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Faria JRC, Tinti M, Marques CA, Zoltner M, Yoshikawa H, Field MC, Horn D. An allele-selective inter-chromosomal protein bridge supports monogenic antigen expression in the African trypanosome. Nat Commun 2023; 14:8200. [PMID: 38081826 PMCID: PMC10713589 DOI: 10.1038/s41467-023-44043-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
UPF1-like helicases play roles in telomeric heterochromatin formation and X-chromosome inactivation, and also in monogenic variant surface glycoprotein (VSG) expression via VSG exclusion-factor-2 (VEX2), a UPF1-related protein in the African trypanosome. We show that VEX2 associates with chromatin specifically at the single active VSG expression site on chromosome 6, forming an allele-selective connection, via VEX1, to the trans-splicing locus on chromosome 9, physically bridging two chromosomes and the VSG transcription and splicing compartments. We further show that the VEX-complex is multimeric and self-regulates turnover to tightly control its abundance. Using single cell transcriptomics following VEX2-depletion, we observed simultaneous derepression of many other telomeric VSGs and multi-allelic VSG expression in individual cells. Thus, an allele-selective, inter-chromosomal, and self-limiting VEX1-2 bridge supports monogenic VSG expression and multi-allelic VSG exclusion.
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Affiliation(s)
- Joana R C Faria
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK.
- Biology Department, University of York, York, UK.
- York Biomedical Research Institute, University of York, York, UK.
| | - Michele Tinti
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Catarina A Marques
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Martin Zoltner
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
| | - Harunori Yoshikawa
- Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
- Division of Cell Signaling, Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Mark C Field
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Biology Centre, Czech Academy of Sciences, Institute of Parasitology, České Budějovice, Czech Republic
| | - David Horn
- Wellcome Centre for Anti-Infectives Research, Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK.
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2
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Othman B, Zeef L, Szestak T, Rchiad Z, Storm J, Askonas C, Satyam R, Madkhali A, Haley M, Wagstaff S, Couper K, Pain A, Craig A. Different PfEMP1-expressing Plasmodium falciparum variants induce divergent endothelial transcriptional responses during co-culture. PLoS One 2023; 18:e0295053. [PMID: 38033133 PMCID: PMC10688957 DOI: 10.1371/journal.pone.0295053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
The human malaria parasite Plasmodium falciparum is responsible for the majority of mortality and morbidity caused by malaria infection and differs from other human malaria species in the degree of accumulation of parasite-infected red blood cells in the microvasculature, known as cytoadherence or sequestration. In P. falciparum, cytoadherence is mediated by a protein called PfEMP1 which, due to its exposure to the host immune system, undergoes antigenic variation resulting in the expression of different PfEMP1 variants on the infected erythrocyte membrane. These PfEMP1s contain various combinations of adhesive domains, which allow for the differential engagement of a repertoire of endothelial receptors on the host microvasculature, with specific receptor usage associated with severe disease. We used a co-culture model of cytoadherence incubating human brain microvascular endothelial cells with erythrocytes infected with two parasite lines expressing different PfEMP1s that demonstrate different binding profiles to vascular endothelium. We determined the transcriptional profile of human brain microvascular endothelial cells (HBMEC) following different incubation periods with infected erythrocytes, identifying different transcriptional profiles of pathways previously found to be involved in the pathology of severe malaria, such as inflammation, apoptosis and barrier integrity, induced by the two PfEMP1 variants.
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Affiliation(s)
- Basim Othman
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Leo Zeef
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Tadge Szestak
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Zineb Rchiad
- Pathogen Genomics Laboratory, Bioscience Program, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, KSA
| | - Janet Storm
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Caroline Askonas
- Pathogen Genomics Laboratory, Bioscience Program, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, KSA
| | - Rohit Satyam
- Pathogen Genomics Laboratory, Bioscience Program, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, KSA
| | - Aymen Madkhali
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Michael Haley
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Simon Wagstaff
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Kevin Couper
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Arnab Pain
- Pathogen Genomics Laboratory, Bioscience Program, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, KSA
| | - Alister Craig
- Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
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3
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Chakrabarti D, Doerig C. Editorial overview: Recent advances in fundamental and translational research on parasitic protists. Curr Opin Microbiol 2023; 75:102360. [PMID: 37467615 DOI: 10.1016/j.mib.2023.102360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Affiliation(s)
- Debopam Chakrabarti
- Molecular Microbiology Division, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, United States.
| | - Christian Doerig
- School of Health and Biomedical Sciences, RMIT University, Bundoora West Campus, Bundoora, VIC 3083, Australia
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4
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Pozzi B, Naguleswaran A, Florini F, Rezaei Z, Roditi I. The RNA export factor TbMex67 connects transcription and RNA export in Trypanosoma brucei and sets boundaries for RNA polymerase I. Nucleic Acids Res 2023; 51:5177-5192. [PMID: 37070196 PMCID: PMC10250216 DOI: 10.1093/nar/gkad251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/21/2023] [Accepted: 03/24/2023] [Indexed: 04/19/2023] Open
Abstract
TbMex67 is the major mRNA export factor known to date in trypanosomes, forming part of the docking platform within the nuclear pore. To explore its role in co-transcriptional mRNA export, recently reported in Trypanosoma brucei, pulse labelling of nascent RNAs with 5-ethynyl uridine (5-EU) was performed with cells depleted of TbMex67 and complemented with a dominant-negative mutant (TbMex67-DN). RNA polymerase (Pol) II transcription was unaffected, but the procyclin loci, which encode mRNAs transcribed by Pol I from internal sites on chromosomes 6 and 10, showed increased levels of 5-EU incorporation. This was due to Pol I readthrough transcription, which proceeded beyond the procyclin and procyclin-associated genes up to the Pol II transcription start site on the opposite strand. Complementation by TbMex67-DN also increased Pol I-dependent formation of R-loops and γ-histone 2A foci. The DN mutant exhibited reduced nuclear localisation and binding to chromatin compared to wild-type TbMex67. Together with its interaction with chromatin remodelling factor TbRRM1 and Pol II, and transcription-dependent association of Pol II with nucleoporins, our findings support a role for TbMex67 in connecting transcription and export in T. brucei. In addition, TbMex67 stalls readthrough by Pol I in specific contexts, thereby limiting R-loop formation and replication stress.
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Affiliation(s)
- Berta Pozzi
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | | | | | - Zahra Rezaei
- Professor Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Isabel Roditi
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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5
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Tenaglia AH, Luján LA, Ríos DN, Molina CR, Midlej V, Iribarren PA, Berazategui MA, Torri A, Saura A, Peralta DO, Rodríguez-Walker M, Fernández EA, Petiti JP, Serradell MC, Gargantini PR, Sparwasser T, Alvarez VE, de Souza W, Luján HD. Antibodies to variable surface antigens induce antigenic variation in the intestinal parasite Giardia lamblia. Nat Commun 2023; 14:2537. [PMID: 37137944 PMCID: PMC10156722 DOI: 10.1038/s41467-023-38317-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 04/25/2023] [Indexed: 05/05/2023] Open
Abstract
The genomes of most protozoa encode families of variant surface antigens. In some parasitic microorganisms, it has been demonstrated that mutually exclusive changes in the expression of these antigens allow parasites to evade the host's immune response. It is widely assumed that antigenic variation in protozoan parasites is accomplished by the spontaneous appearance within the population of cells expressing antigenic variants that escape antibody-mediated cytotoxicity. Here we show, both in vitro and in animal infections, that antibodies to Variant-specific Surface Proteins (VSPs) of the intestinal parasite Giardia lamblia are not cytotoxic, inducing instead VSP clustering into liquid-ordered phase membrane microdomains that trigger a massive release of microvesicles carrying the original VSP and switch in expression to different VSPs by a calcium-dependent mechanism. This novel mechanism of surface antigen clearance throughout its release into microvesicles coupled to the stochastic induction of new phenotypic variants not only changes current paradigms of antigenic switching but also provides a new framework for understanding the course of protozoan infections as a host/parasite adaptive process.
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Affiliation(s)
- Albano H Tenaglia
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lucas A Luján
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
| | - Diego N Ríos
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Clínica Universitaria Reina Fabiola, Universidad Católica de Córdoba, Córdoba, Argentina
| | - Cecilia R Molina
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
| | - Victor Midlej
- Instituto de Biofísica Carlos Chagas Filho and Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro (UFRJ), 21941-170, Rio de Janeiro, Brazil
- Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), 21040-900, Rio de Janeiro, Brazil
| | - Paula A Iribarren
- Instituto de Investigaciones Biotecnológicas (IIBIO), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Nacional de General San Martín (UNSAM), B1650HMP, Buenos Aires, Argentina
| | - María A Berazategui
- Instituto de Investigaciones Biotecnológicas (IIBIO), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Nacional de General San Martín (UNSAM), B1650HMP, Buenos Aires, Argentina
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, London, UK
| | - Alessandro Torri
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche, Institut Pasteur, Paris, France
| | - Alicia Saura
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Cátedra de Química Biológica, Facultad de Ciencias de la Salud, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Damián O Peralta
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
| | - Macarena Rodríguez-Walker
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
| | - Elmer A Fernández
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Fundación para el progreso de la Medicina, Córdoba, Argentina
| | - Juan P Petiti
- Instituto de Investigaciones en Ciencias de la Salud (INICSA), Centro de Microscopía Electrónica, Facultad de Ciencias Médicas. CONICET/Universidad Nacional de Córdoba, X5016HUA, Córdoba, Argentina
| | - Marianela C Serradell
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
- Laboratorio de Parasitología y Micología, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5016HUA, Córdoba, Argentina
| | - Pablo R Gargantini
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina
| | - Tim Sparwasser
- Institute of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Vanina E Alvarez
- Instituto de Investigaciones Biotecnológicas (IIBIO), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Nacional de General San Martín (UNSAM), B1650HMP, Buenos Aires, Argentina
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho and Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro (UFRJ), 21941-170, Rio de Janeiro, Brazil
| | - Hugo D Luján
- Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), X5016HDK, Córdoba, Argentina.
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Garcez EM, Gomes N, Moraes AS, Pogue R, Uenishi RH, Hecht M, Carvalho JL. Extracellular vesicles in the context of Chagas Disease - A systematic review. Acta Trop 2023; 242:106899. [PMID: 36935050 DOI: 10.1016/j.actatropica.2023.106899] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 03/19/2023]
Abstract
Extracellular vesicle (EVs) traffic is considered an important cellular communication process between cells that can be part of a single organism or belong to different living beings. The relevance of EV-mediated cellular communication is increasingly studied and appreciated, especially in relation to pathological conditions, including parasitic disorders, in which the EV release and uptake processes have been documented. In the context of Chagas Disease (CD), EVs have been explored, however, current data have not been systematically revised in order to provide an overview of the published literature and the main results obtained thus far. In this systematic review, 25 studies involving the investigation of EVs in CD were identified. The studies involved Trypanosoma cruzi (Tc)-derived EVs (Tc-EVs), as well as EVs derived from T. cruzi-infected mammalian cells-derived EVs, mainly isolated by ultracentrifugation and poorly characterized. The objectives of the identified studies included the characterization of the protein and RNA cargo of Tc-EVs, as well as investigation of EVs in parasitic infections and immune-related processes. Overall, our systematic review reveals that EVs play critical roles in several mechanisms related to the interaction between T. cruzi and mammalian hosts, their contribution to immune system evasion by the parasite, and to chronic inflammation in the host. Future studies will benefit from the consolidation of isolation and characterization methods, as well as the elucidation of the role of EVs in CD.
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Affiliation(s)
- Emãnuella Melgaço Garcez
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil
| | - Nélio Gomes
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil
| | - Aline Silva Moraes
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil
| | - Robert Pogue
- Genomic Sciences and Biotechnology Program. Catholic University of Brasília, 71966-700, Brasília, DF, Brazil
| | - Rosa Harumi Uenishi
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil
| | - Mariana Hecht
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil
| | - Juliana Lott Carvalho
- Multidisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, 70910-900, Brasília, DF, Brazil; Genomic Sciences and Biotechnology Program. Catholic University of Brasília, 71966-700, Brasília, DF, Brazil.
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Real E, Nardella F, Scherf A, Mancio-Silva L. Repurposing of Plasmodium falciparum var genes beyond the blood stage. Curr Opin Microbiol 2022; 70:102207. [PMID: 36183663 DOI: 10.1016/j.mib.2022.102207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/26/2022] [Accepted: 09/03/2022] [Indexed: 01/25/2023]
Abstract
A commonly observed survival strategy in protozoan parasites is the sequential expression of clonally variant-surface antigens to avoid elimination by the host's immune response. In malaria-causing P. falciparum, the immunovariant erythrocyte-membrane protein-1 (PfEMP1) adhesin family, encoded by var genes, is responsible for both antigenic variation and cytoadherence of infected erythrocytes to the microvasculature. Until recently, the biological function of these variant genes was believed to be restricted to intraerythrocytic developmental stages. With the advent of new technologies, var gene expression has been confirmed in transmission and pre-erythrocytic stages. Here, we discuss how repurposing of var gene expression beyond chronic blood-stage infection may be critical for successful transmission.
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Affiliation(s)
- Eliana Real
- Institut Pasteur, Université Paris Cité, Inserm U1201, CNRS EMR9195, Unité de Biologie des Interactions Hôte-Parasite, 25 Rue du Dr Roux, F-75015 Paris, France
| | - Flore Nardella
- Institut Pasteur, Université Paris Cité, Inserm U1201, CNRS EMR9195, Unité de Biologie des Interactions Hôte-Parasite, 25 Rue du Dr Roux, F-75015 Paris, France
| | - Artur Scherf
- Institut Pasteur, Université Paris Cité, Inserm U1201, CNRS EMR9195, Unité de Biologie des Interactions Hôte-Parasite, 25 Rue du Dr Roux, F-75015 Paris, France.
| | - Liliana Mancio-Silva
- Institut Pasteur, Université Paris Cité, Inserm U1201, CNRS EMR9195, Unité de Biologie des Interactions Hôte-Parasite, 25 Rue du Dr Roux, F-75015 Paris, France.
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8
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Vargas-Villavicencio JA, Cañedo-Solares I, Correa D. Anti-Toxoplasma gondii IgM Long Persistence: What Are the Underlying Mechanisms? Microorganisms 2022; 10:microorganisms10081659. [PMID: 36014077 PMCID: PMC9415799 DOI: 10.3390/microorganisms10081659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Abstract
Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation–encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.
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Affiliation(s)
| | - Irma Cañedo-Solares
- Laboratorio de Inmunología Experimental, Instituto Nacional de Pediatría, Mexico City 04530, Mexico
| | - Dolores Correa
- Dirección de Investigación/Centro de Investigación en Ciencias de la Salud, FCS, Universidad Anáhuac México Campus Norte, Av Universidad Anáhuc 46, Lomas Anáhuac, Huixquilucan 52786, Mexico
- Correspondence: ; Tel.: +52-(55)-5627-0210-7637
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Plasmodium falciparum Nicotinamidase as A Novel Antimalarial Target. Biomolecules 2022; 12:biom12081109. [PMID: 36009002 PMCID: PMC9405955 DOI: 10.3390/biom12081109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/05/2022] [Accepted: 08/11/2022] [Indexed: 11/19/2022] Open
Abstract
Inhibition of Plasmodium falciparum nicotinamidase could represent a potential antimalarial since parasites require nicotinic acid to successfully recycle nicotinamide to NAD+, and importantly, humans lack this biosynthetic enzyme. Recently, mechanism-based inhibitors of nicotinamidase have been discovered. The most potent compound inhibits both recombinant P. falciparum nicotinamidase and parasites replication in infected human red blood cells (RBCs). These studies provide evidence for the importance of nicotinamide salvage through nicotinamidase as a central master player of NAD+ homeostasis in P. falciparum.
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