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Pottenger AE, Roy D, Srinivasan S, Chavas TEJ, Vlaskin V, Ho DK, Livingston VC, Maktabi M, Lin H, Zhang J, Pybus B, Kudyba K, Roth A, Senter P, Tyson G, Huber HE, Wesche D, Rochford R, Burke PA, Stayton PS. Liver-targeted polymeric prodrugs delivered subcutaneously improve tafenoquine therapeutic window for malaria radical cure. SCIENCE ADVANCES 2024; 10:eadk4492. [PMID: 38640243 PMCID: PMC11029812 DOI: 10.1126/sciadv.adk4492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 03/19/2024] [Indexed: 04/21/2024]
Abstract
Approximately 3.3 billion people live with the threat of Plasmodium vivax malaria. Infection can result in liver-localized hypnozoites, which when reactivated cause relapsing malaria. This work demonstrates that an enzyme-cleavable polymeric prodrug of tafenoquine addresses key requirements for a mass administration, eradication campaign: excellent subcutaneous bioavailability, complete parasite control after a single dose, improved therapeutic window compared to the parent oral drug, and low cost of goods sold (COGS) at less than $1.50 per dose. Liver targeting and subcutaneous dosing resulted in improved liver:plasma exposure profiles, with increased efficacy and reduced glucose 6-phosphate dehydrogenase-dependent hemotoxicity in validated preclinical models. A COGS and manufacturability analysis demonstrated global scalability, affordability, and the ability to redesign this fully synthetic polymeric prodrug specifically to increase global equity and access. Together, this polymer prodrug platform is a candidate for evaluation in human patients and shows potential for P. vivax eradication campaigns.
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Affiliation(s)
- Ayumi E. Pottenger
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Debashish Roy
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Selvi Srinivasan
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Thomas E. J. Chavas
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Vladmir Vlaskin
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Duy-Khiet Ho
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | | | - Mahdi Maktabi
- Department of Immunology and Microbiology, University of Colorado Anschutz School of Medicine, Aurora, CO 80045, USA
| | - Hsiuling Lin
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Jing Zhang
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Brandon Pybus
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Karl Kudyba
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Alison Roth
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | | | - George Tyson
- George Tyson Consulting, Los Altos Hills, CA 94022, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Hans E. Huber
- BioTD Strategies LLC, 213 Abbey Ln., Lansdale, PA 19446, USA
| | | | - Rosemary Rochford
- Department of Immunology and Microbiology, University of Colorado Anschutz School of Medicine, Aurora, CO 80045, USA
| | - Paul A. Burke
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Burke Bioventures LLC, 1 Broadway 14th Floor, Cambridge, MA 02142, USA
| | - Patrick S. Stayton
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
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2
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Liu M, Liao MJ, Fisher CJ, Vicetti Miguel RD, Cherpes TL. Methodology to streamline flow cytometric-based detection of early stage Plasmodium parasitemia in mice. J Microbiol Methods 2022; 195:106439. [PMID: 35248600 PMCID: PMC9007886 DOI: 10.1016/j.mimet.2022.106439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 03/01/2022] [Accepted: 03/01/2022] [Indexed: 12/27/2022]
Abstract
Murine infection models are needed to develop therapeutics and vaccines to combat the Plasmodium parasites causing malaria. Herein, we describe an easy to perform flow cytometry-based methodology for detecting green fluorescent protein-expressing Plasmodium berghei in the peripheral red blood cells (RBC) of mice. This methodology uses one-step staining and simplified gating strategies to streamline the process of Plasmodium quantification and can detect parasitemia at an earlier time point after infection compared to traditional light microscopy-based techniques.
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3
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Li Q, Xie LH, Zhang J, Pybus BS. Identification and Assessment of Plasmodium berghei Merozoites and Cell Cycle by Flow Cytometry. Mil Med 2021; 186:108-115. [PMID: 33499463 DOI: 10.1093/milmed/usaa272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/31/2020] [Accepted: 08/19/2020] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The asexual blood stages of the Plasmodium berghei life cycle including merozoites are attractive targets for transmission blocking vaccines and drugs. Improved understanding of P. berghei life cycle stage growth and development would provide new opportunities to evaluate antimalarial vaccines and drugs. METHODS Blood stage samples from C57BL/6 albino mice infected with P. berghei sporozoites were singly stained with a high binding affinity deoxyribonucleic acid dye, YOYO-1, and measured by flow cytometry (FCM). Duplicate slides were made from samples and stained with diluted Giemsa's and YOYO-1, respectively. Correlated results were compared by FCM, light microscopy, and fluorescent microscopy. RESULTS Complete life cycle stage determination and analysis by FCM is reported to include merozoites, ring forms, trophozoites, immature, and mature schizonts. FCM demonstrated a clear separation between each stage using their unique fluorescence distribution. When compared to light microscopy, a strong correlation (r 2 = 0.925 to 0.974) was observed in determining the ring forms, trophozoites, and schizonts phases, but only a moderate correlation (r 2 = 0.684 to 0.778) was observed for merozoites. The identification and measurement of merozoites suggest that FCM is a useful technique to monitor the entire life stage of the parasite. Initial stage-specific data demonstrated that mefloquine has a mode of action on mature parasite forms, and artesunic acid was rapidly effective against merozoites and other immature and mature parasite forms with higher killing. CONCLUSION Blood stage parasites in each individual life stage, including merozoites, are reliably identified and quantified quickly by FCM, making this technique an ideal alternative to microscopy. This integrated whole life stage model, particularly with confirmed determination of merozoite population, could widely be used for drug and vaccine research in malaria therapy and prophylaxis.
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Affiliation(s)
- Qigui Li
- Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA
| | - Lisa H Xie
- Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA
| | - Jing Zhang
- Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA
| | - Brandon S Pybus
- Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA
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4
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Liver-targeted polymeric prodrugs of 8-aminoquinolines for malaria radical cure. J Control Release 2020; 331:213-227. [PMID: 33378692 DOI: 10.1016/j.jconrel.2020.12.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/18/2022]
Abstract
Primaquine and tafenoquine are the two 8-aminoquinoline (8-AQ) antimalarial drugs approved for malarial radical cure - the elimination of liver stage hypnozoites after infection with Plasmodium vivax. A single oral dose of tafenoquine leads to high efficacy against intra-hepatocyte hypnozoites after efficient first pass liver uptake and metabolism. Unfortunately, both drugs cause hemolytic anemia in G6PD-deficient humans. This toxicity prevents their mass administration without G6PD testing given the approximately 400 million G6PD deficient people across malarial endemic regions of the world. We hypothesized that liver-targeted delivery of 8-AQ prodrugs could maximize liver exposure and minimize erythrocyte exposure to increase their therapeutic window. Primaquine and tafenoquine were first synthesized as prodrug vinyl monomers with self-immolative hydrolytic linkers or cathepsin-cleavable valine-citrulline peptide linkers. RAFT polymerization was exploited to copolymerize these prodrug monomers with hepatocyte-targeting GalNAc monomers. Pharmacokinetic studies of released drugs after intravenous administration showed that the liver-to-plasma AUC ratios could be significantly improved, compared to parent drug administered orally. Single doses of the liver-targeted, enzyme-cleavable tafenoquine polymer were found to be as efficacious as an equivalent dose of the oral parent drug in the P. berghei causal prophylaxis model. They also elicited significantly milder hemotoxicity in the humanized NOD/SCID mouse model engrafted with red blood cells from G6PD deficient donors. The clinical application is envisioned as a single subcutaneous administration, and the lead tafenoquine polymer also showed excellent bioavailability and liver-to-blood ratios exceeding the IV administered polymer. The liver-targeted tafenoquine polymers warrant further development as a single-dose therapeutic via the subcutaneous route with the potential for broader patient administration without a requirement for G6PD diagnosis.
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Mohring F, Rawlinson TA, Draper SJ, Moon RW. Multiplication and Growth Inhibition Activity Assays for the Zoonotic Malaria Parasite, Plasmodium knowlesi. Bio Protoc 2020; 10:e3743. [PMID: 33659403 DOI: 10.21769/bioprotoc.3743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 06/15/2020] [Accepted: 07/15/2020] [Indexed: 01/19/2023] Open
Abstract
Malaria remains a major cause of morbidity and mortality globally. Clinical symptoms of the disease arise from the growth and multiplication of Plasmodium parasites within the blood of the host. Thus in vitro assays to determine how drug, antibody and genetic perturbations affect the growth rate of Plasmodium parasites are essential for the development of new therapeutics and improving our understanding of parasite biology. As both P. falciparum and P. knowlesi can be maintained in culture with human red blood cells, the effect of antimalarial drugs and inhibitory antibodies that target the invasion capacity of Plasmodium parasites are routinely investigated by using multiplication assays or growth inhibition assays against these two species. This protocol gives detailed step-by-step procedures to carry out flow cytometry-based multiplication assays and growth inhibition activity assays to test neutralizing antibodies based on the activity of the parasite enzyme lactate dehydrogenase of Plasmodium knowlesi adapted to human red blood cell culture. Whilst similar assays are well established for P. falciparum, P. knowlesi is more closely related to all other human infective species ( Pacheco et al., 2018 ) and so can be used as a surrogate for testing drugs and vaccines for other malaria species such as P. vivax, which is the most widespread cause of malaria outside of Africa, but cannot yet be cultured under laboratory conditions.
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Affiliation(s)
- Franziska Mohring
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Thomas A Rawlinson
- The Jenner Institute, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Simon J Draper
- The Jenner Institute, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Robert W Moon
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
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6
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Kancharla P, Dodean RA, Li Y, Pou S, Pybus B, Melendez V, Read L, Bane CE, Vesely B, Kreishman-Deitrick M, Black C, Li Q, Sciotti RJ, Olmeda R, Luong TL, Gaona H, Potter B, Sousa J, Marcsisin S, Caridha D, Xie L, Vuong C, Zeng Q, Zhang J, Zhang P, Lin H, Butler K, Roncal N, Gaynor-Ohnstad L, Leed SE, Nolan C, Ceja FG, Rasmussen SA, Tumwebaze PK, Rosenthal PJ, Mu J, Bayles BR, Cooper RA, Reynolds KA, Smilkstein MJ, Riscoe MK, Kelly JX. Lead Optimization of Second-Generation Acridones as Broad-Spectrum Antimalarials. J Med Chem 2020; 63:6179-6202. [PMID: 32390431 PMCID: PMC7354843 DOI: 10.1021/acs.jmedchem.0c00539] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The global impact of malaria remains staggering despite extensive efforts to eradicate the disease. With increasing drug resistance and the absence of a clinically available vaccine, there is an urgent need for novel, affordable, and safe drugs for prevention and treatment of malaria. Previously, we described a novel antimalarial acridone chemotype that is potent against both blood-stage and liver-stage malaria parasites. Here, we describe an optimization process that has produced a second-generation acridone series with significant improvements in efficacy, metabolic stability, pharmacokinetics, and safety profiles. These findings highlight the therapeutic potential of dual-stage targeting acridones as novel drug candidates for further preclinical development.
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Affiliation(s)
- Papireddy Kancharla
- Department of Chemistry, Portland State University, Portland, Oregon 97201, United States
| | - Rozalia A. Dodean
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
| | - Yuexin Li
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
| | - Sovitj Pou
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
| | - Brandon Pybus
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Victor Melendez
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Lisa Read
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Charles E. Bane
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Brian Vesely
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Mara Kreishman-Deitrick
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Chad Black
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Qigui Li
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Richard J. Sciotti
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Raul Olmeda
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Thu-Lan Luong
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Heather Gaona
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Brittney Potter
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Jason Sousa
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Sean Marcsisin
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Diana Caridha
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Lisa Xie
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Chau Vuong
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Qiang Zeng
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Jing Zhang
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Ping Zhang
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Hsiuling Lin
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Kirk Butler
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Norma Roncal
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Lacy Gaynor-Ohnstad
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Susan E. Leed
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Christina Nolan
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Frida G. Ceja
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, CA 94901, United States
| | - Stephanie A. Rasmussen
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, CA 94901, United States
| | | | - Philip J. Rosenthal
- Department of Medicine, University of California, San Francisco, CA 94143, United States
| | - Jianbing Mu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville MD 20852, USA
| | - Brett R. Bayles
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, CA 94901, United States
- Global Public Health Program, Dominican University of California, San Rafael CA 94901
| | - Roland A. Cooper
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, CA 94901, United States
| | - Kevin A. Reynolds
- Department of Chemistry, Portland State University, Portland, Oregon 97201, United States
| | - Martin J. Smilkstein
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
| | - Michael K. Riscoe
- Department of Chemistry, Portland State University, Portland, Oregon 97201, United States
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
| | - Jane X. Kelly
- Department of Chemistry, Portland State University, Portland, Oregon 97201, United States
- Department of Veterans Affairs Medical Center, Portland, Oregon 97239, United States
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7
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Updating the modified Thompson test by using whole-body bioluminescence imaging to replace traditional efficacy testing in experimental models of murine malaria. Malar J 2019; 18:38. [PMID: 30767768 PMCID: PMC6376706 DOI: 10.1186/s12936-019-2661-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 01/19/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rodent malaria models are extensively used to predict treatment outcomes in human infections. There is a constant need to improve and refine these models by innovating ways to apply new scientific findings and cutting edge technologies. In addition, and in accordance with the three R's of animal use in research, in vivo studies should be constantly refined to avoid unnecessary pain and distress to the experimental animals by using preemptive euthanasia as soon as the main scientific study objective has been accomplished. METHODS The new methodology described in this manuscript uses the whole-body bioluminescence signal emitted by transgenic, luciferase-expressing Plasmodium berghei parasites to assess the parasite load predicted parasitaemia (PLPP) in drug and control treated female ICR-CD1 mice infected with 1 × 105 luciferase-expressing P. berghei (ANKA strain) infected erythrocytes. This methodology can replace other time-consuming and expensive methods that are routinely used to measure parasitaemia in infected animals, such as Giemsa-stained thin blood smears and flow cytometry. RESULTS There is a good correlation between whole-body bioluminescence signal and parasitaemia measured using Giemsa-stained thin blood smears and flow cytometry respectively in donor and study mice in the modified Thompson test. The algebraic formulas which represent these correlations can be successfully used to assess PLPP in donor and study mice. In addition, the new methodology can pinpoint sick animals 2-8 days before they would have been otherwise diagnosed based on behavioural or any other signs of malaria disease. CONCLUSIONS The new method for predicting parasitaemia in the modified Thompson test is simple, precise, objective, and minimizes false positive results that can lead to the premature removal of animals from study. Furthermore, from the animal welfare perspective of replace, reduce, and refine, this new method facilitates early removal of sick animals from study as soon as the study objective has been achieved, in many cases well before the clinical signs of disease are present.
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8
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Frueh L, Li Y, Mather MW, Li Q, Pou S, Nilsen A, Winter RW, Forquer IP, Pershing AM, Xie LH, Smilkstein MJ, Caridha D, Koop DR, Campbell RF, Sciotti RJ, Kreishman-Deitrick M, Kelly JX, Vesely B, Vaidya AB, Riscoe MK. Alkoxycarbonate Ester Prodrugs of Preclinical Drug Candidate ELQ-300 for Prophylaxis and Treatment of Malaria. ACS Infect Dis 2017; 3:728-735. [PMID: 28927276 DOI: 10.1021/acsinfecdis.7b00062] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ELQ-300 is a preclinical antimalarial drug candidate that is active against liver, blood, and transmission stages of Plasmodium falciparum. While ELQ-300 is highly effective when administered in a low multidose regimen, poor aqueous solubility and high crystallinity have hindered its clinical development. To overcome its challenging physiochemical properties, a number of bioreversible alkoxycarbonate ester prodrugs of ELQ-300 were synthesized. These bioreversible prodrugs are converted to ELQ-300 by host and parasite esterase action in the liver and bloodstream of the host. One such alkoxycarbonate prodrug, ELQ-331, is curative against Plasmodium yoelii with a single low dose of 3 mg/kg in a murine model of patent malaria infection. ELQ-331 is at least as fully protective as ELQ-300 in a murine malaria prophylaxis model when delivered 24 h before sporozoite inoculation at an oral dose of 1 mg/kg. Here, we show that ELQ-331 is a promising prodrug of ELQ-300 with improved physiochemical and metabolic properties and excellent potential for clinical formulation.
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Affiliation(s)
- Lisa Frueh
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
- Department of Molecular Microbiology and
Immunology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Yuexin Li
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - Michael W. Mather
- Department
of Microbiology and Immunology, Drexel University, 2900 W. Queen Lane, Philadelphia, Pennsylvania 19129, United States
| | - Qigui Li
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Sovitj Pou
- Department of Molecular Microbiology and
Immunology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Aaron Nilsen
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - Rolf W. Winter
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - Isaac P. Forquer
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - April M. Pershing
- Department
of Microbiology and Immunology, Drexel University, 2900 W. Queen Lane, Philadelphia, Pennsylvania 19129, United States
| | - Lisa H. Xie
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Martin J. Smilkstein
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - Diana Caridha
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Dennis R. Koop
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Robert F. Campbell
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Richard J. Sciotti
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Mara Kreishman-Deitrick
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Jane X. Kelly
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
| | - Brian Vesely
- Experimental
Therapeutics Branch, Military Malaria Research Program (MMRP), Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, Maryland 20910, United States
| | - Akhil B. Vaidya
- Department
of Microbiology and Immunology, Drexel University, 2900 W. Queen Lane, Philadelphia, Pennsylvania 19129, United States
| | - Michael K. Riscoe
- Experimental Chemotherapy Laboratory, VA Medical Center (Mail code RD-33), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, United States
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9
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Long-Term Prophylaxis and Pharmacokinetic Evaluation of Intramuscular Nano- and Microparticle Decoquinate in Mice Infected with P. berghei Sporozoites. Malar Res Treat 2017; 2017:7508291. [PMID: 28491482 PMCID: PMC5406721 DOI: 10.1155/2017/7508291] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/31/2017] [Indexed: 11/17/2022] Open
Abstract
Decoquinate nanoparticle and microparticle suspended in an oily vehicle to retard drug release are evaluated for long-term malaria prophylaxis. Pharmacokinetic studies in normal animals and antimalarial efficacy in liver stage malaria mice were conducted at various single intramuscular-decoquinate doses for 2, 4, 6, or 8 weeks prior to infection with P. berghei sporozoites. The liver stage efficacy evaluation was monitored by using an in vivo imaging system. Full causal prophylaxis was shown in mice with a single intramuscular dose at 120 mg/kg of nanoparticle decoquinate (0.43 μm) for 2-3 weeks and with microparticle decoquinate (8.31 μm) injected 8 weeks earlier than inoculation. The time above MIC of 1,375 hr observed with the microparticle formulation provided a 2.2-fold longer drug exposure than with the nanoparticle formulation (624 hr). The prophylactic effect of the microparticle formulation observed in mice was shown to be 3-4 times longer than the nanoparticle decoquinate formulation.
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10
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Milner EE, Berman J, Caridha D, Dickson SP, Hickman M, Lee PJ, Marcsisin SR, Read LT, Roncal N, Vesely BA, Xie LH, Zhang J, Zhang P, Li Q. Cytochrome P450 2D-mediated metabolism is not necessary for tafenoquine and primaquine to eradicate the erythrocytic stages of Plasmodium berghei. Malar J 2016; 15:588. [PMID: 27923405 PMCID: PMC5142148 DOI: 10.1186/s12936-016-1632-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/22/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Due to the ability of the 8-aminoquinolines (8AQs) to kill different stages of the malaria parasite, primaquine (PQ) and tafenoquine (TQ) are vital for causal prophylaxis and the eradication of erythrocytic Plasmodium sp. parasites. Recognizing the potential role of cytochrome (CYP) 450 2D6 in the metabolism and subsequent hepatic efficacy of 8-aminoquinolines, studies were designed to explore whether CYP2D-mediated metabolism was related to the ability of single-dose PQ and TQ to eliminate the asexual and sexual erythrocytic stages of Plasmodium berghei. METHODS An IV P. berghei sporozoite murine challenge model was utilized to directly compare causal prophylactic and erythrocytic activity (asexual and sexual parasite stages) dose-response relationships in C57BL/6 wild-type (WT) mice and subsequently compare the erythrocytic activity of PQ and TQ in WT and CYP2D knock-out (KO) mice. RESULTS Single-dose administration of either 25 mg/kg TQ or 40 mg/kg PQ eradicated the erythrocytic stages (asexual and sexual) of P. berghei in C57BL WT and CYP2D KO mice. In WT animals, the apparent elimination of hepatic infections occurs at lower doses of PQ than are required to eliminate erythrocytic infections. In contrast, the minimally effective dose of TQ needed to achieve causal prophylaxis and to eradicate erythrocytic parasites was analogous. CONCLUSION The genetic deletion of the CYP2D cluster does not affect the ability of PQ or TQ to eradicate the blood stages (asexual and sexual) of P. berghei after single-dose administration.
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Affiliation(s)
- Erin E Milner
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA.
| | - Jonathan Berman
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Diana Caridha
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Samuel P Dickson
- United States Army Medical Materiel Development Authority (USAMMDA), Ft Detrick, Frederick, MD, USA
| | - Mark Hickman
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Patricia J Lee
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Sean R Marcsisin
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Lisa T Read
- United States Army Medical Materiel Development Authority (USAMMDA), Ft Detrick, Frederick, MD, USA
| | - Norma Roncal
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Brian A Vesely
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Lisa H Xie
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Jing Zhang
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Ping Zhang
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Qigui Li
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
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11
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Srivastava B, Anvikar AR, Ghosh SK, Mishra N, Kumar N, Houri-Yafin A, Pollak JJ, Salpeter SJ, Valecha N. Computer-vision-based technology for fast, accurate and cost effective diagnosis of malaria. Malar J 2015; 14:526. [PMID: 26714633 PMCID: PMC4696165 DOI: 10.1186/s12936-015-1060-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 12/17/2015] [Indexed: 01/01/2023] Open
Abstract
Background Microscopy
has long been considered to be the gold standard for diagnosis of malaria despite the introduction of newer assays. However, it has many challenges like requirement of trained microscopists and logistic issues. A vision based device that can diagnose malaria, provide speciation and estimate parasitaemia was evaluated. Methods The device was evaluated using samples from 431 consented patients, 361 of which were initially screened by RDT and microscopy and later analysed by PCR. It was a prospective, non-randomized, blinded trial. Quantification of parasitaemia was performed by two experienced technicians. Samples were subjected to diagnosis by Sight Dx digital imaging scanning. Results The sensitivity and specificity of the SightDx P1 device for analysed samples were found to be 97.05 and 96.33 %, respectively, when compared to PCR. When compared to microscopy, sensitivity and specificity were found to be 94.4 and 95.6 %, respectively. The device was able to speciate 73.3 % of the PCR Plasmodium falciparum positive samples and 91.4 % of PCR Plasmodium vivax positive samples. Conclusion The ability of the device to detect parasitaemia as compared with microscopy, was within 50 % in 71.3 % of cases and demonstrated a correlation coefficient of 0.89.
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Affiliation(s)
- Bina Srivastava
- National Institute of Malaria Research, Sector 8 Dwarka, New Delhi, 110 077, India.
| | - Anupkumar R Anvikar
- National Institute of Malaria Research, Sector 8 Dwarka, New Delhi, 110 077, India.
| | - Susanta K Ghosh
- National Institute of Malaria Research Field Unit, Bengaluru, India.
| | - Neelima Mishra
- National Institute of Malaria Research, Sector 8 Dwarka, New Delhi, 110 077, India.
| | - Navin Kumar
- National Institute of Malaria Research, Sector 8 Dwarka, New Delhi, 110 077, India.
| | - Arnon Houri-Yafin
- Sight Diagnostics, 1 Agudat Hasport Hapoel, Jerusalem Technology Park, Jerusalem, Israel.
| | - Joseph Joel Pollak
- Sight Diagnostics, 1 Agudat Hasport Hapoel, Jerusalem Technology Park, Jerusalem, Israel.
| | - Seth J Salpeter
- Sight Diagnostics, 1 Agudat Hasport Hapoel, Jerusalem Technology Park, Jerusalem, Israel.
| | - Neena Valecha
- National Institute of Malaria Research, Sector 8 Dwarka, New Delhi, 110 077, India.
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12
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Flow cytometric enumeration of parasitemia in cultures of Plasmodium falciparum stained with SYBR Green I and CD235A. ScientificWorldJournal 2014; 2014:536723. [PMID: 25548783 PMCID: PMC4274835 DOI: 10.1155/2014/536723] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 10/10/2014] [Indexed: 11/17/2022] Open
Abstract
A flow cytometric (FACS) detection method for Plasmodium falciparum cultures (P. falciparum) was developed using SYBR Green I and CD235A and compared against the Giemsa stained microscopic examination. The cultured P. falciparum were spiked into red blood cells (RBCs) to yield parasitemia, ranging from 0.01% to 22.0%. FACS analysis demonstrated a clear separation between P. falciparum infected and uninfected RBCs. The measured percentage of parasitemia by FACS revealed higher precision (CV of 2.2-37.2%) with the sensitivity of 0.01% parasitemia than Giemsa stained microscopic examination (CV of 7.2-66.0%). High correlation of measured parasitaemia (r=0.98, P<0.05) was observed between FACS and Giemsa stained microscopic analyses. The higher levels of parasitaemia detection were observed in all ranges by FACS in comparison to Giemsa stained microscopic analysis. The currently reported FACS method using SYBR Green I and CD235A is potentially useful for measuring parasitemia in treating patients.
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13
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Li Q, O'Neil M, Xie L, Caridha D, Zeng Q, Zhang J, Pybus B, Hickman M, Melendez V. Assessment of the prophylactic activity and pharmacokinetic profile of oral tafenoquine compared to primaquine for inhibition of liver stage malaria infections. Malar J 2014; 13:141. [PMID: 24731238 PMCID: PMC3989846 DOI: 10.1186/1475-2875-13-141] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/02/2014] [Indexed: 11/10/2022] Open
Abstract
Background As anti-malarial drug resistance escalates, new safe and effective medications are necessary to prevent and treat malaria infections. The US Army is developing tafenoquine (TQ), an analogue of primaquine (PQ), which is expected to be more effective in preventing malaria in deployed military personnel. Methods To compare the prophylactic efficacy of TQ and PQ, a transgenic Plasmodium berghei parasite expressing the bioluminescent reporter protein luciferase was utilized to visualize and quantify parasite development in C57BL/6 albino mice treated with PQ and TQ in single or multiple regimens using a real-time in vivo imaging system (IVIS). As an additional endpoint, blood stage parasitaemia was monitored by flow cytometry. Comparative pharmacokinetic (PK) and liver distribution studies of oral and intravenous PQ and TQ were also performed. Results Mice treated orally with three doses of TQ at 5 mg/kg three doses of PQ at 25 mg/kg demonstrated no bioluminescence liver signal and no blood stage parasitaemia was observed suggesting both drugs showed 100% causal activity at the doses tested. Single dose oral treatment with 5 mg TQ or 25 mg of PQ, however, yielded different results as only TQ treatment resulted in causal prophylaxis in P. berghei sporozoite-infected mice. TQ is highly effective for causal prophylaxis in mice at a minimal curative single oral dose of 5 mg/kg, which is a five-fold improvement in potency versus PQ. PK studies of the two drugs administered orally to mice showed that the absolute bioavailability of oral TQ was 3.5-fold higher than PQ, and the AUC of oral TQ was 94-fold higher than oral PQ. The elimination half-life of oral TQ in mice was 28 times longer than PQ, and the liver tissue distribution of TQ revealed an AUC that was 188-fold higher than PQ. Conclusions The increased drug exposure levels and longer exposure time of oral TQ in the plasma and livers of mice highlight the lead quality attributes that explain the much improved efficacy of TQ when compared to PQ.
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Affiliation(s)
- Qigui Li
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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14
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Varela ML, Razakandrainibe R, Aldebert D, Barale JC, Jambou R. Cytometric measurement of in vitro inhibition of Plasmodium falciparum field isolates by drugs: a new approach for re-invasion inhibition study. Malar J 2014; 13:110. [PMID: 24649924 PMCID: PMC3973617 DOI: 10.1186/1475-2875-13-110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 03/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A flow cytometric method is proposed to study in vitro drug sensitivity of Plasmodium falciparum. Standard [(3)H]-hypoxanthine incorporation assay gives only information on inhibition of maturation by drugs. This method is usable on field isolates and provides data on both inhibition of maturation and re-invasion. METHODS The method is based on the staining of parasites with hydroethidine (HE) and thiazole orange (TO) which allow differential identification of early, trophozoite and late stage of the parasite by flow cytometry. Late stages of the parasites are obtained by incubation in culture for 24 hours. Reinvasion is followed by culturing parasitized red blood cells for 24 h more. RESULTS Compared to the standard [(3)H]-hypoxanthine incorporation assay, it gave similar results as expressed by 50% inhibitory concentrations for chloroquine of laboratory strains and "field" isolates. The effect of quinine on the schizont-ring transition was also explored using this method. First data on the inhibition of re-invasion induced by quinine are presented for both P. falciparum-cultured strains and field isolates. DISCUSSION This method is simple to use event for field isolate study. It is suitable to analyse effect of drugs on steps of the parasite life cycle different for the maturation one. Using this method quinine was found to have a inhibitory effect on re-invasion of red cells by Plasmodium.
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Affiliation(s)
| | | | | | | | - Ronan Jambou
- Unité d'immunologie Institut Pasteur de Madagascar, Antananarivo BP1274, Madagascar.
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15
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Screening and Evaluation of Inhibitors of Plasmodium falciparum Merozoite Egress and Invasion Using Cytometry. Methods Mol Biol 2012. [PMID: 22990802 DOI: 10.1007/978-1-62703-026-7_36] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
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16
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17
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Wacker MA, Turnbull LB, Walker LA, Mount MC, Ferdig MT. Quantification of multiple infections of Plasmodium falciparum in vitro. Malar J 2012; 11:180. [PMID: 22646748 PMCID: PMC3483182 DOI: 10.1186/1475-2875-11-180] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 03/13/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human malaria infections caused by the parasite Plasmodium falciparum often contain more than one genetically distinct parasite. Despite this fact, nearly all studies of multiple strain P. falciparum infections have been limited to determining relative densities of each parasite within an infection. In light of this, new methods are needed that can quantify the absolute number of parasites within a single infection. METHODS A quantitative PCR (qPCR) method was developed to track the dynamic interaction of P. falciparum infections containing genetically distinct parasite clones in cultured red blood cells. Allele-specific primers were used to generate a standard curve and to quantify the absolute concentration of parasite DNA within multi-clonal infections. Effects on dynamic growth relationships between parasites under drug pressure were examined by treating mixed cultures of drug sensitive and drug resistant parasites with the anti-malarial drug chloroquine at different dosing schedules. RESULTS An absolute quantification method was developed to monitor the dynamics of P. falciparum cultures in vitro. This method allowed for the observation of competitive suppression, the reduction of parasites numbers due to the presence of another parasite, and competitive release, the improved performance of a parasite after the removal of a competitor. These studies demonstrated that the presence of two parasites led to the reduction in density of at least one parasite. The introduction of drug to a mixed culture containing both a drug resistant and drug sensitive parasites resulted in an increased proportion of the drug resistant parasite. Moreover, following drug treatment, the resistant parasite experienced competitive release by exhibiting a fitness benefit greater than simply surviving drug treatment, due to the removal of competitive suppression by the sensitive parasite. CONCLUSIONS The newly developed assay allowed for the examination of the dynamics of two distinct clones in vitro; both competitive suppression and release were observed. A deeper understanding of the dynamic growth responses of multiple strain P. falciparum infections, with and without drug pressure, can improve the understanding of the role of parasite interactions in the spread of drug resistant parasites, perhaps suggesting different treatment strategies.
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Affiliation(s)
- Mark A Wacker
- Eck Institute of Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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18
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Somsak V, Srichairatanakool S, Yuthavong Y, Kamchonwongpaisan S, Uthaipibull C. Flow cytometric enumeration of Plasmodium berghei-infected red blood cells stained with SYBR Green I. Acta Trop 2012; 122:113-8. [PMID: 22222185 DOI: 10.1016/j.actatropica.2011.12.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 12/19/2011] [Accepted: 12/21/2011] [Indexed: 01/21/2023]
Abstract
High-throughput methods for evaluation of in vivo efficacy of candidate compounds against Plasmodium parasites are necessary during the antimalarial drug development process. It is essential that enumeration of parasitemia in the infected blood from experimental host animals is accurate and reliable. Flow cytometric enumeration of parasitized cells stained with fluorescent dye is a rapid alternative method to conventional microscopic counting. In this study, a protocol for flow cytometric enumeration of rodent malaria parasite Plasmodium berghei-infected red blood cells (RBC) stained with SYBR Green I was developed. The optimal concentration of SYBR Green I used to stain infected RBC was 4× for 30 min. This SYBR Green I staining protocol in combination with the bi-dimensional FL-1(530)/FL-3(620) detection method accurately detects parasitemia above 0.02%. The dye is stable during the prolonged incubation period necessary for accurate enumeration of parasitemia, with no loss of fluorescent signal over a period of hours. This protocol was validated in an antimalarial assay and the result was comparable to that obtained from conventional microscopic counting. The SYBR Green I flow cytometric protocol is thus a rapid and precise tool for high-throughput in vivo antimalarial drug screening.
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Affiliation(s)
- Voravuth Somsak
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Pathumthani 12120, Thailand
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19
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Gerena Y, Gonzalez-Pons M, Serrano AE. Cytofluorometric detection of rodent malaria parasites using red-excited fluorescent dyes. Cytometry A 2011; 79:965-72. [PMID: 22015734 DOI: 10.1002/cyto.a.21119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 06/23/2011] [Accepted: 07/11/2011] [Indexed: 11/09/2022]
Abstract
Flow cytometry is a potentially efficient approach for the quantification of parasitemias in experimental malaria infections and drug susceptibility assays using rodent malaria models such as Plasmodium berghei. In this study, we used two red DNA-binding fluorochromes, rhodamine 800 (R800) and LD700, to measure parasitemia levels in whole blood samples from mice infected with P. berghei. Blood samples were treated with RNAse A to eliminate RNA-derived signals. Propidium iodide, which stains both DNA and RNA, was used as a positive control. The parasitemia levels determined by R800 and LD700 were comparable to those calculated by microscopic analysis of blood smears and flow cytometry using Hoechst 33258. RNAse treatment did not affect these measurements. We also used R800 or LD700 to quantify parasitemias in mice infected with a GFP-expressing P. berghei line to correlate the parasitemia levels determined by DNA staining versus parasite numbers using GFP fluorescence as a surrogate measurement. A positive correlation was found between levels determined by flow cytometry using these dyes and those measured by GFP expression. Similar results were obtained when parasitemias determined by flow cytometry were compared to those determined by conventional microscopy. The limit of detection of infected red blood cells using R800 or LD700 staining was 0.1% and 0.15%, respectively. This study demonstrates that red laser-based flow cytometry using R800 or LD700 can be used for effective quantification of parasitemia levels in Plasmodium infected red blood cells. Furthermore, this method has the advantage that it does not require RNAse pretreatment and allows for a greater amount of cells to be analyzed for parasite burden than otherwise measured by conventional microscopy. © 2011 International Society for Advancement of Cytometry.
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Affiliation(s)
- Y Gerena
- Department of Pharmaceutical Sciences, University of Puerto Rico, San Juan, Puerto Rico.
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20
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Ekland EH, Schneider J, Fidock DA. Identifying apicoplast-targeting antimalarials using high-throughput compatible approaches. FASEB J 2011; 25:3583-93. [PMID: 21746861 DOI: 10.1096/fj.11-187401] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Malarial parasites have evolved resistance to all previously used therapies, and recent evidence suggests emerging resistance to the first-line artemisinins. To identify antimalarials with novel mechanisms of action, we have developed a high-throughput screen targeting the apicoplast organelle of Plasmodium falciparum. Antibiotics known to interfere with this organelle, such as azithromycin, exhibit an unusual phenotype whereby the progeny of drug-treated parasites die. Our screen exploits this phenomenon by assaying for "delayed death" compounds that exhibit a higher potency after two cycles of intraerythrocytic development compared to one. We report a primary assay employing parasites with an integrated copy of a firefly luciferase reporter gene and a secondary flow cytometry-based assay using a nucleic acid stain paired with a mitochondrial vital dye. Screening of the U.S. National Institutes of Health Clinical Collection identified known and novel antimalarials including kitasamycin. This inexpensive macrolide, used for agricultural applications, exhibited an in vitro IC(50) in the 50 nM range, comparable to the 30 nM activity of our control drug, azithromycin. Imaging and pharmacologic studies confirmed kitasamycin action against the apicoplast, and in vivo activity was observed in a murine malaria model. These assays provide the foundation for high-throughput campaigns to identify novel chemotypes for combination therapies to treat multidrug-resistant malaria.
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Affiliation(s)
- Eric H Ekland
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, 701 W. 168th St., New York, NY 10032, USA.
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Feasibility of flow cytometry for measurements of Plasmodium falciparum parasite burden in studies in areas of malaria endemicity by use of bidimensional assessment of YOYO-1 and autofluorescence. J Clin Microbiol 2011; 49:968-74. [PMID: 21227985 DOI: 10.1128/jcm.01961-10] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The detection and quantification of Plasmodium falciparum in studies of malaria endemicity primarily relies upon microscopy. High-throughput quantitative methods with less subjectivity and greater reliability are needed for investigational studies. The staining of parasitized erythrocytes with YOYO-1 for flow cytometry bears great potential as a tool for assessing malaria parasite burden. Capillary blood was collected from children presenting to the pediatric ward of the Manhiça District Hospital in Mozambique for parasitemia assessment by thick and thin blood films, flow cytometry (YOYO-1(530/585)), and quantitative real-time PCR (qRT-PCR). Whole blood was fixed and stained with YOYO-1 for acquisition on a cytometer to assess the frequency of infected erythrocyte events. qRT-PCR was used as the gold standard for the detection of P. falciparum. The YOYO-1(530/585) method was as sensitive and specific as conventional microscopy (area under the receiver operating characteristic, 0.9 for both methods). The interrater mean difference for YOYO-1(530/585) was near zero. Parasite density using flow cytometry and complete blood counts returned density estimates with a mean difference 2.2 times greater than results by microscopy (confidence interval, 1.46 to 3.60) but with limits of agreement between 10 times lower and 50 times higher than those of microscopy. The YOYO-1(530/585) staining pattern was established exactly as demonstrated in animal models, but the assay was limited by the lack of appropriate negative-control samples for establishing background levels and the definition of positives in areas in which malaria is endemic. YOYO-1(530/585) is a high-throughput tool with great potential if the limitations of negative controls and heterogeneous levels of background signal can be overcome.
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22
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Ma C, Harrison P, Wang L, Coppel RL. Automated estimation of parasitaemia of Plasmodium yoelii-infected mice by digital image analysis of Giemsa-stained thin blood smears. Malar J 2010; 9:348. [PMID: 21122144 PMCID: PMC3245511 DOI: 10.1186/1475-2875-9-348] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 12/01/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Parasitaemia, the percentage of infected erythrocytes, is used to measure progress of experimental Plasmodium infection in infected hosts. The most widely used technique for parasitaemia determination is manual microscopic enumeration of Giemsa-stained blood films. This process is onerous, time consuming and relies on the expertise of the experimenter giving rise to person-to-person variability. Here the development of image-analysis software, named Plasmodium AutoCount, which can automatically generate parasitaemia values from Plasmodium-infected blood smears, is reported. METHODS Giemsa-stained blood smear images were captured with a camera attached to a microscope and analysed using a programme written in the Python programming language. The programme design involved foreground detection, cell and infection detection, and spurious hit filtering. A number of parameters were adjusted by a calibration process using a set of representative images. Another programme, Counting Aid, written in Visual Basic, was developed to aid manual counting when the quality of blood smear preparation is too poor for use with the automated programme. RESULTS This programme has been validated for use in estimation of parasitemia in mouse infection by Plasmodium yoelii and used to monitor parasitaemia on a daily basis for an entire challenge infection. The parasitaemia values determined by Plasmodium AutoCount were shown to be highly correlated with the results obtained by manual counting, and the discrepancy between automated and manual counting results were comparable to those found among manual counts of different experimenters. CONCLUSIONS Plasmodium AutoCount has proven to be a useful tool for rapid and accurate determination of parasitaemia from infected mouse blood. For greater accuracy when smear quality is poor, Plasmodium AutoCount, can be used in conjunction with Counting Aid.
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Affiliation(s)
- Charles Ma
- Department of Microbiology, Monash University, Clayton, Vic 3800, Australia
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Use of flow cytometry to separateLeucocytozoon caulleryigametocytes from avian blood. Parasitology 2010; 137:1899-903. [DOI: 10.1017/s0031182010000880] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYThe highly pathogenic avian protozoanLeucocytozoon caulleryiinfects host chicken cells, and interference by the host genome results in difficulty in obtaining protozoal DNA for genetic analysis. We used flow cytometry analysis to separate expelledL. caulleryigametocytes from infected chicken blood and to analyse cell populations and sorting by FACS efficiency. Infected blood cells stained with SYTO-24 showed a specific area on 2-dimensional scattergrams compared to uninfected blood. The specific area was sorted, and approximately 85% of the sorted cells were identified asL. caulleryigametocytes by microscopic observation. DNA was also extracted from the sorted fraction, and a clear increase in polymerase chain reaction (PCR) amplification of protozoal DNA was observed compared to infected blood without sorting. Host-derived DNA was also detected by PCR; however, its amplification was decreased compared to that in unsorted infected blood. This is the first report of the separation ofL. caulleryigametocytes from infected host blood using flow cytometry. This method may be applied to further genetic analyses such as studies of the dynamics of stage-specificL. caulleryigene expression.
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Bei AK, Desimone TM, Badiane AS, Ahouidi AD, Dieye T, Ndiaye D, Sarr O, Ndir O, Mboup S, Duraisingh MT. A flow cytometry-based assay for measuring invasion of red blood cells by Plasmodium falciparum. Am J Hematol 2010; 85:234-7. [PMID: 20196166 DOI: 10.1002/ajh.21642] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Variability in the ability of the malaria parasite Plasmodium falciparum to invade human erythrocytes is postulated to be an important determinant of disease severity. Both the parasite multiplication rate and erythrocyte selectivity are important parameters that underlie such variable invasion. We have established a flow cytometry-based method for simultaneously calculating both the parasitemia and the number of multiply-infected erythrocytes. Staining with the DNA-specific dye SYBR Green I allows quantitation of parasite invasion at the ring stage of parasite development. We discuss in vitro and in vivo applications and limitations of this method in relation to the study of parasite invasion.
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Affiliation(s)
- Amy K Bei
- Harvard School of Public Health, Boston, Massachusetts, USA
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Jiménez-Díaz MB, Mulet T, Gómez V, Viera S, Alvarez A, Garuti H, Vázquez Y, Fernández A, Ibáñez J, Jiménez M, Gargallo-Viola D, Angulo-Barturen I. Quantitative measurement of Plasmodium-infected erythrocytes in murine models of malaria by flow cytometry using bidimensional assessment of SYTO-16 fluorescence. Cytometry A 2009; 75:225-35. [PMID: 18785271 DOI: 10.1002/cyto.a.20647] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Flow cytometry is a powerful tool for measuring parasitemias in murine malaria models used to test new antimalarials. Measurement of the emission of the nonpermeable nucleic acid dye YOYO-1 (at 530 and 585 nm after excitation at 488 nm) allowed the unambiguous detection of low parasitemias (> or =0.01%) but required prolonged fixation and permeabilization of the sample. Thus, we tested whether this issue could be overcome by use of the cell-permeant dye SYTO-16 with this same bidimensional method. Blood samples from CD1 mice infected with Plasmodium yoelii, Plasmodium vinckei, or Plasmodium chabaudi or from NOD(scidbeta2m-/-) engrafted with human erythrocytes and infected with P. falciparum were stained with SYTO-16 in the presence or absence of TER-119 mAb (for engrafted mice) in 96-well plate format and acquired in Trucount tubes. Bidimensional analysis with SYTO-16 was quantitatively equivalent to YOYO-1. Moreover, by combining SYTO-16 with the use of TER-119-PE antimouse erythrocyte mAb and Trucount tubes, the measurement of the concentration of P. falciparum-infected erythrocytes over a range of five orders of magnitude was achieved. Bidimensional analysis using SYTO-16 can be used to accurately measure the concentration of Plasmodium spp.-infected erythrocytes in mice without complex sample preparation.
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Shapiro HM, Perlmutter NG. Killer applications: Toward affordable rapid cell-based diagnostics for malaria and tuberculosis. CYTOMETRY PART B-CLINICAL CYTOMETRY 2008; 74 Suppl 1:S152-64. [DOI: 10.1002/cyto.b.20401] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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