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Ouattara SB, Hien DFDS, Nao ET, Paré PSL, Guissou E, Cohuet A, Morlais I, Yerbanga RS, Dabiré KR, Ouédraogo JB, Mouline K, Lefèvre T. A simple, field-applicable method to increase the infectivity of wild isolates of Plasmodium falciparum to mosquito vectors. Malar J 2024; 23:135. [PMID: 38711028 DOI: 10.1186/s12936-024-04969-0] [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: 01/10/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024] Open
Abstract
BACKGROUND The direct membrane feeding assay (DMFA), whereby gametocyte-infected blood is collected from human donors and from which mosquitoes feed through a membrane, is proving essential for assessing parameters influencing Plasmodium transmission potential in endemic countries. The success of DMFAs is closely tied to gametocyte density in the blood, with relatively high gametocytaemia ensuring optimal infection levels in mosquitoes. As transmission intensity declines with control efforts, the occurrence of asymptomatic individuals with low gametocyte densities, who can significantly contribute to the infectious reservoir, is increasing. This poses a limitation to studies relying on the experimental infection of large numbers of mosquitoes with natural isolates of Plasmodium. A simple, field-applicable method is presented for improving parasite infectivity by concentrating Plasmodium falciparum gametocytes. METHODS Anopheles gambiae received one of the following 5 blood treatments through DMFA: (i) whole blood (WB) samples from naturally-infected donors; (ii) donor blood whose plasma was replaced with the same volume of Plasmodium-naive AB + serum (1:1 control); (iii) plasma replaced with a volume of malaria-naïve AB + serum equivalent to half (1:1/2), or to a quarter (1:1/4), of the initial plasma volume; and (v) donor blood whose plasma was fully removed (RBC). The experiment was repeated 4 times using 4 distinct wild parasite isolates. Seven days post-infection, a total of 1,095 midguts were examined for oocyst presence. RESULTS Substituting plasma with reduced amounts (1:1/2 and 1:1/4) of Plasmodium-naive AB + serum led to a 31% and 17% increase of the mosquito infection rate and to a 85% and 308% increase in infection intensity compared to the 1:1 control, respectively. The full removal of plasma (RBC) reduced the infection rate by 58% and the intensity by 64% compared to the 1:1 control. Reducing serum volumes (1:1/2; 1:1/4 and RBC) had no impact on mosquito feeding rate and survival when compared to the 1:1 control. CONCLUSIONS Concentrating gametocytic blood by replacing natural plasma by lower amount of naive serum can enhance the success of mosquito infection. In an area with low gametocyte density, this simple and practical method of parasite concentration can facilitate studies on human-to-mosquito transmission such as the evaluation of transmission-blocking interventions.
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Affiliation(s)
- Seydou Bienvenu Ouattara
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso.
- Institut Des Sciences Et Techniques (INSTech Bobo), Bobo-Dioulasso, Burkina Faso.
- Centre Hospitalier Régional de Gaoua (CHRG), Gaoua, Burkina Faso.
| | - Domonbabele F D S Hien
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Ekôbié T Nao
- Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Prisca S L Paré
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Edwige Guissou
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
- Ecole Normale Supérieure, BP 376, Koudougou, Burkina Faso
| | - Anna Cohuet
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Isabelle Morlais
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Rakiswendé S Yerbanga
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- Institut Des Sciences Et Techniques (INSTech Bobo), Bobo-Dioulasso, Burkina Faso
| | - Kounbobr R Dabiré
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
| | - Jean Bosco Ouédraogo
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- Institut Des Sciences Et Techniques (INSTech Bobo), Bobo-Dioulasso, Burkina Faso
| | - Karine Mouline
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Thierry Lefèvre
- Institut de Recherche en Sciences de La Santé, Direction Régionale de L'Ouest (IRSS-DRO), Bobo-Dioulasso, Burkina Faso.
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France.
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Ayo D, Onyige I, Okoth J, Musasizi E, Oruni A, Ramjith J, Arinaitwe E, Rek JC, Drakeley C, Staedke SG, Donnelly MJ, Bousema T, Conrad M, Blanken SL. Susceptibility of Anopheles gambiae to Natural Plasmodium falciparum Infection: A Comparison between the Well-Established Anopheles gambiae s.s Line and a Newly Established Ugandan Anopheles gambiae s.s. Line. Am J Trop Med Hyg 2024; 110:209-213. [PMID: 38150729 PMCID: PMC10859803 DOI: 10.4269/ajtmh.23-0203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 09/23/2023] [Indexed: 12/29/2023] Open
Abstract
Much of our understanding of malaria transmission comes from mosquito feeding assays using Anopheles mosquitoes from colonies that are well adapted to membrane feeding. This raises the question whether results from colony mosquitoes lead to overestimates of outcomes in wild Anopheles mosquitoes. We successfully established an Anopheles colony using progeny of wild Anopheles gambiae s.s. mosquitoes (Busia mosquitoes) and directly compared their susceptibility to infection with Plasmodium falciparum with the widely used An. gambiae s.s. mosquitoes (Kisumu mosquitoes) using gametocyte-infected Ugandan donor blood. The proportion of infectious feeds did not differ between Busia (71.8%, 23/32) and Kisumu (68.8%, 22/32, P = 1.00) mosquitoes. When correcting for random effects of donor blood, we observed a 23% higher proportion of infected Busia mosquitoes than infected Kisumu mosquitoes (RR, 1.23; 95% CI, 1.10-1.38, P < 0.001). This study suggests that feeding assays with Kisumu mosquitoes do not overestimate outcomes in wild An. gambiae s.s. mosquitoes, the mosquito species most relevant to malaria transmission in Uganda.
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Affiliation(s)
- Daniel Ayo
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - Ismail Onyige
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - Joseph Okoth
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - Eric Musasizi
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - Ambrose Oruni
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Jordache Ramjith
- Department for Health Evidence, Radboud University Medical Center, Nijmegen, Netherlands
| | - Emmanuel Arinaitwe
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - John C. Rek
- Infectious Diseases Research Collaboration, Nagongera Hospital, Tororo, Uganda
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Sarah G. Staedke
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Center, Nijmegen
| | - Melissa Conrad
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, California
| | - Sara Lynn Blanken
- Department of Medical Microbiology, Radboud University Nijmegen Medical Center, Nijmegen
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Ramos GQ, Baia-da-Silva DC, Lacerda MVG, Monteiro WM, Lopes SCP. Viability and Infectivity of Plasmodium vivax Gametocytes in Short-Term Culture. Front Cell Infect Microbiol 2021; 11:676276. [PMID: 34141630 PMCID: PMC8204544 DOI: 10.3389/fcimb.2021.676276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/10/2021] [Indexed: 11/13/2022] Open
Abstract
The control and elimination of malaria caused by Plasmodium vivax both represent a great challenge due to the biological aspects of the species. Gametocytes are the forms responsible for the transmission of the parasite to the vector and the search for new strategies for blocking transmission are essential in a scenario of control and elimination The challenges in this search in regard to P. vivax mainly stem from the lack of a long-term culture and the limitation of studies of gametocytes. This study evaluated the viability and infectivity of P. vivax gametocytes in short-term culture. The samples enriched in gametocytes using Percoll (i), using magnetic-activated cell sorting (MACS®) (ii), and using non-enriched samples (iii) were evaluated. After the procedures, gametocytes were cultured in IMDM medium for up to 48 h. Cultured P. vivax gametocytes were viable and infectious for up to 48 h, however differences in viability and infectivity were observed in the samples after 12 h of culture in relation to 0 h. Percoll-enriched samples were shown to be viable in culture for longer intervals than those purified using MACS®. Gametocyte viability after enrichment procedures and short-term culture may provide new avenues in the development of methods for evaluating P. vivax TB.
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Affiliation(s)
- Glenda Quaresma Ramos
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Djane Clarys Baia-da-Silva
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
- Instituto Leônidas & Maria Deane, FIOCRUZ, Manaus, Brazil
| | - Marcus Vinícius Guimarães Lacerda
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
- Instituto Leônidas & Maria Deane, FIOCRUZ, Manaus, Brazil
| | - Wuelton Marcelo Monteiro
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Stefanie Costa Pinto Lopes
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
- Instituto Leônidas & Maria Deane, FIOCRUZ, Manaus, Brazil
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Graumans W, Heutink R, van Gemert GJ, van de Vegte-Bolmer M, Bousema T, Collins KA. A mosquito feeding assay to examine Plasmodium transmission to mosquitoes using small blood volumes in 3D printed nano-feeders. Parasit Vectors 2020; 13:401. [PMID: 32771047 PMCID: PMC7414548 DOI: 10.1186/s13071-020-04269-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/29/2020] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND To understand the dynamics of malaria transmission, membrane feeding assays with glass feeders are used to assess the transmission potential of malaria infected individuals to mosquitoes. However, in some circumstances, use of these assays is hindered by both the blood volume requirement and the availability of fragile, specially crafted glass feeders. 3D printed plastic feeders that require very small volumes of blood would thus expand the utility of membrane feeding assays. METHODS Using two 3D printing production methods, MultiJet (MJ) and Digital Light Processing (DLP), we developed a plastic version of the most commonly used standard glass feeder (the mini-feeder) with an improved design, and also a smaller feeder requiring only 60 µl of blood (the nano-feeder). Performance of the 3D printed feeders was compared to standard glass mini-feeders by assessing infectivity of gametocytes to mosquitoes in standard membrane feeding assays with laboratory reared Anopheles stephensi mosquitoes and cultured Plasmodium falciparum gametocytes. In addition, the optimum number of mosquitoes that can feed on the nano-feeder was determined by evaluating fully fed mosquitoes visually and by assessing blood- meal volume with a colorimetric haemoglobin assay. RESULTS The 3D printing methods allowed quick and inexpensive production of durable feeders. Infectivity of gametocytes to mosquitoes was comparable for MJ and DLP 3D printed feeders and glass feeders, and the performance of the 3D printed feeders was not influenced by repeated washing with bleach. There was no loss in transmission efficiency when the feeder size was reduced from mini-feeder to nano-feeder, and blood-meal volume assessment indicated ~10 An. stephensi mosquitoes can take a full blood-meal (median volume 3.44 µl) on a nano-feeder. CONCLUSIONS Here we present 3D printed mini- and nano-feeders with comparable performance to the currently used glass mini-feeders. These feeders do not require specialized glass craftsmanship, making them easily accessible. Moreover, the smaller nano-feeders will enable evaluation of smaller blood volumes that can be collected from finger prick, thus expanding the utility of membrane feeding assays and facilitating a more thorough evaluation of the human infectious reservoir for malaria.
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Affiliation(s)
- Wouter Graumans
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Roel Heutink
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Katharine A. Collins
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
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Alkema M, Reuling IJ, de Jong GM, Lanke K, Coffeng LE, van Gemert GJ, van de Vegte-Bolmer M, de Mast Q, van Crevel R, Ivinson K, Ockenhouse CF, McCarthy JS, Sauerwein R, Collins KA, Bousema T. A randomized clinical trial to compare P. falciparum gametocytaemia and infectivity following blood-stage or mosquito bite induced controlled malaria infection. J Infect Dis 2020; 224:1257-1265. [PMID: 32239171 PMCID: PMC8514191 DOI: 10.1093/infdis/jiaa157] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 03/31/2020] [Indexed: 11/21/2022] Open
Abstract
Background For malaria elimination efforts, it is important to better understand parasite transmission to mosquitoes and develop models for early-clinical evaluation of transmission-blocking interventions. Methods In a randomized open-label trial, 24 participants were infected by bites from Plasmodium falciparum 3D7-infected mosquitoes (mosquito bite [MB]; n = 12) or by induced blood-stage malaria (IBSM) with the same parasite line (n = 12). After subcurative piperaquine treatment, asexual parasite and gametocytes kinetics were assessed, and mosquito feeding experiments were performed. Results Study procedures were well tolerated. The median peak gametocyte density was 1304/mL (interquartile range, 308–1607/mL) after IBSM, compared with 14/mL (10–64/mL) after MB inoculation (P < .001), despite similar peak asexual parasite densities (P = .48). Peak gametocyte density was correlated with preceding pfap2-g transcripts, indicative of gametocyte commitment (ρ = 0.62; P = .002). Direct feeding assays resulted in mosquito infections from 9 of 12 participants after IBSM versus 0 of 12 after MB inoculation (P < .001). Conclusions We observed a striking effect of inoculation method on gametocyte production, suggesting higher gametocyte commitment after IBSM. Our direct comparison of MB and IBSM establishes the controlled human malaria infection transmission model, using intravenous administration of P. falciparum–infected erythrocytes as a model for early-clinical evaluation of interventions that aim to interrupt malaria transmission. Clinical Trial Registration NCT03454048
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Affiliation(s)
- Manon Alkema
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Isaie J Reuling
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Gerdie M de Jong
- Department of Medical Microbiology and Infectious Diseases, University Medical Center Rotterdam, CA Rotterdam, The Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Luc E Coffeng
- Department of Public Health, University Medical Center Rotterdam, CA Rotterdam, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | | | - Quirijn de Mast
- Department of Internal Medicine, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Reinout van Crevel
- Department of Internal Medicine, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Karen Ivinson
- PATH Malaria Vaccine Initiative, Washington, DC, United States
| | | | - James S McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Katharine A Collins
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud university medical center, HB Nijmegen, The Netherlands
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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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Assessing Plasmodium falciparum transmission in mosquito-feeding assays using quantitative PCR. Malar J 2018; 17:249. [PMID: 29976199 PMCID: PMC6034226 DOI: 10.1186/s12936-018-2382-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/09/2018] [Indexed: 12/29/2022] Open
Abstract
Background Evaluating the efficacy of transmission-blocking interventions relies on mosquito-feeding assays, with transmission typically assessed by microscopic identification of oocysts in mosquito midguts; however, microscopy has limited throughput, sensitivity and specificity. Where low prevalence and intensity mosquito infections occur, as observed during controlled human malaria infection studies or natural transmission, a reliable method for detection and quantification of low-level midgut infection is required. Here, a semi-automated, Taqman quantitative PCR (qPCR) assay sufficiently sensitive to detect a single-oocyst midgut infection is described. Results Extraction of genomic DNA from Anopheles stephensi midguts using a semi-automated extraction process was shown to have equivalent extraction efficiency to manual DNA extraction. An 18S Plasmodium falciparum qPCR assay was adapted for quantitative detection of P. falciparum midgut oocyst infection using synthetic DNA standards. The assay was validated for sensitivity and specificity, and the limit of detection was 0.7 genomes/µL (95% CI 0.4–1.6 genomes/µL). All microscopy-confirmed oocyst infected midgut samples were detected by qPCR, including all single-oocyst positive midguts. The genome number per oocyst was assessed 8–9 days after feeding assay using both qPCR and droplet digital PCR and was 3722 (IQR: 2951–5453) and 3490 (IQR: 2720–4182), respectively. Conclusions This semi-automated qPCR method enables accurate detection of low-level P. falciparum oocyst infections in mosquito midguts, and may improve the sensitivity, specificity and throughput of assays used to evaluate candidate transmission-blocking interventions. Electronic supplementary material The online version of this article (10.1186/s12936-018-2382-6) contains supplementary material, which is available to authorized users.
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8
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Reuling IJ, van de Schans LA, Coffeng LE, Lanke K, Meerstein-Kessel L, Graumans W, van Gemert GJ, Teelen K, Siebelink-Stoter R, van de Vegte-Bolmer M, de Mast Q, van der Ven AJ, Ivinson K, Hermsen CC, de Vlas S, Bradley J, Collins KA, Ockenhouse CF, McCarthy J, Sauerwein RW, Bousema T. A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model. eLife 2018; 7:31549. [PMID: 29482720 PMCID: PMC5828662 DOI: 10.7554/elife.31549] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/14/2018] [Indexed: 12/16/2022] Open
Abstract
Background Malaria elimination strategies require a thorough understanding of parasite transmission from human to mosquito. A clinical model to induce gametocytes to understand their dynamics and evaluate transmission-blocking interventions (TBI) is currently unavailable. Here, we explore the use of the well-established Controlled Human Malaria Infection model (CHMI) to induce gametocyte carriage with different antimalarial drug regimens. Methods In a single centre, open-label randomised trial, healthy malaria-naive participants (aged 18–35 years) were infected with Plasmodium falciparum by bites of infected Anopheles mosquitoes. Participants were randomly allocated to four different treatment arms (n = 4 per arm) comprising low-dose (LD) piperaquine (PIP) or sulfadoxine-pyrimethamine (SP), followed by a curative regimen upon recrudescence. Male and female gametocyte densities were determined by molecular assays. Results Mature gametocytes were observed in all participants (16/16, 100%). Gametocytes appeared 8.5–12 days after the first detection of asexual parasites. Peak gametocyte densities and gametocyte burden was highest in the LD-PIP/SP arm, and associated with the preceding asexual parasite biomass (p=0.026). Male gametocytes had a mean estimated circulation time of 2.7 days (95% CI 1.5–3.9) compared to 5.1 days (95% CI 4.1–6.1) for female gametocytes. Exploratory mosquito feeding assays showed successful sporadic mosquito infections. There were no serious adverse events or significant differences in the occurrence and severity of adverse events between study arms (p=0.49 and p=0.28). Conclusions The early appearance of gametocytes indicates gametocyte commitment during the first wave of asexual parasites emerging from the liver. Treatment by LD-PIP followed by a curative SP regimen, results in the highest gametocyte densities and the largest number of gametocyte-positive days. This model can be used to evaluate the effect of drugs and vaccines on gametocyte dynamics, and lays the foundation for fulfilling the critical unmet need to evaluate transmission-blocking interventions against falciparum malaria for downstream selection and clinical development. Funding Funded by PATH Malaria Vaccine Initiative (MVI). Clinical trial number NCT02836002.
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Affiliation(s)
- Isaie J Reuling
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Lisanne A van de Schans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Wouter Graumans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Quirijn de Mast
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - André J van der Ven
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Karen Ivinson
- PATH Malaria Vaccine Initiative, Washington, United States
| | - Cornelus C Hermsen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Sake de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer, Brisbane, Australia
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
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