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Hviid L, Jensen AR, Deitsch KW. PfEMP1 and var genes - Still of key importance in Plasmodium falciparum malaria pathogenesis and immunity. ADVANCES IN PARASITOLOGY 2024; 125:53-103. [PMID: 39095112 DOI: 10.1016/bs.apar.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The most severe form of malaria, caused by infection with Plasmodium falciparum parasites, continues to be an important cause of human suffering and poverty. The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family of clonally variant antigens, which mediates the adhesion of infected erythrocytes to the vascular endothelium in various tissues and organs, is a central component of the pathogenesis of the disease and a key target of the acquired immune response to malaria. Much new knowledge has accumulated since we published a systematic overview of the PfEMP1 family almost ten years ago. In this chapter, we therefore aim to summarize research progress since 2015 on the structure, function, regulation etc. of this key protein family of arguably the most important human parasite. Recent insights regarding PfEMP1-specific immune responses and PfEMP1-specific vaccination against malaria, as well as an outlook for the coming years are also covered.
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Affiliation(s)
- Lars Hviid
- Centre for translational Medicine and Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
| | - Anja R Jensen
- Centre for translational Medicine and Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, United States
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2
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Walker IS, Rogerson SJ. Pathogenicity and virulence of malaria: Sticky problems and tricky solutions. Virulence 2023; 14:2150456. [PMID: 36419237 PMCID: PMC9815252 DOI: 10.1080/21505594.2022.2150456] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.
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Affiliation(s)
- Isobel S Walker
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
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Inklaar MR, Barillas-Mury C, Jore MM. Deceiving and escaping complement - the evasive journey of the malaria parasite. Trends Parasitol 2022; 38:962-974. [PMID: 36089499 PMCID: PMC9588674 DOI: 10.1016/j.pt.2022.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/03/2022] [Accepted: 08/19/2022] [Indexed: 01/13/2023]
Abstract
During its life cycle, Plasmodium, the malaria parasite, is exposed to the human and mosquito complement systems. Early experiments demonstrated that activation of complement can pose a serious threat to parasites, but recent studies revealed complement-evasion mechanisms important for parasite survival. Blood-stage parasites and gametes recruit regulators to neutralize human complement activation, while ookinetes inhibit mosquito complement by disrupting epithelial nitration in response to midgut invasion. Here we provide an in-depth overview of the evasion mechanisms currently known and speculate on the existence of others not yet identified. Finally, we discuss how these mechanisms could provide novel targets for urgently needed malaria vaccines and therapeutics.
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Affiliation(s)
| | - Carolina Barillas-Mury
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
| | - Matthijs M Jore
- Department of Medical Microbiology, Radboudumc, The Netherlands.
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4
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The impact of human complement on the clinical outcome of malaria infection. Mol Immunol 2022; 151:19-28. [PMID: 36063583 DOI: 10.1016/j.molimm.2022.08.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 08/19/2022] [Accepted: 08/25/2022] [Indexed: 11/21/2022]
Abstract
The tropical disease malaria remains a major cause of global morbidity. Once transmitted to the human by a blood-feeding mosquito, the unicellular malaria parasite comes into contact with the complement system and continues to interact with human complement during its intraerythrocytic replication cycles. In the course of infection, both the classical and the alternative pathway of complement are activated, leading to parasite opsonization and lysis as well as the induction of complement-binding antibodies. While complement activity can be linked to the severity of malaria, it remains to date unclear, whether human complement is beneficial for protective immunity or if extensive complement reactions may rather enhance pathogenesis. In addition, the parasite has evolved molecular strategies to circumvent attack by human complement and has even developed means to utilize complement factors as mediators of host cell infection. In this review, we highlight current knowledge on the role of human complement for the progression of malaria infection. We discuss the various types of interactions between malaria parasites and complement factors with regard to immunity and infection outcome and set a special emphasis on the dual role of complement in the context of parasite fitness.
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Guillochon E, Fraering J, Joste V, Kamaliddin C, Vianou B, Houzé L, Baudrin LG, Faucher JF, Aubouy A, Houzé S, Cot M, Argy N, Taboureau O, Bertin GI. OUP accepted manuscript. J Infect Dis 2022; 225:2187-2196. [PMID: 35255125 PMCID: PMC9200161 DOI: 10.1093/infdis/jiac086] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/03/2022] [Indexed: 11/24/2022] Open
Abstract
Cerebral malaria (CM) is the severest form of Plasmodium falciparum infection. Children under 5 years old are those most vulnerable to CM, and they consequently have the highest risk of malaria-related death. Parasite-associated factors leading to CM are not yet fully elucidated. We therefore sought to characterize the gene expression profile associated with CM, using RNA sequencing data from 15 CM and 15 uncomplicated malaria isolates from Benin. Cerebral malaria parasites displayed reduced circulation times, possibly related to higher cytoadherence capacity. Consistent with the latter, we detected increased var genes abundance in CM isolates. Differential expression analyses showed that distinct transcriptome profiles are signatures of malaria severity. Genes involved in adhesion, excluding variant surface antigens, were dysregulated, supporting the idea of increased cytoadhesion capacity of CM parasites. Finally, we found dysregulated expression of genes in the entry into host pathway that may reflect greater erythrocyte invasion capacity of CM parasites.
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Affiliation(s)
- E Guillochon
- Université Paris Cité, MERIT, IRD, Paris, France
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - J Fraering
- Université Paris Cité, MERIT, IRD, Paris, France
| | - V Joste
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - C Kamaliddin
- Cumming School of Medicine, The University of Calgary, Calgary, Alberta, Canada
| | - B Vianou
- Université Paris Cité, MERIT, IRD, Paris, France
- Institut de Recherche Clinique du Bénin, Cotonou, Bénin
| | - L Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
| | - L G Baudrin
- Institut Curie Genomics of Excellence Platform, PSL Research University, Research Center, Institut Curie, Paris, France
| | - J F Faucher
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - A Aubouy
- Université de Toulouse, PHARMADEV, IRD, UPS, Toulouse, France
| | - S Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - M Cot
- Université Paris Cité, MERIT, IRD, Paris, France
| | - N Argy
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - O Taboureau
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - G I Bertin
- Correspondence: Gwladys I. Bertin, PhD, Université Paris Cité, MERIT, IRD, 4 avenue de l’Observatoire, 75006 Paris, France ()
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Plasmodium falciparum transcription in different clinical presentations of malaria associates with circulation time of infected erythrocytes. Nat Commun 2021; 12:4711. [PMID: 34330920 PMCID: PMC8324851 DOI: 10.1038/s41467-021-25062-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 07/06/2021] [Indexed: 02/07/2023] Open
Abstract
Following Plasmodium falciparum infection, individuals can remain asymptomatic, present with mild fever in uncomplicated malaria cases, or show one or more severe malaria symptoms. Several studies have investigated associations between parasite transcription and clinical severity, but no broad conclusions have yet been drawn. Here, we apply a series of bioinformatic approaches based on P. falciparum's tightly regulated transcriptional pattern during its ~48-hour intraerythrocytic developmental cycle (IDC) to publicly available transcriptomes of parasites obtained from malaria cases of differing clinical severity across multiple studies. Our analysis shows that within each IDC, the circulation time of infected erythrocytes without sequestering to endothelial cells decreases with increasing parasitaemia or disease severity. Accordingly, we find that the size of circulating infected erythrocytes is inversely related to parasite density and disease severity. We propose that enhanced adhesiveness of infected erythrocytes leads to a rapid increase in parasite burden, promoting higher parasitaemia and increased disease severity.
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