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Yahiya S, Jordan S, Smith HX, Gaboriau DCA, Famodimu MT, Dahalan FA, Churchyard A, Ashdown GW, Baum J. Live-cell fluorescence imaging of microgametogenesis in the human malaria parasite Plasmodium falciparum. PLoS Pathog 2022; 18:e1010276. [PMID: 35130301 PMCID: PMC8853644 DOI: 10.1371/journal.ppat.1010276] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/17/2022] [Accepted: 01/12/2022] [Indexed: 12/28/2022] Open
Abstract
Formation of gametes in the malaria parasite occurs in the midgut of the mosquito and is critical to onward parasite transmission. Transformation of the male gametocyte into microgametes, called microgametogenesis, is an explosive cellular event and one of the fastest eukaryotic DNA replication events known. The transformation of one microgametocyte into eight flagellated microgametes requires reorganisation of the parasite cytoskeleton, replication of the 22.9 Mb genome, axoneme formation and host erythrocyte egress, all of which occur simultaneously in <20 minutes. Whilst high-resolution imaging has been a powerful tool for defining stages of microgametogenesis, it has largely been limited to fixed parasite samples, given the speed of the process and parasite photosensitivity. Here, we have developed a live-cell fluorescence imaging workflow that captures the entirety of microgametogenesis. Using the most virulent human malaria parasite, Plasmodium falciparum, our live-cell approach captured early microgametogenesis with three-dimensional imaging through time (4D imaging) and microgamete release with two-dimensional (2D) fluorescence microscopy. To minimise the phototoxic impact to parasites, acquisition was alternated between 4D fluorescence, brightfield and 2D fluorescence microscopy. Combining live-cell dyes specific for DNA, tubulin and the host erythrocyte membrane, 4D and 2D imaging together enables definition of the positioning of newly replicated and segregated DNA. This combined approach also shows the microtubular cytoskeleton, location of newly formed basal bodies, elongation of axonemes and morphological changes to the erythrocyte membrane, the latter including potential echinocytosis of the erythrocyte membrane prior to microgamete egress. Extending the utility of this approach, the phenotypic effects of known transmission-blocking inhibitors on microgametogenesis were confirmed. Additionally, the effects of bortezomib, an untested proteasomal inhibitor, revealed a clear block of DNA replication, full axoneme nucleation and elongation. Thus, as well as defining a framework for broadly investigating microgametogenesis, these data demonstrate the utility of using live imaging to validate potential targets for transmission-blocking antimalarial drug development.
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Affiliation(s)
- Sabrina Yahiya
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Sarah Jordan
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Holly X. Smith
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - David C. A. Gaboriau
- Facility for Imaging by Light Microscopy, Imperial College London, London, United Kingdom
| | | | - Farah A. Dahalan
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alisje Churchyard
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - George W. Ashdown
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Jake Baum
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail: ,
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2
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Yao X, Pathak V, Xi H, Chaware A, Cooke C, Kim K, Xu S, Li Y, Dunn T, Chandra Konda P, Zhou KC, Horstmeyer R. Increasing a microscope's effective field of view via overlapped imaging and machine learning. Opt Express 2022; 30:1745-1761. [PMID: 35209329 PMCID: PMC8970696 DOI: 10.1364/oe.445001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/22/2021] [Accepted: 12/14/2021] [Indexed: 05/03/2023]
Abstract
This work demonstrates a multi-lens microscopic imaging system that overlaps multiple independent fields of view on a single sensor for high-efficiency automated specimen analysis. Automatic detection, classification and counting of various morphological features of interest is now a crucial component of both biomedical research and disease diagnosis. While convolutional neural networks (CNNs) have dramatically improved the accuracy of counting cells and sub-cellular features from acquired digital image data, the overall throughput is still typically hindered by the limited space-bandwidth product (SBP) of conventional microscopes. Here, we show both in simulation and experiment that overlapped imaging and co-designed analysis software can achieve accurate detection of diagnostically-relevant features for several applications, including counting of white blood cells and the malaria parasite, leading to multi-fold increase in detection and processing throughput with minimal reduction in accuracy.
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Affiliation(s)
- Xing Yao
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Vinayak Pathak
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Haoran Xi
- Computer Science, Duke University, Durham, NC 27708, USA
| | - Amey Chaware
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Colin Cooke
- Electrical and Computer Engineering, Duke University, Durham, NC 27708, USA
| | - Kanghyun Kim
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Shiqi Xu
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Yuting Li
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Timothy Dunn
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Neurosurgery, Duke University, Durham, NC 27708, USA
| | | | - Kevin C. Zhou
- Biomedical Engineering, Duke University, Durham, NC 27708, USA
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3
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Amoah LE, Abukari Z, Dawson-Amoah ME, Dieng CC, Lo E, Afrane YA. Population structure and diversity of Plasmodium falciparum in children with asymptomatic malaria living in different ecological zones of Ghana. BMC Infect Dis 2021; 21:439. [PMID: 33985447 PMCID: PMC8120845 DOI: 10.1186/s12879-021-06120-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic diversity in Plasmodium falciparum populations can be used to describe the resilience and spatial distribution of the parasite in the midst of intensified intervention efforts. This study used microsatellite analysis to evaluate the genetic diversity and population dynamics of P. falciparum parasites circulating in three ecological zones of Ghana. METHODS A total of 1168 afebrile children aged between 3 to 13 years were recruited from five (5) Primary schools in 3 different ecological zones (Sahel (Tamale and Kumbungu), Forest (Konongo) and Coastal (Ada and Dodowa)) of Ghana. Asymptomatic malaria parasite carriage was determined using microscopy and PCR, whilst fragment analysis of 6 microsatellite loci was used to determine the diversity and population structure of P. falciparum parasites. RESULTS Out of the 1168 samples examined, 16.1 and 39.5% tested positive for P. falciparum by microscopy and nested PCR respectively. The genetic diversity of parasites in the 3 ecological zones was generally high, with an average heterozygosity (He) of 0.804, 0.787 and 0.608 the rainy (peak) season for the Sahel, Forest and Coastal zones respectively. The mean He for the dry (off-peak) season were 0.562, 0.693 and 0.610 for the Sahel, Forest and Coastal zones respectively. Parasites from the Forest zone were more closely related to those from the Sahel than from the Coastal zone, despite the Coastal zone being closer in physical distance to the Forest zone. The fixation indexes among study sites ranged from 0.049 to 0.112 during the rainy season and 0.112 to 0.348 during the dry season. CONCLUSION A large asymptomatic parasite reservoir was found in the school children during both rainy and dry seasons, especially those in the Forest and Sahel savannah zones where parasites were also found to be related compared to those from the Coastal zone. Further studies are recommended to understand why despite the roll out of several malaria interventions in Ghana, high transmission still persist.
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Affiliation(s)
- Linda Eva Amoah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
- West Africa Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Zakaria Abukari
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
- Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Maame Esi Dawson-Amoah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Cheikh Cambel Dieng
- Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223 USA
| | - Eugenia Lo
- Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223 USA
| | - Yaw Asare Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
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4
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Read DF, Cook K, Lu YY, Le Roch KG, Noble WS. Predicting gene expression in the human malaria parasite Plasmodium falciparum using histone modification, nucleosome positioning, and 3D localization features. PLoS Comput Biol 2019; 15:e1007329. [PMID: 31509524 PMCID: PMC6756558 DOI: 10.1371/journal.pcbi.1007329] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 09/23/2019] [Accepted: 08/12/2019] [Indexed: 12/02/2022] Open
Abstract
Empirical evidence suggests that the malaria parasite Plasmodium falciparum employs a broad range of mechanisms to regulate gene transcription throughout the organism's complex life cycle. To better understand this regulatory machinery, we assembled a rich collection of genomic and epigenomic data sets, including information about transcription factor (TF) binding motifs, patterns of covalent histone modifications, nucleosome occupancy, GC content, and global 3D genome architecture. We used these data to train machine learning models to discriminate between high-expression and low-expression genes, focusing on three distinct stages of the red blood cell phase of the Plasmodium life cycle. Our results highlight the importance of histone modifications and 3D chromatin architecture in Plasmodium transcriptional regulation and suggest that AP2 transcription factors may play a limited regulatory role, perhaps operating in conjunction with epigenetic factors.
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Affiliation(s)
- David F. Read
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Kate Cook
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Yang Y. Lu
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Karine G. Le Roch
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California, United States of America
| | - William Stafford Noble
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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5
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Gomez-Lorenzo MG, Rodríguez-Alejandre A, Moliner-Cubel S, Martínez-Hoyos M, Bahamontes-Rosa N, Gonzalez Del Rio R, Ródenas C, Fuente JDL, Lavandera JL, García-Bustos JF, Mendoza-Losana A. Functional screening of selective mitochondrial inhibitors of Plasmodium. Int J Parasitol Drugs Drug Resist 2018; 8:295-303. [PMID: 29775797 PMCID: PMC6039321 DOI: 10.1016/j.ijpddr.2018.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 04/20/2018] [Accepted: 04/26/2018] [Indexed: 11/25/2022]
Abstract
Phenotypic screening has produced most of the new chemical entities currently in clinical development for malaria, plus many lead compounds active against Plasmodium falciparum asexual stages. However, lack of knowledge about the mode of action of these compounds delays and may even hamper their future development. Identifying the mode of action of the inhibitors greatly helps to prioritise compounds for further development as novel antimalarials. Here we describe a whole-cell method to detect inhibitors of the mitochondrial electron transport chain, using oxygen consumption as high throughput readout in 384-well plate format. The usefulness of the method has been confirmed with the Tres Cantos Antimalarial Compound Set (TCAMS). The assay identified 124 respiratory inhibitors in TCAMS, seven of which were novel anti-plasmodial chemical structures never before described as mitochondrial inhibitors.
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Affiliation(s)
- Maria G Gomez-Lorenzo
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - Ane Rodríguez-Alejandre
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - Sonia Moliner-Cubel
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - María Martínez-Hoyos
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - Noemí Bahamontes-Rosa
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - Rubén Gonzalez Del Rio
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain
| | - Carolina Ródenas
- Centro de Investigación Básica (CIB) GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - Jesús de la Fuente
- Centro de Investigación Básica (CIB) GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - Jose Luis Lavandera
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain; Department of Basic Medical Science, CEU San Pablo University, Julián Romea 23, 28003, Madrid, Spain
| | - Jose F García-Bustos
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain; Department of Microbiology and Biomedicine Discovery Institute, Monash University, 3800, VIC, Australia
| | - Alfonso Mendoza-Losana
- Diseases of the Developing World (DDW), Tres Cantos Medicine Development Campus, GlaxoSmithKline, Severo Ochoa 2, 28760, Tres Cantos, Madrid, Spain.
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6
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Bopp S, Magistrado P, Wong W, Schaffner SF, Mukherjee A, Lim P, Dhorda M, Amaratunga C, Woodrow CJ, Ashley EA, White NJ, Dondorp AM, Fairhurst RM, Ariey F, Menard D, Wirth DF, Volkman SK. Plasmepsin II-III copy number accounts for bimodal piperaquine resistance among Cambodian Plasmodium falciparum. Nat Commun 2018; 9:1769. [PMID: 29720620 PMCID: PMC5931971 DOI: 10.1038/s41467-018-04104-z] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 03/30/2018] [Indexed: 12/30/2022] Open
Abstract
Multidrug resistant Plasmodium falciparum in Southeast Asia endangers regional malaria elimination and threatens to spread to other malaria endemic areas. Understanding mechanisms of piperaquine (PPQ) resistance is crucial for tracking its emergence and spread, and to develop effective strategies for overcoming it. Here we analyze a mechanism of PPQ resistance in Cambodian parasites. Isolates exhibit a bimodal dose-response curve when exposed to PPQ, with the area under the curve quantifying their survival in vitro. Increased copy number for plasmepsin II and plasmepsin III appears to explain enhanced survival when exposed to PPQ in most, but not all cases. A panel of isogenic subclones reinforces the importance of plasmepsin II-III copy number to enhanced PPQ survival. We conjecture that factors producing increased parasite survival under PPQ exposure in vitro may drive clinical PPQ failures in the field.
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Affiliation(s)
- Selina Bopp
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | | | - Wesley Wong
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Stephen F Schaffner
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Angana Mukherjee
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Pharath Lim
- National Institutes of Health, Rockville, MD, 20892, USA
| | - Mehul Dhorda
- Worldwide Antimalarial Resistance Network, Bangkok, 10400, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, 10400, Thailand
- Myanmar-Oxford Clinical Research Unit, Yangon, Myanmar
| | | | - Charles J Woodrow
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, 10400, Thailand
| | - Elizabeth A Ashley
- Myanmar-Oxford Clinical Research Unit, Yangon, Myanmar
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, OX3 7FZ, UK
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, OX3 7FZ, UK
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, OX3 7FZ, UK
| | | | - Frederic Ariey
- Institut Cochin, INSERM U:1016, Parasitology-Mycology Unit, Cochin Hospital Paris Descartes University, Paris, 75014, France
| | - Didier Menard
- Biology of Host-Parasite Interactions Unit, Institut Pasteur, Paris, 75015, France
- CNRS, ERL 9195, Paris, 75794, France
- INSERM, Unit U1201, Paris, 75015, France
| | - Dyann F Wirth
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Sarah K Volkman
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
- Simmons College, Boston, MA, 02115, USA.
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7
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Alencar N, Sola I, Linares M, Juárez-Jiménez J, Pont C, Viayna A, Vílchez D, Sampedro C, Abad P, Pérez-Benavente S, Lameira J, Bautista JM, Muñoz-Torrero D, Luque FJ. First homology model of Plasmodium falciparum glucose-6-phosphate dehydrogenase: Discovery of selective substrate analog-based inhibitors as novel antimalarial agents. Eur J Med Chem 2018; 146:108-122. [PMID: 29407943 DOI: 10.1016/j.ejmech.2018.01.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 12/27/2017] [Accepted: 01/15/2018] [Indexed: 01/07/2023]
Abstract
In Plasmodium falciparum the bifunctional enzyme glucose-6-phosphate dehydrogenase‒6-phosphogluconolactonase (PfG6PD‒6PGL) is involved in the catalysis of the first reaction of the pentose phosphate pathway. Since this enzyme has a key role in parasite development, its unique structure represents a potential target for the discovery of antimalarial drugs. Here we describe the first 3D structural model of the G6PD domain of PfG6PD‒6PGL. Compared to the human enzyme (hG6PD), the 3D model has enabled the identification of a key difference in the substrate-binding site, which involves the replacement of Arg365 in hG6PD by Asp750 in PfG6PD. In a prospective validation of the model, this critical change has been exploited to rationally design a novel family of substrate analog-based inhibitors that can display the necessary selectivity towards PfG6PD. A series of glucose derivatives featuring an α-methoxy group at the anomeric position and different side chains at position 6 bearing distinct basic functionalities has been synthesized, and their PfG6PD and hG6PD inhibitory activities and their toxicity against parasite and mammalian cells have been assessed. Several compounds displayed micromolar affinity (Ki up to 23 μM), favorable selectivity (up to > 26-fold), and low cytotoxicity. Phenotypic assays with P. falciparum cultures revealed high micromolar IC50 values, likely as a result of poor internalization of the compounds in the parasite cell. Overall, these results endorse confidence to the 3D model of PfG6PD, paving the way for the use of target-based drug design approaches in antimalarial drug discovery studies around this promising target.
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Affiliation(s)
- Nelson Alencar
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain
| | - Irene Sola
- Laboratory of Pharmaceutical Chemistry (CSIC Associated Unit), Faculty of Pharmacy and Food Sciences and IBUB, University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
| | - María Linares
- Research Institute Hospital 12 de Octubre, Avda. de Cordoba s/n, 28041 Madrid, Spain
| | - Jordi Juárez-Jiménez
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain
| | - Caterina Pont
- Laboratory of Pharmaceutical Chemistry (CSIC Associated Unit), Faculty of Pharmacy and Food Sciences and IBUB, University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
| | - Antonio Viayna
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain
| | - David Vílchez
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain
| | - Cristina Sampedro
- Laboratory of Pharmaceutical Chemistry (CSIC Associated Unit), Faculty of Pharmacy and Food Sciences and IBUB, University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
| | - Paloma Abad
- Research Institute Hospital 12 de Octubre, Avda. de Cordoba s/n, 28041 Madrid, Spain; Department of Biochemistry and Molecular Biology, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Susana Pérez-Benavente
- Department of Biochemistry and Molecular Biology, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Jerónimo Lameira
- Laboratório de Planejamento e Desenvolvimento de Fármacos-LPDF, Instituto de Ciências Exatas e Naturais- ICEN, Universidade Federal do Pará - UFPA, Av. Augusto Correa, Nº 1- Bairro: Guamá, Cep: 66.075-900 Belém-Pará, Brazil
| | - José M Bautista
- Research Institute Hospital 12 de Octubre, Avda. de Cordoba s/n, 28041 Madrid, Spain; Department of Biochemistry and Molecular Biology, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Diego Muñoz-Torrero
- Laboratory of Pharmaceutical Chemistry (CSIC Associated Unit), Faculty of Pharmacy and Food Sciences and IBUB, University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain.
| | - F Javier Luque
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain.
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8
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Lai L, Xu X, Lim CT, Cao J. Stiffening of Red Blood Cells Induced by Cytoskeleton Disorders: A Joint Theory-Experiment Study. Biophys J 2016; 109:2287-94. [PMID: 26636940 DOI: 10.1016/j.bpj.2015.10.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 09/30/2015] [Accepted: 10/20/2015] [Indexed: 11/17/2022] Open
Abstract
The functions and elasticities of the cell are largely related to the structures of the cytoskeletons underlying the lipid bilayer. Among various cell types, the red blood cell (RBC) possesses a relatively simple cytoskeletal structure. Underneath the membrane, the RBC cytoskeleton takes the form of a two-dimensional triangular network, consisting of nodes of actins (and other proteins) and edges of spectrins. Recent experiments focusing on the malaria-infected RBCs (iRBCs) show that there is a correlation between the elongation of spectrins in the cytoskeletal network and the stiffening of the iRBCs. Here we rationalize the correlation between these two observations by combining the wormlike chain model for single spectrins and the effective medium theory for the network elasticity. We specifically focus on how the disorders in the cytoskeletal network affect its macroscopic elasticity. Analytical and numerical solutions from our model reveal that the stiffness of the membrane increases with increasing end-to-end distances of spectrins, but has a nonmonotonic dependence on the variance of the end-to-end distance distributions. These predictions are verified quantitatively by our atomic force microscopy and micropipette aspiration measurements of iRBCs. The model may, from a molecular level, provide guidelines for future identification of new treatment methods for RBC-related diseases, such as malaria infection.
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Affiliation(s)
- Lipeng Lai
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Singapore; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Xiaofeng Xu
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Singapore; National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Chwee Teck Lim
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Singapore; National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Nano Biomechanics Laboratory, Department of Biomedical Engineering and Department of Mechanical Engineering, National University of Singapore, Singapore; Mechanobiology Institute, National University of Singapore, Singapore
| | - Jianshu Cao
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Singapore; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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9
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Shamriz S, Ofoghi H. Design, structure prediction and molecular dynamics simulation of a fusion construct containing malaria pre-erythrocytic vaccine candidate, PfCelTOS, and human interleukin 2 as adjuvant. BMC Bioinformatics 2016; 17:71. [PMID: 26851942 PMCID: PMC4744421 DOI: 10.1186/s12859-016-0918-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/29/2016] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Malaria infection is still widespread in some parts of the world and threatens the lives of millions of people every year. Vaccines, especially oral vaccines are considered to be effective in reducing the burden of malaria morbidity and mortality. By using recombinant technology, suitable oral hosts could serve as antigen delivering vehicles in developing oral vaccines. This study was aimed towards designing and computational analysis of a fusion protein consisting of Plasmodium falciparum cell-traversal protein for ookinetes and sporozoites (PfCelTOS) fused to human interleukin-2 (IL-2) and M cell-specific peptide ligand (Co1), as a step toward developing a vaccine candidate. RESULTS To our best knowledge, the three dimensional (3D) structure of CelTOS is not reported in protein database. Therefore, we carried out computational modeling and simulation in the hope of understanding the properties and structure of PfCelTOS. Then we fused IL-2 to PfCelTOS by a flexible linker and did in silico analysis to confirm the proper folding of each domain in the designed fusion protein. In the last step, Co1 ligand was added to the confirmed fusion structure using a rigid linker and computational analysis was performed to evaluate the final fusion construct. One structure out of five predicted by I-TASSER for PfCelTOS and fusion constructs was selected based on the highest value for C-score. Molecular dynamics (MD) simulation analysis indicated that predicted structures are stable during the simulation. Ramchandran Plot analysis of PfCelTOS and fusion constructs before and after MD simulation also represented that most residues were fallen in favorable regions. CONCLUSION In silico study showed that Co1-(AEEEK)3- IL-2-(GGGGS)3-PfCelTOS construct has a constant structure and the selected linkers are effectively able to separate the domains. Therefore, data reported in this paper represents the first step toward developing of an oral vaccine candidate against malaria infection.
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Affiliation(s)
- Shabnam Shamriz
- Department of Biotechnology, Iranian Research Organization for Science and Technology, Tehran, Iran.
| | - Hamideh Ofoghi
- Department of Biotechnology, Iranian Research Organization for Science and Technology, Tehran, Iran.
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Horning MP, Delahunt CB, Singh SR, Garing SH, Nichols KP. A paper microfluidic cartridge for automated staining of malaria parasites with an optically transparent microscopy window. Lab Chip 2014; 14:2040-2046. [PMID: 24781199 DOI: 10.1039/c4lc00293h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A paper microfluidic cartridge for the automated staining of malaria parasites (Plasmodium) with acridine orange prior to microscopy is presented. The cartridge enables simultaneous, sub-minute generation of both thin and thick smears of acridine orange stained parasites. Parasites are stained in a cellulose matrix, after which the parasites are ejected via capillary forces into an optically transparent chamber. The unique slanted design of the chamber ensures that a high percentage of the stained blood will be of the required thickness for a thin smear, without resorting to spacers or other methods that can increase production cost or require tight quality controls. A hydrophobic snorkel facilitates the removal of air bubbles during filling. The cartridge contains both a thin smear region, where a single layer of cells is presented unobstructed, for ease of species identification, and a thick smear region, containing multiple cell layers, for enhanced limit of detection.
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Affiliation(s)
- Matthew P Horning
- Intellectual Ventures Laboratory, 1555 132nd Ave NE, Bellevue, WA 98005, USA.
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Wang YB, Kong XL, Xu Y, Zhang Y, Li J, Zhao CL, Miao F, Chen XX. [Large trophozoites in blood smear of falciparum malaria: one case report]. Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi 2014; 26:355-356. [PMID: 25345178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper reports one case of atypical falciparum malaria imported from Africa, whose blood smear contains many large trophozoites, with punctiform or massive brown pigment granules, the body shape of the plasmodium is similar to that of Plasmodium vivax and Plasmodium ovale. After the gene detection by PCR, the case was diagnosed as falciparum malaria. As large trophozoites were rarely seen in the peripheral blood of non-severe falciparum malaria cases, much attention should be paid to the identification of Plasmodium falciparum and other plasmodia in microscopic examinations.
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Carrasco MP, Newton AS, Gonçalves L, Góis A, Machado M, Gut J, Nogueira F, Hänscheid T, Guedes RC, dos Santos DJVA, Rosenthal PJ, Moreira R. Probing the aurone scaffold against Plasmodium falciparum: design, synthesis and antimalarial activity. Eur J Med Chem 2014; 80:523-34. [PMID: 24813880 DOI: 10.1016/j.ejmech.2014.04.076] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 04/24/2014] [Accepted: 04/25/2014] [Indexed: 11/18/2022]
Abstract
A library comprising 44 diversely substituted aurones derivatives was synthesized by straightforward aldol condensation reactions of benzofuranones and the appropriately substituted benzaldehydes. Microwave enhanced synthesis using palladium catalyzed protocols was introduced as a powerful strategy for extending the chemical space around the aurone scaffold. Additionally, Mannich-base derivatives, containing a 7-aminomethyl-6-hydroxy substitution pattern at ring A, were also prepared. Screening against the chloroquine resistant Plasmodium falciparum W2 strain identified novel aurones with IC50 values in the low micromolar range. The most potent compounds contained a basic moiety, with the ability to accumulate in acidic digestive vacuole of the malaria parasite. However, none of those aurones revealed significant activity against hemozoin formation and falcipain-2, two validated targets expressed during the blood stage of P. falciparum infection and functional in digestive vacuole of the parasite. Overall, this study highlight (i) the usefulness of aurones as platforms for synthetic procedures using palladium catalyzed protocols to rapidly deliver lead compounds for further optimization and (ii) the potential of novel aurone derivatives as promising antimalarial compounds.
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Affiliation(s)
- Marta P Carrasco
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
| | - Ana S Newton
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
| | - Lídia Gonçalves
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
| | - Ana Góis
- Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, 1649-028 Lisboa, Portugal
| | - Marta Machado
- Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
| | - Jiri Gut
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, Box 0811, San Francisco, CA 94143, USA
| | - Fátima Nogueira
- Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
| | - Thomas Hänscheid
- Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, 1649-028 Lisboa, Portugal
| | - Rita C Guedes
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
| | - Daniel J V A dos Santos
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
| | - Philip J Rosenthal
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, Box 0811, San Francisco, CA 94143, USA
| | - Rui Moreira
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal.
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Beaudry JT, Krause MA, Diakite SAS, Fay MP, Joshi G, Diakite M, White NJ, Fairhurst RM. Ex-vivo cytoadherence phenotypes of Plasmodium falciparum strains from Malian children with hemoglobins A, S, and C. PLoS One 2014; 9:e92185. [PMID: 24647281 PMCID: PMC3960211 DOI: 10.1371/journal.pone.0092185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 02/20/2014] [Indexed: 11/18/2022] Open
Abstract
Sickle hemoglobin (Hb) S and HbC may protect against malaria by reducing the expression of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) on the surface of parasitized red blood cells (RBCs), thereby weakening their cytoadherence to microvascular endothelial cells (MVECs) and impairing their activation of MVECs to produce pathological responses. Therefore, we hypothesized that parasites causing malaria in HbAS or HbAC heterozygotes have overcome this protective mechanism by expressing PfEMP1 variants which mediate relatively strong binding to MVECs. To test this hypothesis, we performed 31 cytoadherence comparisons between parasites from HbAA and HbAS (or HbAC) Malian children with malaria. Ring-stage parasites from HbAA and HbAS (or HbAC) children were cultivated to trophozoites, purified, and then inoculated in parallel into the same wildtype uninfected RBCs. After one cycle of invasion and maturation to the trophozoite stage expressing PfEMP1, parasite strains were compared for binding to MVECs. In this assay, there were no significant differences in the binding of parasites from HbAS and HbAC children to MVECs compared to those from HbAA children (HbAS, fold-change = 1.46, 95% CI 0.97–2.19, p = 0.07; HbAC, fold-change = 1.19, 95% CI 0.77–1.84, p = 0.43). These data suggest that in-vitro reductions in cytoadherence by HbS and HbC may not be selecting for expression of high-avidity PfEMP1 variants in vivo. Future studies that identify PfEMP1 domains or amino-acid motifs which are selectively expressed in parasites from HbAS children may provide further insights into the mechanism of malaria protection by the sickle-cell trait.
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Affiliation(s)
- Jeanette T. Beaudry
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Michael A. Krause
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Seidina A. S. Diakite
- Faculty of Medicine, Pharmacy and Odontostomatology, Malaria Research and Training Center, University of Bamako, Bamako, Mali
| | - Michael P. Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gyan Joshi
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mahamadou Diakite
- Faculty of Medicine, Pharmacy and Odontostomatology, Malaria Research and Training Center, University of Bamako, Bamako, Mali
| | - Nicholas J. White
- Mahidol-Oxford Tropical Diseases Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rick M. Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Gisselberg JE, Dellibovi-Ragheb TA, Matthews KA, Bosch G, Prigge ST. The suf iron-sulfur cluster synthesis pathway is required for apicoplast maintenance in malaria parasites. PLoS Pathog 2013; 9:e1003655. [PMID: 24086138 PMCID: PMC3784473 DOI: 10.1371/journal.ppat.1003655] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 08/12/2013] [Indexed: 11/19/2022] Open
Abstract
The apicoplast organelle of the malaria parasite Plasmodium falciparum contains metabolic pathways critical for liver-stage and blood-stage development. During the blood stages, parasites lacking an apicoplast can grow in the presence of isopentenyl pyrophosphate (IPP), demonstrating that isoprenoids are the only metabolites produced in the apicoplast which are needed outside of the organelle. Two of the isoprenoid biosynthesis enzymes are predicted to rely on iron-sulfur (FeS) cluster cofactors, however, little is known about FeS cluster synthesis in the parasite or the roles that FeS cluster proteins play in parasite biology. We investigated two putative FeS cluster synthesis pathways (Isc and Suf) focusing on the initial step of sulfur acquisition. In other eukaryotes, these proteins can be located in multiple subcellular compartments, raising the possibility of cross-talk between the pathways or redundant functions. In P. falciparum, SufS and its partner SufE were found exclusively the apicoplast and SufS was shown to have cysteine desulfurase activity in a complementation assay. IscS and its effector Isd11 were solely mitochondrial, suggesting that the Isc pathway cannot contribute to apicoplast FeS cluster synthesis. The Suf pathway was disrupted with a dominant negative mutant resulting in parasites that were only viable when supplemented with IPP. These parasites lacked the apicoplast organelle and its organellar genome--a phenotype not observed when isoprenoid biosynthesis was specifically inhibited with fosmidomycin. Taken together, these results demonstrate that the Suf pathway is essential for parasite survival and has a fundamental role in maintaining the apicoplast organelle in addition to any role in isoprenoid biosynthesis.
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Affiliation(s)
- Jolyn E. Gisselberg
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Teegan A. Dellibovi-Ragheb
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Krista A. Matthews
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Gundula Bosch
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Sean T. Prigge
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Abstract
We present synthetic Fourier transform light scattering, a method for measuring extended angle-resolved light scattering (ARLS) from individual microscopic samples. By measuring the light fields scattered from the sample plane and numerically synthesizing them in Fourier space, the angle range of the ARLS patterns is extended up to twice the numerical aperture of the imaging system with unprecedented sensitivity and precision. Extended ARLS patterns of individual microscopic polystyrene beads, healthy human red blood cells (RBCs), and Plasmodium falciparum-parasitized RBCs are presented.
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Walker DM, Mahfooz N, Kemme KA, Patel VC, Spangler M, Drew ME. Plasmodium falciparum erythrocytic stage parasites require the putative autophagy protein PfAtg7 for normal growth. PLoS One 2013; 8:e67047. [PMID: 23825614 PMCID: PMC3692556 DOI: 10.1371/journal.pone.0067047] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 05/13/2013] [Indexed: 11/19/2022] Open
Abstract
Analysis of the Plasmodium falciparum genome reveals a limited number of putative autophagy genes, specifically the four genes involved in ATG8 lipidation, an essential step in formation of autophagosomes. In yeast, Atg8 lipidation requires the E1-type ligase Atg7, an E2-type ligase Atg3, and a cysteine protease Atg4. These four putative P. falciparum ATG (PfATG) genes are transcribed during the parasite's erythrocytic stages. PfAtg7 has relatively low identity and similarity to yeast Atg7 (14.7% and 32.2%, respectively), due primarily to long insertions typical of P. falciparum. Excluding the insertions the identity and similarity are higher (38.0% and 70.8%, respectively). This and the fact that key residues are conserved, including the catalytic cysteine and ATP binding domain, we hypothesize that PfAtg7 is the activating enzyme of PfAtg8. To assess the role of PfAtg7 we have generated two transgenic parasite lines. In one, the PfATG7 locus was modified to introduce a C-terminal hemagglutinin tag. Western blotting reveals two distinct protein species, one migrating near the predicted 150 kDa and one at approximately 65 kDa. The second transgenic line introduces an inducible degradation domain into the PfATG7 locus, allowing us to rapidly attenuate PfAtg7 protein levels. Corresponding species are also observed in this parasite line at approximately 200 kDa and 100 kDa. Upon PfATG7 attenuation parasites exhibit a slow growth phenotype indicating the essentiality of this putative enzyme for normal growth.
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Affiliation(s)
- Dawn M. Walker
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Najmus Mahfooz
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Katherine A. Kemme
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Viral C. Patel
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Maribeth Spangler
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Mark E. Drew
- Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Division of Medicinal Chemistry, The Ohio State University College of Pharmacy, Columbus, Ohio, United States of America
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Singh S, Chitnis CE. Flow cytometry-based methods for measurement of cytosolic calcium and surface protein expression in Plasmodium falciparum merozoites. Methods Mol Biol 2013; 923:281-290. [PMID: 22990785 DOI: 10.1007/978-1-62703-026-7_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An increased level of cytosolic free calcium (Ca(2+)) is an essential second messenger for apical organelle discharge in Plasmodium falciparum merozoites. Here, we describe a method for isolation of viable and invasive P. falciparum merozoites. We also describe methods to measure cytosolic Ca(2+) levels in merozoites using fluorescent intracellular calcium indicators such as Fluo-4AM by flow cytometry. Further, we also describe a flow cytometry-based method to detect translocation of apical organelle proteins to the surface of merozoites. Using these methods, we have advanced our understanding of signaling pathways involved in apical organelle discharge during erythrocyte invasion by P. falciparum merozoites.
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Affiliation(s)
- Shailja Singh
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Lelièvre J, Almela MJ, Lozano S, Miguel C, Franco V, Leroy D, Herreros E. Activity of clinically relevant antimalarial drugs on Plasmodium falciparum mature gametocytes in an ATP bioluminescence "transmission blocking" assay. PLoS One 2012; 7:e35019. [PMID: 22514702 PMCID: PMC3325938 DOI: 10.1371/journal.pone.0035019] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 03/08/2012] [Indexed: 01/12/2023] Open
Abstract
Background Current anti-malarial drugs have been selected on the basis of their activity against the symptom-causing asexual blood stage of the parasite. Which of these drugs also target gametocytes, in the sexual stage responsible for disease transmission, remains unknown. Blocking transmission is one of the main strategies in the eradication agenda and requires the identification of new molecules that are active against gametocytes. However, to date, the main limitation for measuring the effect of molecules against mature gametocytes on a large scale is the lack of a standardized and reliable method. Here we provide an efficient method to produce and purify mature gametocytes in vitro. Based on this new procedure, we developed a robust, affordable, and sensitive ATP bioluminescence-based assay. We then assessed the activity of 17 gold-standard anti-malarial drugs on Plasmodium late stage gametocytes. Methods and Findings Difficulties in producing large amounts of gametocytes have limited progress in the development of malaria transmission blocking assays. We improved the method established by Ifediba and Vanderberg to obtain viable, mature gametocytes en masse, whatever the strain used. We designed an assay to determine the activity of antimalarial drugs based on the intracellular ATP content of purified stage IV–V gametocytes after 48 h of drug exposure in 96/384-well microplates. Measurements of drug activity on asexual stages and cytotoxicity on HepG2 cells were also obtained to estimate the specificity of the active drugs. Conclusions The work described here represents another significant step towards determination of the activity of new molecules on mature gametocytes of any strain with an automated assay suitable for medium/high-throughput screening. Considering that the biology of the forms involved in the sexual and asexual stages is very different, a screen of our 2 million-compound library may allow us to discover novel anti-malarial drugs to target gametocyte-specific metabolic pathways.
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Affiliation(s)
- Joël Lelièvre
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
- * E-mail: (JL); (EH)
| | - Maria Jesus Almela
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
| | - Sonia Lozano
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
| | - Celia Miguel
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
| | - Virginia Franco
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Esperanza Herreros
- GlaxoSmithKline R&D, Tres Cantos Medicine Development Campus, Malaria Discovery Performance Unit, Madrid, Spain
- * E-mail: (JL); (EH)
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Tonwong N, Sattabongkot J, Tsuboi T, Iriko H, Takeo S, Sirichaisinthop J, Udomsangpetch R. Natural infection of Plasmodium falciparum induces inhibitory antibodies against gametocyte development in human hosts. Jpn J Infect Dis 2012; 65:152-156. [PMID: 22446123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We identified naturally induced antibodies from malaria patients in Thailand and clarified the effect of the antibodies on gametocyte development. Fifty-nine percent of the Plasmodium falciparum-infected blood samples (17 of 29) fed to female Anopheles mosquitoes showed no oocyst infection. Seventeen percent of the samples (5 of 29) distorted the morphology and hampered the maturity of the gametocytes. A possible mechanism for the gametocyte inhibitory activity was shown by the binding of the plasma antibodies to live, immature, intraerythrocytic gametocytes during the incubation period. One hundred fifty-seven proteins specific to different gametocyte stages were explored to find the targets of the antisera that bound to the live gametocytes. However, no additional gametocyte transmission-blocking vaccine candidate was detected. Therefore, the development of alternative transmission-blocking vaccines in high-transmission areas should focus on the identification of more gametocyte antigens-inducing inhibitory antibodies that reduce gametocytemia.
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Affiliation(s)
- Natda Tonwong
- Department of Parasitology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
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Tárnok A. Cytometry for protozoa related diseases. Cytometry A 2011; 79:885-6. [PMID: 22015729 DOI: 10.1002/cyto.a.21156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tamminga C, Sedegah M, Regis D, Chuang I, Epstein JE, Spring M, Mendoza-Silveiras J, McGrath S, Maiolatesi S, Reyes S, Steinbeiss V, Fedders C, Smith K, House B, Ganeshan H, Lejano J, Abot E, Banania GJ, Sayo R, Farooq F, Belmonte M, Murphy J, Komisar J, Williams J, Shi M, Brambilla D, Manohar N, Richie NO, Wood C, Limbach K, Patterson NB, Bruder JT, Doolan DL, King CR, Diggs C, Soisson L, Carucci D, Levine G, Dutta S, Hollingdale MR, Ockenhouse CF, Richie TL. Adenovirus-5-vectored P. falciparum vaccine expressing CSP and AMA1. Part B: safety, immunogenicity and protective efficacy of the CSP component. PLoS One 2011; 6:e25868. [PMID: 22003411 PMCID: PMC3189219 DOI: 10.1371/journal.pone.0025868] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 09/12/2011] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND A protective malaria vaccine will likely need to elicit both cell-mediated and antibody responses. As adenovirus vaccine vectors induce both these responses in humans, a Phase 1/2a clinical trial was conducted to evaluate the efficacy of an adenovirus serotype 5-vectored malaria vaccine against sporozoite challenge. METHODOLOGY/PRINCIPAL FINDINGS NMRC-MV-Ad-PfC is an adenovirus vector encoding the Plasmodium falciparum 3D7 circumsporozoite protein (CSP). It is one component of a two-component vaccine NMRC-M3V-Ad-PfCA consisting of one adenovector encoding CSP and one encoding apical membrane antigen-1 (AMA1) that was evaluated for safety and immunogenicity in an earlier study (see companion paper, Sedegah et al). Fourteen Ad5 seropositive or negative adults received two doses of NMRC-MV-Ad-PfC sixteen weeks apart, at 1 x 1010 particle units per dose. The vaccine was safe and well tolerated. All volunteers developed positive ELISpot responses by 28 days after the first immunization (geometric mean 272 spot forming cells/million[sfc/m]) that declined during the following 16 weeks and increased after the second dose to levels that in most cases were less than the initial peak (geometric mean 119 sfc/m). CD8+ predominated over CD4+ responses, as in the first clinical trial. Antibody responses were poor and like ELISpot responses increased after the second immunization but did not exceed the initial peak. Pre-existing neutralizing antibodies (NAb) to Ad5 did not affect the immunogenicity of the first dose, but the fold increase in NAb induced by the first dose was significantly associated with poorer antibody responses after the second dose, while ELISpot responses remained unaffected. When challenged by the bite of P. falciparum-infected mosquitoes, two of 11 volunteers showed a delay in the time to patency compared to infectivity controls, but no volunteers were sterilely protected. SIGNIFICANCE The NMRC-MV-Ad-PfC vaccine expressing CSP was safe and well tolerated given as two doses, but did not provide sterile protection. TRIAL REGISTRATION ClinicalTrials.gov NCT00392015.
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Affiliation(s)
- Cindy Tamminga
- U.S. Military Malaria Vaccine Program, Naval Medical Research Center, Silver Spring, Maryland, United States of America.
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Mok S, Imwong M, Mackinnon MJ, Sim J, Ramadoss R, Yi P, Mayxay M, Chotivanich K, Liong KY, Russell B, Socheat D, Newton PN, Day NPJ, White NJ, Preiser PR, Nosten F, Dondorp AM, Bozdech Z. Artemisinin resistance in Plasmodium falciparum is associated with an altered temporal pattern of transcription. BMC Genomics 2011; 12:391. [PMID: 21810278 PMCID: PMC3163569 DOI: 10.1186/1471-2164-12-391] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 08/03/2011] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Artemisinin resistance in Plasmodium falciparum malaria has emerged in Western Cambodia. This is a major threat to global plans to control and eliminate malaria as the artemisinins are a key component of antimalarial treatment throughout the world. To identify key features associated with the delayed parasite clearance phenotype, we employed DNA microarrays to profile the physiological gene expression pattern of the resistant isolates. RESULTS In the ring and trophozoite stages, we observed reduced expression of many basic metabolic and cellular pathways which suggests a slower growth and maturation of these parasites during the first half of the asexual intraerythrocytic developmental cycle (IDC). In the schizont stage, there is an increased expression of essentially all functionalities associated with protein metabolism which indicates the prolonged and thus increased capacity of protein synthesis during the second half of the resistant parasite IDC. This modulation of the P. falciparum intraerythrocytic transcriptome may result from differential expression of regulatory proteins such as transcription factors or chromatin remodeling associated proteins. In addition, there is a unique and uniform copy number variation pattern in the Cambodian parasites which may represent an underlying genetic background that contributes to the resistance phenotype. CONCLUSIONS The decreased metabolic activities in the ring stages are consistent with previous suggestions of higher resilience of the early developmental stages to artemisinin. Moreover, the increased capacity of protein synthesis and protein turnover in the schizont stage may contribute to artemisinin resistance by counteracting the protein damage caused by the oxidative stress and/or protein alkylation effect of this drug. This study reports the first global transcriptional survey of artemisinin resistant parasites and provides insight to the complexities of the molecular basis of pathogens with drug resistance phenotypes in vivo.
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Affiliation(s)
- Sachel Mok
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Thailand
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | | | - Joan Sim
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Ramya Ramadoss
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Poravuth Yi
- The National Center for Parasitology, Entomology, and Malaria Control, Phnom Penh, Cambodia
| | - Mayfong Mayxay
- Wellcome Trust-Mahosot Hospital-Oxford University Tropical Medicine Research Collaboration, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Faculty of Postgraduate Studies and Research, University of Health Sciences, Vientiane, Lao People's Democratic Republic
| | - Kesinee Chotivanich
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Kek-Yee Liong
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Bruce Russell
- Singapore Immunology Network, Biopolis, Agency for Science Technology and Research (ASTAR), Singapore
| | - Duong Socheat
- The National Center for Parasitology, Entomology, and Malaria Control, Phnom Penh, Cambodia
| | - Paul N Newton
- Wellcome Trust-Mahosot Hospital-Oxford University Tropical Medicine Research Collaboration, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Nicholas PJ Day
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Nicholas J White
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Peter R Preiser
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - François Nosten
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK
- Shoklo Malaria Research Unit, Mae Sot, Thailand
| | - Arjen M Dondorp
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore
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Gowda NM, Wu X, Gowda DC. The nucleosome (histone-DNA complex) is the TLR9-specific immunostimulatory component of Plasmodium falciparum that activates DCs. PLoS One 2011; 6:e20398. [PMID: 21687712 PMCID: PMC3110622 DOI: 10.1371/journal.pone.0020398] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 05/01/2011] [Indexed: 11/24/2022] Open
Abstract
The systemic clinical symptoms of Plasmodium falciparum infection such as fever and chills correspond to the proinflammatory cytokines produced in response to the parasite components released during the synchronized rupture of schizonts. We recently demonstrated that, among the schizont-released products, merozoites are the predominant components that activate dendritic cells (DCs) by TLR9-specific recognition to induce the maturation of cells and to produce proinflammatory cytokines. We also demonstrated that DNA is the active constituent and that formation of a DNA-protein complex is essential for the entry of parasite DNA into cells for recognition by TLR9. However, the nature of endogenous protein-DNA complex in the parasite is not known. In this study, we show that parasite nucleosome constitute the major protein-DNA complex involved in the activation of DCs by parasite nuclear material. The parasite components were fractionated into the nuclear and non-nuclear materials. The nuclear material was further fractionated into chromatin and the proteins loosely bound to chromatin. Polynucleosomes and oligonucleosomes were prepared from the chromatin. These were tested for their ability to activate DCs obtained by the FLT3 ligand differentiation of bone marrow cells from the wild type, and TLR2(-/-), TLR9(-/-) and MyD88(-/-) mice. DCs stimulated with the nuclear material and polynucleosomes as well as mono- and oligonucleosomes efficiently induced the production of proinflammatory cytokines in a TLR9-dependent manner, demonstrating that nucleosomes (histone-DNA complex) represent the major TLR9-specific DC-immunostimulatory component of the malaria parasite nuclear material. Thus, our data provide a significant insight into the activation of DCs by malaria parasites and have important implications for malaria vaccine development.
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Affiliation(s)
- Nagaraj M. Gowda
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Xianzhu Wu
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - D. Channe Gowda
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
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Zhang Q, Zhang Y, Huang Y, Xue X, Yan H, Sun X, Wang J, McCutchan TF, Pan W. From in vivo to in vitro: dynamic analysis of Plasmodium falciparum var gene expression patterns of patient isolates during adaptation to culture. PLoS One 2011; 6:e20591. [PMID: 21674009 PMCID: PMC3108956 DOI: 10.1371/journal.pone.0020591] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Accepted: 05/04/2011] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by the var gene family, plays a crucial role in disease virulence through its involvement in binding to various host cellular receptors during infection. Growing evidence suggests that differential expression of the various var subgroups may be involved in parasite virulence. To further explore this issue, we have collected isolates from symptomatic patients in south China-Myanmar border, and characterized their sequence diversity and transcription profiles over time of var gene family, and cytoadherence properties from the time of their initial collection and extending through a two month period of adaptation to culture. Initially, we established a highly diverse, DBLα (4 cysteines) subtype-enriched, but unique local repertoire of var-DBL1α sequences by cDNA cloning and sequencing. Next we observed a rapid transcriptional decline of upsA- and upsB-subtype var genes at ring stage through qRT-PCR assays, and a switching event from initial ICAM-I binding to the CD36-binding activity during the first week of adaptive cultivation in vitro. Moreover, predominant transcription of upsA var genes was observed to be correlated with those isolates that showed a higher parasitemia at the time of collection and the ICAM-1-binding phenotype in culture. Taken together, these data indicate that the initial stage of adaptive process in vitro significantly influences the transcription of virulence-related var subtypes and expression of PfEMP1 variants. Further, the specific upregulation of the upsA var genes is likely linked to the rapid propagation of the parasite during natural infection due to the A-type PfEMP1 variant-mediated growth advantages.
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Affiliation(s)
- Qingfeng Zhang
- Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Yilong Zhang
- Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Yufu Huang
- Department of Pathogen Biology, Second Military Medical University, Shanghai, China
| | - Xiangyang Xue
- Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - He Yan
- Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Xiaodong Sun
- Yunnan Institute of Parasitic Diseases, Puer, China
| | - Jian Wang
- Yunnan Institute of Parasitic Diseases, Puer, China
| | - Thomas F. McCutchan
- Department of Pathogen Biology, Second Military Medical University, Shanghai, China
| | - Weiqing Pan
- Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China
- Department of Pathogen Biology, Second Military Medical University, Shanghai, China
- * E-mail:
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Kajla MK, Shi L, Li B, Luckhart S, Li J, Paskewitz SM. A new role for an old antimicrobial: lysozyme c-1 can function to protect malaria parasites in Anopheles mosquitoes. PLoS One 2011; 6:e19649. [PMID: 21573077 PMCID: PMC3089642 DOI: 10.1371/journal.pone.0019649] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 04/13/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Plasmodium requires an obligatory life stage in its mosquito host. The parasites encounter a number of insults while journeying through this host and have developed mechanisms to avoid host defenses. Lysozymes are a family of important antimicrobial immune effectors produced by mosquitoes in response to microbial challenge. METHODOLOGY/PRINCIPAL FINDINGS A mosquito lysozyme was identified as a protective agonist for Plasmodium. Immunohistochemical analyses demonstrated that Anopheles gambiae lysozyme c-1 binds to oocysts of Plasmodium berghei and Plasmodium falciparum at 2 and 5 days after infection. Similar results were observed with Anopheles stephensi and P. falciparum, suggesting wide occurrence of this phenomenon across parasite and vector species. Lysozyme c-1 did not bind to cultured ookinetes nor did recombinant lysozyme c-1 affect ookinete viability. dsRNA-mediated silencing of LYSC-1 in Anopheles gambiae significantly reduced the intensity and the prevalence of Plasmodium berghei infection. We conclude that this host antibacterial protein directly interacts with and facilitates development of Plasmodium oocysts within the mosquito. CONCLUSIONS/SIGNIFICANCE This work identifies mosquito lysozyme c-1 as a positive mediator of Plasmodium development as its reduction reduces parasite load in the mosquito host. These findings improve our understanding of parasite development and provide a novel target to interrupt parasite transmission to human hosts.
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Affiliation(s)
- Mayur K. Kajla
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Lei Shi
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
- Section of Allergy, Pulmonary and Critical Care, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Bin Li
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
- Section of Microbiology, College of Biological Sciences, University of California Davis, Davis, California, United States of America
| | - Shirley Luckhart
- Department of Medical Microbiology and Immunology, University of California Davis, School of Medicine, Davis, California, United States of America
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Susan M. Paskewitz
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
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26
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Paton D, Faragher B, Mustaffa KMF, Szestak T, Barrett SD, Craig AG. Automated counting for Plasmodium falciparum cytoadherence experiments. Malar J 2011; 10:91. [PMID: 21496305 PMCID: PMC3094228 DOI: 10.1186/1475-2875-10-91] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 04/16/2011] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The ability of mature forms of Plasmodium falciparum infected erythrocytes to bind to a range of host receptors including those displayed on endothelial cells has been associated with the pathology of this infection. Investigations into this adhesive phenomenon have used protein and cell-based adhesion assays to quantify the ability of infected red blood cells to bind. These adhesion assays tend to have relatively high inherent variability and so require multiple experiments in order to provide good quantitation. This means that investigators doing these experiments must count many fields of adherent parasites, a task that is time-consuming and laborious. To address this issue and to facilitate cytoadherence research, developed automated protocols were developed for counting parasite adhesion. METHODS Parasite adhesion assays were mainly carried out under static conditions using purified receptors, which is the simplest form of these assays and is translatable to the field. Two different software platforms were used, one commercial (Image Pro-Plus (Media Cybernetics)) and one available in the public domain (ImageSXM) based on the freely available NIH Image software. The adhesion assays were performed and parasite binding quantified using standard manual techniques. Images were also captured using video microscopy and analysed using the two automated systems. The results generated by each system were compared using the Bland and Altman method for assessing the agreement between two methods. RESULTS Both automated counting programs showed concordance compared to the 'gold standard' manual counting within the normal range of adhesion seen with these assays, although the ImageSXM technique had some systematic bias. There was some fall-off in accuracy at very high parasite densities, but this can be resolved through good design of the experiments. Cell based assays were also used as inputs to one of the automated systems (ImageSXM) and produced variable, but encouraging, results. CONCLUSIONS The automated counting programs are an accurate and practical way of quantifying static parasite binding assays to purified proteins. They are less accurate when applied to cell based systems, but can still provide a reasonable level of accuracy to give a semi-quantitative readout.
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Affiliation(s)
- Douglas Paton
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Research Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire ST5 5BG, UK
| | - Brian Faragher
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Khairul MF Mustaffa
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Institute for Research in Molecular Medicine (INFORMM), Health Campus, Universiti Sains Malaysia, Kubang Kerian, 16150 Kelantan, Malaysia
| | - Tadge Szestak
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Steve D Barrett
- Department of Physics, University of Liverpool, Liverpool L69 3BX, UK
| | - Alister G Craig
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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Ochola LB, Siddondo BR, Ocholla H, Nkya S, Kimani EN, Williams TN, Makale JO, Liljander A, Urban BC, Bull PC, Szestak T, Marsh K, Craig AG. Specific receptor usage in Plasmodium falciparum cytoadherence is associated with disease outcome. PLoS One 2011; 6:e14741. [PMID: 21390226 PMCID: PMC3048392 DOI: 10.1371/journal.pone.0014741] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 01/07/2011] [Indexed: 12/22/2022] Open
Abstract
Our understanding of the basis of severe disease in malaria is incomplete. It is clear that pathology is in part related to the pro-inflammatory nature of the host response but a number of other factors are also thought to be involved, including the interaction between infected erythrocytes and endothelium. This is a complex system involving several host receptors and a major parasite-derived variant antigen (PfEMP1) expressed on the surface of the infected erythrocyte membrane. Previous studies have suggested a role for ICAM-1 in the pathology of cerebral malaria, although these have been inconclusive. In this study we have examined the cytoadherence patterns of 101 patient isolates from varying clinical syndromes to CD36 and ICAM-1, and have used variant ICAM-1 proteins to further characterise this adhesive phenotype. Our results show that increased binding to CD36 is associated with uncomplicated malaria while ICAM-1 adhesion is raised in parasites from cerebral malaria cases.
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Affiliation(s)
- Lucy B Ochola
- KEMRI/Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya.
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Liljander A, Bejon P, Mwacharo J, Kai O, Ogada E, Peshu N, Marsh K, Färnert A. Clearance of asymptomatic P. falciparum Infections Interacts with the number of clones to predict the risk of subsequent malaria in Kenyan children. PLoS One 2011; 6:e16940. [PMID: 21383984 PMCID: PMC3044709 DOI: 10.1371/journal.pone.0016940] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 01/17/2011] [Indexed: 12/20/2022] Open
Abstract
Background Protective immunity to malaria is acquired after repeated infections in endemic areas. Asymptomatic multiclonal P. falciparum infections are common and may predict host protection. Here, we have investigated the effect of clearing asymptomatic infections on the risk of clinical malaria. Methods Malaria episodes were continuously monitored in 405 children (1–6 years) in an area of moderate transmission, coastal Kenya. Blood samples collected on four occasions were assessed by genotyping the polymorphic P. falciparum merozoite surface protein 2 using fluorescent PCR and capillary electrophoresis. Following the second survey, asymptomatic infections were cleared with a full course of dihydroartemisinin. Results Children who were parasite negative by PCR had a lower risk of subsequent malaria regardless of whether treatment had been given. Children with ≥2 clones had a reduced risk of febrile malaria compared with 1 clone after clearance of asymptomatic infections, but not if asymptomatic infections were not cleared. Multiclonal infection was associated with an increased risk of re-infection after drug treatment. However, among the children who were re-infected, multiclonal infections were associated with a shift from clinical malaria to asymptomatic parasitaemia. Conclusion The number of clones was associated with exposure as well as blood stage immunity. These effects were distinguished by clearing asymptomatic infection with anti-malarials. Exposure to multiple P. falciparum infections is associated with protective immunity, but there appears to be an additional effect in untreated multiclonal infections that offsets this protective effect.
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Affiliation(s)
- Anne Liljander
- Infectious Diseases Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Philip Bejon
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Oxford University, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jedidah Mwacharo
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Oscar Kai
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Edna Ogada
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Norbert Peshu
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Kevin Marsh
- Centre for Geographical Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Oxford University, John Radcliffe Hospital, Oxford, United Kingdom
| | - Anna Färnert
- Infectious Diseases Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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Kehr S, Sturm N, Rahlfs S, Przyborski JM, Becker K. Compartmentation of redox metabolism in malaria parasites. PLoS Pathog 2010; 6:e1001242. [PMID: 21203490 PMCID: PMC3009606 DOI: 10.1371/journal.ppat.1001242] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 11/23/2010] [Indexed: 01/06/2023] Open
Abstract
Malaria, caused by the apicomplexan parasite Plasmodium, still represents a major threat to human health and welfare and leads to about one million human deaths annually. Plasmodium is a rapidly multiplying unicellular organism undergoing a complex developmental cycle in man and mosquito – a life style that requires rapid adaptation to various environments. In order to deal with high fluxes of reactive oxygen species and maintain redox regulatory processes and pathogenicity, Plasmodium depends upon an adequate redox balance. By systematically studying the subcellular localization of the major antioxidant and redox regulatory proteins, we obtained the first complete map of redox compartmentation in Plasmodium falciparum. We demonstrate the targeting of two plasmodial peroxiredoxins and a putative glyoxalase system to the apicoplast, a non-photosynthetic plastid. We furthermore obtained a complete picture of the compartmentation of thioredoxin- and glutaredoxin-like proteins. Notably, for the two major antioxidant redox-enzymes – glutathione reductase and thioredoxin reductase – Plasmodium makes use of alternative-translation-initiation (ATI) to achieve differential targeting. Dual localization of proteins effected by ATI is likely to occur also in other Apicomplexa and might open new avenues for therapeutic intervention. The unicellular parasite Plasmodium falciparum is the causative agent of tropical malaria, which represents a global health burden. In order to survive in its human host and the malaria vector Anopheles, malaria parasites depend on adequate antioxidant defense and efficient redox regulation. Furthermore, as shown by glucose-6 phosphate dehydrogenase deficiency, a genetic variation protecting from malaria, redox equilibrium plays a vital role in parasite pathogenicity. Using a green fluorescent protein reporter gene, we systematically studied the subcellular compartmentation of redox networks in Plasmodium falciparum. Based on our results and data from literature, we provide the first thorough map of redox compartmentation. Most interestingly, for the two major antioxidant redox-enzymes – glutathione reductase (GR) and thioredoxin reductase (TrxR) – Plasmodium falciparum makes use of alternative translation initiation to translate protein isoforms with differing subcellular localization from one gene. Dual localization of proteins due to alternative translation initiation might occur frequently in Apicomplexa and identification of further genes that have evolved alternative translation initiation is likely to offer new therapeutic strategies against this devastating disease.
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Affiliation(s)
- Sebastian Kehr
- Interdisciplinary Research Centre, Justus Liebig University, Giessen, Germany
| | - Nicole Sturm
- Interdisciplinary Research Centre, Justus Liebig University, Giessen, Germany
| | - Stefan Rahlfs
- Interdisciplinary Research Centre, Justus Liebig University, Giessen, Germany
| | - Jude M. Przyborski
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Katja Becker
- Interdisciplinary Research Centre, Justus Liebig University, Giessen, Germany
- * E-mail:
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30
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Affiliation(s)
- Abbas Hashim Abdulsalam
- Al-yarmouk Teaching Hospital, Teaching Laboratories Department, Haematology Unit, Baghdad, Iraq
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Veiga MI, Ferreira PE, Schmidt BA, Ribacke U, Björkman A, Tichopad A, Gil JP. Antimalarial exposure delays Plasmodium falciparum intra-erythrocytic cycle and drives drug transporter genes expression. PLoS One 2010; 5:e12408. [PMID: 20811640 PMCID: PMC2928296 DOI: 10.1371/journal.pone.0012408] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 08/04/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Multi-drug resistant Plasmodium falciparum is a major obstacle to malaria control and is emerging as a complex phenomenon. Mechanisms of drug evasion based on the intracellular extrusion of the drug and/or modification of target proteins have been described. However, cellular mechanisms related with metabolic activity have also been seen in eukaryotic systems, e.g. cancer cells. Recent observations suggest that such mechanism may occur in P. falciparum. METHODOLOGY/PRINCIPAL FINDINGS We therefore investigated the effect of mefloquine exposure on the cell cycle of three P. falciparum clones (3D7, FCB, W2) with different drug susceptibilities, while investigating in parallel the expression of four genes coding for confirmed and putative drug transporters (pfcrt, pfmdr1, pfmrp1 and pfmrp2). Mefloquine induced a previously not described dose and clone dependent delay in the intra-erythrocytic cycle of the parasite. Drug impact on cell cycle progression and gene expression was then merged using a non-linear regression model to determine specific drug driven expression. This revealed a mild, but significant, mefloquine driven gene induction up to 1.5 fold. CONCLUSIONS/SIGNIFICANCE Both cell cycle delay and induced gene expression represent potentially important mechanisms for parasites to escape the effect of the antimalarial drug.
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Affiliation(s)
- Maria Isabel Veiga
- Malaria Research Lab, Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
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Olszewski KL, Mather MW, Morrisey JM, Garcia BA, Vaidya AB, Rabinowitz JD, Llinás M. Branched tricarboxylic acid metabolism in Plasmodium falciparum. Nature 2010; 466:774-8. [PMID: 20686576 PMCID: PMC2917841 DOI: 10.1038/nature09301] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 06/11/2010] [Indexed: 12/25/2022]
Abstract
A central hub of carbon metabolism is the tricarboxylic acid cycle, which serves to connect the processes of glycolysis, gluconeogenesis, respiration, amino acid synthesis and other biosynthetic pathways. The protozoan intracellular malaria parasites (Plasmodium spp.), however, have long been suspected of possessing a significantly streamlined carbon metabolic network in which tricarboxylic acid metabolism plays a minor role. Blood-stage Plasmodium parasites rely almost entirely on glucose fermentation for energy and consume minimal amounts of oxygen, yet the parasite genome encodes all of the enzymes necessary for a complete tricarboxylic acid cycle. Here, by tracing (13)C-labelled compounds using mass spectrometry we show that tricarboxylic acid metabolism in the human malaria parasite Plasmodium falciparum is largely disconnected from glycolysis and is organized along a fundamentally different architecture from the canonical textbook pathway. We find that this pathway is not cyclic, but rather is a branched structure in which the major carbon sources are the amino acids glutamate and glutamine. As a consequence of this branched architecture, several reactions must run in the reverse of the standard direction, thereby generating two-carbon units in the form of acetyl-coenzyme A. We further show that glutamine-derived acetyl-coenzyme A is used for histone acetylation, whereas glucose-derived acetyl-coenzyme A is used to acetylate amino sugars. Thus, the parasite has evolved two independent production mechanisms for acetyl-coenzyme A with different biological functions. These results significantly clarify our understanding of the Plasmodium metabolic network and highlight the ability of altered variants of central carbon metabolism to arise in response to unique environments.
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Affiliation(s)
- Kellen L. Olszewski
- Department of Molecular Biology & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544
| | - Michael W. Mather
- Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Joanne M. Morrisey
- Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Benjamin A. Garcia
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Akhil B. Vaidya
- Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Joshua D. Rabinowitz
- Department of Chemistry & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544
| | - Manuel Llinás
- Department of Molecular Biology & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544
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Deu E, Yang Z, Wang F, Klemba M, Bogyo M. Use of activity-based probes to develop high throughput screening assays that can be performed in complex cell extracts. PLoS One 2010; 5:e11985. [PMID: 20700487 PMCID: PMC2916841 DOI: 10.1371/journal.pone.0011985] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Accepted: 07/15/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND High throughput screening (HTS) is one of the primary tools used to identify novel enzyme inhibitors. However, its applicability is generally restricted to targets that can either be expressed recombinantly or purified in large quantities. METHODOLOGY AND PRINCIPAL FINDINGS Here, we described a method to use activity-based probes (ABPs) to identify substrates that are sufficiently selective to allow HTS in complex biological samples. Because ABPs label their target enzymes through the formation of a permanent covalent bond, we can correlate labeling of target enzymes in a complex mixture with inhibition of turnover of a substrate in that same mixture. Thus, substrate specificity can be determined and substrates with sufficiently high selectivity for HTS can be identified. In this study, we demonstrate this method by using an ABP for dipeptidyl aminopeptidases to identify (Pro-Arg)2-Rhodamine as a specific substrate for DPAP1 in Plasmodium falciparum lysates and Cathepsin C in rat liver extracts. We then used this substrate to develop highly sensitive HTS assays (Z'>0.8) that are suitable for use in screening large collections of small molecules (i.e >300,000) for inhibitors of these proteases. Finally, we demonstrate that it is possible to use broad-spectrum ABPs to identify target-specific substrates. CONCLUSIONS We believe that this approach will have value for many enzymatic systems where access to large amounts of active enzyme is problematic.
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Affiliation(s)
- Edgar Deu
- Department of Pathology, Stanford School of Medicine, Stanford, California, United States of America
| | - Zhimou Yang
- Department of Pathology, Stanford School of Medicine, Stanford, California, United States of America
| | - Flora Wang
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Michael Klemba
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Matthew Bogyo
- Department of Pathology, Stanford School of Medicine, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, California, United States of America
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Contreras-Dominguez M, Moraes CB, Dorval T, Genovesio A, Dossin FDM, Freitas-Junior LH. A modified fluorescence in situ hybridization protocol for Plasmodium falciparum greatly improves nuclear architecture conservation. Mol Biochem Parasitol 2010; 173:48-52. [PMID: 20433875 DOI: 10.1016/j.molbiopara.2010.04.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Revised: 04/14/2010] [Accepted: 04/19/2010] [Indexed: 12/17/2022]
Abstract
Fluorescence in situ hybridization (FISH) has been used extensively in the study of nuclear organization and gene positioning in Plasmodium falciparum. While performing FISH with published protocols, we observed large variations in parasite nuclear morphology. We hypothesized that these inconsistencies might be due to the type of parasite preparation prior to FISH, which commonly involves air-drying, prompting us to develop a new fixation protocol. Here we show both qualitatively and quantitatively that compared to air-dried and briefly fixed parasites, longer fixation in suspension leads to improved conservation of nuclear structure and lower intra-population variation of nuclear shape as well as area after FISH development. While the fixation protocol per se does not cause detectable disruptions in nuclear morphology, it greatly influences the conservation of nuclear shape and size during the most stringent steps of FISH. The type of fixation used also influences the detection of telomeric clusters, and we show that the new fixation protocol permits improved conservation of the chromosome end cluster perinuclear distribution and higher colocalization indexes for two adjacent chromosome end probes, Rep20 and telomere. Overall, the results indicate that our alternative protocol dramatically improves conservation of the nuclear architecture compared to previously reported Plasmodium DNA-FISH protocols and highlights the necessity of carefully choosing the fixation protocol for FISH.
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Affiliation(s)
- Monica Contreras-Dominguez
- Center for Neglected Diseases Drug Discovery, Institut Pasteur Korea, Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea
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Ouédraogo AL, Bousema T, Schneider P, de Vlas SJ, Ilboudo-Sanogo E, Cuzin-Ouattara N, Nébié I, Roeffen W, Verhave JP, Luty AJF, Sauerwein R. Substantial contribution of submicroscopical Plasmodium falciparum gametocyte carriage to the infectious reservoir in an area of seasonal transmission. PLoS One 2009; 4:e8410. [PMID: 20027314 PMCID: PMC2793432 DOI: 10.1371/journal.pone.0008410] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Accepted: 11/22/2009] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Man to mosquito transmission of malaria depends on the presence of the sexual stage parasites, gametocytes, that often circulate at low densities. Gametocyte densities below the microscopical threshold of detection may be sufficient to infect mosquitoes but the importance of submicroscopical gametocyte carriage in different transmission settings is unknown. METHODOLOGY/PRINCIPAL FINDINGS Membrane feeding experiments were carried out on 80 children below 14 years of age at the end of the wet season in an area of seasonal malaria transmission in Burkina Faso. Gametocytes were quantified by microscopy and by Pfs25-based quantitative nucleic acid sequence-based amplification assay (QT-NASBA). The children's infectiousness was determined by membrane feeding experiments in which a venous blood sample was offered to locally reared Anopheles mosquitoes. Gametocytes were detected in 30.0% (24/80) of the children by microscopy compared to 91.6% (65/71) by QT-NASBA (p<0.001). We observed a strong association between QT-NASBA gametocyte density and infection rates (p = 0.007). Children with microscopically detectable gametocytes were more likely to be infectious (68.2% compared to 31.7% of carriers of submicroscopical gametocytes, p = 0.001), and on average infected more mosquitoes (13.2% compared to 2.3%, p<0.001). However, because of the high prevalence of submicroscopical gametocyte carriage in the study population, carriers of sub-microscopical gametocytes were responsible for 24.2% of the malaria transmission in this population. CONCLUSIONS/SIGNIFICANCE Submicroscopical gametocyte carriage is common in an area of seasonal transmission in Burkina Faso and contributes substantially to the human infectious reservoir. Submicroscopical gametocyte carriage should therefore be considered when implementing interventions that aim to reduce malaria transmission.
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Affiliation(s)
- André Lin Ouédraogo
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
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Brolin KJM, Ribacke U, Nilsson S, Ankarklev J, Moll K, Wahlgren M, Chen Q. Simultaneous transcription of duplicated var2csa gene copies in individual Plasmodium falciparum parasites. Genome Biol 2009; 10:R117. [PMID: 19849836 PMCID: PMC2784332 DOI: 10.1186/gb-2009-10-10-r117] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 08/22/2009] [Accepted: 10/22/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Single nucleotide polymorphisms are common in duplicated genes, causing functional preservation, alteration or silencing. The Plasmodium falciparum genes var2csa and Pf332 are duplicated in the haploid genome of the HB3 parasite line. Whereas the molecular function of Pf332 remains to be elucidated, VAR2CSA is known to be the main adhesin in placental parasite sequestration. Sequence variations introduced upon duplication of these genes provide discriminative possibilities to analyze allele-specific transcription with a bearing towards understanding gene dosage impact on parasite biology. RESULTS We demonstrate an approach combining real-time PCR allelic discrimination and discriminative RNA-FISH to distinguish between highly similar gene copies in P. falciparum parasites. The duplicated var2csa variants are simultaneously transcribed, both on a population level and intriguingly also in individual cells, with nuclear co-localization of the active genes and corresponding transcripts. This indicates transcriptional functionality of duplicated genes, challenges the dogma of mutually exclusive var gene transcription and suggests mechanisms behind antigenic variation, at least in respect to the duplicated and highly similar var2csa genes. CONCLUSIONS Allelic discrimination assays have traditionally been applied to study zygosity in diploid genomes. The assays presented here are instead successfully applied to the identification and evaluation of transcriptional activity of duplicated genes in the haploid genome of the P. falciparum parasite. Allelic discrimination and gene or transcript localization by FISH not only provide insights into transcriptional regulation of genes such as the virulence associated var genes, but also suggest that this sensitive and precise approach could be used for further investigation of genome dynamics and gene regulation.
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Affiliation(s)
- Kim JM Brolin
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
| | - Sandra Nilsson
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
| | - Johan Ankarklev
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
- Department of Cell and Molecular Biology, Uppsala University, Husargatan 3, SE-751 21 Uppsala, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
| | - Qijun Chen
- Department of Microbiology, Tumor and Cell Biology, Nobels Väg 16, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Swedish Institute for Infectious Disease Control, Nobels Väg 18, SE-171 82, Stockholm, Sweden
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, China
- Laboratory of Parasitology, Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Dong Dan San Tiao 9, Beijing 100730, China
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Oesterholt MJAM, Alifrangis M, Sutherland CJ, Omar SA, Sawa P, Howitt C, Gouagna LC, Sauerwein RW, Bousema T. Submicroscopic gametocytes and the transmission of antifolate-resistant Plasmodium falciparum in Western Kenya. PLoS One 2009; 4:e4364. [PMID: 19194499 PMCID: PMC2632751 DOI: 10.1371/journal.pone.0004364] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 12/22/2008] [Indexed: 11/24/2022] Open
Abstract
Background Single nucleotide polymorphisms (SNPs) in the dhfr and dhps genes are associated with sulphadoxine-pyrimethamine (SP) treatment failure and gametocyte carriage. This may result in enhanced transmission of mutant malaria parasites, as previously shown for chloroquine resistant parasites. In the present study, we determine the association between parasite mutations, submicroscopic P. falciparum gametocytemia and malaria transmission to mosquitoes. Methodology/Principal Findings Samples from children treated with SP alone or in combination with artesunate (AS) or amodiaquine were genotyped for SNPs in the dhfr and dhps genes. Gametocytemia was determined by microscopy and Pfs25 RNA–based quantitative nucleic acid sequence–based amplification (Pfs25 QT-NASBA). Transmission was determined by membrane-feeding assays. We observed no wild type infections, 66.5% (127/191) of the infections expressed mutations at all three dhfr codons prior to treatment. The presence of all three mutations was not related to higher Pfs25 QT-NASBA gametocyte prevalence or density during follow-up, compared to double mutant infections. The proportion of infected mosquitoes or oocyst burden was also not related to the number of mutations. Addition of AS to SP reduced gametocytemia and malaria transmission during follow-up. Conclusions/Significance In our study population where all infections had at least a double mutation in the dhfr gene, additional mutations were not related to increased submicroscopic gametocytemia or enhanced malaria transmission. The absence of wild-type infections is likely to have reduced our power to detect differences. Our data further support the use of ACT to reduce the transmission of drug-resistant malaria parasites.
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Affiliation(s)
- Mayke J. A. M. Oesterholt
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Michael Alifrangis
- Centre for Medical Parasitology at the Department of International Health, Immunology and Microbiology, University of Copenhagen, and at the Department of infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Colin J. Sutherland
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Sabah A. Omar
- Kenya Medical Research Institute, Centre for Biotechnology Research and Development, Nairobi, Kenya
| | - Patrick Sawa
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita, Kenya
| | - Christina Howitt
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Louis C. Gouagna
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita, Kenya
- Institut de Recherche pour le Développement, Bobo Dioulasso, Burkina Faso
| | - Robert W. Sauerwein
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail:
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Rada AM, Moreno C, Blair S. [Successful in vitro culture of Plasmodium falciparum gametocytes]. Biomedica 2008; 28:607-615. [PMID: 19462566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
INTRODUCTION The sexual stages of Plasmodium falciparum have not been studied in as much detail as the asexual stages due to the lack of standardized in vitro cultures as well as difficulties in identifying the sexual development stages of the parasite. These difficulties hamper the studies on biology, metabolism, gene expression and protein synthesis during sexual stages. Each of these facets are important targets in antimalarial drug research, particularly the identification of potential therapeutic agents against Plasmodium (derived mainly from plants). OBJECTIVES An in vitro culture of P. falciparum gametocytes was established to standardize the identification of its five developmental stages and ensure their continuous production. MATERIALS AND METHODS The in vitro gametocyte culture was established from the P. falciparum NF54 strain in RPMI culture medium, with assessment of the asexual and sexual parasitaemia. The medium was supplemented with type A Rh+ red blood cells only on the first day of culture. Subsequently, the medium was changed daily, together with addition of gas mixture (90% N2, 5% O2, 5% CO2) and maintenance of the culture temperature at 37 degrees C. When asexual parasitaemia reached 3 to 5%, the medium was changed by doubling its volume. CONCLUSIONS We standardized an in vitro culture for sexual stages of P. falciparum that can be used for future studies about evaluation of compounds of synthetic or natural origen against the sexual stage, which may permit to develop new control strategies against malaria.
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Abstract
The clinical outcomes of human infections by Plasmodium falciparum remain highly unpredictable. A complete understanding of the complex interactions between host cells and the parasite will require in vitro experimental models that simultaneously capture diverse host-parasite interactions relevant to pathogenesis. Here we show that advanced microfluidic devices concurrently model (a) adhesion of infected red blood cells to host cell ligands, (b) rheological responses to changing dimensions of capillaries with shapes and sizes similar to small blood vessels, and (c) phagocytosis of infected erythrocytes by macrophages. All of this is accomplished under physiologically relevant flow conditions for up to 20 h. Using select examples, we demonstrate how this enabling technology can be applied in novel, integrated ways to dissect interactions between host cell ligands and parasitized erythrocytes in synthetic capillaries. The devices are cheap and portable and require small sample volumes; thus, they have the potential to be widely used in research laboratories and at field sites with access to fresh patient samples.
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Affiliation(s)
- Meher Antia
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Thurston Herricks
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Pradipsinh K Rathod
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
- Department of Pathobiology, University of Washington, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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Mok BW, Ribacke U, Rasti N, Kironde F, Chen Q, Nilsson P, Wahlgren M. Default Pathway of var2csa switching and translational repression in Plasmodium falciparum. PLoS One 2008; 3:e1982. [PMID: 18431472 PMCID: PMC2292259 DOI: 10.1371/journal.pone.0001982] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 03/02/2008] [Indexed: 11/19/2022] Open
Abstract
Antigenic variation is a subtle process of fundamental importance to the survival of a microbial pathogen. In Plasmodium falciparum malaria, PfEMP1 is the major variable antigen and adhesin expressed at the surface of the infected erythrocyte, which is encoded for by members of a family of 60 var-genes. Peri-nuclear repositioning and epigenetic mechanisms control their mono-allelic expression. The switching of PfEMP1 depends in part on variable transition rates and short-lived immune responses to shared minor epitopes. Here we show var-genes to switch to a common gene that is highly transcribed, but sparsely translated into PfEMP1 and not expressed at the erythrocyte surface. Highly clonal and adhesive P. falciparum, which expressed distinct var-genes and the corresponding PfEMP1s at onset, were propagated without enrichment or panning. The parasites successively and spontaneously switched to transcribe a shared var-gene (var2csa) matched by the loss of PfEMP1 surface expression and host cell-binding. The var2csa gene repositioned in the peri-nuclear area upon activation, away from the telomeric clusters and heterochromatin to transcribe spliced, full-length RNA. Despite abundant transcripts, the level of intracellular PfEMP1 was low suggesting post-transcriptional mechanisms to partake in protein expression. In vivo, off-switching and translational repression may constitute one pathway, among others, coordinating PfEMP1 expression.
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Affiliation(s)
- Bobo W. Mok
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Niloofar Rasti
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Fred Kironde
- Department of Biochemistry, Faculty of Medicine, Makerere University, Kampala, Uganda
| | - Qijun Chen
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Peter Nilsson
- Department of Gene Technology, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
- * E-mail:
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Joshi S, Singh AR, Kumar A, Misra PC, Siddiqi MI, Saxena JK. Molecular cloning and characterization of Plasmodium falciparum transketolase. Mol Biochem Parasitol 2008; 160:32-41. [PMID: 18456347 DOI: 10.1016/j.molbiopara.2008.03.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 03/13/2008] [Accepted: 03/13/2008] [Indexed: 11/19/2022]
Abstract
The pentose phosphate pathway (PPP) is an important metabolic pathway for yielding reducing power in the form of NADPH and production of pentose sugar needed for nucleic acid synthesis. Transketolase, the key enzyme of non-oxidative arm of PPP, plays a vital role in the survival/replication of the malarial parasite. This enzyme in Plasmodium falciparum is a novel drug target as it has least homology with the human host. In the present study, the P. falciparum transketolase (PfTk) was expressed, localized and biochemically characterized. The recombinant PfTk harboring transketolase activity catalyzed the oxidation of donor substrates, fructose-6-phosphate (F6P) and hydroxypyruvate (HP), with K(m)(app) values of 2.25 and 4.78 mM, respectively. p-Hydroxyphenylpyruvate (HPP) was a potent inhibitor of PfTk, when hydroxypyruvate was used as a substrate, exhibiting a K(i) value of 305 microM. At the same time, noncompetitive inhibition was observed with F6P. The native PfTk is a hexamer with subunit molecular weight of 70kDa, which on treatment with low concentrations of guanidine hydrochloride (GdmCl) dissociated into functionally active dimers. This protein was localized in the cytosol and nucleus of the parasite as studied by confocal microscopy. A model structure of PfTk was constructed based on the crystal structure of the transketolases of Saccharomyces cerevisae, Leishmania mexicana and Escherichia coli to assess the structural homology. Consistent with the homology modeling predictions, CD analysis indicated that PfTk is composed of 39% alpha-helices and 26% beta-sheets. The availability of a structural model of PfTk and the observed differences in its kinetic properties compared to the host enzyme may facilitate designing of novel inhibitors of PfTk with potential anti-malarial activity.
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Affiliation(s)
- Shweta Joshi
- Division of Biochemistry, Central Drug Research Institute, Lucknow 226001, Uttar Pradesh, India
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Beraldo FH, Mikoshiba K, Garcia CRS. Human malarial parasite, Plasmodium falciparum, displays capacitative calcium entry: 2-aminoethyl diphenylborinate blocks the signal transduction pathway of melatonin action on the P. falciparum cell cycle. J Pineal Res 2007; 43:360-4. [PMID: 17910604 DOI: 10.1111/j.1600-079x.2007.00486.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The malarial parasite senses the environment to modulate its own cycle. Knowledge of the mechanisms for regulation signaling processes at the invasion, maturation, as well as division of Plasmodium falciparum before reinvasion would represent a major breakthrough and, therefore, might open new avenues for therapy. We have previously reported that melatonin modulates the circadian rhythm of malarial parasites through the activation of phospholipase C (PLC), production of InsP3, and induction of calcium release from intracellular stores. To further investigate the molecular mechanism of melatonin's action, we have used the InsP3 modulator 2-aminoethyl diphenylborinate (2-APB) given in a culture of P. falciparum parasites. Here we show that the melatonin acts on Plasmodium cell cycle through InsP3 signaling as 2-APB blocks melatonin's effect on calcium release. The function of the InsP3 signaling can be regarded as an important event for parasite invasion and maturation process, since addition of the PLC inhibitor, U73122 into Plasmodium-infected red blood cells impairs parasite invasion in vitro. By using 8BrcAMP, we also report here that Plasmodia displays a 'capacitative calcium entry' mechanism for amplification of calcium signals throughout the cytoplasm.
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Affiliation(s)
- Flávio H Beraldo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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Beraldo FH, Almeida FM, da Silva AM, Garcia CRS. Cyclic AMP and calcium interplay as second messengers in melatonin-dependent regulation of Plasmodium falciparum cell cycle. ACTA ACUST UNITED AC 2007; 170:551-7. [PMID: 16103224 PMCID: PMC2171486 DOI: 10.1083/jcb.200505117] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The host hormone melatonin increases cytoplasmic Ca(2+) concentration and synchronizes Plasmodium cell cycle (Hotta, C.T., M.L. Gazarini, F.H. Beraldo, F.P. Varotti, C. Lopes, R.P. Markus, T. Pozzan, and C.R. Garcia. 2000. Nat. Cell Biol. 2:466-468). Here we show that in Plasmodium falciparum melatonin induces an increase in cyclic AMP (cAMP) levels and cAMP-dependent protein kinase (PKA) activity (40 and 50%, respectively). When red blood cells infected with P. falciparum are treated with cAMP analogue adenosine 3',5'-cyclic monophosphate N6-benzoyl/PKA activator (6-Bz-cAMP) there is an alteration of the parasite cell cycle. This effect appears to depend on activation of PKA (abolished by the PKA inhibitors adenosine 3',5'-cyclic monophosphorothioate/8 Bromo Rp isomer, PKI [cell permeable peptide], and H89). An unexpected cross talk was found to exist between the cAMP and the Ca(2+)-dependent signaling pathways. The increases in cAMP by melatonin are inhibited by blocker of phospholipase C U73122, and addition of 6-Bz-cAMP increases cytosolic Ca(2+) concentration, through PKA activation. These findings suggest that in Plasmodium a highly complex interplay exists between the Ca(2+) and cAMP signaling pathways, but also that the control of the parasite cell cycle by melatonin requires the activation of both second messenger controlled pathways.
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Affiliation(s)
- Flávio H Beraldo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
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Wickert H, Krohne G. The complex morphology of Maurer's clefts: from discovery to three-dimensional reconstructions. Trends Parasitol 2007; 23:502-9. [PMID: 17888738 DOI: 10.1016/j.pt.2007.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 06/29/2007] [Accepted: 08/29/2007] [Indexed: 11/21/2022]
Abstract
Over 100 years ago, Georg Maurer wrote one of the finest scientific accounts of what is now known as Maurer's dots, or clefts, describing the intracellular changes in red blood cells infected with Plasmodium falciparum. Maurer's clefts have since attracted much attention, and they form an intriguing aspect of parasite biology that may hold the key to the mechanisms by which the intracellular parasite alters red blood cell properties, leading to host pathogenesis and death. This review will focus on the description of the morphology of these clefts, from the first light-microscopic report up to recent three-dimensional reconstructions. Detailed knowledge of these structures should further our understanding of their functions.
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Affiliation(s)
- Hannes Wickert
- Division of Infectious Diseases, University Hospitals Case Medical Center, 2061 Cornell Road, 4th Floor, Cleveland, OH 44106, USA.
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Abstract
Sexual differentiation and parasite transmission are intimately linked in the life cycle of malaria parasites. The specialized cells providing this crucial link are the Plasmodium gametocytes. These are formed in the vertebrate host and are programmed to mature into gametes emerging from the erythrocytes in the midgut of a blood-feeding mosquito. The ensuing fusion into a zygote establishes parasite infection in the insect vector. Although key mechanisms of gametogenesis and fertilization are becoming progressively clear, the fundamental biology of gametocyte formation still presents open questions, some of which are specific to the human malaria parasite Plasmodium falciparum. Developmental commitment to sexual differentiation, regulation of stage-specific gene expression, the profound molecular and cellular changes accompanying gametocyte specialization, the requirement for tissue-specific sequestration in P. falciparum gametocytogenesis are proposed here as areas for future investigation. The epidemiological relevance of parasite transmission from humans to mosquito in the spread of malaria and of Plasmodium drug resistance genes indicates that understanding molecular mechanisms of gametocyte formation is highly relevant to design strategies able to interfere with the transmission of this disease.
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Affiliation(s)
- Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena n. 299, 00161 Rome, Italy.
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46
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Moyano EM, González LM, Arahuetes S, Benito A. Liver stage antigen 3 isolated from a cDNA library of Plasmodium falciparum erythrocytic stages. Parasitol Res 2007; 102:111-5. [PMID: 17828606 DOI: 10.1007/s00436-007-0737-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 08/21/2007] [Indexed: 11/25/2022]
Abstract
An expression library of P. falciparum erythrocyte stages (clon Dd2) was constructed and immunoscreened with a sera pool from malaria patients. Isolated clones were analysed, and the liver stage antigen 3 (LSA-3) antigen was identified. The partial nucleotide sequence of LSA-3 has 1,623 bp. The open reading frame coded for the putative protein with 541 amino acid residues. We have demonstrated by reverse transcriptase polymerase chain reaction the transcription of the LSA-3 gene in ring form, trophozoite, and schizont, stages of asexual erythrocyte cycle.
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Affiliation(s)
- Eva M Moyano
- Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III, Sinesio Delgado, 6, Pabellózn 13, 28020, Madrid, Spain
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47
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Puskar L, Tuckermann R, Frosch T, Popp J, Ly V, McNaughton D, Wood BR. Raman acoustic levitation spectroscopy of red blood cells and Plasmodium falciparum trophozoites. Lab Chip 2007; 7:1125-31. [PMID: 17713610 DOI: 10.1039/b706997a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Methods to probe the molecular structure of living cells are of paramount importance in understanding drug interactions and environmental influences in these complex dynamical systems. The coupling of an acoustic levitation device with a micro-Raman spectrometer provides a direct molecular probe of cellular chemistry in a containerless environment minimizing signal attenuation and eliminating the affects of adhesion to walls and interfaces. We show that the Raman acoustic levitation spectroscopic (RALS) approach can be used to monitor the heme dynamics of a levitated 5 microL suspension of red blood cells and to detect hemozoin in malaria infected cells. The spectra obtained have an excellent signal-to-noise ratio and demonstrate for the first time the utility of the technique as a diagnostic and monitoring tool for minute sample volumes of living animal cells.
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Affiliation(s)
- Ljiljana Puskar
- Centre for Biospectroscopy and School of Chemistry, Monash University, Wellington Road, 3800, Victoria, Australia.
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48
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Adisa A, Frankland S, Rug M, Jackson K, Maier AG, Walsh P, Lithgow T, Klonis N, Gilson PR, Cowman AF, Tilley L. Re-assessing the locations of components of the classical vesicle-mediated trafficking machinery in transfected Plasmodium falciparum. Int J Parasitol 2007; 37:1127-41. [PMID: 17428488 DOI: 10.1016/j.ijpara.2007.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 02/15/2007] [Accepted: 02/16/2007] [Indexed: 11/16/2022]
Abstract
The malaria parasite, Plasmodium falciparum, exports proteins beyond the confines of its own plasma membrane, however there is debate regarding the machinery used for these trafficking events. We have generated transgenic parasites expressing chimeric proteins and used immunofluorescence studies to determine the locations of plasmodial homologues of the COPII component, Sar1p, and the Golgi-docking protein, Bet3p. The P. falciparum Sar1p (PfSar1p) chimeras bind to the endoplasmic reticulum surface and define a network of membranes wrapped around parasite nuclei. As the parasite matures, the endomembrane systems of individual merozoites remain interconnected until very late in schizogony. Antibodies raised against plasmodial Bet3p recognise two foci of reactivity in early parasite stages that increase in number as the parasite matures. Some of the P. falciparum Bet3p (PfBet3p) compartments are juxtaposed to compartments defined by the cis Golgi marker, PfGRASP, while others are distributed through the cytoplasm. The compartments defined by the trans Golgi marker, PfRab6, are separate, suggesting that the Golgi is dispersed. Bet3p-green fluorescent protein (GFP) is partly associated with punctate structures but a substantial population diffuses freely in the parasite cytoplasm. By contrast, yeast Bet3p is very tightly associated with immobile structures. This study challenges the view that the COPII complex and the Golgi apparatus are exported into the infected erythrocyte cytoplasm.
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Affiliation(s)
- Akinola Adisa
- Department of Biochemistry, La Trobe University, Melbourne 3086, Vic., Australia
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49
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Abstract
SUMMARYSerum-derived fatty acids are essential for the intraerythrocytic proliferation of Plasmodium falciparum in humans. We previously reported that only limited combinations of fatty acids can support long-term parasite culture, and palmitic acid (C16:0)/oleic acid (C18:1, n-9), palmitic acid (C16:0)/vaccenic acid (C18:1, n-7), or stearic acid (C18:0) are required in these combinations, implying that these fatty acids are key molecules for intraerythrocytic parasite growth (Mi-Ichi et al.2006). Here, we analysed profiles of parasitaemia changes as well as morphologies during the erythrocytic cycle and confirmed the importance of C16:0 and C18:1, n-9. We also provide evidence that C18:1, n-9 but not other C18 monoenoic or dienoic acids maintain the synchronicity of parasite development in serum-free medium when paired with C16:0, resulting in maintained exponential growth. Thus, C18:1, n-9 is indispensable for the intraerythrocytic proliferation of P. falciparum.
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Affiliation(s)
- F Mi-Ichi
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Madhunapantula SV, Achur RN, Gowda DC. Developmental stage- and cell cycle number-dependent changes in characteristics of Plasmodium falciparum-infected erythrocyte adherence to placental chondroitin-4-sulfate proteoglycan. Infect Immun 2007; 75:4409-15. [PMID: 17591790 PMCID: PMC1951145 DOI: 10.1128/iai.00478-07] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adherence of Plasmodium falciparum-infected red blood cells (IRBCs) in the human placenta is mediated by chondroitin-4-sulfate (C4S). Although IRBC binding to C4S has been unequivocally established, the adherence characteristics of IRBCs at different stages of parasite development and through successive parasite generations after selection for C4S adherence are not known. Here we show that IRBCs acquire a significant capacity to bind to C4S at as early as 14 h and exhibit maximum binding at 22 to 26 h postinvasion. Surprisingly, the IRBC binding ability decreases by approximately 50% at the late trophozoite and schizont stages. The binding strength of the IRBCs also gradually decreases during successive generations after selection for C4S binding, and at the 32nd generation, the binding capacity was only approximately 31% of that of IRBCs at the 2nd generation, suggesting that IRBCs eventually lose their C4S-adherent capacity. We also tested the susceptibility of the adhesive protein(s) on the IRBC surface to trypsin treatment at different stages of parasite development. The data show that IRBCs with late trophozoites are more resistant to trypsin treatment than those containing early trophozoites, indicating that parasite proteins expressed on the IRBC surface during trophozoite maturation partially mask accessibility of adhesive protein for binding to C4S. These data provide important insights into the expression pattern of the C4S-adhesive protein(s) on the IRBC surface, emphasizing the need for understanding the regulation of genes involved in IRBC binding to C4S. Our data also define the parasite stage at which IRBCs are suitable for studying structural interactions with C4S.
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Affiliation(s)
- Subbarao V Madhunapantula
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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