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Freville A, Stewart LB, Tetteh KKA, Treeck M, Cortes A, Voss TS, Tarr SJ, Baker DA, Conway DJ. Expression of the MSPDBL2 antigen in a discrete subset of Plasmodium falciparum schizonts is regulated by GDV1 but may not be linked to sexual commitment. mBio 2024; 15:e0314023. [PMID: 38530030 PMCID: PMC11077968 DOI: 10.1128/mbio.03140-23] [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: 11/21/2023] [Accepted: 03/04/2024] [Indexed: 03/27/2024] Open
Abstract
The Plasmodium falciparum merozoite surface protein MSPDBL2 is a polymorphic antigen targeted by acquired immune responses, and normally expressed in only a minority of mature schizonts. The potential relationship of MSPDBL2 to sexual commitment is examined, as variable mspdbl2 transcript levels and proportions of MSPDBL2-positive mature schizonts in clinical isolates have previously correlated with levels of many sexual stage parasite gene transcripts, although not with the master regulator ap2-g. It is demonstrated that conditional overexpression of the gametocyte development protein GDV1, which promotes sexual commitment, also substantially increases the proportion of MSPDBL2-positive schizonts in culture. Conversely, truncation of the gdv1 gene is shown to prevent any expression of MSPDBL2. However, across diverse P. falciparum cultured lines, the variable proportions of MSPDBL2 positivity in schizonts do not correlate significantly with variable gametocyte conversion rates, indicating it is not involved in sexual commitment. Confirming this, examining a line with endogenous hemagglutinin-tagged AP2-G showed that the individual schizonts expressing MSPDBL2 are mostly different from those expressing AP2-G. Using a selection-linked integration system, modified P. falciparum lines were engineered to express an intact or disrupted version of MSPDBL2, showing the protein is not required for sexual commitment or early gametocyte development. Asexual parasite multiplication rates were also not affected by expression of either intact or disrupted MSPDBL2 in a majority of schizonts. Occurring alongside sexual commitment, the role of the discrete MSPDBL2-positive schizont subpopulation requires further investigation in natural infections where it is under immune selection. IMPORTANCE Malaria parasites in the blood are remarkably variable, able to switch antigenic targets so they may survive within humans who have already developed specific immune responses. This is one of the challenges in developing vaccines against malaria. MSPDBL2 is a target of naturally acquired immunity expressed in minority proportions of schizonts, the end stages of each 2-day replication cycle in red blood cells which contain merozoites prepared to invade new red blood cells. Results show that the proportion of schizonts expressing MSPDBL2 is positively controlled by the expression of the regulatory gametocyte development protein GDV1. It was previously known that expression of GDV1 leads to increased expression of AP2-G which causes parasites to switch to sexual development, so a surprising finding here is that MSPDBL2-positive parasites are mostly distinct from those that express AP2-G. This discrete antigenic subpopulation of mostly asexual parasites is regulated alongside sexually committed parasites, potentially enabling survival under stress conditions.
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Affiliation(s)
- Aline Freville
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Lindsay B. Stewart
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kevin K. A. Tetteh
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Alfred Cortes
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Catalonia, Spain
- ICREA, Barcelona, Catalonia, Spain
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Sarah J. Tarr
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David A. Baker
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David J. Conway
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Himmel T, Harl J, Matt J, Nedorost N, Iezhova T, Ilgūnas M, Valkiūnas G, Weissenböck H. RNAscope in situ hybridization reveals microvascular sequestration of Plasmodium relictum pSGS1 blood stages but absence of exo-erythrocytic dormant stages during latent infection of Serinus canaria. Malar J 2024; 23:70. [PMID: 38459560 PMCID: PMC10924391 DOI: 10.1186/s12936-024-04899-x] [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: 12/25/2023] [Accepted: 03/02/2024] [Indexed: 03/10/2024] Open
Abstract
BACKGROUND Birds chronically infected with avian malaria parasites often show relapses of parasitaemia after latent stages marked by absence of parasites in the peripheral circulation. These relapses are assumed to result from the activation of dormant exo-erythrocytic stages produced during secondary (post-erythrocytic) merogony of avian Plasmodium spp. Yet, there is no morphological proof of persistent or dormant tissue stages in the avian host during latent infections. This study investigated persistence of Plasmodium relictum pSGS1 in birds with latent infections during winter, with the goal to detect presumed persisting tissue stages using a highly sensitive RNAscope® in situ hybridization technology. METHODS Fourteen domestic canaries were infected with P. relictum pSGS1 by blood-inoculation in spring, and blood films examined during the first 4 months post infection, and during winter and spring of the following year. After parasitaemia was no longer detectable, half of the birds were dissected, and tissue samples investigated for persisting tissue stages using RNAscope ISH and histology. The remaining birds were blood-checked and dissected after re-appearance of parasitaemia, and their tissues equally examined. RESULTS Systematic examination of tissues showed no exo-erythrocytic stages in birds exhibiting latent infections by blood-film microscopy, indicating absence of dormant tissue stages in P. relictum pSGS1-infected canaries. Instead, RNAscope ISH revealed rare P. relictum blood stages in capillaries of various tissues and organs, demonstrating persistence of the parasites in the microvasculature. Birds examined after re-appearance of parasitemia showed higher numbers of P. relictum blood stages in both capillaries and larger blood vessels, indicating replication during early spring and re-appearance in the peripheral circulation. CONCLUSIONS The findings suggest that persistence of P. relictum pSGS1 during latent infection is mediated by continuous low-level erythrocytic merogony and possibly tissue sequestration of infected blood cells. Re-appearance of parasitaemia in spring seems to result from increased erythrocytic merogony, therefore representing recrudescence and not relapse in blood-inoculated canaries. Further, the study highlights strengths and limitations of the RNAscope ISH technology for the detection of rare parasite stages in tissues, providing directions for future research on persistence and tissue sequestration of avian malaria and related haemosporidian parasites.
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Affiliation(s)
- Tanja Himmel
- Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria.
| | - Josef Harl
- Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
| | - Julia Matt
- Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
| | - Nora Nedorost
- Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
| | - Tatjana Iezhova
- Nature Research Centre, Akademijos 2, 08412, Vilnius, Lithuania
| | - Mikas Ilgūnas
- Nature Research Centre, Akademijos 2, 08412, Vilnius, Lithuania
| | | | - Herbert Weissenböck
- Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
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Kengne-Ouafo JA, Bah SY, Kemp A, Stewart L, Amenga-Etego L, Deitsch KW, Rayner JC, Billker O, Binka FN, Sutherland CJ, Awandare GA, Urban BC, Dinko B. The global transcriptome of Plasmodium falciparum mid-stage gametocytes (stages II-IV) appears largely conserved and gametocyte-specific gene expression patterns vary in clinical isolates. Microbiol Spectr 2023; 11:e0382022. [PMID: 37698406 PMCID: PMC10581088 DOI: 10.1128/spectrum.03820-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 07/09/2023] [Indexed: 09/13/2023] Open
Abstract
Our overall understanding of the developmental biology of malaria parasites has been greatly enhanced by recent advances in transcriptomic analysis. However, most of these investigations rely on laboratory strains (LS) that were adapted into in vitro culture many years ago, and the transcriptomes of clinical isolates (CI) circulating in human populations have not been assessed. In this study, RNA-seq was used to compare the global transcriptome of mid-stage gametocytes derived from three short-term cultured CI, with gametocytes derived from the NF54 reference laboratory strain. The core transcriptome appeared to be consistent between CI- and LS-derived gametocyte preparations, but some important differences were also observed. A majority of gametocyte-specific genes (43/53) appear to have relatively higher expression in CI-derived gametocytes than in LS-derived gametocytes, but a K-means clustering analysis showed that genes involved in flagellum- and microtubule-based processes (movement/motility) were more abundant in both groups, albeit with some differences between them. In addition, gametocytes from one CI described as CI group II gametocytes (CI:GGII) showed gene expression variation in the form of reduced gametocyte-specific gene expression compared to the other two CI-derived gametocytes (CI gametocyte group I, CI:GGI), although the mixed developmental stages used in our study is a potential confounder, only partially mitigated by the inclusion of multiple replicates for each CI. Overall, our study suggests that there may be subtle differences in the gene expression profiles of mid-stage gametocytes from CI relative to the NF54 reference strain of Plasmodium falciparum. Thus, it is necessary to deploy gametocyte-producing clinical parasite isolates to fully understand the diversity of gene expression strategies that may occur during the sequestered development of parasite sexual stages. IMPORTANCE Maturing gametocytes of Plasmodium falciparum are known to sequester away from peripheral circulation into the bone marrow until they are mature. Blocking gametocyte sequestration can prevent malaria transmission from humans to mosquitoes, but most studies aim to understand gametocyte development utilizing long-term adapted laboratory lines instead of clinical isolates. This is a particular issue for our understanding of the sexual stages, which are known to decrease rapidly during adaptation to long-term culture, meaning that many LS are unable to produce transmissible gametocytes. Using RNA-seq, we investigated the global transcriptome of mid-stage gametocytes derived from three clinical isolates and a reference strain (NF54). This identified important differences in gene expression profiles between immature gametocytes of CI and the NF54 reference strain of P. falciparum, suggesting increased investment in gametocytogenesis in clinical isolates. Our transcriptomic data highlight the use of clinical isolates in studying the morphological, cellular features and molecular biology of gametocytes.
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Affiliation(s)
- Jonas A. Kengne-Ouafo
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Saikou Y. Bah
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
- Vaccine and Immunity Theme, MRC Unit The Gambia at London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Alison Kemp
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Lindsay Stewart
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lucas Amenga-Etego
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Kirk W. Deitsch
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York City, New York, USA
| | - Julian C. Rayner
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Oliver Billker
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Fred N. Binka
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Ho, Ghana
| | - Colin J. Sutherland
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gordon A. Awandare
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Britta C. Urban
- Faculty of Biological Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Bismarck Dinko
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana
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Dumonteil E, Desale H, Tu W, Hernandez-Cuevas N, Shroyer M, Goff K, Marx PA, Herrera C. Intra-host Trypanosoma cruzi strain dynamics shape disease progression: the missing link in Chagas disease pathogenesis. Microbiol Spectr 2023; 11:e0423622. [PMID: 37668388 PMCID: PMC10581044 DOI: 10.1128/spectrum.04236-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 07/10/2023] [Indexed: 09/06/2023] Open
Abstract
Chronic Chagasic cardiomyopathy develops years after infection in 20-40% of patients, but disease progression is poorly understood. Here, we assessed Trypanosoma cruzi parasite dynamics and pathogenesis over a 2.5-year period in naturally infected rhesus macaques. Individuals with better control of parasitemia were infected with a greater diversity of parasite strains compared to those with increasing parasitemia over time. Also, the in vivo parasite multiplication rate decreased with increasing parasite diversity, suggesting competition among strains or a stronger immune response in multiple infections. Significant differences in electrocardiographic (ECG) profiles were observed in Chagasic macaques compared to uninfected controls, suggesting early conduction defects, and changes in ECG patterns over time were observed only in macaques with increasing parasitemia and lower parasite diversity. Disease progression was also associated with plasma fibronectin degradation, which may serve as a biomarker. These data provide a novel framework for the understanding of Chagas disease pathogenesis, with parasite diversity shaping disease progression.IMPORTANCEChagas disease progression remains poorly understood, and patients at increased risk of developing severe cardiac disease cannot be distinguished from those who may remain asymptomatic. Monitoring of Trypanosoma cruzi strain dynamics and pathogenesis over 2-3 years in naturally infected macaques shows that increasing parasite diversity in hosts is detrimental to parasite multiplication and Chagasic cardiomyopathy disease progression. This provides a novel framework for the understanding of Chagas disease pathogenesis.
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Affiliation(s)
- Eric Dumonteil
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, USA
| | - Hans Desale
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, USA
| | - Weihong Tu
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, USA
| | - Nora Hernandez-Cuevas
- Laboratorio de Parasitologia, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autonoma de Yucatan, Merida, Yucatan, Mexico
| | - Monica Shroyer
- Division of Veterinary Medicine, Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Kelly Goff
- Division of Microbiology, Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Preston A. Marx
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, USA
- Division of Microbiology, Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Claudia Herrera
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, USA
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Greischar MA, Childs LM. Extraordinary parasite multiplication rates in human malaria infections. Trends Parasitol 2023; 39:626-637. [PMID: 37336700 DOI: 10.1016/j.pt.2023.05.006] [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: 03/15/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/21/2023]
Abstract
For pathogenic organisms, faster rates of multiplication promote transmission success, the potential to harm hosts, and the evolution of drug resistance. Parasite multiplication rates (PMRs) are often quantified in malaria infections, given the relative ease of sampling. Using modern and historical human infection data, we show that established methods return extraordinarily - and implausibly - large PMRs. We illustrate how inflated PMRs arise from two facets of malaria biology that are far from unique: (i) some developmental ages are easier to sample than others; (ii) the distribution of developmental ages changes over the course of infection. The difficulty of accurately quantifying PMRs demonstrates a need for robust methods and a subsequent re-evaluation of what is known even in the well-studied system of malaria.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA.
| | - Lauren M Childs
- Department of Mathematics, Virginia Tech, Blacksburg, VA, USA
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6
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Nkhoma SC, Ahmed AOA, Porier D, Rashid S, Bradford R, Molestina RE, Stedman TT. Dynamics of parasite growth in genetically diverse Plasmodium falciparum isolates. Mol Biochem Parasitol 2023; 254:111552. [PMID: 36731750 PMCID: PMC10149587 DOI: 10.1016/j.molbiopara.2023.111552] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/24/2022] [Accepted: 01/26/2023] [Indexed: 02/01/2023]
Abstract
Multiple parasite lineages with different proliferation rates or fitness may coexist within a clinical malaria isolate, resulting in complex growth interactions and variations in phenotype. To elucidate the dynamics of parasite growth in multiclonal isolates, we measured growth rates (GRs) of three Plasmodium falciparum Cambodian isolates, including IPC_3445 (MRA-1236), IPC_5202 (MRA-1240), IPC_6403 (MRA-1285), and parasite lineages previously cloned from each of these isolates by limiting dilution. Following synchronization, in vitro cultures of each parasite line were maintained over four consecutive asexual cycles (192 h), with thin smears prepared at each 48-h cycle to estimate GR and fold change in parasitemia (FCP). Cell cycle time (CCT), the duration it takes for ring-stage parasites to develop into mature schizonts, was measured by monitoring the development of 0-3-h post-invasion rings for up to 52 h post-incubation. Laboratory lines 3D7 (MRA-102) and Dd2 (MRA-150) were used as controls. Significant differences in GR, FCP, and CCT were observed between parasite isolates and clonal lineages from each isolate. The parasite lines studied here have well-defined growth phenotypes and will facilitate basic malaria research and development of novel malaria interventions. These lines are available to malaria researchers through the MR4 collection of NIAID's BEI Resources Program.
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Affiliation(s)
- Standwell C Nkhoma
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA.
| | - Amel O A Ahmed
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
| | - Danielle Porier
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
| | - Sujatha Rashid
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
| | - Rebecca Bradford
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
| | - Robert E Molestina
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
| | - Timothy T Stedman
- BEI Resources, American Type Culture Collection, 10801 University Boulevard, Manassas, VA 20110-2209, USA
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Claessens A, Stewart LB, Drury E, Ahouidi AD, Amambua-Ngwa A, Diakite M, Kwiatkowski DP, Awandare GA, Conway DJ. Genomic variation during culture adaptation of genetically complex Plasmodium falciparum clinical isolates. Microb Genom 2023; 9:mgen001009. [PMID: 37204422 PMCID: PMC10272863 DOI: 10.1099/mgen.0.001009] [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: 09/14/2022] [Accepted: 03/06/2023] [Indexed: 05/20/2023] Open
Abstract
Experimental studies on the biology of malaria parasites have mostly been based on laboratory-adapted lines, but there is limited understanding of how these may differ from parasites in natural infections. Loss-of-function mutants have previously been shown to emerge during culture of some Plasmodium falciparum clinical isolates in analyses focusing on single-genotype infections. The present study included a broader array of isolates, mostly representing multiple-genotype infections, which are more typical in areas where malaria is highly endemic. Genome sequence data from multiple time points over several months of culture adaptation of 28 West African isolates were analysed, including previously available sequences along with new genome sequences from additional isolates and time points. Some genetically complex isolates eventually became fixed over time to single surviving genotypes in culture, whereas others retained diversity, although proportions of genotypes varied over time. Drug resistance allele frequencies did not show overall directional changes, suggesting that resistance-associated costs are not the main causes of fitness differences among parasites in culture. Loss-of-function mutants emerged during culture in several of the multiple-genotype isolates, affecting genes (including AP2-HS, EPAC and SRPK1) for which loss-of-function mutants were previously seen to emerge in single-genotype isolates. Parasite clones were derived by limiting dilution from six of the isolates, and sequencing identified de novo variants not detected in the bulk isolate sequences. Interestingly, several of these were nonsense mutants and frameshifts disrupting the coding sequence of EPAC, the gene with the largest number of independent nonsense mutants previously identified in laboratory-adapted lines. Analysis of genomic identity by descent to explore relatedness among clones revealed co-occurring non-identical sibling parasites, illustrative of the natural genetic structure within endemic populations.
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Affiliation(s)
- Antoine Claessens
- LPHI, MIVEGEC, INSERM, CNRS, IRD, University of Montpellier, France
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK
- MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Lindsay B. Stewart
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK
| | | | | | - Alfred Amambua-Ngwa
- MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Mahamadou Diakite
- Malaria Research and Training Center, University of Bamako, Bamako, Mali
| | | | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
| | - David J. Conway
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK
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Stewart LB, Freville A, Voss TS, Baker DA, Awandare GA, Conway DJ. Plasmodium falciparum Sexual Commitment Rate Variation among Clinical Isolates and Diverse Laboratory-Adapted Lines. Microbiol Spectr 2022; 10:e0223422. [PMID: 36409095 PMCID: PMC9769538 DOI: 10.1128/spectrum.02234-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022] Open
Abstract
Asexual blood-stage malaria parasites must produce sexual progeny to infect mosquitoes. It is important to understand the scope and causes of intraspecific variation in sexual commitment rates, particularly for the major human parasite P. falciparum. First, two alternative assay methods of measuring sexual commitment were compared to test a genetically modified P. falciparum line with elevated commitment rates inducible by overexpression of GDV1. The methods yielded correlated measurements with higher sensitivity and precision being achieved by one employing detection of the early gametocyte differentiation marker Pfs16. Thus, this was used to survey a diverse range of parasite lines and test each in multiple biological replicate assays in a serum-free medium supplemented with Albumax. There were differences among six recent clinical isolates from Ghana in their mean rates of sexual commitment per cycle, ranging from 3.3% to 12.2%. Among 13 diverse long-term laboratory-adapted lines, mean sexual commitment rates for most ranged from 4.7% to 13.4%, a few had lower rates with means from 0.3 to 1.6%, and one with a nonfunctional ap2-g gene always showed zero commitment. Among a subset of lines tested for the effects of exogenous choline to suppress commitment, there were significant differences. As expected, there was no effect in a line that had lost the gdv1 gene and that had generally low commitment, whereas the others showed quantitatively variable but significant responses to choline, suggesting potential trait variation. The results indicated the value of performing multiple replicate assays for understanding the variation of this key reproductive trait that likely affects transmission. IMPORTANCE Only sexual-stage malaria parasites are transmitted from human blood to mosquitoes. Thus, it is vital to understand variations in sexual commitment rates because these may be modifiable or susceptible to blocking. Two different methods of commitment rate measurement were first compared, demonstrating higher sensitivity and precision by the detection of an early differentiation marker, which was subsequently used to survey diverse lines. Clinical isolates from Ghana showed significant variation in mean per-cycle commitment rates and variation among biological replicates. Laboratory-adapted lines of diverse origins had a wider range with most being within the range observed for the clinical isolates, while a minority consistently had lower or zero rates. There was quantitative variation in the effects when adding choline to suppress commitment, indicating differing responsiveness of parasites to this environmental modification. Performing multiple assay replicates and comparisons of diverse isolates was important to understand this trait and its potential effects on transmission.
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Affiliation(s)
- Lindsay B. Stewart
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Aline Freville
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basal, Switzerland
| | - David A. Baker
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - David J. Conway
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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McDonald J, Merrick CJ. DNA replication dynamics during erythrocytic schizogony in the malaria parasites Plasmodium falciparum and Plasmodium knowlesi. PLoS Pathog 2022; 18:e1010595. [PMID: 35731838 PMCID: PMC9255763 DOI: 10.1371/journal.ppat.1010595] [Citation(s) in RCA: 10] [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: 12/20/2021] [Revised: 07/05/2022] [Accepted: 05/13/2022] [Indexed: 12/01/2022] Open
Abstract
Malaria parasites are unusual, early-diverging protozoans with non-canonical cell cycles. They do not undergo binary fission, but divide primarily by schizogony. This involves the asynchronous production of multiple nuclei within the same cytoplasm, culminating in a single mass cytokinesis event. The rate and efficiency of parasite reproduction is fundamentally important to malarial disease, which tends to be severe in hosts with high parasite loads. Here, we have studied for the first time the dynamics of schizogony in two human malaria parasite species, Plasmodium falciparum and Plasmodium knowlesi. These differ in their cell-cycle length, the number of progeny produced and the genome composition, among other factors. Comparing them could therefore yield new information about the parameters and limitations of schizogony. We report that the dynamics of schizogony differ significantly between these two species, most strikingly in the gap phases between successive nuclear multiplications, which are longer in P. falciparum and shorter, but more heterogenous, in P. knowlesi. In both species, gaps become longer as schizogony progresses, whereas each period of active DNA replication grows shorter. In both species there is also extreme variability between individual cells, with some schizonts producing many more nuclei than others, and some individual nuclei arresting their DNA replication for many hours while adjacent nuclei continue to replicate. The efficiency of schizogony is probably influenced by a complex set of factors in both the parasite and its host cell. Malaria parasites are unusual, early-diverging single-celled organisms. One of their atypical features is their mode of producing new cells. Most cells replicate their genome, segregate the copies into two nuclei and then split the whole cell in two: a process called binary fission. Malaria parasites, by contrast, multiply primarily by schizogony. Each cell replicates its genome several times over, asynchronously, generating many nuclei within the same cytoplasm, before splitting into many new daughter cells in a single mass event. All malaria species do this, but there are stark differences between species in how long schizogony takes and how many progeny each cell can produce. Understanding this is important because the rate of parasite reproduction is fundamentally important to malarial disease: humans who have a high burden of parasites in their blood are most likely to suffer severe malaria. Here we compare the process of schizogony in two different species, by developing cell lines in which we can follow de novo DNA replication at high spatial and temporal resolution, at both whole-cell and single-molecule levels. We establish the dynamics of schizogony, highlighting similarities and differences between two species and setting parameters for future studies of interventions that could interfere with parasite reproduction.
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Affiliation(s)
- Jennifer McDonald
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Catherine J. Merrick
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
- * E-mail:
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10
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Tintó-Font E, Michel-Todó L, Russell TJ, Casas-Vila N, Conway DJ, Bozdech Z, Llinás M, Cortés A. A heat-shock response regulated by the PfAP2-HS transcription factor protects human malaria parasites from febrile temperatures. Nat Microbiol 2021; 6:1163-1174. [PMID: 34400833 PMCID: PMC8390444 DOI: 10.1038/s41564-021-00940-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/22/2021] [Indexed: 02/07/2023]
Abstract
Periodic fever is a characteristic clinical feature of human malaria, but how parasites survive febrile episodes is not known. Although the genomes of Plasmodium species encode a full set of chaperones, they lack the conserved eukaryotic transcription factor HSF1, which activates the expression of chaperones following heat shock. Here, we show that PfAP2-HS, a transcription factor in the ApiAP2 family, regulates the protective heat-shock response in Plasmodium falciparum. PfAP2-HS activates the transcription of hsp70-1 and hsp90 at elevated temperatures. The main binding site of PfAP2-HS in the entire genome coincides with a tandem G-box DNA motif in the hsp70-1 promoter. Engineered parasites lacking PfAP2-HS have reduced heat-shock survival and severe growth defects at 37 °C but not at 35 °C. Parasites lacking PfAP2-HS also have increased sensitivity to imbalances in protein homeostasis (proteostasis) produced by artemisinin, the frontline antimalarial drug, or the proteasome inhibitor epoxomicin. We propose that PfAP2-HS contributes to the maintenance of proteostasis under basal conditions and upregulates specific chaperone-encoding genes at febrile temperatures to protect the parasite against protein damage.
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Affiliation(s)
- Elisabet Tintó-Font
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona 08036, Catalonia, Spain
| | - Lucas Michel-Todó
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona 08036, Catalonia, Spain
| | - Timothy J. Russell
- Department of Biochemistry & Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, University Park 16802, PA, USA
| | - Núria Casas-Vila
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona 08036, Catalonia, Spain
| | - David J. Conway
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Manuel Llinás
- Department of Biochemistry & Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, University Park 16802, PA, USA,Department of Chemistry, Pennsylvania State University, University Park 16802, PA, USA
| | - Alfred Cortés
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona 08036, Catalonia, Spain,ICREA, Barcelona 08010, Catalonia, Spain,Correspondence: (Alfred Cortés)
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11
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Simon CS, Stürmer VS, Guizetti J. How Many Is Enough? - Challenges of Multinucleated Cell Division in Malaria Parasites. Front Cell Infect Microbiol 2021; 11:658616. [PMID: 34026661 PMCID: PMC8137892 DOI: 10.3389/fcimb.2021.658616] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/21/2021] [Indexed: 12/12/2022] Open
Abstract
Regulating the number of progeny generated by replicative cell cycles is critical for any organism to best adapt to its environment. Classically, the decision whether to divide further is made after cell division is completed by cytokinesis and can be triggered by intrinsic or extrinsic factors. Contrarily, cell cycles of some species, such as the malaria-causing parasites, go through multinucleated cell stages. Hence, their number of progeny is determined prior to the completion of cell division. This should fundamentally affect how the process is regulated and raises questions about advantages and challenges of multinucleation in eukaryotes. Throughout their life cycle Plasmodium spp. parasites undergo four phases of extensive proliferation, which differ over three orders of magnitude in the amount of daughter cells that are produced by a single progenitor. Even during the asexual blood stage proliferation parasites can produce very variable numbers of progeny within one replicative cycle. Here, we review the few factors that have been shown to affect those numbers. We further provide a comparative quantification of merozoite numbers in several P. knowlesi and P. falciparum parasite strains, and we discuss the general processes that may regulate progeny number in the context of host-parasite interactions. Finally, we provide a perspective of the critical knowledge gaps hindering our understanding of the molecular mechanisms underlying this exciting and atypical mode of parasite multiplication.
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Affiliation(s)
| | | | - Julien Guizetti
- Centre for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
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