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Guo B, Takala-Harrison S, O’Connor TD. Benchmarking and Optimization of Methods for the Detection of Identity-By-Descent in High-Recombining Plasmodium falciparum Genomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.04.592538. [PMID: 38746392 PMCID: PMC11092787 DOI: 10.1101/2024.05.04.592538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Genomic surveillance is crucial for identifying at-risk populations for targeted malaria control and elimination. Identity-by-descent (IBD) is increasingly being used in Plasmodium population genomics to estimate genetic relatedness, effective population size (N e ), population structure, and signals of positive selection. Despite its potential, a thorough evaluation of IBD segment detection tools for species with high recombination rates, such as P. falciparum, remains absent. Here, we perform comprehensive benchmarking of IBD callers - probabilistic (hmmIBD, isoRelate), identity-by-state-based (hap-IBD, phased IBD) and others (Refined IBD) - using population genetic simulations tailored for high recombination, and IBD quality metrics at both the IBD segment level and the IBD-based downstream inference level. Our results demonstrate that low marker density per genetic unit, related to high recombination relative to mutation, significantly compromises the accuracy of detected IBD segments. In genomes with high recombination rates resembling P. falciparum, most IBD callers exhibit high false negative rates for shorter IBD segments, which can be partially mitigated through optimization of IBD caller parameters, especially those related to marker density. Notably, IBD detected with optimized parameters allows for more accurate capture of selection signals and population structure; IBD-based N e inference is very sensitive to IBD detection errors, with IBD called from hmmIBD uniquely providing less biased estimates of N e in this context. Validation with empirical data from the MalariaGEN Pf 7 database, representing different transmission settings, corroborates these findings. We conclude that context-specific evaluation and parameter optimization are essential for accurate IBD detection in high-recombining species and recommend hmmIBD for quality-sensitive analysis, such as estimation of N e in these species. Our optimization and high-level benchmarking methods not only improve IBD segment detection in high-recombining genomes but also enhance overall genomic analysis, paving the way for more accurate genomic surveillance and targeted intervention strategies for malaria.
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Affiliation(s)
- Bing Guo
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shannon Takala-Harrison
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD USA
| | - Timothy D. O’Connor
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
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2
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Schäfer TM, Pessanha de Carvalho L, Inoue J, Kreidenweiss A, Held J. The problem of antimalarial resistance and its implications for drug discovery. Expert Opin Drug Discov 2024; 19:209-224. [PMID: 38108082 DOI: 10.1080/17460441.2023.2284820] [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: 07/28/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
INTRODUCTION Malaria remains a devastating infectious disease with hundreds of thousands of casualties each year. Antimalarial drug resistance has been a threat to malaria control and elimination for many decades and is still of concern today. Despite the continued effectiveness of current first-line treatments, namely artemisinin-based combination therapies, the emergence of drug-resistant parasites in Southeast Asia and even more alarmingly the occurrence of resistance mutations in Africa is of great concern and requires immediate attention. AREAS COVERED A comprehensive overview of the mechanisms underlying the acquisition of drug resistance in Plasmodium falciparum is given. Understanding these processes provides valuable insights that can be harnessed for the development and selection of novel antimalarials with reduced resistance potential. Additionally, strategies to mitigate resistance to antimalarial compounds on the short term by using approved drugs are discussed. EXPERT OPINION While employing strategies that utilize already approved drugs may offer a prompt and cost-effective approach to counter antimalarial drug resistance, it is crucial to recognize that only continuous efforts into the development of novel antimalarial drugs can ensure the successful treatment of malaria in the future. Incorporating resistance propensity assessment during this developmental process will increase the likelihood of effective and enduring malaria treatments.
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Affiliation(s)
| | | | - Juliana Inoue
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Andrea Kreidenweiss
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), Tübingen, Germany
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), Tübingen, Germany
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3
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Amambua-Ngwa A, Button-Simons KA, Li X, Kumar S, Brenneman KV, Ferrari M, Checkley LA, Haile MT, Shoue DA, McDew-White M, Tindall SM, Reyes A, Delgado E, Dalhoff H, Larbalestier JK, Amato R, Pearson RD, Taylor AB, Nosten FH, D'Alessandro U, Kwiatkowski D, Cheeseman IH, Kappe SHI, Avery SV, Conway DJ, Vaughan AM, Ferdig MT, Anderson TJC. Chloroquine resistance evolution in Plasmodium falciparum is mediated by the putative amino acid transporter AAT1. Nat Microbiol 2023; 8:1213-1226. [PMID: 37169919 PMCID: PMC10322710 DOI: 10.1038/s41564-023-01377-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 03/29/2023] [Indexed: 05/13/2023]
Abstract
Malaria parasites break down host haemoglobin into peptides and amino acids in the digestive vacuole for export to the parasite cytoplasm for growth: interrupting this process is central to the mode of action of several antimalarial drugs. Mutations in the chloroquine (CQ) resistance transporter, pfcrt, located in the digestive vacuole membrane, confer CQ resistance in Plasmodium falciparum, and typically also affect parasite fitness. However, the role of other parasite loci in the evolution of CQ resistance is unclear. Here we use a combination of population genomics, genetic crosses and gene editing to demonstrate that a second vacuolar transporter plays a key role in both resistance and compensatory evolution. Longitudinal genomic analyses of the Gambian parasites revealed temporal signatures of selection on a putative amino acid transporter (pfaat1) variant S258L, which increased from 0% to 97% in frequency between 1984 and 2014 in parallel with the pfcrt1 K76T variant. Parasite genetic crosses then identified a chromosome 6 quantitative trait locus containing pfaat1 that is selected by CQ treatment. Gene editing demonstrated that pfaat1 S258L potentiates CQ resistance but at a cost of reduced fitness, while pfaat1 F313S, a common southeast Asian polymorphism, reduces CQ resistance while restoring fitness. Our analyses reveal hidden complexity in CQ resistance evolution, suggesting that pfaat1 may underlie regional differences in the dynamics of resistance evolution, and modulate parasite resistance or fitness by manipulating the balance between both amino acid and drug transport.
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Affiliation(s)
- Alfred Amambua-Ngwa
- MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Katrina A Button-Simons
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Xue Li
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Katelyn Vendrely Brenneman
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Marco Ferrari
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Lisa A Checkley
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Meseret T Haile
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Douglas A Shoue
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Marina McDew-White
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Sarah M Tindall
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Ann Reyes
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Elizabeth Delgado
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Haley Dalhoff
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - James K Larbalestier
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | | | | | - Alexander B Taylor
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, Antonio, TX, USA
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Umberto D'Alessandro
- MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | | | - Ian H Cheeseman
- Host Pathogen Interactions Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Stefan H I Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Department of Global Health, University of Washington, Seattle, WA, USA
| | - Simon V Avery
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - David J Conway
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Ashley M Vaughan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
| | - Michael T Ferdig
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
| | - Timothy J C Anderson
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA.
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Kümpornsin K, Kochakarn T, Yeo T, Okombo J, Luth MR, Hoshizaki J, Rawat M, Pearson RD, Schindler KA, Mok S, Park H, Uhlemann AC, Jana GP, Maity BC, Laleu B, Chenu E, Duffy J, Moliner Cubel S, Franco V, Gomez-Lorenzo MG, Gamo FJ, Winzeler EA, Fidock DA, Chookajorn T, Lee MCS. Generation of a mutator parasite to drive resistome discovery in Plasmodium falciparum. Nat Commun 2023; 14:3059. [PMID: 37244916 DOI: 10.1038/s41467-023-38774-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 05/12/2023] [Indexed: 05/29/2023] Open
Abstract
In vitro evolution of drug resistance is a powerful approach for identifying antimalarial targets, however, key obstacles to eliciting resistance are the parasite inoculum size and mutation rate. Here we sought to increase parasite genetic diversity to potentiate resistance selections by editing catalytic residues of Plasmodium falciparum DNA polymerase δ. Mutation accumulation assays reveal a ~5-8 fold elevation in the mutation rate, with an increase of 13-28 fold in drug-pressured lines. Upon challenge with the spiroindolone PfATP4-inhibitor KAE609, high-level resistance is obtained more rapidly and at lower inocula than wild-type parasites. Selections also yield mutants with resistance to an "irresistible" compound, MMV665794 that failed to yield resistance with other strains. We validate mutations in a previously uncharacterised gene, PF3D7_1359900, which we term quinoxaline resistance protein (QRP1), as causal for resistance to MMV665794 and a panel of quinoxaline analogues. The increased genetic repertoire available to this "mutator" parasite can be leveraged to drive P. falciparum resistome discovery.
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Affiliation(s)
- Krittikorn Kümpornsin
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
- Calibr, Division of the Scripps Research Institute, La Jolla, CA, USA
| | - Theerarat Kochakarn
- The Laboratory for Molecular Infection Medicine Sweden and Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Tomas Yeo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - John Okombo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Madeline R Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | | | - Mukul Rawat
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
| | | | - Kyra A Schindler
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Sachel Mok
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Heekuk Park
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Anne-Catrin Uhlemann
- Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Gouranga P Jana
- TCG Lifesciences Private Limited, Salt-lake Electronics Complex, Kolkata, India
| | - Bikash C Maity
- TCG Lifesciences Private Limited, Salt-lake Electronics Complex, Kolkata, India
| | - Benoît Laleu
- Medicines for Malaria Venture, International Centre Cointrin, Geneva, Switzerland
| | - Elodie Chenu
- Medicines for Malaria Venture, International Centre Cointrin, Geneva, Switzerland
| | - James Duffy
- Medicines for Malaria Venture, International Centre Cointrin, Geneva, Switzerland
| | | | - Virginia Franco
- Global Health Medicines R&D, GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | | | | | - Elizabeth A Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Thanat Chookajorn
- The Laboratory for Molecular Infection Medicine Sweden and Department of Molecular Biology, Umeå University, Umeå, Sweden
- Genomics and Evolutionary Medicine Unit, Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Marcus C S Lee
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.
- Biological Chemistry and Drug Discovery, Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee, UK.
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5
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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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6
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Ebel ER, Kim BY, McDew-White M, Egan ES, Anderson TJC, Petrov DA. Antigenic diversity in malaria parasites is maintained on extrachromosomal DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526885. [PMID: 36778235 PMCID: PMC9915586 DOI: 10.1101/2023.02.02.526885] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sequence variation among antigenic var genes enables Plasmodium falciparum malaria parasites to evade host immunity. Using long sequence reads from haploid clones from a mutation accumulation experiment, we detect var diversity inconsistent with simple chromosomal inheritance. We discover putatively circular DNA that is strongly enriched for var genes, which exist in multiple alleles per locus separated by recombination and indel events. Extrachromosomal DNA likely contributes to rapid antigenic diversification in P. falciparum.
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Affiliation(s)
- Emily R Ebel
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Pediatrics, School of Medicine, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Bernard Y Kim
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Marina McDew-White
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
- Present address: Host Pathogen Interaction Program, Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Elizabeth S Egan
- Department of Pediatrics, School of Medicine, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Timothy J C Anderson
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Dmitri A Petrov
- Department of Biology, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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7
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Gill SE, Chain FJJ. Very Low Rates of Spontaneous Gene Deletions and Gene Duplications in Dictyostelium discoideum. J Mol Evol 2023; 91:24-32. [PMID: 36484794 PMCID: PMC9849192 DOI: 10.1007/s00239-022-10081-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022]
Abstract
The study of spontaneous mutation rates has revealed a wide range of heritable point mutation rates across species, but there are comparatively few estimates for large-scale deletion and duplication rates. The handful of studies that have directly calculated spontaneous rates of deletion and duplication using mutation accumulation lines have estimated that genes are duplicated and deleted at orders of magnitude greater rates than the spontaneous point mutation rate. In our study, we tested whether spontaneous gene deletion and gene duplication rates are also high in Dictyostelium discoideum, a eukaryote with among the lowest point mutation rates (2.5 × 10-11 per site per generation) and an AT-rich genome (GC content of 22%). We calculated mutation rates of gene deletions and duplications using whole-genome sequencing data originating from a mutation accumulation experiment and determined the association between the copy number mutations and GC content. Overall, we estimated an average of 3.93 × 10-8 gene deletions and 1.18 × 10-8 gene duplications per gene per generation. While orders of magnitude greater than their point mutation rate, these rates are much lower compared to gene deletion and duplication rates estimated from mutation accumulation lines in other organisms (that are on the order of ~ 10-6 per gene/generation). The deletions and duplications were enriched in regions that were AT-rich even compared to the genomic background, in contrast to our expectations if low GC content was contributing to low mutation rates. The low deletion and duplication mutation rates in D. discoideum compared to other eukaryotes mirror their low point mutation rates, supporting previous work suggesting that this organism has high replication fidelity and effective molecular machinery to avoid the accumulation of mutations in their genome.
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Affiliation(s)
- Shelbi E Gill
- Department of Biology, University of Massachusetts Lowell, Lowell, MA, 01854-2874, USA.
| | - Frédéric J J Chain
- Department of Biology, University of Massachusetts Lowell, Lowell, MA, 01854-2874, USA.
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8
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Abstract
Malaria symptoms are caused by the development of the parasites within the blood of an infected host. Bulk RNA sequencing (RNA-seq) of infected blood can reveal interactions between parasites and the host immune system during an infection, but because multiple developmental stages with distinct transcriptional profiles are concurrently present in infected blood, it is necessary to correct such analyses for differences in cell composition among samples. Gene expression deconvolution is a statistical approach that has been developed for inferring the cell composition of complex tissues characterized by bulk RNA-seq using gene expression profiles from reference cell types. Here, we describe the evaluation of a species-agnostic reference data set that can be used for efficient and accurate gene expression deconvolution of bulk RNA-seq data generated from any Plasmodium species and for correct gene expression analyses for biases caused by differences in stage composition among samples. IMPORTANCE Differences in cell type proportions among samples can introduce artifacts in gene expression analyses and mask genuine differences in gene regulation. Gene expression deconvolution allows estimation of the proportion of each cell type present in one sample directly from bulk RNA sequencing data, but this approach requires a reference data set with the signature profile of each cell type. Here, we evaluate the suitability of a rodent malaria parasite gene expression data set for estimating the proportions of each parasite developmental stage present in bulk RNA sequencing data generated from blood-stage infections with the human parasites Plasmodium falciparum and Plasmodium vivax. These analyses provide a species-agnostic approach for reliably estimating stage proportions in infected human blood and correcting subsequent gene expression analyses for these variations.
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9
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Kumar S, Li X, McDew-White M, Reyes A, Delgado E, Sayeed A, Haile MT, Abatiyow BA, Kennedy SY, Camargo N, Checkley LA, Brenneman KV, Button-Simons KA, Duraisingh MT, Cheeseman IH, Kappe SHI, Nosten F, Ferdig MT, Vaughan AM, Anderson TJC. A Malaria Parasite Cross Reveals Genetic Determinants of Plasmodium falciparum Growth in Different Culture Media. Front Cell Infect Microbiol 2022; 12:878496. [PMID: 35711667 PMCID: PMC9197316 DOI: 10.3389/fcimb.2022.878496] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/28/2022] [Indexed: 12/21/2022] Open
Abstract
What genes determine in vitro growth and nutrient utilization in asexual blood-stage malaria parasites? Competition experiments between NF54, clone 3D7, a lab-adapted African parasite, and a recently isolated Asian parasite (NHP4026) reveal contrasting outcomes in different media: 3D7 outcompetes NHP4026 in media containing human serum, while NHP4026 outcompetes 3D7 in media containing AlbuMAX, a commercial lipid-rich bovine serum formulation. To determine the basis for this polymorphism, we conducted parasite genetic crosses using humanized mice and compared genome-wide allele frequency changes in three independent progeny populations cultured in media containing human serum or AlbuMAX. This bulk segregant analysis detected three quantitative trait loci (QTL) regions [on chromosome (chr) 2 containing aspartate transaminase AST; chr 13 containing EBA-140; and chr 14 containing cysteine protease ATG4] linked with differential growth in serum or AlbuMAX in each of the three independent progeny pools. Selection driving differential growth was strong (s = 0.10 – 0.23 per 48-hour lifecycle). We conducted validation experiments for the strongest QTL on chr 13: competition experiments between ΔEBA-140 and 3D7 wildtype parasites showed fitness reversals in the two medium types as seen in the parental parasites, validating this locus as the causative gene. These results (i) demonstrate the effectiveness of bulk segregant analysis for dissecting fitness traits in P. falciparum genetic crosses, and (ii) reveal intimate links between red blood cell invasion and nutrient composition of growth media. Use of parasite crosses combined with bulk segregant analysis will allow systematic dissection of key nutrient acquisition/metabolism and red blood cell invasion pathways in P. falciparum.
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Affiliation(s)
- Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Xue Li
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Marina McDew-White
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Ann Reyes
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Elizabeth Delgado
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Abeer Sayeed
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Meseret T. Haile
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Biley A. Abatiyow
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Spencer Y. Kennedy
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Nelly Camargo
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Lisa A. Checkley
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Katelyn V. Brenneman
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Katrina A. Button-Simons
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Manoj T. Duraisingh
- Immunology and Infectious Diseases Department, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Ian H. Cheeseman
- Program in Host Pathogen Interactions, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Stefan H. I. Kappe
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research building, University of Oxford, Oxford, United Kingdom
| | - Michael T. Ferdig
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Ashley M. Vaughan
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
- *Correspondence: Ashley M. Vaughan, ; Tim J. C. Anderson,
| | - Tim J. C. Anderson
- Program in Disease Intervention and Prevention, Texas Biomedical Research Institute, San Antonio, TX, United States
- *Correspondence: Ashley M. Vaughan, ; Tim J. C. Anderson,
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10
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Han J, Munro JE, Kocoski A, Barry AE, Bahlo M. Population-level genome-wide STR discovery and validation for population structure and genetic diversity assessment of Plasmodium species. PLoS Genet 2022; 18:e1009604. [PMID: 35007277 PMCID: PMC8782505 DOI: 10.1371/journal.pgen.1009604] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 01/21/2022] [Accepted: 12/14/2021] [Indexed: 11/18/2022] Open
Abstract
Short tandem repeats (STRs) are highly informative genetic markers that have been used extensively in population genetics analysis. They are an important source of genetic diversity and can also have functional impact. Despite the availability of bioinformatic methods that permit large-scale genome-wide genotyping of STRs from whole genome sequencing data, they have not previously been applied to sequencing data from large collections of malaria parasite field samples. Here, we have genotyped STRs using HipSTR in more than 3,000 Plasmodium falciparum and 174 Plasmodium vivax published whole-genome sequence data from samples collected across the globe. High levels of noise and variability in the resultant callset necessitated the development of a novel method for quality control of STR genotype calls. A set of high-quality STR loci (6,768 from P. falciparum and 3,496 from P. vivax) were used to study Plasmodium genetic diversity, population structures and genomic signatures of selection and these were compared to genome-wide single nucleotide polymorphism (SNP) genotyping data. In addition, the genome-wide information about genetic variation and other characteristics of STRs in P. falciparum and P. vivax have been available in an interactive web-based R Shiny application PlasmoSTR (https://github.com/bahlolab/PlasmoSTR).
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Affiliation(s)
- Jiru Han
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Jacob E. Munro
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Anthony Kocoski
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
| | - Alyssa E. Barry
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
- Disease Elimination Program, Burnet Institute, Melbourne, Australia
- IMPACT Institute for Innovation in Mental and Physical Health and Clinical Translation, Deakin University, Geelong, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
- * E-mail:
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11
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Comparative Analysis of Plasmodium falciparum Genotyping via SNP Detection, Microsatellite Profiling, and Whole-Genome Sequencing. Antimicrob Agents Chemother 2021; 66:e0116321. [PMID: 34694871 PMCID: PMC8765236 DOI: 10.1128/aac.01163-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Research efforts to combat antimalarial drug resistance rely on quick, robust, and sensitive methods to genetically characterize Plasmodium falciparum parasites. We developed a single-nucleotide polymorphism (SNP)-based genotyping method that can assess 33 drug resistance-conferring SNPs in dhfr, dhps, pfmdr1, pfcrt, and k13 in nine PCRs, performed directly from P. falciparum cultures or infected blood. We also optimized multiplexed fragment analysis and gel electrophoresis-based microsatellite typing methods using a set of five markers that can distinguish 12 laboratory strains of diverse geographical and temporal origin. We demonstrate how these methods can be applied to screen for the multidrug-resistant KEL1/PLA1/PfPailin (KelPP) lineage that has been sweeping across the Greater Mekong Subregion, verify parasite in vitro SNP-editing, identify novel recombinant genetic cross progeny, or cluster strains to infer their geographical origins. Results were compared with Illumina-based whole-genome sequence analysis that provides the most detailed sequence information but is cost-prohibitive. These adaptable, simple, and inexpensive methods can be easily implemented into routine genotyping of P. falciparum parasites in both laboratory and field settings.
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12
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Dia A, Jett C, Trevino SG, Chu CS, Sriprawat K, Anderson TJC, Nosten F, Cheeseman IH. Single-genome sequencing reveals within-host evolution of human malaria parasites. Cell Host Microbe 2021; 29:1496-1506.e3. [PMID: 34492224 DOI: 10.1016/j.chom.2021.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 06/17/2021] [Accepted: 08/13/2021] [Indexed: 02/06/2023]
Abstract
Population genomics of bulk malaria infections is unable to examine intrahost evolution; therefore, most work has focused on the role of recombination in generating genetic variation. We used single-cell sequencing protocol for low-parasitaemia infections to generate 406 near-complete single Plasmodium vivax genomes from 11 patients sampled during sequential febrile episodes. Parasite genomes contain hundreds of de novo mutations, showing strong signatures of selection, which are enriched in the ApiAP2 family of transcription factors, known targets of adaptation. Comparing 315 P. falciparum single-cell genomes from 15 patients with our P. vivax data, we find broad complementary patterns of de novo mutation at the gene and pathway level, revealing the importance of within-host evolution during malaria infections.
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Affiliation(s)
- Aliou Dia
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Catherine Jett
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Simon G Trevino
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Cindy S Chu
- Disease Intervention and Prevention, Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research building, University of Oxford, Old Road campus, Oxford, UK; Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Kanlaya Sriprawat
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Timothy J C Anderson
- Disease Prevention and Intervention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - François Nosten
- Disease Intervention and Prevention, Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research building, University of Oxford, Old Road campus, Oxford, UK; Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Ian H Cheeseman
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA.
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13
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Dia A, Cheeseman IH. Single-cell genome sequencing of protozoan parasites. Trends Parasitol 2021; 37:803-814. [PMID: 34172399 PMCID: PMC8364489 DOI: 10.1016/j.pt.2021.05.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/21/2021] [Accepted: 05/26/2021] [Indexed: 12/27/2022]
Abstract
Despite considerable genetic variation within hosts, most parasite genome sequencing studies focus on bulk samples composed of millions of cells. Analysis of bulk samples is biased toward the dominant genotype, concealing cell-to-cell variation and rare variants. To tackle this, single-cell sequencing approaches have been developed and tailored to specific host-parasite systems. These are allowing the genetic diversity and kinship in complex parasite populations to be deciphered and for de novo genetic variation to be captured. Here, we outline the methodologies being used for single-cell sequencing of parasitic protozoans, such as Plasmodium and Leishmania spp., and how these tools are being applied to understand parasite biology.
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Affiliation(s)
- Aliou Dia
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Ian H Cheeseman
- Host-Pathogen Interaction Program, Texas Biomedical Research Institute, San Antonio, TX, USA.
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14
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Abstract
Almost 20 years have passed since the first reference genome assemblies were published for Plasmodium falciparum, the deadliest malaria parasite, and Anopheles gambiae, the most important mosquito vector of malaria in sub-Saharan Africa. Reference genomes now exist for all human malaria parasites and nearly half of the ~40 important vectors around the world. As a foundation for genetic diversity studies, these reference genomes have helped advance our understanding of basic disease biology and drug and insecticide resistance, and have informed vaccine development efforts. Population genomic data are increasingly being used to guide our understanding of malaria epidemiology, for example by assessing connectivity between populations and the efficacy of parasite and vector interventions. The potential value of these applications to malaria control strategies, together with the increasing diversity of genomic data types and contexts in which data are being generated, raise both opportunities and challenges in the field. This Review discusses advances in malaria genomics and explores how population genomic data could be harnessed to further support global disease control efforts.
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Affiliation(s)
- Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA, USA.
| | - Aimee R Taylor
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Bronwyn L MacInnis
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA, USA.
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15
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Liu S, Huckaby AC, Brown AC, Moore CC, Burbulis I, McConnell MJ, Güler JL. Single-cell sequencing of the small and AT-skewed genome of malaria parasites. Genome Med 2021; 13:75. [PMID: 33947449 PMCID: PMC8094492 DOI: 10.1186/s13073-021-00889-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/17/2021] [Indexed: 12/23/2022] Open
Abstract
Single-cell genomics is a rapidly advancing field; however, most techniques are designed for mammalian cells. We present a single-cell sequencing pipeline for an intracellular parasite, Plasmodium falciparum, with a small genome of extreme base content. Through optimization of a quasi-linear amplification method, we target the parasite genome over contaminants and generate coverage levels allowing detection of minor genetic variants. This work, as well as efforts that build on these findings, will enable detection of parasite heterogeneity contributing to P. falciparum adaptation. Furthermore, this study provides a framework for optimizing single-cell amplification and variant analysis in challenging genomes.
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Affiliation(s)
- Shiwei Liu
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Adam C Huckaby
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Audrey C Brown
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Christopher C Moore
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | - Ian Burbulis
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
- Escuela de Medicina, Universidad San Sebastian, Puerto Montt, Chile
| | - Michael J McConnell
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
- Current address: Lieber Institute for Brain Development, Baltimore, MD, USA
| | - Jennifer L Güler
- Department of Biology, University of Virginia, Charlottesville, VA, USA.
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA.
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16
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Abstract
The relative contribution of imported vs. locally acquired infections to urban malaria burden remains largely unexplored in Latin America, the most urbanised region in the developing world. Here we use a simple molecular epidemiology framework to examine the transmission dynamics of Plasmodium vivax in Mâncio Lima, the Amazonian municipality with the highest malaria incidence rate in Brazil. We prospectively genotyped 177 P. vivax infections diagnosed in urban residents between June 2014 and July 2015 and showed that local parasites are structured into several lineages of closely related microsatellite haplotypes, with the largest genetic cluster comprising 32% of all infections. These findings are very unlikely under the hypothesis of multiple independent imports of parasite strains from the rural surroundings. Instead, the presence of an endemic near-clonal parasite lineage circulating over 13 consecutive months is consistent with a local P. vivax transmission chain in the town, with major implications for malaria elimination efforts in this and similar urban environments across the Amazon.
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17
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Li X, Kumar S, McDew-White M, Haile M, Cheeseman IH, Emrich S, Button-Simons K, Nosten F, Kappe SHI, Ferdig MT, Anderson TJC, Vaughan AM. Genetic mapping of fitness determinants across the malaria parasite Plasmodium falciparum life cycle. PLoS Genet 2019; 15:e1008453. [PMID: 31609965 PMCID: PMC6821138 DOI: 10.1371/journal.pgen.1008453] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 10/30/2019] [Accepted: 10/01/2019] [Indexed: 12/14/2022] Open
Abstract
Determining the genetic basis of fitness is central to understanding evolution and transmission of microbial pathogens. In human malaria parasites (Plasmodium falciparum), most experimental work on fitness has focused on asexual blood stage parasites, because this stage can be easily cultured, although the transmission of malaria requires both female Anopheles mosquitoes and vertebrate hosts. We explore a powerful approach to identify the genetic determinants of parasite fitness across both invertebrate and vertebrate life-cycle stages of P. falciparum. This combines experimental genetic crosses using humanized mice, with selective whole genome amplification and pooled sequencing to determine genome-wide allele frequencies and identify genomic regions under selection across multiple lifecycle stages. We applied this approach to genetic crosses between artemisinin resistant (ART-R, kelch13-C580Y) and ART-sensitive (ART-S, kelch13-WT) parasites, recently isolated from Southeast Asian patients. Two striking results emerge: we observed (i) a strong genome-wide skew (>80%) towards alleles from the ART-R parent in the mosquito stage, that dropped to ~50% in the blood stage as selfed ART-R parasites were selected against; and (ii) repeatable allele specific skews in blood stage parasites with particularly strong selection (selection coefficient (s) ≤ 0.18/asexual cycle) against alleles from the ART-R parent at loci on chromosome 12 containing MRP2 and chromosome 14 containing ARPS10. This approach robustly identifies selected loci and has strong potential for identifying parasite genes that interact with the mosquito vector or compensatory loci involved in drug resistance.
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Affiliation(s)
- Xue Li
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - Marina McDew-White
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Meseret Haile
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - Ian H. Cheeseman
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Scott Emrich
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
- Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Katie Button-Simons
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Stefan H. I. Kappe
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Michael T. Ferdig
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Tim J. C. Anderson
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
- * E-mail: (TJCA); (AMV)
| | - Ashley M. Vaughan
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- * E-mail: (TJCA); (AMV)
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