1
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Diffendall G, Scherf A. Deciphering the Plasmodium falciparum perinuclear var gene expression site. Trends Parasitol 2024; 40:707-716. [PMID: 38910098 DOI: 10.1016/j.pt.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/03/2024] [Accepted: 06/03/2024] [Indexed: 06/25/2024]
Abstract
The protozoan parasite Plasmodium falciparum, responsible for the deadliest form of human malaria, employs antigenic variation via monoallelic expression as a key survival strategy. The selective activation of one out of the 60-member var gene family is key to understanding the parasite's ability to cause severe disease and evade the host immune response. var gene activation is initiated by its relocation to a specialized expression site. While the perinuclear expression site (PES) plays a crucial role in enabling the expression of a single allele, the characteristics of this PES remain largely obscure. Recent breakthroughs in genome editing tools and the discovery of regulatory noncoding RNAs have shed light on this intriguing biological feature, offering significant insights into the mechanisms of pathogen virulence.
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Affiliation(s)
- Gretchen Diffendall
- Institut Pasteur, Universite Paris Cité, INSERM U1201, CNRS EMR9195, Paris, France
| | - Artur Scherf
- Institut Pasteur, Universite Paris Cité, INSERM U1201, CNRS EMR9195, Paris, France.
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2
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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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3
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Liu J, Fike KR, Dapper C, Klemba M. Metabolism of host lysophosphatidylcholine in Plasmodium falciparum-infected erythrocytes. Proc Natl Acad Sci U S A 2024; 121:e2320262121. [PMID: 38349879 PMCID: PMC10895272 DOI: 10.1073/pnas.2320262121] [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: 11/28/2023] [Accepted: 01/09/2024] [Indexed: 02/15/2024] Open
Abstract
The human malaria parasite Plasmodium falciparum requires exogenous fatty acids to support its growth during the pathogenic, asexual erythrocytic stage. Host serum lysophosphatidylcholine (LPC) is a significant fatty acid source, yet the metabolic processes responsible for the liberation of free fatty acids from exogenous LPC are unknown. Using an assay for LPC hydrolysis in P. falciparum-infected erythrocytes, we have identified small-molecule inhibitors of key in situ lysophospholipase activities. Competitive activity-based profiling and generation of a panel of single-to-quadruple knockout parasite lines revealed that two enzymes of the serine hydrolase superfamily, termed exported lipase (XL) 2 and exported lipase homolog (XLH) 4, constitute the dominant lysophospholipase activities in parasite-infected erythrocytes. The parasite ensures efficient exogenous LPC hydrolysis by directing these two enzymes to distinct locations: XL2 is exported to the erythrocyte, while XLH4 is retained within the parasite. While XL2 and XLH4 were individually dispensable with little effect on LPC hydrolysis in situ, loss of both enzymes resulted in a strong reduction in fatty acid scavenging from LPC, hyperproduction of phosphatidylcholine, and an enhanced sensitivity to LPC toxicity. Notably, growth of XL/XLH-deficient parasites was severely impaired when cultured in media containing LPC as the sole exogenous fatty acid source. Furthermore, when XL2 and XLH4 activities were ablated by genetic or pharmacologic means, parasites were unable to proliferate in human serum, a physiologically relevant fatty acid source, revealing the essentiality of LPC hydrolysis in the host environment and its potential as a target for anti-malarial therapy.
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Affiliation(s)
- Jiapeng Liu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
| | | | - Christie Dapper
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
| | - Michael Klemba
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
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4
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Lenz T, Zhang X, Chakraborty A, Ardakany AR, Prudhomme J, Ay F, Deitsch K, Le Roch KG. Chromatin structure and var2csa - a tango in regulation of var gene expression in the human malaria parasite, Plasmodium falciparum? BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.580059. [PMID: 38405848 PMCID: PMC10888805 DOI: 10.1101/2024.02.13.580059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Over the last few decades, novel methods have been developed to study how chromosome positioning within the nucleus may play a role in gene regulation. Adaptation of these methods in the human malaria parasite, Plasmodium falciparum, has recently led to the discovery that the three-dimensional structure of chromatin within the nucleus may be critical in controlling expression of virulence genes (var genes). Recent work has implicated an unusual, highly conserved var gene called var2csa in contributing to coordinated transcriptional switching, however how this gene functions in this capacity is unknown. To further understand how var2csa influences var gene switching, targeted DNA double-strand breaks (DSBs) within the sub-telomeric region of chromosome 12 were used to delete the gene and the surrounding chromosomal region. To characterize the changes in chromatin architecture stemming from this deletion and how these changes could affect var gene expression, we used a combination of RNA-seq, Chip-seq and Hi-C to pinpoint epigenetic and chromatin structural modifications in regions of differential gene expression. We observed a net gain of interactions in sub-telomeric regions and internal var gene regions following var2csa knockout, indicating an increase of tightly controlled heterochromatin structures. Our results suggest that disruption of var2csa results not only in changes in var gene transcriptional regulation but also a significant tightening of heterochromatin clusters thereby disrupting coordinated activation of var genes throughout the genome. Altogether our result confirms a strong link between the var2csa locus, chromatin structure and var gene expression.
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Affiliation(s)
- Todd Lenz
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
| | - Xu Zhang
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Abhijit Chakraborty
- La Jolla Institute for Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | | | - Jacques Prudhomme
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
| | - Ferhat Ay
- La Jolla Institute for Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Kirk Deitsch
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Karine G. Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
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5
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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6
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Tan MH, Tiedje KE, Feng Q, Zhan Q, Pascual M, Shim H, Chan YB, Day KP. A paradoxical population structure of var DBLα types in Africa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.05.565723. [PMID: 37986738 PMCID: PMC10659346 DOI: 10.1101/2023.11.05.565723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The var multigene family encodes the P. falciparum erythrocyte membrane protein 1 (PfEMP1), which is important in host-parasite interaction as a virulence factor and major surface antigen of the blood stages of the parasite, responsible for maintaining chronic infection. Whilst important in the biology of P. falciparum, these genes (50 to 60 genes per parasite genome) are routinely excluded from whole genome analyses due to their hyper-diversity, achieved primarily through recombination. The PfEMP1 head structure almost always consists of a DBLα-CIDR tandem. Categorised into different groups (upsA, upsB, upsC), different head structures have been associated with different ligand-binding affinities and disease severities. We study how conserved individual DBLα types are at the country, regional, and local scales in Sub-Saharan Africa. Using publicly-available sequence datasets and a novel ups classification algorithm, cUps, we performed an in silico exploration of DBLα conservation through time and space in Africa. In all three ups groups, the population structure of DBLα types in Africa consists of variants occurring at rare, low, moderate, and high frequencies. Non-rare variants were found to be temporally stable in a local area in endemic Ghana. When inspected across different geographical scales, we report different levels of conservation; while some DBLα types were consistently found in high frequencies in multiple African countries, others were conserved only locally, signifying local preservation of specific types. Underlying this population pattern is the composition of DBLα types within each isolate DBLα repertoire, revealed to also consist of a mix of types found at rare, low, moderate, and high frequencies in the population. We further discuss the adaptive forces and balancing selection, including host genetic factors, potentially shaping the evolution and diversity of DBLα types in Africa.
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Affiliation(s)
- Mun Hua Tan
- Department of Microbiology and Immunology, The University of Melbourne, Bio21 Institute and Peter Doherty Institute, Melbourne, AU
| | - Kathryn E Tiedje
- Department of Microbiology and Immunology, The University of Melbourne, Bio21 Institute and Peter Doherty Institute, Melbourne, AU
| | - Qian Feng
- School of Mathematics and Statistics / Melbourne Integrative Genomics, The University of Melbourne, Melbourne, Australia
| | - Qi Zhan
- Department of Ecology and Evolution, University of Chicago; Chicago, Illinois, USA
| | - Mercedes Pascual
- Department of Ecology and Evolution, University of Chicago; Chicago, Illinois, USA
| | - Heejung Shim
- School of Mathematics and Statistics / Melbourne Integrative Genomics, The University of Melbourne, Melbourne, Australia
| | - Yao-Ban Chan
- School of Mathematics and Statistics / Melbourne Integrative Genomics, The University of Melbourne, Melbourne, Australia
| | - Karen P Day
- Department of Microbiology and Immunology, The University of Melbourne, Bio21 Institute and Peter Doherty Institute, Melbourne, AU
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7
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Vydyam P, Roy N, Bhattacharyya MK. Uncovering the role of Rad51 in homologous recombination-mediated antigenic diversification in the human malaria parasite Plasmodium falciparum. Front Mol Biosci 2023; 10:1223682. [PMID: 37593128 PMCID: PMC10427863 DOI: 10.3389/fmolb.2023.1223682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/13/2023] [Indexed: 08/19/2023] Open
Abstract
The human malaria parasite Plasmodium falciparum maintains the chronicity of infections through antigenic variation, a well-coordinated immune evasion mechanism. The most prominent molecular determinant of antigenic variation in this parasite includes the members of the var multigene family. Homologous recombination (HR)-mediated genomic rearrangements have been implicated to play a major role in var gene diversification. However, the key molecular factors involved in the generation of diversity at var loci are less known. Here, we tested the hypothesis that PfRad51 could carry out recombination between var genes that are not homologous but homeologous in nature. We employed the whole-genome sequencing (WGS) approach to investigate recombination events among var sequences over 100 generations and compared the rate of sequence rearrangement at the var loci in both PfRad51-proficient and -deficient parasite lines. This brief report provides evidence that the loss of the key recombinase function renders the parasite with inefficient HR and results in fewer recombination events among the var sequences, thereby impacting the diversification of the var gene repertoire.
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8
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Barcons-Simon A, Carrington M, Siegel TN. Decoding the impact of nuclear organization on antigenic variation in parasites. Nat Microbiol 2023; 8:1408-1418. [PMID: 37524976 DOI: 10.1038/s41564-023-01424-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 06/13/2023] [Indexed: 08/02/2023]
Abstract
Antigenic variation as a strategy to evade the host adaptive immune response has evolved in divergent pathogens. Antigenic variation involves restricted, and often mutually exclusive, expression of dominant antigens and a periodic switch in antigen expression during infection. In eukaryotes, nuclear compartmentalization, including three-dimensional folding of the genome and physical separation of proteins in compartments or condensates, regulates mutually exclusive gene expression and chromosomal translocations. In this Review, we discuss the impact of nuclear organization on antigenic variation in the protozoan pathogens Trypanosoma brucei and Plasmodium falciparum. In particular, we highlight the relevance of nuclear organization in both mutually exclusive antigen expression and genome stability, which underlie antigenic variation.
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Affiliation(s)
- Anna Barcons-Simon
- Division of Experimental Parasitology, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
- Biomedical Center, Division of Physiological Chemistry, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - T Nicolai Siegel
- Division of Experimental Parasitology, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
- Biomedical Center, Division of Physiological Chemistry, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
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9
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Liu J, Dapper C, Klemba M. Metabolism of host lysophosphatidylcholine in Plasmodium falciparum-infected erythrocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537066. [PMID: 37131712 PMCID: PMC10153170 DOI: 10.1101/2023.04.17.537066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The human malaria parasite Plasmodium falciparum requires exogenous fatty acids to support its growth during the pathogenic, asexual erythrocytic stage. Host serum lysophosphatidylcholine (LPC) is a significant fatty acid source, yet the metabolic processes responsible for the liberation of free fatty acids from exogenous LPC are unknown. Using a novel assay for LPC hydrolysis in P. falciparum-infected erythrocytes, we have identified small-molecule inhibitors of key in situ lysophospholipase activities. Competitive activity-based profiling and generation of a panel of single-to-quadruple knockout parasite lines revealed that two enzymes of the serine hydrolase superfamily, termed exported lipase (XL) 2 and exported lipase homolog (XLH) 4, are the dominant lysophospholipase activities in parasite-infected erythrocytes. The parasite ensures efficient exogenous LPC hydrolysis by directing these two enzymes to distinct locations: XL2 is exported to the erythrocyte, while XLH4 is retained within the parasite. While XL2 and XLH4 were individually dispensable with little effect on LPC hydrolysis in situ, loss of both enzymes resulted in a strong reduction in fatty acid scavenging from LPC, hyperproduction of phosphatidylcholine, and an enhanced sensitivity to LPC toxicity. Notably, growth of XL/XLH-deficient parasites was severely impaired when cultured in media containing LPC as the sole exogenous fatty acid source. Furthermore, when XL2 and XLH4 activities were ablated by genetic or pharmacologic means, parasites were unable to proliferate in human serum, a physiologically-relevant fatty acid source, revealing the essentiality of LPC hydrolysis in the host environment and its potential as a target for anti-malarial therapy.
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Affiliation(s)
- Jiapeng Liu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
| | - Christie Dapper
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
| | - Michael Klemba
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
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10
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Honma H, Takahashi N, Arisue N, Sugishita T. Analysis of genome instability and implications for the consequent phenotype in Plasmodium falciparum containing mutated MSH2-1 (P513T). Microb Genom 2023; 9. [PMID: 37083479 DOI: 10.1099/mgen.0.001003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
Malarial parasites exhibit extensive genomic plasticity, which induces the antigen diversification and the development of antimalarial drug resistance. Only a few studies have examined the genome maintenance mechanisms of parasites. The study aimed at elucidating the impact of a mutation in a DNA mismatch repair gene on genome stability by maintaining the mutant and wild-type parasites through serial in vitro cultures for approximately 400 days and analysing the subsequent spontaneous mutations. A P513T mutant of the DNA mismatch repair protein PfMSH2-1 from Plasmodium falciparum 3D7 was created. The mutation did not influence the base substitution rate but significantly increased the insertion/deletion (indel) mutation rate in short tandem repeats (STRs) and minisatellite loci. STR mutability was affected by allele size, genomic category and certain repeat motifs. In the mutants, significant telomere healing and homologous recombination at chromosomal ends caused extensive gene loss and generation of chimeric genes, resulting in large-scale chromosomal alteration. Additionally, the mutant showed increased tolerance to N-methyl-N'-nitro-N-nitrosoguanidine, suggesting that PfMSH2-1 was involved in recognizing DNA methylation damage. This work provides valuable insights into the role of PfMSH2-1 in genome stability and demonstrates that the genomic destabilization caused by its dysfunction may lead to antigen diversification.
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Affiliation(s)
- Hajime Honma
- Section of Global Health, Division of Public Health, Department of Hygiene and Public Health, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
- Department of International Affairs and Tropical Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
| | - Nobuyuki Takahashi
- Section of Global Health, Division of Public Health, Department of Hygiene and Public Health, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
- Department of International Affairs and Tropical Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
| | - Nobuko Arisue
- Section of Global Health, Division of Public Health, Department of Hygiene and Public Health, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
| | - Tomohiko Sugishita
- Section of Global Health, Division of Public Health, Department of Hygiene and Public Health, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
- Department of International Affairs and Tropical Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan
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11
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Disulfide bond and crosslinking analyses reveal inter-domain interactions that contribute to the rigidity of placental malaria VAR2CSA structure and formation of CSA binding channel. Int J Biol Macromol 2023; 226:143-158. [PMID: 36470436 DOI: 10.1016/j.ijbiomac.2022.11.258] [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: 08/26/2022] [Revised: 11/15/2022] [Accepted: 11/24/2022] [Indexed: 12/11/2022]
Abstract
VAR2CSA, a multidomain Plasmodium falciparum protein, mediates the adherence of parasite-infected red blood cells to chondroitin 4-sulfate (C4S) in the placenta, contributing to placental malaria. Therefore, detailed understanding of VAR2CSA structure likely help developing strategies to treat placental malaria. The VAR2CSA ectodomain consists of an N-terminal segment (NTS), six Duffy binding-like (DBL) domains, and three interdomains (IDs) present in sequence NTS-DBL1x-ID1-DBL2x-ID2-DBL3x-DBL4ε-ID3-DBL5ε-DBL6ε. Recent electron microscopy studies showed that VAR2CSA is compactly organized into a globular structure containing C4S-binding channel, and that DBL5ε-DBL6ε arm is attached to the NTS-ID3 core structure. However, the structural elements involved in inter-domain interactions that stabilize the VAR2CSA structure remain largely not understood. Here, limited proteolysis and peptide mapping by mass spectrometry showed that VAR2CSA contains several inter-domain disulfide bonds that stabilize its compact structure. Chemical crosslinking-mass spectrometry showed that all IDs interact with DBL4ε; additionally, IDs interact with other DBL domains, demonstrating that IDs are the key structural scaffolds that shape the functional NTS-ID3 core. Ligand binding analysis suggested that NTS considerably restricts the C4S binding. Overall, our study revealed that inter-domain disulfide bonds and interactions between IDs and DBL domains contribute to the stability of VAR2CSA structural architecture and formation of C4S-binding channel.
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12
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Abdel Hamid MM, Abdelraheem MH, Acheampong DO, Ahouidi A, Ali M, Almagro-Garcia J, Amambua-Ngwa A, Amaratunga C, Amenga-Etego L, Andagalu B, Anderson T, Andrianaranjaka V, Aniebo I, Aninagyei E, Ansah F, Ansah PO, Apinjoh T, Arnaldo P, Ashley E, Auburn S, Awandare GA, Ba H, Baraka V, Barry A, Bejon P, Bertin GI, Boni MF, Borrmann S, Bousema T, Bouyou-Akotet M, Branch O, Bull PC, Cheah H, Chindavongsa K, Chookajorn T, Chotivanich K, Claessens A, Conway DJ, Corredor V, Courtier E, Craig A, D'Alessandro U, Dama S, Day N, Denis B, Dhorda M, Diakite M, Djimde A, Dolecek C, Dondorp A, Doumbia S, Drakeley C, Drury E, Duffy P, Echeverry DF, Egwang TG, Enosse SMM, Erko B, Fairhurst RM, Faiz A, Fanello CA, Fleharty M, Forbes M, Fukuda M, Gamboa D, Ghansah A, Golassa L, Goncalves S, Harrison GLA, Healy SA, Hendry JA, Hernandez-Koutoucheva A, Hien TT, Hill CA, Hombhanje F, Hott A, Htut Y, Hussein M, Imwong M, Ishengoma D, Jackson SA, Jacob CG, Jeans J, Johnson KJ, Kamaliddin C, Kamau E, Keatley J, Kochakarn T, Konate DS, Konaté A, Kone A, Kwiatkowski DP, Kyaw MP, Kyle D, Lawniczak M, Lee SK, Lemnge M, Lim P, Lon C, Loua KM, Mandara CI, Marfurt J, Marsh K, Maude RJ, Mayxay M, Maïga-Ascofaré O, Miotto O, Mita T, Mobegi V, Mohamed AO, Mokuolu OA, Montgomery J, Morang’a CM, Mueller I, Murie K, Newton PN, Ngo Duc T, Nguyen T, Nguyen TN, Nguyen Thi Kim T, Nguyen Van H, Noedl H, Nosten F, Noviyanti R, Ntui VNN, Nzila A, Ochola-Oyier LI, Ocholla H, Oduro A, Omedo I, Onyamboko MA, Ouedraogo JB, Oyebola K, Oyibo WA, Pearson R, Peshu N, Phyo AP, Plowe CV, Price RN, Pukrittayakamee S, Quang HH, Randrianarivelojosia M, Rayner JC, Ringwald P, Rosanas-Urgell A, Rovira-Vallbona E, Ruano-Rubio V, Ruiz L, Saunders D, Shayo A, Siba P, Simpson VJ, Sissoko MS, Smith C, Su XZ, Sutherland C, Takala-Harrison S, Talman A, Tavul L, Thanh NV, Thathy V, Thu AM, Toure M, Tshefu A, Verra F, Vinetz J, Wellems TE, Wendler J, White NJ, Whitton G, Yavo W, van der Pluijm RW. Pf7: an open dataset of Plasmodium falciparum genome variation in 20,000 worldwide samples. Wellcome Open Res 2023; 8:22. [PMID: 36864926 PMCID: PMC9971654 DOI: 10.12688/wellcomeopenres.18681.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2022] [Indexed: 01/18/2023] Open
Abstract
We describe the MalariaGEN Pf7 data resource, the seventh release of Plasmodium falciparum genome variation data from the MalariaGEN network. It comprises over 20,000 samples from 82 partner studies in 33 countries, including several malaria endemic regions that were previously underrepresented. For the first time we include dried blood spot samples that were sequenced after selective whole genome amplification, necessitating new methods to genotype copy number variations. We identify a large number of newly emerging crt mutations in parts of Southeast Asia, and show examples of heterogeneities in patterns of drug resistance within Africa and within the Indian subcontinent. We describe the profile of variations in the C-terminal of the csp gene and relate this to the sequence used in the RTS,S and R21 malaria vaccines. Pf7 provides high-quality data on genotype calls for 6 million SNPs and short indels, analysis of large deletions that cause failure of rapid diagnostic tests, and systematic characterisation of six major drug resistance loci, all of which can be freely downloaded from the MalariaGEN website.
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Affiliation(s)
| | | | - Mohamed Hassan Abdelraheem
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
- Nuclear Applications In Biological Sciences, Sudan Atomic Energy Commission, Khartoum, Sudan
| | - Desmond Omane Acheampong
- Department of Biomedical Sciences, School of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Ambroise Ahouidi
- Health Research Epidemiological Surveillance and Training Institute (IRESSEF), Université Cheikh Anta Diop, Dakar, Senegal
| | - Mozam Ali
- Wellcome Sanger Institute, Hinxton, UK
| | | | - Alfred Amambua-Ngwa
- Wellcome Sanger Institute, Hinxton, UK
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Chanaki Amaratunga
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
| | - Lucas Amenga-Etego
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Ghana
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Ben Andagalu
- United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project, Kisumu, Kenya
| | - Tim Anderson
- Texas Biomedical Research Institute, San Antonio, USA
| | | | | | - Enoch Aninagyei
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health & Allied Sciences, Ho, Ghana
| | - Felix Ansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Ghana
| | - Patrick O Ansah
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | | | - Paulo Arnaldo
- Instituto Nacional de Saúde (INS), Maputo, Mozambique
| | - Elizabeth Ashley
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Sarah Auburn
- Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
- Nuffield Department of Medicine, University of Oxford, UK
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Ghana
| | - Hampate Ba
- Institut National de Recherche en Santé Publique, Nouakchott, Mauritania
| | - Vito Baraka
- National Institute for Medical Research (NIMR), Dar es Salaam, Tanzania
- Department of Epidemiology, International Health Unit, Universiteit Antwerpen, Antwerp, Belgium
| | - Alyssa Barry
- Walter and Eliza Hall Institute, Melbourne, Australia
- Deakin University, Geelong, Australia
- Burnet Institute, Melbourne, Australia
| | - Philip Bejon
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Maciej F Boni
- Nuffield Department of Medicine, University of Oxford, UK
- Oxford University Clinical Research Unit (OUCRU), Ho Chi Minh City, Vietnam
| | - Steffen Borrmann
- Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Teun Bousema
- London School of Hygiene and Tropical Medicine, London, UK
- Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marielle Bouyou-Akotet
- Department of Parasitology-Mycology, Université des Sciences de la Santé, Libreville, Gabon
| | - Oralee Branch
- NYU School of Medicine Langone Medical Center, New York, USA
| | - Peter C Bull
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Huch Cheah
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | | | | | | | - Antoine Claessens
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
- LPHI, MIVEGEC, INSERM, CNRS, IRD, University of Montpellier, Montpellier, France
| | - David J Conway
- London School of Hygiene and Tropical Medicine, London, UK
| | | | | | - Alister Craig
- Liverpool School of Tropical Medicine, Liverpool, UK
- Malawi-Liverpool-Wellcome Trust Clinical Research Program, Blantyre, Malawi
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Souleymane Dama
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Nicholas Day
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Brigitte Denis
- Malawi-Liverpool-Wellcome Trust Clinical Research Program, Blantyre, Malawi
| | - Mehul Dhorda
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- WorldWide Antimalarial Resistance Network – Asia Regional Centre, Bangkok, Thailand
| | - Mahamadou Diakite
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
- University Clinical Research Center (UCRC), Bamako, Mali
| | - Abdoulaye Djimde
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Arjen Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Seydou Doumbia
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
- University Clinical Research Center (UCRC), Bamako, Mali
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, UK
| | | | - Patrick Duffy
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
| | - Diego F Echeverry
- Departamento de Microbiología, Universidad del Valle, Cali, Colombia
- Centro Internacional de Entrenamiento e Investigaciones Médicas - CIDEIM, Cali, Colombia
| | | | | | - Berhanu Erko
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | - Caterina A Fanello
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
| | - Mark Fleharty
- Broad Institute of Harvard and MIT and Harvard, Cambridge, MA, USA
| | | | - Mark Fukuda
- Department of Immunology and Medicine, US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Bangkok, Thailand
| | - Dionicia Gamboa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Anita Ghansah
- Nogouchi Memorial Institute for Medical Research, Legon-Accra, Ghana
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | - Sara Anne Healy
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
| | - Jason A Hendry
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | | | - Tran Tinh Hien
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Oxford University Clinical Research Unit (OUCRU), Ho Chi Minh City, Vietnam
| | - Catherine A Hill
- Department of Entomology, Purdue University, West Lafayette, USA
| | - Francis Hombhanje
- Centre for Health Research & Diagnostics, Divine Word University, Madang, Papua New Guinea
| | | | - Ye Htut
- Department of Medical Research, Yangon, Myanmar
| | - Mazza Hussein
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | | | - Deus Ishengoma
- National Institute for Medical Research (NIMR), Dar es Salaam, Tanzania
- East African Consortium for Clinical Research (EACCR), Dar es Salaam, Tanzania
| | - Scott A Jackson
- Center for Applied Genetic Technologies, University of Georgia, Athens, GA, USA
| | | | | | | | - Claire Kamaliddin
- Institute of Research for Development (IRD), Paris, France
- The University of Calgary, Calgary, Canada
| | - Edwin Kamau
- U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | | | | | - Drissa S Konate
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Aminatou Kone
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Myat P Kyaw
- Myanmar Oxford Clinical Research Unit, University of Oxford, Yangon, Myanmar
- University of Public Health, Yangon, Myanmar
| | - Dennis Kyle
- University of South Florida, Tampa, USA
- University of Georgia, Athens, USA
| | | | - Samuel K Lee
- Broad Institute of Harvard and MIT and Harvard, Cambridge, MA, USA
| | - Martha Lemnge
- National Institute for Medical Research (NIMR), Dar es Salaam, Tanzania
| | - Pharath Lim
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
- Medical Care Development International, Maryland, USA
| | - Chanthap Lon
- National Institute of Allergy and Infectious Diseases, Phnom Penh, Cambodia
| | - Kovana M Loua
- University Gamal Abdel Nasser of Conakry, Conakry, Guinea
- Institut National de Santé Publique, Conakry, Guinea
| | - Celine I Mandara
- National Institute for Medical Research (NIMR), Dar es Salaam, Tanzania
| | - Jutta Marfurt
- Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Kevin Marsh
- Nuffield Department of Medicine, University of Oxford, UK
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Richard James Maude
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Harvard TH Chan School of Public Health, Harvard University, Boston, USA
| | - Mayfong Mayxay
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Institute of Research and Education Development (IRED), University of Health Sciences, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Oumou Maïga-Ascofaré
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Research in Tropical Medicine, Kwame Nkrumah University of Sciences and Technology, Kumasi, Ghana
| | - Olivo Miotto
- Wellcome Sanger Institute, Hinxton, UK
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- MRC Centre for Genomics and Global Health, Big Data Institute, Oxford University, Oxford, UK
| | | | - Victor Mobegi
- Department of Biochemistry and Centre for Biotechnology and Bioinformatics, University of Nairobi, Nairobi, Kenya
| | | | - Olugbenga A Mokuolu
- Department of Paediatrics and Child Health, University of Ilorin, Ilorin, Nigeria
| | - Jaqui Montgomery
- Malawi-Liverpool-Wellcome Trust Clinical Research Program, Blantyre, Malawi
- World Mosquito Program, Monash University, Melbourne, Australia
| | - Collins Misita Morang’a
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Ghana
| | - Ivo Mueller
- Walter and Eliza Hall Institute, Melbourne, Australia
- University of Melbourne, Melbourne, Australia
| | | | - Paul N Newton
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Thang Ngo Duc
- National Institute of Malariology, Parasitology and Entomology (NIMPE), Hanoi, Vietnam
| | | | - Thuy-Nhien Nguyen
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Oxford University Clinical Research Unit (OUCRU), Ho Chi Minh City, Vietnam
| | | | - Hong Nguyen Van
- National Institute of Malariology, Parasitology and Entomology (NIMPE), Hanoi, Vietnam
| | - Harald Noedl
- MARIB - Malaria Research Initiative Bandarban, Bandarban, Bangladesh
- Medical University of Vienna, Vienna, Austria
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | | | | | - Alexis Nzila
- King Fahid University of Petroleum and Minerals (KFUMP), Dhahran, Saudi Arabia
| | | | - Harold Ocholla
- KEMRI Centres for Disease Control and Prevention (CDC) Research Program, Kisumu, Kenya
- Centre for Bioinformatics and Biotechnology, University of Nairobi, Nairobi, Kenya
| | - Abraham Oduro
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Irene Omedo
- Wellcome Sanger Institute, Hinxton, UK
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Marie A Onyamboko
- Kinshasa School of Public Health, University of Kinshasa, Kinshasa, Congo, Democratic Republic
| | | | - Kolapo Oyebola
- Nigerian Institute of Medical Research, Lagos, Nigeria
- Parasitology and Bioinformatics Unit, Faculty of Science, University of Lagos, Lagos, Nigeria
| | | | | | - Norbert Peshu
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Aung P Phyo
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Shoklo Malaria Research Unit, Bangkok, Thailand
| | | | - Ric N Price
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | | | - Huynh Hong Quang
- Institute of Malariology, Parasitology, and Entomology (IMPE) Quy Nhon, Ministry of Health, Quy Nhon, Vietnam
| | - Milijaona Randrianarivelojosia
- Institut Pasteur de Madagascar, Antananarivo, Madagascar
- Universités d'Antananarivo et de Mahajanga, Antananarivo, Madagascar
| | - Julian C Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | | | | | | | | | - Lastenia Ruiz
- Universidad Nacional de la Amazonia Peruana, Iquitos, Peru
| | - David Saunders
- Department of Medicine, Uniformed Services University, Bethesda, MD, USA
| | - Alex Shayo
- Nelson Mandela Institute of Science and Technology, Arusha, Tanzania
| | - Peter Siba
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | | | - Mahamadou S. Sissoko
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Xin-zhuan Su
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
| | | | - Shannon Takala-Harrison
- Center for Vaccine Development and Global Health, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Arthur Talman
- MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Livingstone Tavul
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Ngo Viet Thanh
- Oxford University Clinical Research Unit (OUCRU), Ho Chi Minh City, Vietnam
| | - Vandana Thathy
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Aung Myint Thu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Mahamoudou Toure
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | | | - Joseph Vinetz
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Yale School of Medicine, New Haven, CT, USA
| | - Thomas E Wellems
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
| | - Jason Wendler
- National Institute of Allergy and Infectious Diseases (NIAID), NIH, Maryland, USA
- Seattle Children’s Hospital, Seattle, USA
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | | | - William Yavo
- University Félix Houphouët-Boigny, Abidjan, Cote d'Ivoire
- Malaria Research and Control Center of the National Institute of Public Health, Abidjan, Cote d'Ivoire
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Tan MH, Shim H, Chan YB, Day KP. Unravelling var complexity: Relationship between DBLα types and var genes in Plasmodium falciparum. FRONTIERS IN PARASITOLOGY 2023; 1. [PMID: 36998722 PMCID: PMC10060044 DOI: 10.3389/fpara.2022.1006341] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The enormous diversity and complexity of var genes that diversify rapidly by recombination has led to the exclusion of assembly of these genes from major genome initiatives (e.g., Pf6). A scalable solution in epidemiological surveillance of var genes is to use a small ‘tag’ region encoding the immunogenic DBLα domain as a marker to estimate var diversity. As var genes diversify by recombination, it is not clear the extent to which the same tag can appear in multiple var genes. This relationship between marker and gene has not been investigated in natural populations. Analyses of in vitro recombination within and between var genes have suggested that this relationship would not be exclusive. Using a dataset of publicly-available assembled var sequences, we test this hypothesis by studying DBLα-var relationships for four study sites in four countries: Pursat (Cambodia) and Mae Sot (Thailand), representing low malaria transmission, and Navrongo (Ghana) and Chikwawa (Malawi), representing high malaria transmission. In all study sites, DBLα-var relationships were shown to be predominantly 1-to-1, followed by a second largest proportion of 1-to-2 DBLα-var relationships. This finding indicates that DBLα tags can be used to estimate not just DBLα diversity but var gene diversity when applied in a local endemic area. Epidemiological applications of this result are discussed.
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Affiliation(s)
- Mun Hua Tan
- Department of Microbiology and Immunology, The University of Melbourne, Bio21 Institute, Melbourne, VIC, Australia
| | - Heejung Shim
- School of Mathematics and Statistics/Melbourne Integrative Genomics, The University of Melbourne, Melbourne, VIC, Australia
| | - Yao-ban Chan
- School of Mathematics and Statistics/Melbourne Integrative Genomics, The University of Melbourne, Melbourne, VIC, Australia
| | - Karen P. Day
- Department of Microbiology and Immunology, The University of Melbourne, Bio21 Institute, Melbourne, VIC, Australia
- CORRESPONDENCE Karen P. Day,
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Zhang X, Deitsch KW. The mystery of persistent, asymptomatic Plasmodium falciparum infections. Curr Opin Microbiol 2022; 70:102231. [PMID: 36327690 PMCID: PMC10500611 DOI: 10.1016/j.mib.2022.102231] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/31/2022] [Accepted: 10/12/2022] [Indexed: 01/25/2023]
Abstract
Plasmodium falciparum causes millions of malaria infections and hundreds of thousands of deaths annually. These parasites avoid the adaptive immune response by systematically cycling through a limited repertoire of variant surface antigens after which the number of circulating parasites drops to extremely low levels, coinciding with a loss of symptoms and eventual clearance of the infection. However, in regions with extended dry seasons or in individuals who no longer reside in endemic areas, asymptomatic infections have been observed to persist for many months or years, potentially serving as reservoirs for transmission. Recent work suggests the possibility that parasites can assume a state in which no variant surface antigens are expressed, thus rendering them virtually invisible to the immune system and enabling them to persist at low levels indefinitely.
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Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
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15
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Bendezu J, Torres K, Villasis E, Incardona S, Bell D, Vinetz J, Gamboa D. Geographical distribution and genetic characterization of pfhrp2 negative Plasmodium falciparum parasites in the Peruvian Amazon. PLoS One 2022; 17:e0273872. [PMID: 36413547 PMCID: PMC9681099 DOI: 10.1371/journal.pone.0273872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/16/2022] [Indexed: 11/23/2022] Open
Abstract
Malaria rapid diagnostic tests (RDTs) have been evaluated in the Peruvian Amazon region and their performance has been variable. This region is known for being the first with documented evidence of wild Plasmodium falciparum parasites lacking pfhrp2 and pfhrp3 genes, leading to false-positive results with HRP2-based RDTs. In our attempt to further characterize the deletion pattern of these genes and their evolutionary relationship, 93 P. falciparum samples, collected in different communities from the Peruvian Amazon region between 2009 and 2010, were analyzed in this study. Genomic DNA was used to amplify 18S rRNA, pfmsp2 and pfglurp to confirm the diagnosis and DNA quality, respectively; pfhrp2, pfhrp3, and their flanking genes were amplified by PCR to assess the pattern of the gene deletions. In addition, microsatellite analysis were performed using seven neutral microsatellites (MS) and five microsatellite loci flanking pfhrp2. The data showed the absence of pfhrp3 gene in 53.76% (50/93) of the samples, reflecting a higher frequency than the proportion of pfhrp2 gene deletions (33.33%; 31/93). Among the flanking genes, the highest frequency of deletion was observed in the PF3D7_0831900 gene (78.49%; 73/93) for pfhrp2. MS marker analysis showed the presence of 8 P. falciparum lineages. The lineage Bv1 was the most prevalent among parasites lacking pfhrp2 and pfhrp3 genes. Additionally, using MS flanking pfhrp2 gene, the haplotypes α and δ were found to be the most abundant in this region. This study confirms the presence in this area of field isolates with deletions in either pfhrp2, pfhrp3, or both genes, along with their respective flanking regions. Our data suggest that some pfhrp2/pfhrp3 deletion haplotypes, in special the lineage Bv1, are widely dispersed within the Peruvian Amazon. The persistence of these haplotypes ensures a proportion of P.falciparum parasites lacking the pfhrp2/pfhrp3 genes in this area, which ultimately leads to false-negative results on PfHRP2-detecting malaria RDTs. However, additional studies are needed to not only confirm this hypothesis but also to further delineate the origin and genetic basis for the pfhrp2- and pfhrp3 gene deletions in wild P. falciparum parasites.
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Affiliation(s)
- Jorge Bendezu
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Escuela Universitaria de Posgrado, Universidad Nacional Federico Villareal, Lima, Peru
| | - Katherine Torres
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicina Tropical “Alexander von Humboldt” Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Elizabeth Villasis
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicina Tropical “Alexander von Humboldt” Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - David Bell
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | - Joseph Vinetz
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, United States of America
| | - Dionicia Gamboa
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicina Tropical “Alexander von Humboldt” Universidad Peruana Cayetano Heredia, Lima, Peru
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16
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Johnson EK, Larremore DB. Bayesian estimation of community size and overlap from random subsamples. PLoS Comput Biol 2022; 18:e1010451. [PMID: 36121879 PMCID: PMC9522272 DOI: 10.1371/journal.pcbi.1010451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/29/2022] [Accepted: 07/28/2022] [Indexed: 11/19/2022] Open
Abstract
Counting the number of species, items, or genes that are shared between two groups, sets, or communities is a simple calculation when sampling is complete. However, when only partial samples are available, quantifying the overlap between two communities becomes an estimation problem. Furthermore, to calculate normalized measures of β-diversity, such as the Jaccard and Sorenson-Dice indices, one must also estimate the total sizes of the communities being compared. Previous efforts to address these problems have assumed knowledge of total community sizes and then used Bayesian methods to produce unbiased estimates with quantified uncertainty. Here, we address communities of unknown size and show that this produces systematically better estimates—both in terms of central estimates and quantification of uncertainty in those estimates. We further show how to use species, item, or gene count data to refine estimates of community size in a Bayesian joint model of community size and overlap.
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Affiliation(s)
- Erik K. Johnson
- Department of Applied Mathematics, University of Colorado Boulder, Boulder, Colorado, United States of America
- * E-mail: (EKJ); (DBL)
| | - Daniel B. Larremore
- Department of Computer Science, University of Colorado Boulder, Boulder, Colorado, United States of America
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, United States of America
- * E-mail: (EKJ); (DBL)
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Abstract
In eukaryotic organisms, noncoding RNAs (ncRNAs) have been implicated as important regulators of multifaceted biological processes, including transcriptional, posttranscriptional, and epigenetic regulation of gene expression. In recent years, it is becoming clear that protozoan parasites encode diverse ncRNA transcripts; however, little is known about their cellular functions. Recent advances in high-throughput “omic” studies identified many novel long ncRNAs (lncRNAs) in apicomplexan parasites, some of which undergo splicing, polyadenylation, and encode small proteins. To date, only a few of them are characterized, leaving a big gap in our understanding regarding their origin, mode of action, and functions in parasite biology. In this review, we focus on lncRNAs of the human malaria parasite Plasmodium falciparum and highlight their cellular functions and possible mechanisms of action.
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Affiliation(s)
- Karina Simantov
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Manish Goyal
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Ron Dzikowski
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- * E-mail:
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18
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Allred DR. Integration of DNA Repair, Antigenic Variation, Cytoadhesion, and Chance in Babesia Survival: A Perspective. Front Cell Infect Microbiol 2022; 12:869696. [PMID: 35493746 PMCID: PMC9047050 DOI: 10.3389/fcimb.2022.869696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites live in hostile environments in which they are challenged chemically and their hosts attempt in many ways to kill them. In response, the parasites have evolved multiple mechanisms that take advantage of these challenges to enhance their survival. Perhaps the most impressive example is the evolutionary co-option of DNA repair mechanisms by the parasites as a means to rapidly manipulate the structure, antigenicity, and expression of the products of specific multigene families. The purpose of variant proteins that mediate cytoadhesion has long been thought to be primarily the avoidance of splenic clearance. Based upon known biology, I present an alternative perspective in which it is survival of the oxidative environment within which Babesia spp. parasites live that has driven integration of DNA repair, antigenic variation, and cytoadhesion, and speculate on how genome organization affects that integration. This perspective has ramifications for the development of parasite control strategies.
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Affiliation(s)
- David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, United States
- Genetics Institute, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
- *Correspondence: David R. Allred,
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19
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Florini F, Visone JE, Deitsch KW. Shared Mechanisms for Mutually Exclusive Expression and Antigenic Variation by Protozoan Parasites. Front Cell Dev Biol 2022; 10:852239. [PMID: 35350381 PMCID: PMC8957917 DOI: 10.3389/fcell.2022.852239] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/17/2022] [Indexed: 01/05/2023] Open
Abstract
Cellular decision-making at the level of gene expression is a key process in the development and evolution of every organism. Variations in gene expression can lead to phenotypic diversity and the development of subpopulations with adaptive advantages. A prime example is the mutually exclusive activation of a single gene from within a multicopy gene family. In mammals, this ranges from the activation of one of the two immunoglobulin (Ig) alleles to the choice in olfactory sensory neurons of a single odorant receptor (OR) gene from a family of more than 1,000. Similarly, in parasites like Trypanosoma brucei, Giardia lamblia or Plasmodium falciparum, the process of antigenic variation required to escape recognition by the host immune system involves the monoallelic expression of vsg, vsp or var genes, respectively. Despite the importance of this process, understanding how this choice is made remains an enigma. The development of powerful techniques such as single cell RNA-seq and Hi-C has provided new insights into the mechanisms these different systems employ to achieve monoallelic gene expression. Studies utilizing these techniques have shown how the complex interplay between nuclear architecture, physical interactions between chromosomes and different chromatin states lead to single allele expression. Additionally, in several instances it has been observed that high-level expression of a single gene is preceded by a transient state where multiple genes are expressed at a low level. In this review, we will describe and compare the different strategies that organisms have evolved to choose one gene from within a large family and how parasites employ this strategy to ensure survival within their hosts.
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20
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Zhang X, Florini F, Visone JE, Lionardi I, Gross MR, Patel V, Deitsch KW. A coordinated transcriptional switching network mediates antigenic variation of human malaria parasites. eLife 2022; 11:83840. [PMID: 36515978 PMCID: PMC9833823 DOI: 10.7554/elife.83840] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022] Open
Abstract
Malaria parasites avoid immune clearance through their ability to systematically alter antigens exposed on the surface of infected red blood cells. This is accomplished by tightly regulated transcriptional control of individual members of a large, multicopy gene family called var and is the key to both the virulence and chronic nature of malaria infections. Expression of var genes is mutually exclusive and controlled epigenetically, however how large populations of parasites coordinate var gene switching to avoid premature exposure of the antigenic repertoire is unknown. Here, we provide evidence for a transcriptional network anchored by a universally conserved gene called var2csa that coordinates the switching process. We describe a structured switching bias that shifts overtime and could shape the pattern of var expression over the course of a lengthy infection. Our results provide an explanation for a previously mysterious aspect of malaria infections and shed light on how parasites possessing a relatively small repertoire of variant antigen-encoding genes can coordinate switching events to limit antigen exposure, thereby maintaining chronic infections.
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Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Francesca Florini
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Joseph E Visone
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Irina Lionardi
- Jill Roberts Center for Inflammatory Bowel Disease, Weill Cornell Medical CollegeNew YorkUnited States
| | - Mackensie R Gross
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Valay Patel
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical CollegeNew YorkUnited States
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21
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Zhang X, Deitsch KW, Dzikowski R. CRISPR-Cas9 Editing of the Plasmodium falciparum Genome: Special Applications. Methods Mol Biol 2022; 2470:241-253. [PMID: 35881350 DOI: 10.1007/978-1-0716-2189-9_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The virulence of Plasmodium falciparum has been attributed in large part to the expression on the surface of infected red blood cells of the variant surface antigen Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Different forms of this protein are encoded by individual members of the multicopy gene family called var. Two attributes of the var gene family are key to the pathogenesis of malaria caused by P. falciparum; the hyperrecombinogenic nature of the var gene family that continuously generates antigenic diversity within parasite populations, and the ability of parasites to express only a single var gene at a time and to switch which gene is expressed over the course of an infection. The unique attributes of CRISPR-Cas9 have been applied to help decipher the molecular mechanisms underlying these unusual properties of the var gene family, both as a source of the DNA double strand breaks that initiate var gene recombination and as a way to recruit molecular probes to specific regions of the genome. In this chapter, we describe these somewhat unusual applications of the CRISPR-Cas9 system.
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Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY, USA
| | - Kirk William Deitsch
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY, USA
| | - Ron Dzikowski
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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22
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Dumaine JE, Sateriale A, Gibson AR, Reddy AG, Gullicksrud JA, Hunter EN, Clark JT, Striepen B. The enteric pathogen Cryptosporidium parvum exports proteins into the cytosol of the infected host cell. eLife 2021; 10:70451. [PMID: 34866573 PMCID: PMC8687662 DOI: 10.7554/elife.70451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022] Open
Abstract
The parasite Cryptosporidium is responsible for diarrheal disease in young children causing death, malnutrition, and growth delay. Cryptosporidium invades enterocytes where it develops in a unique intracellular niche. Infected cells exhibit profound changes in morphology, physiology, and transcriptional activity. How the parasite effects these changes is poorly understood. We explored the localization of highly polymorphic proteins and found members of the Cryptosporidium parvum MEDLE protein family to be translocated into the cytosol of infected cells. All intracellular life stages engage in this export, which occurs after completion of invasion. Mutational studies defined an N-terminal host-targeting motif and demonstrated proteolytic processing at a specific leucine residue. Direct expression of MEDLE2 in mammalian cells triggered an ER stress response, which was also observed during infection. Taken together, our studies reveal the presence of a Cryptosporidium secretion system capable of delivering parasite proteins into the infected enterocyte.
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Affiliation(s)
- Jennifer E Dumaine
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Adam Sateriale
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Alexis R Gibson
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Amita G Reddy
- Franklin College of Arts and Science, University of Georgia, Athens, United States
| | - Jodi A Gullicksrud
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Emma N Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Joseph T Clark
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, United States
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23
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021; 49:7571-7587. [PMID: 34165564 PMCID: PMC8287924 DOI: 10.1093/nar/gkab534] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/01/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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24
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021. [PMID: 34165564 DOI: 10.1101/2021.01.29.428817)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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25
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Gross MR, Hsu R, Deitsch KW. Evolution of transcriptional control of antigenic variation and virulence in human and ape malaria parasites. BMC Ecol Evol 2021; 21:139. [PMID: 34238209 PMCID: PMC8265125 DOI: 10.1186/s12862-021-01872-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/02/2021] [Indexed: 11/13/2022] Open
Abstract
Background The most severe form of human malaria is caused by the protozoan parasite Plasmodium falciparum. This unicellular organism is a member of a subgenus of Plasmodium called the Laverania that infects apes, with P. falciparum being the only member that infects humans. The exceptional virulence of this species to humans can be largely attributed to a family of variant surface antigens placed by the parasites onto the surface of infected red blood cells that mediate adherence to the vascular endothelium. These proteins are encoded by a large, multicopy gene family called var, with each var gene encoding a different form of the protein. By changing which var gene is expressed, parasites avoid immune recognition, a process called antigenic variation that underlies the chronic nature of malaria infections. Results Here we show that the common ancestor of the branch of the Laverania lineage that includes the human parasite underwent a remarkable change in the organization and structure of elements linked to the complex transcriptional regulation displayed by the var gene family. Unlike the other members of the Laverania, the clade that gave rise to P. falciparum evolved distinct subsets of var genes distinguishable by different upstream transcriptional regulatory regions that have been associated with different expression profiles and virulence properties. In addition, two uniquely conserved var genes that have been proposed to play a role in coordinating transcriptional switching similarly arose uniquely within this clade. We hypothesize that these changes originated at a time of dramatic climatic change on the African continent that is predicted to have led to significant changes in transmission dynamics, thus selecting for patterns of antigenic variation that enabled lengthier, more chronic infections. Conclusions These observations suggest that changes in transmission dynamics selected for significant alterations in the transcriptional regulatory mechanisms that mediate antigenic variation in the parasite lineage that includes P. falciparum. These changes likely underlie the chronic nature of these infections as well as their exceptional virulence. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01872-z.
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Affiliation(s)
- Mackensie R Gross
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Rosie Hsu
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
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26
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Li B. Keeping Balance Between Genetic Stability and Plasticity at the Telomere and Subtelomere of Trypanosoma brucei. Front Cell Dev Biol 2021; 9:699639. [PMID: 34291053 PMCID: PMC8287324 DOI: 10.3389/fcell.2021.699639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/08/2021] [Indexed: 12/13/2022] Open
Abstract
Telomeres, the nucleoprotein complexes at chromosome ends, are well-known for their essential roles in genome integrity and chromosome stability. Yet, telomeres and subtelomeres are frequently less stable than chromosome internal regions. Many subtelomeric genes are important for responding to environmental cues, and subtelomeric instability can facilitate organismal adaptation to extracellular changes, which is a common theme in a number of microbial pathogens. In this review, I will focus on the delicate and important balance between stability and plasticity at telomeres and subtelomeres of a kinetoplastid parasite, Trypanosoma brucei, which causes human African trypanosomiasis and undergoes antigenic variation to evade the host immune response. I will summarize the current understanding about T. brucei telomere protein complex, the telomeric transcript, and telomeric R-loops, focusing on their roles in maintaining telomere and subtelomere stability and integrity. The similarities and differences in functions and underlying mechanisms of T. brucei telomere factors will be compared with those in human and yeast cells.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, Cleveland, OH, United States.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.,Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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27
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Abstract
Infections caused by protozoans remain a public health issue, especially in tropical countries. Serious adverse events, lack of efficacy at the different stages of the infection and routes of administration that have a negative impact on treatment adherence are some of the problems with currently available therapy against these diseases. Here we describe an epigenetic target, sirtuin 2 and its related proteins, that is promising given the results in phenotypic assays and in vivo models against Sir2 of Plasmodium falciparum, Leishmania donovani, Leishmania infantum, Schistosoma mansoni, Trypanosoma brucei and Trypanosoma cruzi parasites. The results we present highlight how this target can be extensively explored and how its inhibitors might be employed in the clinic.
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28
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Tonkin-Hill G, Ruybal-Pesántez S, Tiedje KE, Rougeron V, Duffy MF, Zakeri S, Pumpaibool T, Harnyuttanakorn P, Branch OH, Ruiz-Mesía L, Rask TS, Prugnolle F, Papenfuss AT, Chan YB, Day KP. Evolutionary analyses of the major variant surface antigen-encoding genes reveal population structure of Plasmodium falciparum within and between continents. PLoS Genet 2021; 17:e1009269. [PMID: 33630855 PMCID: PMC7906310 DOI: 10.1371/journal.pgen.1009269] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 11/10/2020] [Indexed: 11/18/2022] Open
Abstract
Malaria remains a major public health problem in many countries. Unlike influenza and HIV, where diversity in immunodominant surface antigens is understood geographically to inform disease surveillance, relatively little is known about the global population structure of PfEMP1, the major variant surface antigen of the malaria parasite Plasmodium falciparum. The complexity of the var multigene family that encodes PfEMP1 and that diversifies by recombination, has so far precluded its use in malaria surveillance. Recent studies have demonstrated that cost-effective deep sequencing of the region of var genes encoding the PfEMP1 DBLα domain and subsequent classification of within host sequences at 96% identity to define unique DBLα types, can reveal structure and strain dynamics within countries. However, to date there has not been a comprehensive comparison of these DBLα types between countries. By leveraging a bioinformatic approach (jumping hidden Markov model) designed specifically for the analysis of recombination within var genes and applying it to a dataset of DBLα types from 10 countries, we are able to describe population structure of DBLα types at the global scale. The sensitivity of the approach allows for the comparison of the global dataset to ape samples of Plasmodium Laverania species. Our analyses show that the evolution of the parasite population emerging out of Africa underlies current patterns of DBLα type diversity. Most importantly, we can distinguish geographic population structure within Africa between Gabon and Ghana in West Africa and Uganda in East Africa. Our evolutionary findings have translational implications in the context of globalization. Firstly, DBLα type diversity can provide a simple diagnostic framework for geographic surveillance of the rapidly evolving transmission dynamics of P. falciparum. It can also inform efforts to understand the presence or absence of global, regional and local population immunity to major surface antigen variants. Additionally, we identify a number of highly conserved DBLα types that are present globally that may be of biological significance and warrant further characterization.
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Affiliation(s)
- Gerry Tonkin-Hill
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
- Bioinformatics Division, Walter and Eliza Hall Institute, Melbourne, Australia
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Shazia Ruybal-Pesántez
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Kathryn E. Tiedje
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, Australia
| | - Virginie Rougeron
- Laboratoire MIVEGEC, Université de Montpellier-CNRS-IRD, Montpellier, France
| | - Michael F. Duffy
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, Australia
| | - Sedigheh Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Tepanata Pumpaibool
- Biomedical Science, Graduate School, Chulalongkorn University, Bangkok, Thailand
- Malaria Research Programme, College of Public Health Science, Chulalongkorn University, Bangkok, Thailand
| | - Pongchai Harnyuttanakorn
- Malaria Research Programme, College of Public Health Science, Chulalongkorn University, Bangkok, Thailand
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - OraLee H. Branch
- Concordia University, Portland, Oregon, United States of America
- Universidad Nacional de la Amazonía Peruana, Iquitos, Perú
| | | | - Thomas S. Rask
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Franck Prugnolle
- Laboratoire MIVEGEC, Université de Montpellier-CNRS-IRD, Montpellier, France
| | - Anthony T. Papenfuss
- Bioinformatics Division, Walter and Eliza Hall Institute, Melbourne, Australia
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
- Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Australia
| | - Yao-ban Chan
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
- Melbourne Integrative Genomics, The University of Melbourne, Melbourne, Australia
| | - Karen P. Day
- School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, Australia
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, Australia
- * E-mail:
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29
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Reed J, Kirkman LA, Kafsack BF, Mason CE, Deitsch KW. Telomere length dynamics in response to DNA damage in malaria parasites. iScience 2021; 24:102082. [PMID: 33644714 PMCID: PMC7887396 DOI: 10.1016/j.isci.2021.102082] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/03/2020] [Accepted: 01/14/2021] [Indexed: 10/26/2022] Open
Abstract
Malaria remains a major cause of morbidity and mortality in the developing world. Recent work has implicated chromosome end stability and the repair of DNA breaks through telomere healing as potent drivers of variant antigen diversification, thus associating basic mechanisms for maintaining genome integrity with aspects of host-parasite interactions. Here we applied long-read sequencing technology to precisely examine the dynamics of telomere addition and chromosome end stabilization in response to double-strand breaks within subtelomeric regions. We observed that the process of telomere healing induces the initial synthesis of telomere repeats well in excess of the minimal number required for end stability. However, once stabilized, these newly created telomeres appear to function normally, eventually returning to a length nearing that of intact chromosome ends. These results parallel recent observations in humans, suggesting an evolutionarily conserved mechanism for chromosome end repair.
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Affiliation(s)
- Jake Reed
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Laura A Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.,Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, USA
| | - Björn F Kafsack
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Christopher E Mason
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA.,Jill Roberts Center for Inflammatory Bowel Disease, Weill Cornell Medical College, New York, NY, USA.,HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY, USA.,WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
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30
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Zhang X, Deitsch KW, Kirkman LA. The contribution of extrachromosomal DNA to genome plasticity in malaria parasites. Mol Microbiol 2020; 115:503-507. [PMID: 33103309 DOI: 10.1111/mmi.14632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/19/2020] [Accepted: 10/19/2020] [Indexed: 01/20/2023]
Abstract
Malaria caused by the protozoan parasite Plasmodium falciparum continues to impose significant morbidity and mortality, despite substantial investment into drug and vaccine development and deployment. Underlying the resilience of this parasite is its remarkable ability to undergo genome modifications, thus, providing parasite populations with extensive genetic variability that accelerates selection of drug resistance and limits the efficacy of most vaccines. This genome plasticity is rooted in the mechanisms of DNA repair that parasites employ to maintain genome integrity, a process skewed toward homologous recombination through the evolutionary loss of classical nonhomologous end joining. Repair of DNA double-strand breaks have been shown to enable "shuffling" of antigen-encoding gene sequences to vastly increase antigen diversity and to enable copy number expansion of genes that contribute to drug resistance. The latter phenomenon has been proposed to be a major contributor to the rise of resistance to several classes of antimalarial drugs. In this issue of Molecular Microbiology, McDaniels and colleagues add yet another mechanism that malaria parasites use to reduce drug susceptibility by demonstrating that P. falciparum can maintain expanded arrays of drug resistance cassettes as stably replicating, circular, extrachromosomal DNAs, thus, expanding genome plasticity beyond the parasite's 14 nuclear chromosomes.
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Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Laura A Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.,Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, USA
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Su XZ, Zhang C, Joy DA. Host-Malaria Parasite Interactions and Impacts on Mutual Evolution. Front Cell Infect Microbiol 2020; 10:587933. [PMID: 33194831 PMCID: PMC7652737 DOI: 10.3389/fcimb.2020.587933] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 09/22/2020] [Indexed: 12/22/2022] Open
Abstract
Malaria is the most deadly parasitic disease, affecting hundreds of millions of people worldwide. Malaria parasites have been associated with their hosts for millions of years. During the long history of host-parasite co-evolution, both parasites and hosts have applied pressure on each other through complex host-parasite molecular interactions. Whereas the hosts activate various immune mechanisms to remove parasites during an infection, the parasites attempt to evade host immunity by diversifying their genome and switching expression of targets of the host immune system. Human intervention to control the disease such as antimalarial drugs and vaccination can greatly alter parasite population dynamics and evolution, particularly the massive applications of antimalarial drugs in recent human history. Vaccination is likely the best method to prevent the disease; however, a partially protective vaccine may have unwanted consequences that require further investigation. Studies of host-parasite interactions and co-evolution will provide important information for designing safe and effective vaccines and for preventing drug resistance. In this essay, we will discuss some interesting molecules involved in host-parasite interactions, including important parasite antigens. We also discuss subjects relevant to drug and vaccine development and some approaches for studying host-parasite interactions.
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Affiliation(s)
- Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Cui Zhang
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Deirdre A Joy
- Parasitology and International Programs Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
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Oyedeji SI, Bassi PU, Oyedeji SA, Ojurongbe O, Awobode HO. Genetic diversity and complexity of Plasmodium falciparum infections in the microenvironment among siblings of the same household in North-Central Nigeria. Malar J 2020; 19:338. [PMID: 32938438 PMCID: PMC7493857 DOI: 10.1186/s12936-020-03415-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/10/2020] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium falciparum parasites are known to exhibit extensive genetic diversity in areas of high transmission intensity and infected individuals in such communities often harbour several complex mixtures of parasite clones with different genetic characteristics. However, in the micro-environment, the extent of genetic diversity of P. falciparum parasites remain largely unknown. In this study therefore, the complexity of P. falciparum infections in households was investigated among symptomatic siblings, living under the same roof in north-central Nigeria. Methods Children were enrolled into the study if they were at least two from a household and presented with symptoms of uncomplicated malaria. Clinical malaria was confirmed by light microscopy of Giemsa-stained thick and thin blood films. Genomic DNA was isolated from blood spots on filter paper. Molecular characterization of P. falciparum isolates was done by allele-specific nested PCR of the highly polymorphic merozoite surface protein-2 (msp-2) gene. Results Ninety-three children from 43 households were enrolled into this study. A total of 26 different msp-2 alleles were identified from 215 fragments (range: 180–480 bp). Majority of the isolates [65.6% (n = 61)] were polyclonal infections consisting of 2–6 clones and were significantly more common with the FC27 allelic family (p = 0.036). The multiplicity of infection (MOI) per household ranged from 1.0 to 4.5 while the overall MOI in the study population was 2.31. The pattern of distribution of msp-2 allele types among the households fell into two categories: households where both msp-2 allele types (FC27 and 3D7) were present; households where only one msp-2 allele type (FC27 or 3D7) was present. Majority of the households [88.4% (n = 38)], had both msp-2 allele types but they were disproportionately distributed among the children while in a few households [11.6% (n = 5)], all the children were infected with only one type of msp-2 allele. Conclusion These findings showed that P. falciparum isolates exhibit remarkable degree of genetic diversity in the micro-environment and are composed mainly of multiclonal infections, which is an indication of a high ongoing parasite transmission. This suggests that the micro-environment is an important area of focus for malaria control interventions and for evaluating intervention programmes.
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Affiliation(s)
- Segun Isaac Oyedeji
- Molecular Genetics and Parasitology Unit, Department of Animal & Environmental Biology, Federal University Oye-Ekiti, Oye-Ekiti, Nigeria.
| | - Peter Usman Bassi
- Department of Pharmacology and Therapeutics, University of Abuja, Abuja, Nigeria
| | | | - Olusola Ojurongbe
- Department of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Osogbo, Nigeria
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Mack EA, Tagliamonte MS, Xiao YP, Quesada S, Allred DR. Babesia bovis Rad51 ortholog influences switching of ves genes but is not essential for segmental gene conversion in antigenic variation. PLoS Pathog 2020; 16:e1008772. [PMID: 32866214 PMCID: PMC7485966 DOI: 10.1371/journal.ppat.1008772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/11/2020] [Accepted: 08/13/2020] [Indexed: 01/04/2023] Open
Abstract
The tick-borne apicomplexan parasite, Babesia bovis, a highly persistent bovine pathogen, expresses VESA1 proteins on the infected erythrocyte surface to mediate cytoadhesion. The cytoadhesion ligand, VESA1, which protects the parasite from splenic passage, is itself protected from a host immune response by rapid antigenic variation. B. bovis relies upon segmental gene conversion (SGC) as a major mechanism to vary VESA1 structure. Gene conversion has been considered a form of homologous recombination (HR), a process for which Rad51 proteins are considered pivotal components. This could make BbRad51 a choice target for development of inhibitors that both interfere with parasite genome integrity and disrupt HR-dependent antigenic variation. Previously, we knocked out the Bbrad51 gene from the B. bovis haploid genome, resulting in a phenotype of sensitivity to methylmethane sulfonate (MMS) and apparent loss of HR-dependent integration of exogenous DNA. In a further characterization of BbRad51, we demonstrate here that ΔBbrad51 parasites are not more sensitive than wild-type to DNA damage induced by γ-irradiation, and repair their genome with similar kinetics. To assess the need for BbRad51 in SGC, RT-PCR was used to observe alterations to a highly variant region of ves1α transcripts over time. Mapping of these amplicons to the genome revealed a significant reduction of in situ transcriptional switching (isTS) among ves loci, but not cessation. By combining existing pipelines for analysis of the amplicons, we demonstrate that SGC continues unabated in ΔBbrad51 parasites, albeit at an overall reduced rate, and a reduction in SGC tract lengths was observed. By contrast, no differences were observed in the lengths of homologous sequences at which recombination occurred. These results indicate that, whereas BbRad51 is not essential to babesial antigenic variation, it influences epigenetic control of ves loci, and its absence significantly reduces successful variation. These results necessitate a reconsideration of the likely enzymatic mechanism(s) underlying SGC and suggest the existence of additional targets for development of small molecule inhibitors. B. bovis establishes highly persistent infections in cattle, in part by using cytoadhesion to avoid passage through the spleen. While protective, a host antibody response targeting the cytoadhesion ligand is quickly rendered ineffective by antigenic variation. In B. bovis, antigenic variation relies heavily upon segmental gene conversion (SGC), presumed to be a form of homologous recombination (HR), to generate variants. As Rad51 is generally considered essential to HR, we investigated its contribution to SGC. While diminishing the parasite’s capacity for HR-dependent integration of exogenous DNA, the loss of BbRad51 did not affect the parasite’s sensitivity to ionizing radiation, overall genome stability, or competence for SGC. Instead, loss of BbRad51 diminished the extent of in situ transcriptional switching (isTS) among ves gene loci, the accumulation of SGC recombinants, and the mean lengths of SGC sequence tracts. Given the overall reductions in VESA1 variability, compromise of the parasite’s capacity for in vivo persistence is predicted.
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Affiliation(s)
- Erin A. Mack
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - Massimiliano S. Tagliamonte
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Yu-Ping Xiao
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - Samantha Quesada
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Genetics Institute, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Kirkman LA, Deitsch KW. Vive la Différence: Exploiting the Differences between Rodent and Human Malarias. Trends Parasitol 2020; 36:504-511. [PMID: 32407681 DOI: 10.1016/j.pt.2020.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/23/2020] [Accepted: 03/23/2020] [Indexed: 12/14/2022]
Abstract
Experimental research into malaria biology and pathogenesis has historically focused on two model systems, in vitro culture of the human parasite Plasmodium falciparum and in vivo infections of laboratory animals using rodent parasites. While there is clear value in having a manipulatable animal model for studying malaria, there have occasionally been controversies around how representative the rodent model is of the human disease, and therefore significant emphasis has been placed on the similarities between the two biological systems. By focusing on basic nuclear functions, we wish to highlight that identifying key differences in the parasites and their interactions with their mammalian hosts can be equally informative and provide remarkable insights into the biology and evolution of these important infectious organisms.
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Affiliation(s)
- Laura A Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA; Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
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Evolution of Host Specificity by Malaria Parasites through Altered Mechanisms Controlling Genome Maintenance. mBio 2020; 11:mBio.03272-19. [PMID: 32184256 PMCID: PMC7078485 DOI: 10.1128/mbio.03272-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Malaria remains one of the most prevalent and deadly infectious diseases of the developing world, causing approximately 228 million clinical cases and nearly half a million deaths annually. The disease is caused by protozoan parasites of the genus Plasmodium, and of the five species capable of infecting humans, infections with P. falciparum are the most severe. In addition to the parasites that infect people, there are hundreds of additional species that infect birds, reptiles, and other mammals, each exquisitely evolved to meet the specific challenges inherent to survival within their respective hosts. By comparing the unique strategies that each species has evolved, key insights into host-parasite interactions can be gained, including discoveries regarding the pathogenesis of human disease. Here, we describe the surprising observation that closely related parasites with different hosts have evolved remarkably different methods for repairing their genomes. This observation has important implications for the ability of parasites to maintain chronic infections and for the development of host immunity. The protozoan parasites that cause malaria infect a wide variety of vertebrate hosts, including birds, reptiles, and mammals, and the evolutionary pressures inherent to the host-parasite relationship have profoundly shaped the genomes of both host and parasite. Here, we report that these selective pressures have resulted in unexpected alterations to one of the most basic aspects of eukaryotic biology, the maintenance of genome integrity through DNA repair. Malaria parasites that infect humans continuously generate genetic diversity within their antigen-encoding gene families through frequent ectopic recombination between gene family members, a process that is a crucial feature of the persistence of malaria globally. The continuous generation of antigen diversity ensures that different parasite isolates are antigenically distinct, thus preventing extensive cross-reactive immunity and enabling parasites to maintain stable transmission within human populations. However, the molecular basis of the recombination between gene family members is not well understood. Through computational analyses of the antigen-encoding, multicopy gene families of different Plasmodium species, we report the unexpected observation that malaria parasites that infect rodents do not display the same degree of antigen diversity as observed in Plasmodium falciparum and appear to undergo significantly less ectopic recombination. Using comparative genomics, we also identify key molecular components of the diversification process, thus shedding new light on how malaria parasites balance the maintenance of genome integrity with the requirement for continuous genetic diversification.
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Otto TD, Assefa SA, Böhme U, Sanders MJ, Kwiatkowski D, Berriman M, Newbold C. Evolutionary analysis of the most polymorphic gene family in falciparum malaria. Wellcome Open Res 2019; 4:193. [PMID: 32055709 PMCID: PMC7001760 DOI: 10.12688/wellcomeopenres.15590.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/22/2022] Open
Abstract
The var gene family of the human malaria parasite Plasmodium falciparum encode proteins that are crucial determinants of both pathogenesis and immune evasion and are highly polymorphic. Here we have assembled nearly complete var gene repertoires from 2398 field isolates and analysed a normalised set of 714 from across 12 countries. This therefore represents the first large scale attempt to catalogue the worldwide distribution of var gene sequences We confirm the extreme polymorphism of this gene family but also demonstrate an unexpected level of sequence sharing both within and between continents. We show that this is likely due to both the remnants of selective sweeps as well as a worrying degree of recent gene flow across continents with implications for the spread of drug resistance. We also address the evolution of the var repertoire with respect to the ancestral genes within the Laverania and show that diversity generated by recombination is concentrated in a number of hotspots. An analysis of the subdomain structure indicates that some existing definitions may need to be revised From the analysis of this data, we can now understand the way in which the family has evolved and how the diversity is continuously being generated. Finally, we demonstrate that because the genes are distributed across the genome, sequence sharing between genotypes acts as a useful population genetic marker.
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Affiliation(s)
- Thomas D. Otto
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
- Institute of Infection, Immunity & Inflammation, MVLS, University of Glasgow, Glasgow, UK
| | - Sammy A. Assefa
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Ulrike Böhme
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
| | | | - Dominic Kwiatkowski
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
- The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Pf3k consortium
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
- Institute of Infection, Immunity & Inflammation, MVLS, University of Glasgow, Glasgow, UK
- The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Matt Berriman
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Chris Newbold
- Parasite Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
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Arnot DE. Tying up Loose Ends in the Malaria Antigenic Variation Story. Trends Parasitol 2019; 35:588-590. [PMID: 31266710 DOI: 10.1016/j.pt.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 06/14/2019] [Indexed: 10/26/2022]
Abstract
A recent paper (Zhang et al., PLoS Biol., 2019) shines remarkable new light onto the malaria antigenic variation story. Using CRISPR/Cas9-targeted chromosome breaks and long-read whole-genome sequencing, they followed the fate of detached subtelomeric PfEMP1/var genes and demonstrated that these initiate cascades of recombination at sites far from the original break.
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Affiliation(s)
- David E Arnot
- Zhejiang University-University of Edinburgh (ZJE) Institute and Second Affiliated Hospital, Zhejiang University School of Medicine, China.
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