds L, Selman W, Beeman S, Edlefsen PT, Kappe SHI, Sather DN. Coimmunization with Preerythrocytic Antigens alongside Circumsporozoite Protein Can Enhance Sterile Protection against Plasmodium Sporozoite Infection. Microbiol Spectr 2023; 11:e0379122. [PMID: 36847573 PMCID: PMC10100930 DOI: 10.1128/spectrum.03791-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/10/2023] [Indexed: 03/01/2023] Open
Abstract
Malaria-causing Plasmodium parasites have a complex life cycle and present numerous antigen targets that may contribute to protective immune responses. The currently recommended vaccine-RTS,S-functions by targeting the Plasmodium falciparum circumsporozoite protein (CSP), which is the most abundant surface protein of the sporozoite form responsible for initiating infection of the human host. Despite showing only moderate efficacy, RTS,S has established a strong foundation for the development of next-generation subunit vaccines. Our previous work characterizing the sporozoite surface proteome identified additional non-CSP antigens that may be useful as immunogens individually or in combination with CSP. In this study, we examined eight such antigens using the rodent malaria parasite Plasmodium yoelii as a model system. We demonstrate that despite conferring weak protection individually, coimmunizing each of several of these antigens alongside CSP could significantly enhance the sterile protection achieved by CSP immunization alone. Thus, our work provides compelling evidence that a multiantigen preerythrocytic vaccine approach may enhance protection compared to CSP-only vaccines. This lays the groundwork for further studies aimed at testing the identified antigen combinations in human vaccination trials that assess efficacy with controlled human malaria infection. IMPORTANCE The currently approved malaria vaccine targets a single parasite protein (CSP) and results in only partial protection. We tested several additional vaccine targets in combination with CSP to identify those that could enhance protection from infection upon challenge in the mouse malaria model. In identifying several such enhancing vaccine targets, our work indicates that a multiprotein immunization approach may be a promising avenue to achieving higher levels of protection from infection. Our work identified several candidate leads for follow-up in the models relevant for human malaria and provides an experimental framework for efficiently carrying out such screens for other combinations of vaccine targets.
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Affiliation(s)
- Vladimir Vigdorovich
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Hardik Patel
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Alexander Watson
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Andrew Raappana
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Laura Reynolds
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - William Selman
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Suzannah Beeman
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Paul T. Edlefsen
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Stefan H. I. Kappe
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | - D. Noah Sather
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
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3
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Sá M, Costa DM, Teixeira AR, Pérez-Cabezas B, Formaglio P, Golba S, Sefiane-Djemaoune H, Amino R, Tavares J. MAEBL Contributes to Plasmodium Sporozoite Adhesiveness. Int J Mol Sci 2022; 23:5711. [PMID: 35628522 DOI: 10.3390/ijms23105711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023] Open
Abstract
The sole currently approved malaria vaccine targets the circumsporozoite protein-the protein that densely coats the surface of sporozoites, the parasite stage deposited in the skin of the mammalian host by infected mosquitoes. However, this vaccine only confers moderate protection against clinical diseases in children, impelling a continuous search for novel candidates. In this work, we studied the importance of the membrane-associated erythrocyte binding-like protein (MAEBL) for infection by Plasmodium sporozoites. Using transgenic parasites and live imaging in mice, we show that the absence of MAEBL reduces Plasmodium berghei hemolymph sporozoite infectivity to mice. Moreover, we found that maebl knockout (maebl-) sporozoites display reduced adhesion, including to cultured hepatocytes, which could contribute to the defects in multiple biological processes, such as in gliding motility, hepatocyte wounding, and invasion. The maebl- defective phenotypes in mosquito salivary gland and liver infection were reverted by genetic complementation. Using a parasite line expressing a C-terminal myc-tagged MAEBL, we found that MAEBL levels peak in midgut and hemolymph parasites but drop after sporozoite entry into the salivary glands, where the labeling was found to be heterogeneous among sporozoites. MAEBL was found associated, not only with micronemes, but also with the surface of mature sporozoites. Overall, our data provide further insight into the role of MAEBL in sporozoite infectivity and may contribute to the design of future immune interventions.
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Fabra-García A, Yang AS, Behet MC, Yap XZ, van Waardenburg Y, Kaviraj S, Lanke K, van Gemert GJ, Jore MM, Bousema T, Sauerwein RW. Human antibodies against non-circumsporozoite proteins block Plasmodium falciparum parasite development in hepatocytes. JCI Insight 2022; 7:153524. [PMID: 35167490 PMCID: PMC8986077 DOI: 10.1172/jci.insight.153524] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/09/2022] [Indexed: 12/02/2022] Open
Abstract
Sporozoite-based approaches currently represent the most effective vaccine strategies for induction of sterile protection against Plasmodium falciparum (Pf) malaria. Clinical development of subunit vaccines is almost exclusively centered on the circum-sporozoite protein (CSP), an abundantly expressed protein on the sporozoite membrane. Anti-CSP antibodies are able to block sporozoite invasion and development in human hepatocytes and subsequently prevent clinical malaria. Here, we have investigated whether sporozoite-induced human antibodies with specificities different from CSP can reduce Pf-liver stage development. IgG preparations were obtained from 12 volunteers inoculated with a protective immunization regime of whole sporozoites under chloroquine prophylaxis. These IgGs were depleted for CSP specificity by affinity chromatography. Recovered non-CSP antibodies were tested for sporozoite membrane binding and for functional inhibition of sporozoite invasion of a human hepatoma cell line and hepatocytes both in vitro and in vivo. Postimmunization IgGs depleted for CS specificity of 9 of 12 donors recognized sporozoite surface antigens. Samples from 5 of 12 donors functionally reduced parasite-liver cell invasion or development using the hepatoma cell line HC-04 and FRG-huHep mice containing human liver cells. The combined data provide clear evidence that non-CSP proteins, as yet undefined, do represent antibody targets for functional immunity against Pf parasites responsible for malaria.
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Affiliation(s)
- Amanda Fabra-García
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Annie Sp Yang
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Marije C Behet
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Xi Zen Yap
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Youri van Waardenburg
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | | | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Matthijs M Jore
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
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5
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Malleret B, El Sahili A, Tay MZ, Carissimo G, Ong ASM, Novera W, Lin J, Suwanarusk R, Kosaisavee V, Chu TTT, Sinha A, Howland SW, Fan Y, Gruszczyk J, Tham WH, Colin Y, Maurer-Stroh S, Snounou G, Ng LFP, Chan JKY, Chacko AM, Lescar J, Chandramohanadas R, Nosten F, Russell B, Rénia L. Plasmodium vivax binds host CD98hc (SLC3A2) to enter immature red blood cells. Nat Microbiol 2021; 6:991-9. [PMID: 34294905 DOI: 10.1038/s41564-021-00939-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 06/18/2021] [Indexed: 12/16/2022]
Abstract
More than one-third of the world's population is exposed to Plasmodium vivax malaria, mainly in Asia1. P. vivax preferentially invades reticulocytes (immature red blood cells)2-4. Previous work has identified 11 parasite proteins involved in reticulocyte invasion, including erythrocyte binding protein 2 (ref. 5) and the reticulocyte-binding proteins (PvRBPs)6-10. PvRBP2b binds to the transferrin receptor CD71 (ref. 11), which is selectively expressed on immature reticulocytes12. Here, we identified CD98 heavy chain (CD98), a heteromeric amino acid transporter from the SLC3 family (also known as SLCA2), as a reticulocyte-specific receptor for the PvRBP2a parasite ligand using mass spectrometry, flow cytometry, biochemical and parasite invasion assays. We characterized the expression level of CD98 at the surface of immature reticulocytes (CD71+) and identified an interaction between CD98 and PvRBP2a expressed at the merozoite surface. Our results identify CD98 as an additional host membrane protein, besides CD71, that is directly associated with P. vivax reticulocyte tropism. These findings highlight the potential of using PvRBP2a as a vaccine target against P. vivax malaria.
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Loubens M, Vincensini L, Fernandes P, Briquet S, Marinach C, Silvie O. Plasmodium sporozoites on the move: Switching from cell traversal to productive invasion of hepatocytes. Mol Microbiol 2021; 115:870-881. [PMID: 33191548 PMCID: PMC8247013 DOI: 10.1111/mmi.14645] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/18/2022]
Abstract
Parasites of the genus Plasmodium, the etiological agent of malaria, are transmitted through the bite of anopheline mosquitoes, which deposit sporozoites into the host skin. Sporozoites migrate through the dermis, enter the bloodstream, and rapidly traffic to the liver. They cross the liver sinusoidal barrier and traverse several hepatocytes before switching to productive invasion of a final one for replication inside a parasitophorous vacuole. Cell traversal and productive invasion are functionally independent processes that require proteins secreted from specialized secretory organelles known as micronemes. In this review, we summarize the current understanding of how sporozoites traverse through cells and productively invade hepatocytes, and discuss the role of environmental sensing in switching from a migratory to an invasive state. We propose that timely controlled secretion of distinct microneme subsets could play a key role in successful migration and infection of hepatocytes. A better understanding of these essential biological features of the Plasmodium sporozoite may contribute to the development of new strategies to fight against the very first and asymptomatic stage of malaria.
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Affiliation(s)
- Manon Loubens
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Laetitia Vincensini
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Priyanka Fernandes
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Sylvie Briquet
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Carine Marinach
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Olivier Silvie
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
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Abstract
Introduction: Despite decades of research into the development of a vaccine to combat the malaria parasite, a highly efficacious malaria vaccine is not yet available. Different whole parasite-based vaccine approaches, including deliberate Plasmodium infection and drug cure (IDC), have been evaluated in pre-clinical and early phase clinical trials. The advantage of whole parasite vaccines is that they induce immune responses against multiple parasite antigens, thus lowering the impact of antigenic diversity. Deliberate Plasmodium IDC, as a vaccine approach, involves administering infectious, live parasites in combination with an anti-malarial drug, which controls the infection and enables induction of protective immune responses.
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Affiliation(s)
- Reshma J Nevagi
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia
| | - Michael F Good
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia
| | - Danielle I Stanisic
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia
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8
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Arredondo SA, Schepis A, Reynolds L, Kappe SHI. Secretory Organelle Function in the Plasmodium Sporozoite. Trends Parasitol 2021; 37:651-663. [PMID: 33589364 DOI: 10.1016/j.pt.2021.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/20/2021] [Accepted: 01/20/2021] [Indexed: 12/14/2022]
Abstract
Plasmodium sporozoites exhibit a complex infection biology in the mosquito and mammalian hosts. The sporozoite apical secretory organelles, the micronemes and rhoptries, store protein mediators of parasite/host/vector interactions and must secrete them in a temporally and spatially well orchestrated manner. Micronemal proteins are critical for sporozoite motility throughout its journey from the mosquito midgut oocyst to the mammalian liver, and also for cell traversal (CT) and hepatocyte invasion. Rhoptry proteins, until recently thought to be only important for hepatocyte invasion, appear to also play an unexpected role in motility and in the interaction with mosquito tissue. Therefore, navigating the different microenvironments with secretion likely requires the sporozoite to have a more complex system of secretory organelles than previously appreciated.
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Affiliation(s)
- Silvia A Arredondo
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Antonino Schepis
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Laura Reynolds
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Stefan H I Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Department of Global Health, University of Washington, Seattle, WA 98105, USA.
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Atcheson E, Cabral-Miranda G, Salman AM, Reyes-Sandoval A. Discovery of four new B-cell protective epitopes for malaria using Q beta virus-like particle as platform. NPJ Vaccines 2020; 5:92. [PMID: 33083027 DOI: 10.1038/s41541-020-00242-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 09/17/2020] [Indexed: 12/26/2022] Open
Abstract
Malaria remains one of the world’s most urgent global health problems, with almost half a million deaths and hundreds of millions of clinical cases each year. Existing interventions by themselves will not be enough to tackle infection in high-transmission areas. The best new intervention would be an effective vaccine; but the leading P. falciparum and P. vivax vaccine candidates, RTS,S and VMP001, show only modest to low field efficacy. New antigens and improved ways for screening antigens for protective efficacy will be required. This study exploits the potential of Virus-Like Particles (VLP) to enhance immune responses to antigens, the ease of coupling peptides to the Q beta (Qβ) VLP and the existing murine malaria challenge to screen B-cell epitopes for protective efficacy. We screened P. vivax TRAP (PvTRAP) immune sera against individual 20-mer PvTRAP peptides. The most immunogenic peptides associated with protection were loaded onto Qβ VLPs to assess protective efficacy in a malaria sporozoite challenge. A second approach focused on identifying conserved regions within known sporozoite invasion proteins and assessing them as part of the Qβ. Using this VLP as a peptide scaffold, four new protective B-cell epitopes were discovered: three from the disordered region of PvTRAP and one from Thrombospondin-related sporozoite protein (TRSP). Antigenic interference between these and other B-cell epitopes was also explored using the virus-like particle/peptide platform. This approach demonstrates the utility of VLPs to help identifying new B-cell epitopes for inclusion in next-generation malaria vaccines.
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Yap XZ, McCall MBB, Sauerwein RW. Fast and fierce versus slow and smooth: Heterogeneity in immune responses to Plasmodium in the controlled human malaria infection model. Immunol Rev 2020; 293:253-269. [PMID: 31605396 PMCID: PMC6973142 DOI: 10.1111/imr.12811] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/11/2019] [Accepted: 09/13/2019] [Indexed: 12/19/2022]
Abstract
Controlled human malaria infection (CHMI) is an established model in clinical malaria research. Upon exposure to Plasmodium falciparum parasites, malaria-naive volunteers differ in dynamics and composition of their immune profiles and subsequent capacity to generate protective immunity. CHMI volunteers are either inflammatory responders who have prominent cellular IFN-γ production primarily driven by adaptive T cells, or tempered responders who skew toward antibody-mediated humoral immunity. When exposed to consecutive CHMIs under antimalarial chemoprophylaxis, individuals who can control parasitemia after a single immunization (fast responders) are more likely to be protected against a subsequent challenge infection. Fast responders tend to be inflammatory responders who can rapidly induce long-lived IFN-γ+ T cell responses. Slow responders or even non-responders can also be protected, but via a more diverse range of responses that take a longer time to reach full protective efficacy, in part due to their tempered phenotype. The latter group can be identified at baseline before CHMI by higher expression of inhibitory ligands CTLA-4 and TIM-3 on CD4+ T cells. Delineating heterogeneity in human immune responses to P. falciparum will facilitate rational design and strategy towards effective malaria vaccines.
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Affiliation(s)
- Xi Zen Yap
- Department of Medical MicrobiologyRadboud University Medical CenterNijmegenThe Netherlands
- Radboud Center for Infectious DiseasesRadboud University Medical CenterNijmegenThe Netherlands
| | - Matthew B. B. McCall
- Department of Medical MicrobiologyRadboud University Medical CenterNijmegenThe Netherlands
- Radboud Center for Infectious DiseasesRadboud University Medical CenterNijmegenThe Netherlands
| | - Robert W. Sauerwein
- Department of Medical MicrobiologyRadboud University Medical CenterNijmegenThe Netherlands
- Radboud Center for Infectious DiseasesRadboud University Medical CenterNijmegenThe Netherlands
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11
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Zanghì G, Vembar SS, Baumgarten S, Ding S, Guizetti J, Bryant JM, Mattei D, Jensen ATR, Rénia L, Goh YS, Sauerwein R, Hermsen CC, Franetich JF, Bordessoulles M, Silvie O, Soulard V, Scatton O, Chen P, Mecheri S, Mazier D, Scherf A. A Specific PfEMP1 Is Expressed in P. falciparum Sporozoites and Plays a Role in Hepatocyte Infection. Cell Rep 2018; 22:2951-63. [PMID: 29539423 DOI: 10.1016/j.celrep.2018.02.075] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Heterochromatin plays a central role in the process of immune evasion, pathogenesis, and transmission of the malaria parasite Plasmodium falciparum during blood stage infection. Here, we use ChIP sequencing to demonstrate that sporozoites from mosquito salivary glands expand heterochromatin at subtelomeric regions to silence blood-stage-specific genes. Our data also revealed that heterochromatin enrichment is predictive of the transcription status of clonally variant genes members that mediate cytoadhesion in blood stage parasites. A specific member (here called NF54varsporo) of the var gene family remains euchromatic, and the resultant PfEMP1 (NF54_SpzPfEMP1) is expressed at the sporozoite surface. NF54_SpzPfEMP1-specific antibodies efficiently block hepatocyte infection in a strain-specific manner. Furthermore, human volunteers immunized with infective sporozoites developed antibodies against NF54_SpzPfEMP1. Overall, we show that the epigenetic signature of var genes is reset in mosquito stages. Moreover, the identification of a strain-specific sporozoite PfEMP1 is highly relevant for vaccine design based on sporozoites. Sporozoites expand subtelomeric heterochromatin to silence blood-stage-specific genes A strain-specific PfEMP1 is expressed on the surface of sporozoites NF54_SpzPfEMP1 is immunogenic in sporozoite-infected human volunteers Antibodies against NF54_SpzPfEMP1 block sporozoite infection of hepatocytes
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Abstract
Despite continuous efforts, the century-old goal of eradicating malaria still remains. Multiple control interventions need to be in place simultaneously to achieve this goal. In addition to effective control measures, drug therapies and insecticides, vaccines are critical to reduce mortality and morbidity. Hence, there are numerous studies investigating various malaria vaccine candidates. Most of the malaria vaccine candidates are subunit vaccines. However, they have shown limited efficacy in Phase II and III studies. To date, only whole parasite formulations have been shown to induce sterile immunity in human. In this article, we review and discuss the recent developments in vaccination with sporozoites and the mechanisms of protection involved.
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Affiliation(s)
- Yun Shan Goh
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (ASTAR), Biopolis, Singapore, Singapore
| | - Daniel McGuire
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (ASTAR), Biopolis, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Laurent Rénia
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (ASTAR), Biopolis, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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13
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Mehrizi AA, Ameri Torzani M, Zakeri S, Jafary Zadeh A, Babaeekhou L. Th1 immune response to Plasmodium falciparum recombinant thrombospondin-related adhesive protein (TRAP) antigen is enhanced by TLR3-specific adjuvant, poly(I:C) in BALB/c mice. Parasite Immunol 2019; 40:e12538. [PMID: 29799636 DOI: 10.1111/pim.12538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 05/21/2018] [Indexed: 12/12/2022]
Abstract
Sporozoite-based malaria vaccines have provided a gold standard for malaria vaccine development, and thrombospondin-related adhesive protein (TRAP) serves as the main vaccine candidate antigen on sporozoites. As recombinant malaria vaccine candidate antigens are poorly immunogenic, additional appropriate immunostimulants, such as an efficient adjuvant, are highly essential to modulate Th1-cell predominance and also to induce a protective and long-lived immune response. In this study, polyinosinic:polycytidylic acid [poly(I:C)], the ligand of TLR3, was considered as the potential adjuvant for vaccines targeting stronger Th1-based immune responses. For this purpose, BALB/c mice were immunized with rPfTRAP delivered in putative poly(I:C) adjuvant, and humoural and cellular immune responses were determined in different immunized mouse groups. Delivery of rPfTRAP with poly(I:C) induced high levels and titres of persisted and also high-avidity anti-rPfTRAP IgG antibodies comparable to complete Freund's adjuvant (CFA)/incomplete Freund's adjuvant (IFA) adjuvant after the second boost. In addition, rPfTRAP formulated with poly(I:C) elicited a higher ratio of IFN-γ/IL-5, IgG2a/IgG1, and IgG2b/IgG1 than with CFA/IFA, indicating that poly(I:C) supports the induction of a stronger Th1-based immune response. This is a first time study which reveals the potential of rPfTRAP delivery in poly(I:C) to increase the level, avidity and durability of both anti-PfTRAP cytophilic antibodies and Th1 cytokines.
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Affiliation(s)
- A A Mehrizi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - M Ameri Torzani
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.,Department of Biology, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran
| | - S Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - A Jafary Zadeh
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - L Babaeekhou
- Department of Biology, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran
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14
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Jaenisch T, Heiss K, Fischer N, Geiger C, Bischoff FR, Moldenhauer G, Rychlewski L, Sié A, Coulibaly B, Seeberger PH, Wyrwicz LS, Breitling F, Loeffler FF. High-density Peptide Arrays Help to Identify Linear Immunogenic B-cell Epitopes in Individuals Naturally Exposed to Malaria Infection. Mol Cell Proteomics 2019; 18:642-656. [PMID: 30630936 PMCID: PMC6442360 DOI: 10.1074/mcp.ra118.000992] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/28/2018] [Indexed: 01/31/2023] Open
Abstract
High-density peptide arrays are an excellent means to profile anti-plasmodial antibody responses. Different protein intrinsic epitopes can be distinguished, and additional insights are gained, when compared with assays involving the full-length protein. Distinct reactivities to specific epitopes within one protein may explain differences in published results, regarding immunity or susceptibility to malaria. We pursued three approaches to find specific epitopes within important plasmodial proteins, (1) twelve leading vaccine candidates were mapped as overlapping 15-mer peptides, (2) a bioinformatical approach served to predict immunogenic malaria epitopes which were subsequently validated in the assay, and (3) randomly selected peptides from the malaria proteome were screened as a control. Several peptide array replicas were prepared, employing particle-based laser printing, and were used to screen 27 serum samples from a malaria-endemic area in Burkina Faso, West Africa. The immunological status of the individuals was classified as "protected" or "unprotected" based on clinical symptoms, parasite density, and age. The vaccine candidate screening approach resulted in significant hits in all twelve proteins and allowed us (1) to verify many known immunogenic structures, (2) to map B-cell epitopes across the entire sequence of each antigen and (3) to uncover novel immunogenic epitopes. Predicting immunogenic regions in the proteome of the human malaria parasite Plasmodium falciparum, via the bioinformatics approach and subsequent array screening, confirmed known immunogenic sequences, such as in the leading malaria vaccine candidate CSP and discovered immunogenic epitopes derived from hypothetical or unknown proteins.
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Affiliation(s)
- Thomas Jaenisch
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;.
| | - Kirsten Heiss
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - Nico Fischer
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany
| | - Carolin Geiger
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - F Ralf Bischoff
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Gerhard Moldenhauer
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Leszek Rychlewski
- BioInfoBank Institute, Św. Marcin 80/82 lok. 355, 61-809 Poznań, Poland
| | - Ali Sié
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Boubacar Coulibaly
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Peter H Seeberger
- §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany
| | - Lucjan S Wyrwicz
- Department of Oncology and Radiotherapy, M Sklodowska Curie Memorial Cancer Center, Wawelska 15, 02-034 Warsaw, Poland
| | - Frank Breitling
- ‖‖Institute of Microstructure Technology, Karlsruhe Institute of Technology, Germany Hermann-von-Helmholtz-Platz 1, D 76344 Eggenstein-Leopoldshafen, Germany
| | - Felix F Loeffler
- ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;; §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany;.
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15
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Obiero JM, Campo JJ, Scholzen A, Randall A, Bijker EM, Roestenberg M, Hermsen CC, Teng A, Jain A, Davies DH, Sauerwein RW, Felgner PL. Antibody Biomarkers Associated with Sterile Protection Induced by Controlled Human Malaria Infection under Chloroquine Prophylaxis. mSphere 2019; 4:e00027-19. [PMID: 30787114 DOI: 10.1128/mSphereDirect.00027-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Infection by Plasmodium parasites has been a major cause of mortality and morbidity in humans for thousands of years. Despite the considerable reduction of deaths, according to the WHO, over 5 billion people are still at risk, with about 216 million worldwide cases occurring in 2016. More compelling, 15 countries in sub-Saharan Africa bore 80% of the worldwide malaria burden. Complete eradication has been challenging, and the development of an affordable and effective vaccine will go a long way in achieving elimination. However, identifying vaccine candidate targets has been difficult. In the present study, we use a highly effective immunization protocol that confers long-lasting sterile immunity in combination with a whole P. falciparum proteome microarray to identify antibody responses associated with protection. This study characterizes a novel antibody profile associated with sterile protective immunity and trimodal humoral responses that sheds light on the possible mechanism of CPS-induced immunity against P. falciparum parasites. Immunization with sporozoites under chloroquine chemoprophylaxis (CPS) induces distinctly preerythrocytic and long-lasting sterile protection against homologous controlled human malaria infection (CHMI). To identify possible humoral immune correlates of protection, plasma samples were collected from 38 CPS-immunized Dutch volunteers for analysis using a whole Plasmodium falciparum proteome microarray with 7,455 full-length or segmented protein features displaying about 91% of the total P. falciparum proteome. We identified 548 reactive antigens representing 483 unique proteins. Using the breadth of antibody responses for each subject in a mixture-model algorithm, we observed a trimodal pattern, with distinct groups of 16 low responders, 19 medium responders, and 3 high responders. Fifteen out of 16 low responders, 12 of the 19 medium responders, and 3 out of 3 high responders were fully protected from a challenge infection. In the medium-responder group, we identified six novel antigens associated with protection (area under the curve [AUC] value of ≥0.75; P < 0.05) and six other antigens that were specifically increased in nonprotected volunteers (AUC value of ≤0.25; P < 0.05). When used in combination, the multiantigen classifier predicts CPS-induced protective efficacy with 83% sensitivity and 88% specificity. The antibody response patterns characterized in this study represent surrogate markers that may provide rational guidance for clinical vaccine development. IMPORTANCE Infection by Plasmodium parasites has been a major cause of mortality and morbidity in humans for thousands of years. Despite the considerable reduction of deaths, according to the WHO, over 5 billion people are still at risk, with about 216 million worldwide cases occurring in 2016. More compelling, 15 countries in sub-Saharan Africa bore 80% of the worldwide malaria burden. Complete eradication has been challenging, and the development of an affordable and effective vaccine will go a long way in achieving elimination. However, identifying vaccine candidate targets has been difficult. In the present study, we use a highly effective immunization protocol that confers long-lasting sterile immunity in combination with a whole P. falciparum proteome microarray to identify antibody responses associated with protection. This study characterizes a novel antibody profile associated with sterile protective immunity and trimodal humoral responses that sheds light on the possible mechanism of CPS-induced immunity against P. falciparum parasites.
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16
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van den Hoogen LL, Walk J, Oulton T, Reuling IJ, Reiling L, Beeson JG, Coppel RL, Singh SK, Draper SJ, Bousema T, Drakeley C, Sauerwein R, Tetteh KKA. Antibody Responses to Antigenic Targets of Recent Exposure Are Associated With Low-Density Parasitemia in Controlled Human Plasmodium falciparum Infections. Front Microbiol 2019; 9:3300. [PMID: 30700984 PMCID: PMC6343524 DOI: 10.3389/fmicb.2018.03300] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 12/18/2018] [Indexed: 12/05/2022] Open
Abstract
The majority of malaria infections in low transmission settings remain undetectable by conventional diagnostics. A powerful model to identify antibody responses that allow accurate detection of recent exposure to low-density infections is controlled human malaria infection (CHMI) studies in which healthy volunteers are infected with the Plasmodium parasite. We aimed to evaluate antibody responses in malaria-naïve volunteers exposed to a single CHMI using a custom-made protein microarray. All participants developed a blood-stage infection with peak parasite densities up to 100 parasites/μl in the majority of participants (50/54), while the remaining four participants had peak densities between 100 and 200 parasites/μl. There was a strong correlation between parasite density and antibody responses associated with the most reactive blood-stage targets 1 month after CHMI (Etramp 5, GLURP-R2, MSP4 and MSP1-19; Spearman’s ρ = 0.82, p < 0.001). Most volunteers developed antibodies against a potential marker of recent exposure: Etramp 5 (37/45, 82%). Our findings justify validation in endemic populations to define a minimum set of antigens needed to detect exposure to natural low-density infections.
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Affiliation(s)
- Lotus L van den Hoogen
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Jona Walk
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Tate Oulton
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Isaie J Reuling
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Ross L Coppel
- Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Susheel K Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Department of International Health, Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Simon J Draper
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Kevin K A Tetteh
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
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17
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Garrido-Cardenas JA, González-Cerón L, Manzano-Agugliaro F, Mesa-Valle C. Plasmodium genomics: an approach for learning about and ending human malaria. Parasitol Res 2019; 118:1-27. [PMID: 30402656 DOI: 10.1007/s00436-018-6127-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/19/2018] [Indexed: 12/31/2022]
Abstract
Malaria causes high levels of morbidity and mortality in human beings worldwide. According to the World Health Organization (WHO), about half a million people die of this disease each year. Malaria is caused by six species of parasites belonging to the Plasmodium genus: P. falciparum, P. knowlesi, P. vivax, P. malariae, P. ovale curtisi, and P. ovale wallikeri. Currently, malaria is being kept under control with varying levels of elimination success in different countries. The development of new molecular tools as well as the use of next-generation sequencing (NGS) technologies and novel bioinformatic approaches has improved our knowledge of malarial epidemiology, diagnosis, treatment, vaccine development, and surveillance strategies. In this work, the genetics and genomics of human malarias have been analyzed. Since the first P. falciparum genome was sequenced in 2002, various population-level genetic and genomic surveys, together with transcriptomic and proteomic studies, have shown the importance of molecular approaches in supporting malaria elimination.
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18
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Cockburn IA, Seder RA. Malaria prevention: from immunological concepts to effective vaccines and protective antibodies. Nat Immunol 2018; 19:1199-1211. [PMID: 30333613 DOI: 10.1038/s41590-018-0228-6] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/31/2018] [Indexed: 02/08/2023]
Abstract
Development of a malaria vaccine remains a critical priority to decrease clinical disease and mortality and facilitate eradication. Accordingly, RTS,S, a protein-subunit vaccine, has completed phase III clinical trials and confers ~30% protection against clinical infection over 4 years. Whole-attenuated-sporozoite and viral-subunit vaccines induce between 20% and 100% protection against controlled human malaria infection, but there is limited published evidence to date for durable, high-level efficacy (>50%) against natural exposure. Importantly, fundamental scientific advances related to the potency, durability, breadth and location of immune responses will be required for improving vaccine efficacy with these and other vaccine approaches. In this Review, we focus on the current understanding of immunological mechanisms of protection from animal models and human vaccine studies, and on how these data should inform the development of next-generation vaccines. Furthermore, we introduce the concept of using passive immunization with monoclonal antibodies as a new approach to prevent and eliminate malaria.
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Affiliation(s)
- Ian A Cockburn
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Robert A Seder
- Vaccine Research Center, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA.
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19
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Behet MC, Kurtovic L, van Gemert GJ, Haukes CM, Siebelink-Stoter R, Graumans W, van de Vegte-Bolmer MG, Scholzen A, Langereis JD, Diavatopoulos DA, Beeson JG, Sauerwein RW. The Complement System Contributes to Functional Antibody-Mediated Responses Induced by Immunization with Plasmodium falciparum Malaria Sporozoites. Infect Immun 2018; 86:e00920-17. [PMID: 29735521 PMCID: PMC6013677 DOI: 10.1128/iai.00920-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/16/2018] [Indexed: 11/20/2022] Open
Abstract
Long-lasting and sterile homologous protection against malaria can be achieved by the exposure of malaria-naive volunteers under chemoprophylaxis to Plasmodium falciparum-infected mosquitoes (chemoprophylaxis and sporozoite [CPS] immunization). While CPS-induced antibodies neutralize sporozoite infectivity in vitro and in vivo, antibody-mediated effector mechanisms are still poorly understood. Here, we investigated whether complement contributes to CPS-induced preerythrocytic immunity. Sera collected before and after CPS immunization in the presence of active or inactive complement were assessed for the recognition of homologous NF54 and heterologous NF135.C10 sporozoites, complement fixation, sporozoite lysis, and possible subsequent effects on in vitro sporozoite infectivity in human hepatocytes. CPS immunization induced sporozoite-specific IgM (P < 0.0001) and IgG (P = 0.001) antibodies with complement-fixing capacities (P < 0.0001). Sporozoite lysis (P = 0.017), traversal (P < 0.0001), and hepatocyte invasion inhibition (P < 0.0001) by CPS-induced antibodies were strongly enhanced in the presence of active complement. Complement-mediated invasion inhibition in the presence of CPS-induced antibodies negatively correlated with cumulative parasitemia during CPS immunizations (P = 0.013). While IgG antibodies similarly recognized homologous and heterologous sporozoites, IgM binding to heterologous sporozoites was reduced (P = 0.023). Although CPS-induced antibodies did not differ in their abilities to fix complement, lyse sporozoites, or inhibit the traversal of homologous and heterologous sporozoites, heterologous sporozoite invasion was more strongly inhibited in the presence of active complement (P = 0.008). These findings demonstrate that CPS-induced antibodies have complement-fixing activity, thereby significantly further enhancing the functional inhibition of homologous and heterologous sporozoite infectivity in vitro The combined data highlight the importance of complement as an additional immune effector mechanism in preerythrocytic immunity after whole-parasite immunization against Plasmodium falciparum malaria.
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Affiliation(s)
- Marije C Behet
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Liriye Kurtovic
- Burnet Institute, Melbourne, Australia
- Department of Immunology and Pathology, Monash University, Melbourne, Australia
| | - Geert-Jan van Gemert
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Celine M Haukes
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Rianne Siebelink-Stoter
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Wouter Graumans
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | | | - Anja Scholzen
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Jeroen D Langereis
- Laboratory of Pediatric Infectious Diseases, Radboud University Medical Center and Radboud Center for Infectious Diseases, Nijmegen, The Netherlands
| | - Dimitri A Diavatopoulos
- Laboratory of Pediatric Infectious Diseases, Radboud University Medical Center and Radboud Center for Infectious Diseases, Nijmegen, The Netherlands
| | - James G Beeson
- Burnet Institute, Melbourne, Australia
- Department of Immunology and Pathology, Monash University, Melbourne, Australia
- Department of Medical Microbiology, Monash University, Clayton, Australia
| | - Robert W Sauerwein
- Radboud University Medical Center, Department of Medical Microbiology, Nijmegen, The Netherlands
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20
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Cravo P, Machado RB, Leite JA, Leda T, Suwanarusk R, Bittencourt N, Albrecht L, Judice C, Lopes SCP, Lacerda MVG, Ferreira MU, Soares IS, Goh YS, Bargieri DY, Nosten F, Russell B, Rénia L, Costa FTM. In silico epitope mapping and experimental evaluation of the Merozoite Adhesive Erythrocytic Binding Protein (MAEBL) as a malaria vaccine candidate. Malar J 2018; 17:20. [PMID: 29316918 PMCID: PMC5761135 DOI: 10.1186/s12936-017-2144-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 12/18/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Technical limitations for culturing the human malaria parasite Plasmodium vivax have impaired the discovery of vaccine candidates, challenging the malaria eradication agenda. The immunogenicity of the M2 domain of the Merozoite Adhesive Erythrocytic Binding Protein (MAEBL) antigen cloned from the Plasmodium yoelii murine parasite, has been previously demonstrated. RESULTS Detailed epitope mapping of MAEBL through immunoinformatics identified several MHCI, MHCII and B cell epitopes throughout the peptide, with several of these lying in the M2 domain and being conserved between P. vivax, P. yoelii and Plasmodium falciparum, hinting that the M2-MAEBL is pan-reactive. This hypothesis was tested through functional assays, showing that P. yoelii M2-MAEBL antisera are able to recognize and inhibit erythrocyte invasion from both P. falciparum and P. vivax parasites isolated from Thai patients, in ex vivo assays. Moreover, the sequence of the M2-MAEBL is shown to be highly conserved between P. vivax isolates from the Amazon and Thailand, indicating that the MAEBL antigen may constitute a vaccine candidate outwitting strain-specific immunity. CONCLUSIONS The MAEBL antigen is promising candidate towards the development of a malaria vaccine.
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Affiliation(s)
- Pedro Cravo
- Global Health and Tropical Medicine Centre (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa, Rua da Junqueira, nº 100, 1349-008, Lisbon, Portugal. .,GenoBio, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO, Brazil. .,PPG-SOMA, Centro Universitário de Anápolis, Anápolis, GO, Brazil.
| | - Renato B Machado
- GenoBio, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Juliana A Leite
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Taizy Leda
- GenoBio, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Rossarin Suwanarusk
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Najara Bittencourt
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Letusa Albrecht
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil.,Instituto Carlos Chagas, Fundação Oswaldo Cruz-FIOCRUZ, Curitiba, PR, Brazil
| | - Carla Judice
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Stefanie C P Lopes
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil.,Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz-FIOCRUZ, Manaus, AM, Brazil
| | - Marcus V G Lacerda
- Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz-FIOCRUZ, Manaus, AM, Brazil.,Fundação de Medicina Tropical-Dr. Heitor Vieira Dourado, Gerência de Malária, Manaus, AM, Brazil
| | - Marcelo U Ferreira
- Department of Parasitology, University of São Paulo-USP, São Paulo, SP, Brazil
| | - Irene S Soares
- Department of Clinical and Toxicological Analyses, Pharmaceutical Sciences, University of São Paulo-USP, São Paulo, SP, Brazil
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Daniel Y Bargieri
- Department of Parasitology, University of São Paulo-USP, São Paulo, SP, Brazil
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Bruce Russell
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Fabio T M Costa
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
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21
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Abstract
Controlled human malaria infection (CHMI) entails deliberate infection with malaria parasites either by mosquito bite or by direct injection of sporozoites or parasitized erythrocytes. When required, the resulting blood-stage infection is curtailed by the administration of antimalarial drugs. Inducing a malaria infection via inoculation with infected blood was first used as a treatment (malariotherapy) for neurosyphilis in Europe and the United States in the early 1900s. More recently, CHMI has been applied to the fields of malaria vaccine and drug development, where it is used to evaluate products in well-controlled early-phase proof-of-concept clinical studies, thus facilitating progression of only the most promising candidates for further evaluation in areas where malaria is endemic. Controlled infections have also been used to immunize against malaria infection. Historically, CHMI studies have been restricted by the need for access to insectaries housing infected mosquitoes or suitable malaria-infected individuals. Evaluation of vaccine and drug candidates has been constrained in these studies by the availability of a limited number of Plasmodium falciparum isolates. Recent advances have included cryopreservation of sporozoites, the manufacture of well-characterized and genetically distinct cultured malaria cell banks for blood-stage infection, and the availability of Plasmodium vivax-specific reagents. These advances will help to accelerate malaria vaccine and drug development by making the reagents for CHMI more widely accessible and also enabling a more rigorous evaluation with multiple parasite strains and species. Here we discuss the different applications of CHMI, recent advances in the use of CHMI, and ongoing challenges for consideration.
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22
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Roestenberg M, Mordmüller B, Ockenhouse C, Mo A, Yazdanbakhsh M, Kremsner PG. The frontline of controlled human malaria infections: A report from the controlled human infection models Workshop in Leiden University Medical Centre 5 May 2016. Vaccine 2017; 35:7065-7069. [PMID: 29153778 DOI: 10.1016/j.vaccine.2017.10.093] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/30/2017] [Accepted: 10/31/2017] [Indexed: 12/22/2022]
Abstract
Controlled Human Malaria Infection (CHMI) is the most practiced controlled human infection model nowadays and there is an exponential increase in implementation of the model worldwide. During the Controlled Human Infection Models Workshop in Leiden, one day was dedicated to the discussion of the advances made and gaps in Controlled Human Malaria Infection (CHMI) trials. Factors contributing to this impressive expansion in the number of CHMI trials have been related to the ability to perform CHMI using injectable cryopreserved sporozoites (a product from Sanaria Inc. - PfSPZ Challenge), the development of a transmission blocking CHMI model and the need to test more vaccine candidates particularly in the field of whole-sporozoite vaccine development. However, with an increasing number of CHMI trials being undertaken, in an ever-growing number of trial sites, heterogeneity in trial design may compromise universal interpretation of results and require an ongoing dialogue on the need and feasibility of standardization. At the workshop, CHMI investigators convened to share their experiences in CHMI trials and discuss the possibilities for future trials.
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Affiliation(s)
| | - Benjamin Mordmüller
- Universitätsklinikum Tübingen, Germany and Centre de Recherches Médicales de Lambaréné, Gabon
| | | | - Annie Mo
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA
| | | | - Peter G Kremsner
- Universitätsklinikum Tübingen, Germany and Centre de Recherches Médicales de Lambaréné, Gabon
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23
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Tuju J, Kamuyu G, Murungi LM, Osier FHA. Vaccine candidate discovery for the next generation of malaria vaccines. Immunology 2017; 152:195-206. [PMID: 28646586 PMCID: PMC5588761 DOI: 10.1111/imm.12780] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 12/21/2022] Open
Abstract
Although epidemiological observations, IgG passive transfer studies and experimental infections in humans all support the feasibility of developing highly effective malaria vaccines, the precise antigens that induce protective immunity remain uncertain. Here, we review the methodologies applied to vaccine candidate discovery for Plasmodium falciparum malaria from the pre- to post-genomic era. Probing of genomic and cDNA libraries with antibodies of defined specificities or functional activity predominated the former, whereas reverse vaccinology encompassing high throughput in silico analyses of genomic, transcriptomic or proteomic parasite data sets is the mainstay of the latter. Antibody-guided vaccine design spanned both eras but currently benefits from technological advances facilitating high-throughput screening and downstream applications. We make the case that although we have exponentially increased our ability to identify numerous potential vaccine candidates in a relatively short space of time, a significant bottleneck remains in their validation and prioritization for evaluation in clinical trials. Longitudinal cohort studies provide supportive evidence but results are often conflicting between studies. Demonstration of antigen-specific antibody function is valuable but the relative importance of one mechanism over another with regards to protection remains undetermined. Animal models offer useful insights but may not accurately reflect human disease. Challenge studies in humans are preferable but prohibitively expensive. In the absence of reliable correlates of protection, suitable animal models or a better understanding of the mechanisms underlying protective immunity in humans, vaccine candidate discovery per se may not be sufficient to provide the paradigm shift necessary to develop the next generation of highly effective subunit malaria vaccines.
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Affiliation(s)
- James Tuju
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Department of BiochemistryPwani UniversityKilifiKenya
| | - Gathoni Kamuyu
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Linda M. Murungi
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Faith H. A. Osier
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Centre for Infectious DiseasesHeidelberg University HospitalHeidelbergGermany
- Department of Biomedical SciencesPwani UniversityKilifiKenya
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24
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Yang ASP, Lopaticki S, O'Neill MT, Erickson SM, Douglas DN, Kneteman NM, Boddey JA. AMA1 and MAEBL are important for Plasmodium falciparum sporozoite infection of the liver. Cell Microbiol 2017; 19. [PMID: 28371168 DOI: 10.1111/cmi.12745] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/23/2017] [Accepted: 03/28/2017] [Indexed: 12/20/2022]
Abstract
The malaria sporozoite injected by a mosquito migrates to the liver by traversing host cells. The sporozoite also traverses hepatocytes before invading a terminal hepatocyte and developing into exoerythrocytic forms. Hepatocyte infection is critical for parasite development into merozoites that infect erythrocytes, and the sporozoite is thus an important target for antimalarial intervention. Here, we investigated two abundant sporozoite proteins of the most virulent malaria parasite Plasmodium falciparum and show that they play important roles during cell traversal and invasion of human hepatocytes. Incubation of P. falciparum sporozoites with R1 peptide, an inhibitor of apical merozoite antigen 1 (AMA1) that blocks merozoite invasion of erythrocytes, strongly reduced cell traversal activity. Consistent with its inhibitory effect on merozoites, R1 peptide also reduced sporozoite entry into human hepatocytes. The strong but incomplete inhibition prompted us to study the AMA-like protein, merozoite apical erythrocyte-binding ligand (MAEBL). MAEBL-deficient P. falciparum sporozoites were severely attenuated for cell traversal activity and hepatocyte entry in vitro and for liver infection in humanized chimeric liver mice. This study shows that AMA1 and MAEBL are important for P. falciparum sporozoites to perform typical functions necessary for infection of human hepatocytes. These two proteins therefore have important roles during infection at distinct points in the life cycle, including the blood, mosquito, and liver stages.
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Affiliation(s)
- Annie S P Yang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Sash Lopaticki
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Matthew T O'Neill
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Sara M Erickson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donna N Douglas
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Norman M Kneteman
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Justin A Boddey
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
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25
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Abstract
INTRODUCTION An effective malaria vaccine would be considered a milestone of modern medicine, yet has so far eluded research and development efforts. This can be attributed to the extreme complexity of the malaria parasites, presenting with a multi-stage life cycle, high genome complexity and the parasite's sophisticated immune evasion measures, particularly antigenic variation during pathogenic blood stage infection. However, the pre-erythrocytic (PE) early infection forms of the parasite exhibit relatively invariant proteomes, and are attractive vaccine targets as they offer multiple points of immune system attack. Areas covered: We cover the current state of and roadblocks to the development of an effective, antibody-based PE vaccine, including current vaccine candidates, limited biological knowledge, genetic heterogeneity, parasite complexity, and suboptimal preclinical models as well as the power of early stage clinical models. Expert commentary: PE vaccines will need to elicit broad and durable immunity to prevent infection. This could be achievable if recent innovations in studying the parasites' infection biology, rational vaccine selection and design as well as adjuvant formulation are combined in a synergistic and multipronged approach. Improved preclinical assays as well as the iterative testing of vaccine candidates in controlled human malaria infection trials will further accelerate this effort.
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Affiliation(s)
- Brandon Sack
- a Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute) , Seattle , WA , USA
| | - Stefan H I Kappe
- a Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute) , Seattle , WA , USA.,b Department of Global Health , University of Washington , Seattle , WA , USA
| | - D Noah Sather
- a Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute) , Seattle , WA , USA
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26
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Yang ASP, Boddey JA. Molecular mechanisms of host cell traversal by malaria sporozoites. Int J Parasitol 2016; 47:129-136. [PMID: 27825827 DOI: 10.1016/j.ijpara.2016.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 07/22/2016] [Accepted: 09/05/2016] [Indexed: 11/19/2022]
Abstract
Malaria is a pernicious infectious disease caused by apicomplexan parasites of the genus Plasmodium. Each year, malaria afflicts over 200million people, causing considerable morbidity, loss to gross domestic product of endemic countries, and more than 420,000 deaths. A central feature of the virulence of malaria parasites is the ability of sporozoite forms injected by a mosquito to navigate from the inoculation site in the skin through host tissues to infect the liver. The ability for sporozoites to traverse through different host cell types is very important for the successful development of parasites within the mammalian host. Over the past decade, our understanding of the role of host cell traversal has become clearer through important studies with rodent models of malaria. However, we still do not understand the stepwise process of host cell entry and exit or know the molecular mechanisms governing each step. We know even less about cell traversal by malaria parasite species that infect humans. Here, we review current knowledge regarding the role and molecular mechanisms of sporozoite cell traversal and highlight recent advances that prompt new ways of thinking about this important process.
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Affiliation(s)
- Annie S P Yang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Justin A Boddey
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
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27
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Goh YS, Peng K, Chia WN, Siau A, Chotivanich K, Gruner AC, Preiser P, Mayxay M, Pukrittayakamee S, Sriprawat K, Nosten F, White NJ, Renia L. Neutralizing Antibodies against Plasmodium falciparum Associated with Successful Cure after Drug Therapy. PLoS One 2016; 11:e0159347. [PMID: 27427762 PMCID: PMC4948787 DOI: 10.1371/journal.pone.0159347] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 06/30/2016] [Indexed: 12/15/2022] Open
Abstract
An effective antibody response can assist drug treatment to contribute to better parasite clearance in malaria patients. To examine this, sera were obtained from two groups of adult patients with acute falciparum malaria, prior to drug treatment: patients who (1) have subsequent recrudescent infection, or (2) were cured by Day 28 following treatment. Using a Plasmodium falciparum antigen library, we examined the antibody specificities in these sera. While the antibody repertoire of both sera groups was extremely broad and varied, there was a differential antibody profile between the two groups of sera. The proportion of cured patients with antibodies against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 was higher than the proportion of patients with recrudescent infection. The presence of these antibodies was associated with higher odds of treatment cure. Sera containing all six antibodies impaired the invasion of P. falciparum clinical isolates into erythrocytes. These results suggest that antibodies specific against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 in P. falciparum infections could assist anti-malarial drug treatment and contribute to the resolution of the malarial infection.
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MESH Headings
- Acute Disease
- Adolescent
- Adult
- Antibodies, Neutralizing/biosynthesis
- Antibodies, Neutralizing/blood
- Antibodies, Protozoan/biosynthesis
- Antibodies, Protozoan/blood
- Antibody Specificity
- Antigens, Protozoan/blood
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antimalarials/therapeutic use
- Artemether
- Artemisinins/therapeutic use
- Azithromycin/therapeutic use
- Cohort Studies
- Erythrocytes/drug effects
- Erythrocytes/parasitology
- Ethanolamines/therapeutic use
- Female
- Fluorenes/therapeutic use
- Humans
- Immune Sera/pharmacology
- Immunity, Humoral
- Lumefantrine
- Malaria, Falciparum/blood
- Malaria, Falciparum/drug therapy
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Male
- Plasmodium falciparum/drug effects
- Plasmodium falciparum/growth & development
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Recurrence
- Treatment Outcome
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Affiliation(s)
- Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
| | - Kaitian Peng
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
| | - Wan Ni Chia
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Anthony Siau
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | | | - Anne-Charlotte Gruner
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
| | - Peter Preiser
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | | | - Kanlaya Sriprawat
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Laurent Renia
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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