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Barber BE, Webster R, Potter AJ, Llewellyn S, Sahai N, Leelasena I, Mathison S, Kuritz K, Flynn J, Chalon S, Marrast AC, Gobeau N, Moehrle JJ. Characterising the blood-stage antimalarial activity of pyronaridine in healthy volunteers experimentally infected with Plasmodium falciparum. Int J Antimicrob Agents 2024; 64:107196. [PMID: 38734217 DOI: 10.1016/j.ijantimicag.2024.107196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 04/23/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Abstract
With the spread of artemisinin resistance throughout Southeast Asia and now in Africa, the antimalarial drug pyronaridine is likely to become an increasingly important component of new antimalarial drug regimens. However, the antimalarial activity of pyronaridine in humans has not been completely characterised. This volunteer infection study aimed to determine the pharmacokinetic/pharmacodynamic (PK/PD) relationship of pyronaridine in malaria naïve adults. Volunteers were inoculated with Plasmodium falciparum-infected erythrocytes on day 0 and administered different single oral doses of pyronaridine on day 8. Parasitaemia and concentrations of pyronaridine were measured and standard safety assessments performed. Curative artemether-lumefantrine therapy was administered if parasite regrowth occurred, or on day 47 ± 2. Outcomes were parasite clearance kinetics, PK and PK/PD parameters from modelling. Ten participants were inoculated and administered 360 mg (n = 4), 540 mg (n = 4) or 720 mg (n = 1) pyronaridine. One participant was withdrawn without receiving pyronaridine. The time to maximum pyronaridine concentration was 1-2 h, the elimination half-life was 8-9 d, and the parasite clearance half-life was approximately 5 h. Parasite regrowth occurred with 360 mg (4/4 participants) and 540 mg (2/4 participants). Key efficacy parameters including the minimum inhibitory concentration (5.5 ng/mL) and minimum parasiticidal concentration leading to 90% of maximum effect (MPC90: 8 ng/mL) were derived from the PK/PD model. Adverse events considered related to pyronaridine were predominantly mild to moderate gastrointestinal symptoms. There were no serious adverse events. Data obtained in this study will support the use of pyronaridine in new antimalarial combination therapies by informing partner drug selection and dosing considerations.
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Affiliation(s)
- Bridget E Barber
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia; University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia; Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Rebecca Webster
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Adam J Potter
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Stacey Llewellyn
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Nischal Sahai
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | - Indika Leelasena
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | - Susan Mathison
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | | | - Julia Flynn
- Medicines for Malaria Venture, Geneva, Switzerland
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2
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Goodwin J, Kajubi R, Wang K, Li F, Wade M, Orukan F, Huang L, Whalen M, Aweeka FT, Mwebaza N, Parikh S. Persistent and multiclonal malaria parasite dynamics despite extended artemether-lumefantrine treatment in children. Nat Commun 2024; 15:3817. [PMID: 38714692 PMCID: PMC11076639 DOI: 10.1038/s41467-024-48210-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/24/2024] [Indexed: 05/10/2024] Open
Abstract
Standard diagnostics used in longitudinal antimalarial studies are unable to characterize the complexity of submicroscopic parasite dynamics, particularly in high transmission settings. We use molecular markers and amplicon sequencing to characterize post-treatment stage-specific malaria parasite dynamics during a 42 day randomized trial of 3- versus 5 day artemether-lumefantrine in 303 children with and without HIV (ClinicalTrials.gov number NCT03453840). The prevalence of parasite-derived 18S rRNA is >70% in children throughout follow-up, and the ring-stage marker SBP1 is detectable in over 15% of children on day 14 despite effective treatment. We find that the extended regimen significantly lowers the risk of recurrent ring-stage parasitemia compared to the standard 3 day regimen, and that higher day 7 lumefantrine concentrations decrease the probability of ring-stage parasites in the early post-treatment period. Longitudinal amplicon sequencing reveals remarkably dynamic patterns of multiclonal infections that include new and persistent clones in both the early post-treatment and later time periods. Our data indicate that post-treatment parasite dynamics are highly complex despite efficacious therapy, findings that will inform strategies to optimize regimens in the face of emerging partial artemisinin resistance in Africa.
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Affiliation(s)
- Justin Goodwin
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
- Yale School of Medicine, New Haven, CT, USA
| | - Richard Kajubi
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Kaicheng Wang
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT, USA
| | - Fangyong Li
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT, USA
| | - Martina Wade
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Francis Orukan
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Liusheng Huang
- University of California, San Francisco, San Francisco, CA, USA
| | - Meghan Whalen
- University of California, San Francisco, San Francisco, CA, USA
| | | | - Norah Mwebaza
- Infectious Disease Research Collaboration, Kampala, Uganda
- Department of Pharmacology and Therapeutics, Makerere University College of Health Sciences, Kampala, Uganda
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA.
- Yale School of Medicine, New Haven, CT, USA.
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3
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Webster R, Mitchell H, Peters JM, Heunis J, O'Neill B, Gower J, Lynch S, Jennings H, Amante FH, Llewellyn S, Marquart L, Potter AJ, Birrell GW, Edstein MD, Shanks GD, McCarthy JS, Barber BE. Transmission Blocking Activity of Low-dose Tafenoquine in Healthy Volunteers Experimentally Infected With Plasmodium falciparum. Clin Infect Dis 2023; 76:506-512. [PMID: 35731843 DOI: 10.1093/cid/ciac503] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Blocking the transmission of parasites from humans to mosquitoes is a key component of malaria control. Tafenoquine exhibits activity against all stages of the malaria parasite and may have utility as a transmission blocking agent. We aimed to characterize the transmission blocking activity of low-dose tafenoquine. METHODS Healthy adults were inoculated with Plasmodium falciparum 3D7-infected erythrocytes on day 0. Piperaquine was administered on days 9 and 11 to clear asexual parasitemia while allowing gametocyte development. A single 50-mg oral dose of tafenoquine was administered on day 25. Transmission was determined by enriched membrane feeding assays predose and at 1, 4, and 7 days postdose. Artemether-lumefantrine was administered following the final assay. Outcomes were the reduction in mosquito infection and gametocytemia after tafenoquine and safety parameters. RESULTS Six participants were enrolled, and all were infective to mosquitoes before tafenoquine, with a median 86% (range, 22-98) of mosquitoes positive for oocysts and 57% (range, 4-92) positive for sporozoites. By day 4 after tafenoquine, the oocyst and sporozoite positivity rate had reduced by a median 35% (interquartile range [IQR]: 16-46) and 52% (IQR: 40-62), respectively, and by day 7, 81% (IQR 36-92) and 77% (IQR 52-98), respectively. The decline in gametocyte density after tafenoquine was not significant. No significant participant safety concerns were identified. CONCLUSIONS Low-dose tafenoquine (50 mg) reduces P. falciparum transmission to mosquitoes, with a delay in effect.
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Affiliation(s)
- Rebecca Webster
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Hayley Mitchell
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jenny M Peters
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Juanita Heunis
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Brighid O'Neill
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jeremy Gower
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Sean Lynch
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Helen Jennings
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Fiona H Amante
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | | | - Adam J Potter
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Geoffrey W Birrell
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - Michael D Edstein
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - G Dennis Shanks
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
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4
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Cruz Camacho A, Kiper E, Oren S, Zaharoni N, Nir N, Soffer N, Noy Y, Ben David B, Rivkin A, Rotkopf R, Michael D, Carvalho TG, Regev-Rudzki N. High-throughput analysis of the transcriptional patterns of sexual genes in malaria. Parasit Vectors 2023; 16:14. [PMID: 36639683 PMCID: PMC9838061 DOI: 10.1186/s13071-022-05624-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/17/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Plasmodium falciparum (Pf) is the leading protozoan causing malaria, the most devastating parasitic disease. To ensure transmission, a small subset of Pf parasites differentiate into the sexual forms (gametocytes). Since the abundance of these essential parasitic forms is extremely low within the human host, little is currently known about the molecular regulation of their sexual differentiation, highlighting the need to develop tools to investigate Pf gene expression during this fundamental mechanism. METHODS We developed a high-throughput quantitative Reverse-Transcription PCR (RT-qPCR) platform to robustly monitor Pf transcriptional patterns, in particular, systematically profiling the transcriptional pattern of a large panel of gametocyte-related genes (GRG). Initially, we evaluated the technical performance of the systematic RT-qPCR platform to ensure it complies with the accepted quality standards for: (i) RNA extraction, (ii) cDNA synthesis and (iii) evaluation of gene expression through RT-qPCR. We then used this approach to monitor alterations in gene expression of a panel of GRG upon treatment with gametocytogenesis regulators. RESULTS We thoroughly elucidated GRG expression profiles under treatment with the antimalarial drug dihydroartemisinin (DHA) or the metabolite choline over the course of a Pf blood cycle (48 h). We demonstrate that both significantly alter the expression pattern of PfAP2-G, the gametocytogenesis master regulator. However, they also markedly modify the developmental rate of the parasites and thus might bias the mRNA expression. Additionally, we screened the effect of the metabolites lactate and kynurenic acid, abundant in severe malaria, as potential regulators of gametocytogenesis. CONCLUSIONS Our data demonstrate that the high-throughput RT-qPCR method enables studying the immediate transcriptional response initiating gametocytogenesis of the parasites from a very low volume of malaria-infected RBC samples. The obtained data expand the current knowledge of the initial alterations in mRNA profiles of GRG upon treatment with reported regulators. In addition, using this method emphasizes that asexual parasite stage composition is a crucial element that must be considered when interpreting changes in GRG expression by RT-qPCR, specifically when screening for novel compounds that could regulate Pf sexual differentiation.
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Affiliation(s)
- Abel Cruz Camacho
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Edo Kiper
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Sonia Oren
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Nir Zaharoni
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Netta Nir
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Noam Soffer
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Yael Noy
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Bar Ben David
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Anna Rivkin
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ron Rotkopf
- grid.13992.300000 0004 0604 7563Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dan Michael
- grid.13992.300000 0004 0604 7563Feinberg Graduate School, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Teresa G. Carvalho
- grid.1018.80000 0001 2342 0938Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Melbourne, VIC 3086 Australia
| | - Neta Regev-Rudzki
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
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5
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Persistence of Residual Submicroscopic P. falciparum Parasitemia following Treatment of Artemether-Lumefantrine in Ethio-Sudan Border, Western Ethiopia. Antimicrob Agents Chemother 2022; 66:e0000222. [PMID: 35993723 PMCID: PMC9487599 DOI: 10.1128/aac.00002-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The emergence of artemisinin-resistant parasites in Africa has had a devastating impact, causing most malaria cases and related deaths reported on the continent. In Ethiopia, artemether-lumefantrine (AL) is the first-line drug for the treatment of uncomplicated falciparum malaria. This study is one of the earliest evaluations of artemether-lumefantrine (AL) efficacy in western Ethiopia, 17 years after the introduction of this drug in the study area. This study aimed at assessing PCR- corrected clinical and parasitological responses at 28 days following AL treatment. Sixty uncomplicated falciparum malaria patients were enrolled, treated with standard doses of AL, and monitored for 28 days with clinical and parasitological assessments from September 15 to December 15, 2020. Microscopy was used for patient recruitment and molecular diagnosis of P. falciparum was performed by Var gene acidic terminal sequence (varATS) real-time PCR on dried blood spots collected from each patient from day 0 and on follow-up days 1, 2, 3, 7, 14, 21, and 28. MspI and msp2 genotyping was done to confirm occurrence of recrudescence. Data entry and analysis were done by using the WHO-designed Excel spreadsheet and SPSS version 20 for Windows. A P value of less or equal to 0.05 was considered significant. From a total of 60 patients enrolled in this efficacy study, 10 were lost to follow-up; the results were analyzed for 50 patients. All the patients were fever-free on day 3. The asexual parasite positivity rate on day 3 was zero. However; 60% of the patients were PCR positive on day 3. PCR positivity on day 3 was more common among patients <15 years old as compared with those ≥15 years old (AOR = 6.44, P = 0.027). Only two patients met the case definition of treatment failure. These patients were classified as a late clinical failure as they showed symptoms of malaria and asexual stages of the parasite detected by microscopy on day 14 of their follow-ups. Hence, the Kaplan-Meier analysis of PCR- corrected adequate clinical and parasitological response (ACPR) rate of AL among study participants was 96% (95% CI: 84.9-99). In seven patients, the residual submicroscopic parasitemia persists from day 0 to day 28 of the follow-up. In addition, 16% (8/50) of patients were PCR- and then turned PCR+ after day 7 of the follow-up. AL remains efficacious for the treatment of uncomplicated falciparum malaria in the study area. However, the persistence of PCR-detected residual submicroscopic parasitemia following AL might compromise this treatment and need careful monitoring.
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6
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Meibalan E, Barry A, Gibbins MP, Awandu S, Meerstein-Kessel L, Achcar F, Bopp S, Moxon C, Diarra A, Debe S, Ouédraogo N, Barry-Some I, Badoum ES, Fagnima T, Lanke K, Gonçalves BP, Bradley J, Wirth D, Drakeley C, Guelbeogo WM, Tiono AB, Marti M, Bousema T. Plasmodium falciparum Gametocyte Density and Infectivity in Peripheral Blood and Skin Tissue of Naturally Infected Parasite Carriers in Burkina Faso. J Infect Dis 2021; 223:1822-1830. [PMID: 31875909 PMCID: PMC8161640 DOI: 10.1093/infdis/jiz680] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/23/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Plasmodium falciparum transmission depends on mature gametocytes that can be ingested by mosquitoes taking a blood meal on human skin. Although gametocyte skin sequestration has long been hypothesized as important contributor to efficient malaria transmission, this has never been formally tested. METHODS In naturally infected gametocyte carriers from Burkina Faso, we assessed infectivity to mosquitoes by direct skin feeding and membrane feeding. We directly quantified male and female gametocytes and asexual parasites in finger-prick and venous blood samples, skin biopsy samples, and in of mosquitoes that fed on venous blood or directly on skin. Gametocytes were visualized in skin tissue with confocal microscopy. RESULTS Although more mosquitoes became infected when feeding directly on skin then when feeding on venous blood (odds ratio, 2.01; 95% confidence interval, 1.21-3.33; P = .007), concentrations of gametocytes were not higher in the subdermal skin vasculature than in other blood compartments; only sparse gametocytes were observed in skin tissue. DISCUSSION Our data strongly suggest that there is no significant skin sequestration of P. falciparum gametocytes. Gametocyte densities in peripheral blood are thus informative for predicting onward transmission potential to mosquitoes and can be used to target and monitor malaria elimination initiatives.
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Affiliation(s)
- Elamaran Meibalan
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, USA
| | - Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Radboud Institute for Health Sciences, Radboud University Medical Center, the Netherlands
| | - Matthew P Gibbins
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Shehu Awandu
- Radboud Institute for Health Sciences, Radboud University Medical Center, the Netherlands
| | | | - Fiona Achcar
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Selina Bopp
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Christopher Moxon
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Siaka Debe
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Nicolas Ouédraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Ines Barry-Some
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Emilie S Badoum
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Traoré Fagnima
- Centre Hospitalier Universitaire Régional de Ouahigoua, Université de Ouahigouya, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, the Netherlands
| | - Bronner P Gonçalves
- Immunology and Infection Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Dyann Wirth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Chris Drakeley
- Immunology and Infection Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Matthias Marti
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, the Netherlands
- Immunology and Infection Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
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7
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Wang CYT, Ballard EL, Pava Z, Marquart L, Gaydon J, Murphy SC, Whiley D, O'Rourke P, McCarthy JS. Analytical validation of a real-time hydrolysis probe PCR assay for quantifying Plasmodium falciparum parasites in experimentally infected human adults. Malar J 2021; 20:181. [PMID: 33838672 PMCID: PMC8035755 DOI: 10.1186/s12936-021-03717-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 03/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background Volunteer infection studies have become a standard model for evaluating drug efficacy against Plasmodium infections. Molecular techniques such as qPCR are used in these studies due to their ability to provide robust and accurate estimates of parasitaemia at increased sensitivity compared to microscopy. The validity and reliability of assays need to be ensured when used to evaluate the efficacy of candidate drugs in clinical trials. Methods A previously described 18S rRNA gene qPCR assay for quantifying Plasmodium falciparum in blood samples was evaluated. Assay performance characteristics including analytical sensitivity, reportable range, precision, accuracy and specificity were assessed using experimental data and data compiled from phase 1 volunteer infection studies conducted between 2013 and 2019. Guidelines for validation of laboratory-developed molecular assays were followed. Results The reportable range was 1.50 to 6.50 log10 parasites/mL with a limit of detection of 2.045 log10 parasites/mL of whole blood based on a parasite diluted standard series over this range. The assay was highly reproducible with minimal intra-assay (SD = 0.456 quantification cycle (Cq) units [0.137 log10 parasites/mL] over 21 replicates) and inter-assay (SD = 0.604 Cq units [0.182 log10 parasites/mL] over 786 qPCR runs) variability. Through an external quality assurance program, the QIMR assay was shown to generate accurate results (quantitative bias + 0.019 log10 parasites/mL against nominal values). Specificity was 100% after assessing 164 parasite-free human blood samples. Conclusions The 18S rRNA gene qPCR assay is specific and highly reproducible and can provide reliable and accurate parasite quantification. The assay is considered fit for use in evaluating drug efficacy in malaria clinical trials. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03717-y.
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Affiliation(s)
- Claire Y T Wang
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia. .,Child Health Research Centre, The University of Queensland, Brisbane, Australia.
| | - Emma L Ballard
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Zuleima Pava
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jane Gaydon
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia.,Child Health Research Centre, The University of Queensland, Brisbane, Australia
| | - Sean C Murphy
- Departments of Laboratory Medicine and Microbiology, University of Washington, Seattle, WA, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - David Whiley
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia.,UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Peter O'Rourke
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Medicine, The University of Queensland, Brisbane, Australia
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8
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Yadavalli R, Umeda K, Waugh HA, Tracy AN, Sidhu AV, Hernández DE, Fernández Robledo JA. CRISPR/Cas9 Ribonucleoprotein-Based Genome Editing Methodology in the Marine Protozoan Parasite Perkinsus marinus. Front Bioeng Biotechnol 2021; 9:623278. [PMID: 33898400 PMCID: PMC8062965 DOI: 10.3389/fbioe.2021.623278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/09/2021] [Indexed: 11/15/2022] Open
Abstract
Perkinsus marinus (Perkinsozoa), a close relative of apicomplexans, is an osmotrophic facultative intracellular marine protozoan parasite responsible for "Dermo" disease in oysters and clams. Although there is no clinical evidence of this parasite infecting humans, HLA-DR40 transgenic mice studies strongly suggest the parasite as a natural adjuvant in oral vaccines. P. marinus is being developed as a heterologous gene expression platform for pathogens of medical and veterinary relevance and a novel platform for delivering vaccines. We previously reported the transient expression of two rodent malaria genes Plasmodium berghei HAP2 and MSP8. In this study, we optimized the original electroporation-based protocol to establish a stable heterologous expression method. Using 20 μg of pPmMOE[MOE1]:GFP and 25.0 × 106 P. marinus cells resulted in 98% GFP-positive cells. Furthermore, using the optimized protocol, we report for the first time the successful knock-in of GFP at the C-terminus of the PmMOE1 using ribonucleoprotein (RNP)-based CRISPR/Cas9 gene editing methodology. The GFP was expressed 18 h post-transfection, and expression was observed for 8 months post-transfection, making it a robust and stable knock-in system.
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Affiliation(s)
| | - Kousuke Umeda
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
| | - Hannah A. Waugh
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
- Southern Maine Community College, South Portland, ME, United States
| | - Adrienne N. Tracy
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
- Colby College, Waterville, ME, United States
| | - Asha V. Sidhu
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
- Colby College, Waterville, ME, United States
| | - Derek E. Hernández
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
- Colby College, Waterville, ME, United States
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9
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Yadavalli R, Peterson JW, Drazba JA, Sam-Yellowe TY. Trafficking and Association of Plasmodium falciparum MC-2TM with the Maurer's Clefts. Pathogens 2021; 10:pathogens10040431. [PMID: 33916455 PMCID: PMC8066109 DOI: 10.3390/pathogens10040431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/28/2021] [Accepted: 03/30/2021] [Indexed: 12/05/2022] Open
Abstract
In this study, we investigated stage specific expression, trafficking, solubility and topology of endogenous PfMC-2TM in P. falciparum (3D7) infected erythrocytes. Following Brefeldin A (BFA) treatment of parasites, PfMC-2TM traffic was evaluated using immunofluorescence with antibodies reactive with PfMC-2TM. PfMC-2TM is sensitive to BFA treatment and permeabilization of infected erythrocytes with streptolysin O (SLO) and saponin, showed that the N and C-termini of PfMC-2TM are exposed to the erythrocyte cytoplasm with the central portion of the protein protected in the MC membranes. PfMC-2TM was expressed as early as 4 h post invasion (hpi), was tightly colocalized with REX-1 and trafficked to the erythrocyte membrane without a change in solubility. PfMC-2TM associated with the MC and infected erythrocyte membrane and was resistant to extraction with alkaline sodium carbonate, suggestive of protein-lipid interactions with membranes of the MC and erythrocyte. PfMC-2TM is an additional marker of the nascent MCs.
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Affiliation(s)
- Raghavendra Yadavalli
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA;
| | - John W. Peterson
- Imaging Core Facility, The Cleveland Clinic, Cleveland, OH 44195, USA; (J.W.P.); (J.A.D.)
| | - Judith A. Drazba
- Imaging Core Facility, The Cleveland Clinic, Cleveland, OH 44195, USA; (J.W.P.); (J.A.D.)
| | - Tobili Y. Sam-Yellowe
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA;
- Correspondence: ; Tel.: +1-216-687-2068
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10
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Mahamar A, Lanke K, Graumans W, Diawara H, Sanogo K, Diarra K, Niambele SM, Gosling R, Drakeley C, Chen I, Dicko A, Bousema T, Roh ME. Persistence of mRNA indicative of Plasmodium falciparum ring-stage parasites 42 days after artemisinin and non-artemisinin combination therapy in naturally infected Malians. Malar J 2021; 20:34. [PMID: 33422068 PMCID: PMC7797096 DOI: 10.1186/s12936-020-03576-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 12/31/2020] [Indexed: 11/10/2022] Open
Abstract
Background Malaria control in sub-Saharan Africa relies upon prompt case management with artemisinin-based combination therapy (ACT). Ring-stage parasite mRNA, measured by sbp1 quantitative reverse-transcriptase PCR (qRT-PCR), was previously reported to persist after ACT treatment and hypothesized to reflect temporary arrest of the growth of ring-stage parasites (dormancy) following exposure to artemisinins. Here, the persistence of ring-stage parasitaemia following ACT and non-ACT treatment was examined. Methods Samples were used from naturally infected Malian gametocyte carriers who received dihydroartemisinin–piperaquine (DP) or sulfadoxine–pyrimethamine (SP–AQ) with or without gametocytocidal drugs. Gametocytes and ring-stage parasites were quantified by qRT-PCR during 42 days of follow-up. Results At baseline, 89% (64/73) of participants had measurable ring-stage parasite mRNA. Following treatment, the proportion of ring-stage parasite-positive individuals and estimated densities declined for all four treatment groups. Ring-stage parasite prevalence and density was generally lower in arms that received DP compared to SP–AQ. This finding was most apparent days 1, 2, and 42 of follow-up (p < 0.01). Gametocytocidal drugs did not influence ring-stage parasite persistence. Ring-stage parasite density estimates on days 14 and 28 after initiation of treatment were higher among individuals who subsequently experienced recurrent parasitaemia compared to those who remained free of parasites until day 42 after initiation of treatment (pday 14 = 0.011 and pday 28 = 0.068). No association of ring-stage persistence with gametocyte carriage was observed. Conclusions The current findings of lower ring-stage persistence after ACT without an effect of gametocytocidal partner drugs affirms the use of sbp1 as ring-stage marker. Lower persistence of ring-stage mRNA after ACT treatment suggests the marker may not reflect dormant parasites whilst it was predictive of re-appearance of parasitaemia.
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Affiliation(s)
- Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, PO Box 9101, 6525GA, Nijmegen, The Netherlands
| | - Wouter Graumans
- Radboud Institute for Health Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, PO Box 9101, 6525GA, Nijmegen, The Netherlands
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Koualy Sanogo
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Kalifa Diarra
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Sidi Mohamed Niambele
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Roly Gosling
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA
| | - Chris Drakeley
- Department of Infection & Immunity, London School of Hygiene & Tropical Medicine, London, UK
| | - Ingrid Chen
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, PO Box 9101, 6525GA, Nijmegen, The Netherlands. .,Department of Infection & Immunity, London School of Hygiene & Tropical Medicine, London, UK.
| | - Michelle E Roh
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA
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11
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Mhamilawa LE, Ngasala B, Morris U, Kitabi EN, Barnes R, Soe AP, Mmbando BP, Björkman A, Mårtensson A. Parasite clearance, cure rate, post-treatment prophylaxis and safety of standard 3-day versus an extended 6-day treatment of artemether-lumefantrine and a single low-dose primaquine for uncomplicated Plasmodium falciparum malaria in Bagamoyo district, Tanzania: a randomized controlled trial. Malar J 2020; 19:216. [PMID: 32576258 PMCID: PMC7310382 DOI: 10.1186/s12936-020-03287-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 06/12/2020] [Indexed: 11/19/2022] Open
Abstract
Background Artemisinin-based combination therapy (ACT) resistant Plasmodium falciparum represents an increasing threat to Africa. Extended ACT regimens from standard 3 to 6 days may represent a means to prevent its development and potential spread in Africa. Methods Standard 3-day treatment with artemether–lumefantrine (control) was compared to extended 6-day treatment and single low-dose primaquine (intervention); in a randomized controlled, parallel group, superiority clinical trial of patients aged 1–65 years with microscopy confirmed uncomplicated P. falciparum malaria, enrolled in Bagamoyo district, Tanzania. The study evaluated parasite clearance, including proportion of PCR detectable P. falciparum on days 5 and 7 (primary endpoint), cure rate, post-treatment prophylaxis, safety and tolerability. Clinical, and laboratory assessments, including ECG were conducted during 42 days of follow-up. Blood samples were collected for parasite detection (by microscopy and PCR), molecular genotyping and pharmacokinetic analyses. Kaplan–Meier survival analyses were done for both parasite clearance and recurrence. Results A total of 280 patients were enrolled, 141 and 139 in the control and intervention arm, respectively, of whom 121 completed 42 days follow-up in each arm. There was no difference in proportion of PCR positivity across the arms at day 5 (80/130 (61.5%) vs 89/134 (66.4%), p = 0.44), or day 7 (71/129 (55.0%) vs 70/134 (52.2%), p = 0.71). Day 42 microscopy determined cure rates (PCR adjusted) were 97.4% (100/103) and 98.3% (110/112), p = 0.65, in the control and intervention arm, respectively. Microscopy determined crude recurrent parasitaemia during follow-up was 21/121 (17.4%) in the control and 14/121 (11.6%) in the intervention arm, p = 0.20, and it took 34 days and 42 days in the respective arms for 90% of the patients to remain without recurrent parasitaemia. Lumefantrine exposure was significantly higher in intervention arm from D3 to D42, but cardiac, biochemical and haematological safety was high and similar in both arms. Conclusion Extended 6-day artemether–lumefantrine treatment and a single low-dose of primaquine was not superior to standard 3-day treatment for ACT sensitive P. falciparum infections but, importantly, equally efficacious and safe. Thus, extended artemether–lumefantrine treatment may be considered as a future treatment regimen for ACT resistant P. falciparum, to prolong the therapeutic lifespan of ACT in Africa. Trial registration ClinicalTrials.gov, NCT03241901. Registered July 27, 2017 https://clinicaltrials.gov/show/NCT03241901
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Affiliation(s)
- Lwidiko E Mhamilawa
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden. .,Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania.
| | - Billy Ngasala
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden.,Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Ulrika Morris
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Eliford Ngaimisi Kitabi
- Office of Clinical Pharmacology, Division of Pharmacometrics, Food and Drugs Administration, Silver Spring, MD, USA
| | - Rory Barnes
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Aung Paing Soe
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden.,Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Bruno P Mmbando
- Tanga Centre, National Institute for Medical Research, Tanga, Tanzania
| | - Anders Björkman
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Andreas Mårtensson
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden
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12
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Mwaiswelo R, Ngasala B. Evaluation of residual submicroscopic Plasmodium falciparum parasites 3 days after initiation of treatment with artemisinin-based combination therapy. Malar J 2020; 19:162. [PMID: 32316974 PMCID: PMC7175519 DOI: 10.1186/s12936-020-03235-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 04/15/2020] [Indexed: 11/25/2022] Open
Abstract
Plasmodium falciparum resistance against artemisinin has not emerged in Africa; however, there are reports of the presence of polymerase chain reaction-determined residual submicroscopic parasitaemia detected on day 3 after artemisinin-based combination therapy (ACT). These residual submicroscopic parasites are thought to represent tolerant/resistant parasites against artemisinin, the fast-acting component of the combination. This review focused on residual submicroscopic parasitaemia, what it represents, and its significance on the emergence and spread of artemisinin resistance in Africa. Presence of residual submicroscopic parasitemia on day 3 after treatment initiation leaves question on whether successful treatment is attained with ACT. Thus there is a need to determine the potential public health implication of the PCR-determined residual submicroscopic parasitaemia observed on day 3 after ACT. Robust techniques, such as in vitro cultivation, should be used to evaluate if the residual submicroscopic parasites detected on day 3 after ACT are viable asexual parasites, or gametocytes, or the DNA of the dead parasites waiting to be cleared from the circulation. Such techniques would also evaluate the transmissibility of these residual parasites.
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Affiliation(s)
- Richard Mwaiswelo
- Department of Microbiology, Immunology and Parasitology, Hubert Kairuki Memorial University, Dar es Salaam, Tanzania.
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania.
| | - Bill Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
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13
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Graumans W, Andolina C, Awandu SS, Grignard L, Lanke K, Bousema T. Plasmodium falciparum Gametocyte Enrichment in Peripheral Blood Samples by Magnetic Fractionation: Gametocyte Yields and Possibilities to Reuse Columns. Am J Trop Med Hyg 2020; 100:572-577. [PMID: 30608048 PMCID: PMC6402936 DOI: 10.4269/ajtmh.18-0773] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Gametocytes are sexual stage malaria parasites responsible for transmission to mosquitoes. Multiple gametocyte-producing clones may be present in natural infections, but the molecular characterization of gametocytes is challenging. Because of their magnetic properties, gametocyte enrichment can be achieved by magnetic fractionation. This increases detection sensitivity and allows specific genotyping of clones that contribute to malaria transmission. Here, we determined the percentage of Plasmodium falciparum gametocytes successfully bound to magnetic activated cell sorting (MACS) LS columns during magnetic fractionation and assessed whether columns can be reused without risking contamination or affecting column binding efficiency. Bound column fractions were quantified using multiplex quantitative reverse transcription polymerase chain reaction (qRT-PCR) for male (pfMGET) and female (CCp4) gametocytes and ring-stage asexual parasites (SBP1). To investigate cross contamination between columns, parasite strain identity was determined by merozoite surface protein 2 genotyping followed by capillary electrophoresis fragment sizing. A reproducible high percentage of gametocytes was bound to MACS LS columns with < 5% gametocytes appearing in the flow-through and < 0.6% asexual ring-stage parasites appearing in the gametocyte fraction. A high yield (> 94%) of gametocyte enrichment was achieved when columns were used up to five times with lower binding success after eight times (79%). We observed no evidence for cross contamination between columns.
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Affiliation(s)
- Wouter Graumans
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Shehu S Awandu
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kjerstin Lanke
- 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.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
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14
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DSM265 at 400 Milligrams Clears Asexual Stage Parasites but Not Mature Gametocytes from the Blood of Healthy Subjects Experimentally Infected with Plasmodium falciparum. Antimicrob Agents Chemother 2019; 63:AAC.01837-18. [PMID: 30858218 PMCID: PMC6437518 DOI: 10.1128/aac.01837-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/25/2019] [Indexed: 12/19/2022] Open
Abstract
DSM265 is a novel antimalarial drug in clinical development that acts as a selective inhibitor of Plasmodium dihydroorotate dehydrogenase. In a previous phase 1b study, a single 150-mg dose of DSM265 showed partial efficacy against experimentally induced blood-stage Plasmodium falciparum malaria (IBSM). DSM265 is a novel antimalarial drug in clinical development that acts as a selective inhibitor of Plasmodium dihydroorotate dehydrogenase. In a previous phase 1b study, a single 150-mg dose of DSM265 showed partial efficacy against experimentally induced blood-stage Plasmodium falciparum malaria (IBSM). Pharmacokinetic/pharmacodynamic modeling predicted a human efficacious dose of 340 mg. The primary objectives of the current study were to determine the safety and efficacy of a single oral 400-mg dose of DSM265 against P. falciparum in the IBSM model. Eight healthy participants were inoculated intravenously with 2,800 parasites and treated with DSM265 7 days later. Unexpectedly, one participant did not develop parasitemia during the study. All other participants developed parasitemia, with the complete clearance of asexual parasites occurring following DSM265 treatment. All seven subjects also became gametocytemic. The secondary objectives were to investigate the gametocytocidal and transmission-blocking activity of a second 400-mg dose of DSM265, which was administered 23 days after inoculation. Gametocytes were not cleared by the second dose of DSM265, and transmission-blocking activity could not be determined due to low gametocyte densities. Three DSM265-related adverse events occurred, including a cutaneous rash in one subject on the day of the second DSM265 dose. The results obtained in this study support the prediction of the efficacious dose of DSM265 and provide further evidence that DSM265 is generally safe and well tolerated. In addition, this study confirms preclinical data indicating that DSM265 permits the development and maturation of gametocytes and does not clear mature circulating gametocytes. (This study has been registered at ClinicalTrials.gov under identifier NCT02573857.)
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15
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Murphy SC, Ishizuka AS, Billman ZP, Olsen TM, Seilie AM, Chang M, Smith N, Chuenchob V, Chakravarty S, Sim BKL, Kappe SHI, Hoffman SL, Seder RA. Plasmodium 18S rRNA of intravenously administered sporozoites does not persist in peripheral blood. Malar J 2018; 17:275. [PMID: 30053881 PMCID: PMC6062992 DOI: 10.1186/s12936-018-2422-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/19/2018] [Indexed: 01/14/2023] Open
Abstract
Background Plasmodium 18S rRNA is a biomarker used to monitor blood-stage infections in malaria clinical trials. Plasmodium sporozoites also express this biomarker, and there is conflicting evidence about how long sporozoite-derived 18S rRNA persists in peripheral blood. If present in blood for an extended timeframe, sporozoite-derived 18S rRNA could complicate use as a blood-stage biomarker. Methods Blood samples from Plasmodium yoelii infected mice were tested for Plasmodium 18S rRNA and their coding genes (rDNA) using sensitive quantitative reverse transcription PCR and quantitative PCR assays, respectively. Blood and tissues from Plasmodium falciparum sporozoite (PfSPZ)-infected rhesus macaques were similarly tested. Results In mice, when P. yoelii sporozoite inoculation and blood collection were performed at the same site (tail vein), low level rDNA positivity persisted for 2 days post-infection. Compared to intact parasites with high rRNA-to-rDNA ratios, this low level positivity was accompanied by no increase in rRNA-to-rDNA, indicating detection of residual, non-viable parasite rDNA. When P. yoelii sporozoites were administered via the retro-orbital vein and blood sampled by cardiac puncture, neither P. yoelii 18S rRNA nor rDNA were detected 24 h post-infection. Similarly, there was no P. falciparum 18S rRNA detected in blood of rhesus macaques 3 days after intravenous injection with extremely high doses of PfSPZ. Plasmodium 18S rRNA in the rhesus livers increased by approximately 101-fold from 3 to 6 days post infection, indicating liver-stage proliferation. Conclusions Beyond the first few hours after injection, sporozoite-derived Plasmodium 18S rRNA was not detected in peripheral blood. Diagnostics based on 18S rRNA are unlikely to be confounded by sporozoite inocula in human clinical trials.
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Affiliation(s)
- Sean C Murphy
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA. .,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA.
| | - Andrew S Ishizuka
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 40, Room 3512, 40 Convent Drive, Bethesda, MD, 20814, USA
| | - Zachary P Billman
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Tayla M Olsen
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Annette M Seilie
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Ming Chang
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Nahum Smith
- Departments of Laboratory Medicine and Microbiology, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Vorada Chuenchob
- Center for Infectious Disease Research, 307 Westlake Ave N #500, Seattle, WA, 98109, USA
| | - Sumana Chakravarty
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - B Kim Lee Sim
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Stefan H I Kappe
- Center for Infectious Disease Research, 307 Westlake Ave N #500, Seattle, WA, 98109, USA
| | - Stephen L Hoffman
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Robert A Seder
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 40, Room 3512, 40 Convent Drive, Bethesda, MD, 20814, USA
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16
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Collins KA, Wang CY, Adams M, Mitchell H, Rampton M, Elliott S, Reuling IJ, Bousema T, Sauerwein R, Chalon S, Möhrle JJ, McCarthy JS. A controlled human malaria infection model enabling evaluation of transmission-blocking interventions. J Clin Invest 2018; 128:1551-1562. [PMID: 29389671 PMCID: PMC5873858 DOI: 10.1172/jci98012] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/30/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND. Drugs and vaccines that can interrupt the transmission of Plasmodium falciparum will be important for malaria control and elimination. However, models for early clinical evaluation of candidate transmission-blocking interventions are currently unavailable. Here, we describe a new model for evaluating malaria transmission from humans to Anopheles mosquitoes using controlled human malaria infection (CHMI). METHODS. Seventeen healthy malaria-naive volunteers underwent CHMI by intravenous inoculation of P. falciparum–infected erythrocytes to initiate blood-stage infection. Seven to eight days after inoculation, participants received piperaquine (480 mg) to attenuate asexual parasite replication while allowing gametocytes to develop and mature. Primary end points were development of gametocytemia, the transmissibility of gametocytes from humans to mosquitoes, and the safety and tolerability of the CHMI transmission model. To investigate in vivo gametocytocidal drug activity in this model, participants were either given an experimental antimalarial, artefenomel (500 mg), or a known gametocytocidal drug, primaquine (15 mg), or remained untreated during the period of gametocyte carriage. RESULTS. Male and female gametocytes were detected in all participants, and transmission to mosquitoes was achieved from 8 of 11 (73%) participants evaluated. Compared with results in untreated controls (n = 7), primaquine (15 mg, n = 5) significantly reduced gametocyte burden (P = 0.01), while artefenomel (500 mg, n = 4) had no effect. Adverse events (AEs) were mostly mild or moderate. Three AEs were assessed as severe — fatigue, elevated alanine aminotransferase, and elevated aspartate aminotransferase — and were attributed to malaria infection. Transaminase elevations were transient, asymptomatic, and resolved without intervention. CONCLUSION. We report the safe and reproducible induction of P. falciparum gametocytes in healthy malaria-naive volunteers at densities infectious to mosquitoes, thereby demonstrating the potential for evaluating transmission-blocking interventions in this model. TRIAL REGISTRATION. ClinicalTrials.gov NCT02431637 and NCT02431650. FUNDING. Bill & Melinda Gates Foundation.
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Affiliation(s)
| | - Claire Yt Wang
- Queensland Paediatric Infectious Diseases (QPID) Laboratory, Centre for Children's Health Research, Brisbane, Queensland, Australia
| | - Matthew Adams
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Hayley Mitchell
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Melanie Rampton
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | - Isaie J Reuling
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | - Teun Bousema
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | - Robert Sauerwein
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | | | | | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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17
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Vafa Homann M, Emami SN, Yman V, Stenström C, Sondén K, Ramström H, Karlsson M, Asghar M, Färnert A. Detection of Malaria Parasites After Treatment in Travelers: A 12-months Longitudinal Study and Statistical Modelling Analysis. EBioMedicine 2017; 25:66-72. [PMID: 29050948 PMCID: PMC5704054 DOI: 10.1016/j.ebiom.2017.10.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/21/2017] [Accepted: 10/02/2017] [Indexed: 01/30/2023] Open
Abstract
The rapid clearance of malaria parasite DNA from circulation has widely been accepted as a fact without being systemically investigated. We assessed the persistence of parasite DNA in travelers treated for Plasmodium falciparum malaria in a malaria-free area. Venous blood was collected at the time of admission and prospectively up to one year. DNA and RNA were extracted and analyzed using species-specific and gametocyte-specific real-time PCR as well as merozoite surface protein 2 (msp2)-PCR. In 31 successfully treated individuals, asexual parasites were seen by microscopy until two days after treatment, whereas parasite DNA was detected by msp2- and species-specific PCR up to days 31 and 42, respectively. Statistical modelling predicted 26% (±0·05 SE) species-specific PCR positivity until day 40 and estimated 48days for all samples to become PCR negative. Gametocytes were detected by microscopy and PCR latest two days after treatment. CT values correlated well with microscopy-defined parasite densities before but not after treatment started. These results reveal that PCR positivity can persist several weeks after treatment without evidence of viable sexual or asexual parasites, indicating that PCR may overestimate parasite prevalence after treatment.
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Affiliation(s)
- Manijeh Vafa Homann
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
| | - S Noushin Emami
- Department of Molecular Bioscience, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Victor Yman
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Christine Stenström
- Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Klara Sondén
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Hanna Ramström
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Mattias Karlsson
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
| | - Muhammad Asghar
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
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