1
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Johnson RM, Stopard IJ, Byrne HM, Armstrong PM, Brackney DE, Lambert B. Investigating the dose-dependency of the midgut escape barrier using a mechanistic model of within-mosquito dengue virus population dynamics. PLoS Pathog 2024; 20:e1011975. [PMID: 38557892 PMCID: PMC11008821 DOI: 10.1371/journal.ppat.1011975] [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: 09/28/2023] [Revised: 04/11/2024] [Accepted: 01/16/2024] [Indexed: 04/04/2024] Open
Abstract
Arboviruses can emerge rapidly and cause explosive epidemics of severe disease. Some of the most epidemiologically important arboviruses, including dengue virus (DENV), Zika virus (ZIKV), Chikungunya (CHIKV) and yellow fever virus (YFV), are transmitted by Aedes mosquitoes, most notably Aedes aegypti and Aedes albopictus. After a mosquito blood feeds on an infected host, virus enters the midgut and infects the midgut epithelium. The virus must then overcome a series of barriers before reaching the mosquito saliva and being transmitted to a new host. The virus must escape from the midgut (known as the midgut escape barrier; MEB), which is thought to be mediated by transient changes in the permeability of the midgut-surrounding basal lamina layer (BL) following blood feeding. Here, we present a mathematical model of the within-mosquito population dynamics of DENV (as a model system for mosquito-borne viruses more generally) that includes the interaction of the midgut and BL which can account for the MEB. Our results indicate a dose-dependency of midgut establishment of infection as well as rate of escape from the midgut: collectively, these suggest that the extrinsic incubation period (EIP)-the time taken for DENV virus to be transmissible after infection-is shortened when mosquitoes imbibe more virus. Additionally, our experimental data indicate that multiple blood feeding events, which more closely mimic mosquito-feeding behavior in the wild, can hasten the course of infections, and our model predicts that this effect is sensitive to the amount of virus imbibed. Our model indicates that mutations to the virus which impact its replication rate in the midgut could lead to even shorter EIPs when double-feeding occurs. Mechanistic models of within-vector viral infection dynamics provide a quantitative understanding of infection dynamics and could be used to evaluate novel interventions that target the mosquito stages of the infection.
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Affiliation(s)
- Rebecca M. Johnson
- Center for Vector-Borne and Zoonotic Diseases, Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America
| | - Isaac J. Stopard
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Helen M. Byrne
- Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - Philip M. Armstrong
- Center for Vector-Borne and Zoonotic Diseases, Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America
| | - Douglas E. Brackney
- Center for Vector-Borne and Zoonotic Diseases, Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America
| | - Ben Lambert
- Department of Statistics, University of Oxford, Oxford, United Kingdom
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2
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Carrillo-Bustamante P, Costa G, Lampe L, Levashina EA. Evolutionary modelling indicates that mosquito metabolism shapes the life-history strategies of Plasmodium parasites. Nat Commun 2023; 14:8139. [PMID: 38097582 PMCID: PMC10721866 DOI: 10.1038/s41467-023-43810-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
Within-host survival and between-host transmission are key life-history traits of single-celled malaria parasites. Understanding the evolutionary forces that shape these traits is crucial to predict malaria epidemiology, drug resistance, and virulence. However, very little is known about how Plasmodium parasites adapt to their mosquito vectors. Here, we examine the evolution of the time Plasmodium parasites require to develop within the vector (extrinsic incubation period) with an individual-based model of malaria transmission that includes mosquito metabolism. Specifically, we model the metabolic cascade of resource allocation induced by blood-feeding, as well as the influence of multiple blood meals on parasite development. Our model predicts that successful vector-to-human transmission events are rare, and are caused by long-lived mosquitoes. Importantly, our results show that the life-history strategies of malaria parasites depend on the mosquito's metabolic status. In our model, additional resources provided by multiple blood meals lead to selection for parasites with slow or intermediate developmental time. These results challenge the current assumption that evolution favors fast developing parasites to maximize their chances to complete their within-mosquito life cycle. We propose that the long sporogonic cycle observed for Plasmodium is not a constraint but rather an adaptation to increase transmission potential.
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Affiliation(s)
| | - Giulia Costa
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany
| | - Lena Lampe
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany
- Physiology and Metabolism Laboratory, The Francis Crick Institute, NW11AT, London, UK
| | - Elena A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany.
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3
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Guissou E, Da DF, Hien DFDS, Yameogo KB, Yerbanga SR, Ouédraogo GA, Dabiré KR, Lefèvre T, Cohuet A. Intervention reducing malaria parasite load in vector mosquitoes: No impact on Plasmodium falciparum extrinsic incubation period and the survival of Anopheles gambiae. PLoS Pathog 2023; 19:e1011084. [PMID: 37195964 PMCID: PMC10191285 DOI: 10.1371/journal.ppat.1011084] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 04/18/2023] [Indexed: 05/19/2023] Open
Abstract
In the fight against malaria, transmission blocking interventions (TBIs) such as transmission blocking vaccines or drugs, are promising approaches to complement conventional tools. They aim to prevent the infection of vectors and thereby reduce the subsequent exposure of a human population to infectious mosquitoes. The effectiveness of these approaches has been shown to depend on the initial intensity of infection in mosquitoes, often measured as the mean number of oocysts resulting from an infectious blood meal in absence of intervention. In mosquitoes exposed to a high intensity of infection, current TBI candidates are expected to be ineffective at completely blocking infection but will decrease parasite load and therefore, potentially also affect key parameters of vector transmission. The present study investigated the consequences of changes in oocyst intensity on subsequent parasite development and mosquito survival. To address this, we experimentally produced different intensities of infection for Anopheles gambiae females from Burkina Faso by diluting gametocytes from three natural Plasmodium falciparum local isolates and used a newly developed non-destructive method based on the exploitation of mosquito sugar feeding to track parasite and mosquito life history traits throughout sporogonic development. Our results indicate the extrinsic incubation period (EIP) of P. falciparum and mosquito survival did not vary with parasite density but differed significantly between parasite isolates with estimated EIP50 of 16 (95% CI: 15-18), 14 (95% CI: 12-16) and 12 (95% CI: 12-13) days and median longevity of 25 (95% CI: 22-29), 15 (95% CI: 13-15) and 18 (95% CI: 17-19) days for the three isolates respectively. Our results here do not identify unintended consequences of the decrease of parasite loads in mosquitoes on the parasite incubation period or on mosquito survival, two key parameters of vectorial capacity, and hence support the use of transmission blocking strategies to control malaria.
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Affiliation(s)
- Edwige Guissou
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Université Nazi Boni, Bobo-Dioulasso, Burkina Faso
- Ecole Normale Supérieure, Koudougou, Burkina Faso
| | - Dari Frédéric Da
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | | | | | | | | | | | - Thierry Lefèvre
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
| | - Anna Cohuet
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
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4
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Abidha CA, Amoako YA, Nyamekye RK, Bedu-Addo G, Grziwotz F, Mockenhaupt FP, Telschow A, Danquah I. Fasting blood glucose in a Ghanaian adult is causally affected by malaria parasite load: a mechanistic case study using convergent cross mapping. Malar J 2022; 21:93. [PMID: 35303892 PMCID: PMC8932323 DOI: 10.1186/s12936-022-04076-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/06/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Adults with diabetes mellitus (DM) in malaria-endemic areas might be more susceptible to Plasmodium infection than healthy individuals. Herein, the study was aimed at verifying the hypothesis that increased fasting blood glucose (FBG) promotes parasite growth as reflected by increased parasite density. METHODS Seven adults without DM were recruited in rural Ghana to determine the relationships between FBG and malaria parasite load. Socio-economic data were recorded in questionnaire-based interviews. Over a period of 6 weeks, FBG and Plasmodium sp. Infection were measured in peripheral blood samples photometrically and by polymerase chain reaction (PCR)-assays, respectively. Daily physical activity and weather data were documented via smartphone recording. For the complex natural systems of homeostatic glucose control and Plasmodium sp. life cycle, empirical dynamic modelling was applied. RESULTS At baseline, four men and three women (median age, 33 years; interquartile range, 30-48) showed a median FBG of 5.5 (5.1-6.0 mmol/L); one participant had an asymptomatic Plasmodium sp. infection (parasite density: 240/µL). In this participant, convergent cross mapping (CCM) for 34 consecutive days, showed that FBG was causally affected by parasite density (p < 0.02), while the reciprocal relationship was not discernible (p > 0.05). Additionally, daily ambient temperature affected parasite density (p < 0.01). CONCLUSION In this study population living in a malaria-endemic area, time series analyses were successfully piloted for the relationships between FBG and Plasmodium sp. density. Longer observation periods and larger samples are required to confirm these findings and determine the direction of causality.
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Affiliation(s)
- Carol A Abidha
- Faculty of Medicine and University Hospital, Heidelberg Institute of Global Health (HIGH), Heidelberg University, Heidelberg, Germany.
| | - Yaw Ampem Amoako
- Komfo Anokye Teaching Hospital, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - George Bedu-Addo
- Komfo Anokye Teaching Hospital, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Florian Grziwotz
- Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Frank P Mockenhaupt
- Institute of Tropical Medicine and International Health, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität Zu Berlin, Berlin, Germany
| | - Arndt Telschow
- Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Institute for Environmental Systems Research, Osnabrück University, Osnabrück, Germany
| | - Ina Danquah
- Faculty of Medicine and University Hospital, Heidelberg Institute of Global Health (HIGH), Heidelberg University, Heidelberg, Germany
- Department Molecular Epidemiology, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
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5
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Watson OJ, Okell LC, Hellewell J, Slater HC, Unwin HJT, Omedo I, Bejon P, Snow RW, Noor AM, Rockett K, Hubbart C, Nankabirwa JI, Greenhouse B, Chang HH, Ghani AC, Verity R. Evaluating the Performance of Malaria Genetics for Inferring Changes in Transmission Intensity Using Transmission Modeling. Mol Biol Evol 2021; 38:274-289. [PMID: 32898225 PMCID: PMC7783189 DOI: 10.1093/molbev/msaa225] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Substantial progress has been made globally to control malaria, however there is a growing need for innovative new tools to ensure continued progress. One approach is to harness genetic sequencing and accompanying methodological approaches as have been used in the control of other infectious diseases. However, to utilize these methodologies for malaria, we first need to extend the methods to capture the complex interactions between parasites, human and vector hosts, and environment, which all impact the level of genetic diversity and relatedness of malaria parasites. We develop an individual-based transmission model to simulate malaria parasite genetics parameterized using estimated relationships between complexity of infection and age from five regions in Uganda and Kenya. We predict that cotransmission and superinfection contribute equally to within-host parasite genetic diversity at 11.5% PCR prevalence, above which superinfections dominate. Finally, we characterize the predictive power of six metrics of parasite genetics for detecting changes in transmission intensity, before grouping them in an ensemble statistical model. The model predicted malaria prevalence with a mean absolute error of 0.055. Different assumptions about the availability of sample metadata were considered, with the most accurate predictions of malaria prevalence made when the clinical status and age of sampled individuals is known. Parasite genetics may provide a novel surveillance tool for estimating the prevalence of malaria in areas in which prevalence surveys are not feasible. However, the findings presented here reinforce the need for patient metadata to be recorded and made available within all future attempts to use parasite genetics for surveillance.
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Affiliation(s)
- Oliver J Watson
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Joel Hellewell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - H Juliette T Unwin
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute—Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Kirk Rockett
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Christina Hubbart
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Hsiao-Han Chang
- Center for Communicable Disease Dynamics, Harvard TH Chan School of Public Health, Boston, MA
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Robert Verity
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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6
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Hajkazemian M, Bossé C, Mozūraitis R, Emami SN. Battleground midgut: The cost to the mosquito for hosting the malaria parasite. Biol Cell 2020; 113:79-94. [PMID: 33125724 DOI: 10.1111/boc.202000039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/31/2020] [Accepted: 10/12/2020] [Indexed: 12/27/2022]
Abstract
In eco-evolutionary studies of parasite-host interactions, virulence is defined as a reduction in host fitness as a result of infection relative to an uninfected host. Pathogen virulence may either promote parasite transmission, when correlated with higher parasite replication rate, or decrease the transmission rate if the pathogen quickly kills the host. This evolutionary mechanism, referred to as 'trade-off' theory, proposes that pathogen virulence evolves towards a level that most benefits the transmission. It has been generally predicted that pathogens evolve towards low virulence in their insect vectors, mainly due to the high dependence of parasite transmission on their vector survival. Therefore, the degree of virulence which malaria parasites impose on mosquito vectors may depend on several external and internal factors. Here, we review briefly (i) the role of mosquito in parasite development, with a particular focus on mosquito midgut as the battleground between Plasmodium and the mosquito host. We aim to point out (ii) the histology of the mosquito midgut epithelium and its role in host defence against parasite's countermeasures in the three main battle sites, namely (a) the lumen (microbiota and biochemical environment), (b) the peritrophic membrane (physical barrier) and (c) the tubular epithelium including the basal membrane (physical and biochemical barrier). Lastly, (iii) we describe the impact which malaria parasite and its virulence factors have on mosquito fitness.
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Affiliation(s)
- Melika Hajkazemian
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Clément Bossé
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,François Rabelais University, Tours, France
| | - Raimondas Mozūraitis
- Laboratory of Chemical and Behavioural Ecology, Institute of Ecology, Nature Research Centre, Vilnius, Lithuania.,Department of Zoology, Stockholm University, Stockholm, Sweden
| | - S Noushin Emami
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,Molecular Attraction AB, Hägersten, Stockholm, Sweden.,Natural Resources Institute, FES, University of Greenwich, London, UK
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7
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Childs LM, Prosper OF. The impact of within-vector parasite development on the extrinsic incubation period. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192173. [PMID: 33204441 PMCID: PMC7657899 DOI: 10.1098/rsos.192173] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Mosquito-borne diseases, in particular malaria, have a significant burden worldwide leading to nearly half a million deaths each year. The malaria parasite requires a vertebrate host, such as a human, and a vector host, the Anopheles mosquito, to complete its full life cycle. Here, we focus on the parasite dynamics within the vector to examine the first appearance of sporozoites in the salivary glands, which indicates a first time of infectiousness of mosquitoes. The timing of this period of pathogen development in the mosquito until transmissibility, known as the extrinsic incubation period, remains poorly understood. We develop compartmental models of within-mosquito parasite dynamics fitted with experimental data on oocyst and sporozoite counts. We find that only a fraction of oocysts burst to release sporozoites and bursting must be delayed either via a time-dependent function or a gamma-distributed set of compartments. We use Bayesian inference to estimate distributions of parameters and determine that bursting rate is a key epidemiological parameter. A better understanding of the factors impacting the extrinsic incubation period will aid in the development of interventions to slow or stop the spread of malaria.
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Affiliation(s)
- Lauren M. Childs
- Department of Mathematics, Virginia Tech, 225 Stanger St, Blacksburg, VA 24060, USA
| | - Olivia F. Prosper
- Department of Mathematics, University of Tennessee, 1403 Circle Dr, Knoxville, TN 37996, USA
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8
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McLaughlin K, Russell TL, Apairamo A, Bugoro H, Oscar J, Cooper RD, Beebe NW, Ritchie SA, Burkot TR. Smallest Anopheles farauti occur during the peak transmission season in the Solomon Islands. Malar J 2019; 18:208. [PMID: 31234876 PMCID: PMC6591980 DOI: 10.1186/s12936-019-2847-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 06/18/2019] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Malaria transmission varies in intensity amongst Solomon Island villages where Anopheles farauti is the only vector. This variation in transmission intensity might be explained by density-dependent processes during An. farauti larval development, as density dependence can impact adult size with associated fitness costs and daily survivorship. METHODS Adult anophelines were sampled from six villages in Western and Central Provinces, Solomon Islands between March 2014 and February 2017. The size of females was estimated by measuring wing lengths, and then analysed for associations with biting densities and rainfall. RESULTS In the Solomon Islands, three anopheline species, An. farauti, Anopheles hinesorum and Anopheles lungae, differed in size. The primary malaria vector, An. farauti, varied significantly in size among villages. Greater rainfall was directly associated with higher densities of An. farauti biting rates, but inversely associated with body size with the smallest mean sized mosquitoes present during the peak transmission period. A measurable association between body size and survivorship was not found. CONCLUSIONS Density dependent effects are likely impacting the size of adult An. farauti emerging from a range of larval habitats. The data suggest that rainfall increases An. farauti numbers and that these more abundant mosquitoes are significantly smaller in size, but without any reduced survivorship being associated with smaller size. The higher malaria transmission rate in a high malaria focus village appears to be determined more by vector numbers than size or survivorship of the vectors.
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Affiliation(s)
- Kimberley McLaughlin
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, 4870, Australia
| | - Tanya L Russell
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, 4870, Australia
| | - Allan Apairamo
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
| | - Hugo Bugoro
- Research Department, Solomon Islands National University, Honiara, Solomon Islands
| | - Jance Oscar
- Western Province Malaria Control, Gizo, Western Province, Solomon Islands
| | - Robert D Cooper
- Australian Defense Force Malaria and Infectious Disease Institute, Gallipoli Barracks, Enoggera, 4052, Australia
| | - Nigel W Beebe
- School of Biological Sciences, University of Queensland, St. Lucia, QLD, 4068, Australia.,CSIRO, Dutton Park, Brisbane, QLD, 4001, Australia
| | - Scott A Ritchie
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, 4870, Australia
| | - Thomas R Burkot
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, 4870, Australia.
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9
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Meerstein-Kessel L, Andolina C, Carrio E, Mahamar A, Sawa P, Diawara H, van de Vegte-Bolmer M, Stone W, Collins KA, Schneider P, Dicko A, Drakeley C, Felger I, Voss T, Lanke K, Bousema T. A multiplex assay for the sensitive detection and quantification of male and female Plasmodium falciparum gametocytes. Malar J 2018; 17:441. [PMID: 30497508 PMCID: PMC6267050 DOI: 10.1186/s12936-018-2584-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 11/21/2018] [Indexed: 11/23/2022] Open
Abstract
Background The transmission of malaria to mosquitoes depends on the presence of gametocytes that circulate in the peripheral blood of infected human hosts. Sensitive estimates of the densities of female gametocytes (FG) and male gametocytes (MG) may allow the prediction of infectivity to mosquitoes and thus a molecular estimate of the human infectious reservoir for transmission. Methods A novel multiplex qRT-PCR assay with intron-spanning primers was developed for the parallel quantification of FG and MG. CCp4 (PF3D7_0903800) transcripts specific for FG and PfMGET (PF3D7_1469900) transcripts specific for MG were quantified in total nucleic acids. The assay was validated on sex-sorted gametocytes from culture material and on samples from clinical trials with gametocytocidal drugs. Synthetic RNA standards were generated for the two targets genes and calibrated against known gametocyte quantities. Results The limit of detection was determined at 0.1 male and 0.1 female gametocyte/µL, which was equal to the limit of quantification (LOQ) for MG, while the LOQ for FG was 1 FG/µL. Results from previously reported clinical trials that used separate gametocyte qRT-PCR assays for FG (targeting Pfs25) and MG (targeting PfMGET) were reproduced with the multiplex assay. High levels of agreement between separate assays and the multiplex approach were observed (R2 = 0.9473, 95% CI 0.9314–0.9632, for FG measured by transcript levels of Pfs25 in qRT-PCR or CCp4 in multiplex; R2 = 0.8869, 95% CI 0.8541–0.9197, for MG measured by PfMGET in either single or multiplex qRT-PCR). FG and MG transcripts were detected in pure ring stage parasites at 10,000- and 100,000-fold reduced frequency for CCp4 and PfMGET, respectively. The CCp4 and PfMGET transcripts were equally stable under suboptimal storage conditions. Conclusions Gametocyte densities and their sex ratios can be determined in the presented one-step multiplex assay with higher throughput than single assays. The interpretation of low gametocyte densities at asexual parasite densities above 1000 parasites/µL requires caution to avoid false positive gametocyte signals from spurious transcript levels in ring stage parasites. Electronic supplementary material The online version of this article (10.1186/s12936-018-2584-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lisette Meerstein-Kessel
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.,Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Chiara Andolina
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elvira Carrio
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Patrick Sawa
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Halimatou Diawara
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Will Stone
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Katharine A Collins
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Petra Schneider
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Alassane Dicko
- Malaria Research and Training Centre, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Till Voss
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
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10
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Smith NR, Trauer JM, Gambhir M, Richards JS, Maude RJ, Keith JM, Flegg JA. Agent-based models of malaria transmission: a systematic review. Malar J 2018; 17:299. [PMID: 30119664 PMCID: PMC6098619 DOI: 10.1186/s12936-018-2442-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/04/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Much of the extensive research regarding transmission of malaria is underpinned by mathematical modelling. Compartmental models, which focus on interactions and transitions between population strata, have been a mainstay of such modelling for more than a century. However, modellers are increasingly adopting agent-based approaches, which model hosts, vectors and/or their interactions on an individual level. One reason for the increasing popularity of such models is their potential to provide enhanced realism by allowing system-level behaviours to emerge as a consequence of accumulated individual-level interactions, as occurs in real populations. METHODS A systematic review of 90 articles published between 1998 and May 2018 was performed, characterizing agent-based models (ABMs) relevant to malaria transmission. The review provides an overview of approaches used to date, determines the advantages of these approaches, and proposes ideas for progressing the field. RESULTS The rationale for ABM use over other modelling approaches centres around three points: the need to accurately represent increased stochasticity in low-transmission settings; the benefits of high-resolution spatial simulations; and heterogeneities in drug and vaccine efficacies due to individual patient characteristics. The success of these approaches provides avenues for further exploration of agent-based techniques for modelling malaria transmission. Potential extensions include varying elimination strategies across spatial landscapes, extending the size of spatial models, incorporating human movement dynamics, and developing increasingly comprehensive parameter estimation and optimization techniques. CONCLUSION Collectively, the literature covers an extensive array of topics, including the full spectrum of transmission and intervention regimes. Bringing these elements together under a common framework may enhance knowledge of, and guide policies towards, malaria elimination. However, because of the diversity of available models, endorsing a standardized approach to ABM implementation may not be possible. Instead it is recommended that model frameworks be contextually appropriate and sufficiently described. One key recommendation is to develop enhanced parameter estimation and optimization techniques. Extensions of current techniques will provide the robust results required to enhance current elimination efforts.
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Affiliation(s)
- Neal R Smith
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia.
| | - James M Trauer
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
| | - Manoj Gambhir
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
- IBM Research Australia, Melbourne, Australia
| | - Jack S Richards
- Life Sciences, Burnet Institute, Melbourne, Australia
- Department of Medicine, University of Melbourne, Parkville, Australia
- Department of Infectious Diseases, Monash University, Melbourne, Australia
| | - Richard J Maude
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Harvard TH Chan School of Public Health, Harvard University, Boston, USA
| | - Jonathan M Keith
- School of Mathematical Sciences, Monash University, Clayton, Australia
| | - Jennifer A Flegg
- School of Mathematics and Statistics, University of Melbourne, Parkville, Australia
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11
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Graumans W, Tadesse FG, Andolina C, van Gemert GJ, Teelen K, Lanke K, Gadisa E, Yewhalaw D, van de Vegte-Bolmer M, Siebelink-Stoter R, Reuling I, Sauerwein R, Bousema T. Semi-high-throughput detection of Plasmodium falciparum and Plasmodium vivax oocysts in mosquitoes using bead-beating followed by circumsporozoite ELISA and quantitative PCR. Malar J 2017; 16:356. [PMID: 28877707 PMCID: PMC5588624 DOI: 10.1186/s12936-017-2011-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/02/2017] [Indexed: 01/03/2023] Open
Abstract
Background The malaria infection status of mosquitoes is commonly determined by microscopic detection of oocysts on the dissected mosquito midgut. This method is labour-intensive, does not allow processing of large numbers of mosquitoes and can be challenging in terms of objective classification of oocysts. Here, a semi-high-throughput bead-beating ELISA method is proposed for detection of the circumsporozoite protein (CSP) followed by confirmation by quantitative PCR (qPCR). Methods Cultured Plasmodium falciparum gametocytes were offered to Anopheles stephensi mosquitoes and examined by microscopy. After bead-beating, mosquito homogenate was examined by CSP-ELISA and 18S qPCR. As negative controls, mosquitoes that were offered a heat-inactivated gametocyte blood meal were used. The CSP-ELISA/qPCR methodology was applied to high and low-intensity infections of cultured P. falciparum gametocytes. A similar methodology optimized for P. vivax was used on mosquitoes that were offered blood from Ethiopian donors who were naturally infected with P. vivax. Results There was considerable variation in CSP-ELISA signal and qPCR values in mosquitoes with low oocyst intensities. There was a strong agreement mosquito positivity by CSP-ELISA and by qPCR in mosquitoes that fed on cultured P. falciparum material (agreement 96.9%; kappa = 0.97) and naturally infected P. vivax parasite carriers [agreement 92.4% (kappa = 0.83)]. Conclusions The proposed bead-beating CSP-ELISA/qPCR methodology considerably increases throughput for the detection of mosquito infection. qPCR remains necessary to confirm infections in mosquitoes with low CSP-ELISA signal. This methodology may prove particularly useful for studies where very low mosquito infection prevalence is expected and study sites where experience with oocyst detection is limited. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2011-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wouter Graumans
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Fitsum G Tadesse
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.,Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | - Delenasaw Yewhalaw
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia.,Department of Medical Laboratory Sciences and Pathology, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Isaïe Reuling
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. .,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
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12
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LCCL protein complex formation in Plasmodium is critically dependent on LAP1. Mol Biochem Parasitol 2017; 214:87-90. [PMID: 28414172 PMCID: PMC5482319 DOI: 10.1016/j.molbiopara.2017.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/03/2017] [Accepted: 04/12/2017] [Indexed: 01/09/2023]
Abstract
Successful sporogony of Plasmodium berghei in vector mosquitoes requires expression of a family of six modular proteins named LCCL lectin domain adhesive-like proteins (LAPs). The LAPs share a subcellular localization in the crystalloid, a unique parasite organelle that forms during ookinete development. Here, LAP interactions in P. berghei were studied using a series of parasite lines stably expressing reporter-tagged LAPs combined with affinity purification and high accuracy label free quantitative mass spectrometry. Our results show that abundant complexes containing LAP1, LAP2 and LAP3 are formed in gametocytes through high avidity interactions. Following fertilization, LAP4, LAP5 and LAP6 are recruited to this complex, a process that is facilitated by LAP1 chiefly through its scavenger receptor cysteine-rich modules. These collective findings provide new insight into the temporal and molecular dynamics of protein complex formation that lead up to, and are required for, crystalloid biogenesis and downstream sporozoite transmission of malaria parasites.
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13
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Chaurio RA, Pacheco MA, Cornejo OE, Durrego E, Stanley CE, Castillo AI, Herrera S, Escalante AA. Evolution of the Transmission-Blocking Vaccine Candidates Pvs28 and Pvs25 in Plasmodium vivax: Geographic Differentiation and Evidence of Positive Selection. PLoS Negl Trop Dis 2016; 10:e0004786. [PMID: 27347876 PMCID: PMC4922550 DOI: 10.1371/journal.pntd.0004786] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/28/2016] [Indexed: 11/23/2022] Open
Abstract
Transmission-blocking (TB) vaccines are considered an important tool for malaria control and elimination. Among all the antigens characterized as TB vaccines against Plasmodium vivax, the ookinete surface proteins Pvs28 and Pvs25 are leading candidates. These proteins likely originated by a gene duplication event that took place before the radiation of the known Plasmodium species to primates. We report an evolutionary genetic analysis of a worldwide sample of pvs28 and pvs25 alleles. Our results show that both genes display low levels of genetic polymorphism when compared to the merozoite surface antigens AMA-1 and MSP-1; however, both ookinete antigens can be as polymorphic as other merozoite antigens such as MSP-8 and MSP-10. We found that parasite populations in Asia and the Americas are geographically differentiated with comparable levels of genetic diversity and specific amino acid replacements found only in the Americas. Furthermore, the observed variation was mainly accumulated in the EGF2- and EGF3-like domains for P. vivax in both proteins. This pattern was shared by other closely related non-human primate parasites such as Plasmodium cynomolgi, suggesting that it could be functionally important. In addition, examination with a suite of evolutionary genetic analyses indicated that the observed patterns are consistent with positive natural selection acting on Pvs28 and Pvs25 polymorphisms. The geographic pattern of genetic differentiation and the evidence for positive selection strongly suggest that the functional consequences of the observed polymorphism should be evaluated during development of TBVs that include Pvs25 and Pvs28. Plasmodium vivax is the most prevalent human malarial parasite outside Africa. The fact that patients can relapse due to the parasite dormant liver stages, among other biologic and epidemiologic characteristics of vivax malaria, facilitates the persistence of the disease in many endemic areas. These challenges have fueled the search for new control tools, including transmission blocking (TB) vaccines targeting the parasite sexual stages. Here we study the genetic diversity of two major TB vaccine antigens, Pvs25 and Pvs28. We show that these genes are relatively conserved worldwide but still harbor diversity that is not evenly distributed across the genes. These patterns are shared by the same proteins in closely related parasite species suggesting their functional importance. We also identify strong geographic differentiation between the circulating variants found in Asia and the Americas. Finally, evolutionary genetic analyses indicate that the observed variation in both genes could be maintained by natural selection. Thus, these polymorphisms may confer an adaptive advantage to the parasite. These results indicate that the genetic variation found in these genes and their geographic distribution should be considered by vaccine developers.
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Affiliation(s)
- Ricardo A Chaurio
- Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - M Andreína Pacheco
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Omar E Cornejo
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Ester Durrego
- Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Craig E Stanley
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Andreína I Castillo
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | | | - Ananias A Escalante
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
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14
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Gonçalves D, Hunziker P. Transmission-blocking strategies: the roadmap from laboratory bench to the community. Malar J 2016; 15:95. [PMID: 26888537 PMCID: PMC4758146 DOI: 10.1186/s12936-016-1163-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 02/11/2016] [Indexed: 11/10/2022] Open
Abstract
Malaria remains one of the most prevalent tropical and infectious diseases in the world, with an estimated more than 200 million clinical cases every year. In recent years, the mosquito stages of the parasite life cycle have received renewed attention with some progress being made in the development of transmission-blocking strategies. From gametocytes to late ookinetes, some attractive antigenic targets have been found and tested in order to develop a transmission blocking vaccine, and drugs are being currently screened for gametocytocidal activity, and also some new and less conventional approaches are drawing increased attention, such as genetically modified and fungus-infected mosquitoes that become refractory to Plasmodium infection. In this review some of those strategies focusing on the progress made so far will be summarized, but also, the challenges that come from the translation of early promising benchwork resulting in successful applications in the field. To do this, the available literature will be screened and all the pieces of the puzzle must be combined: from molecular biology to epidemiologic and clinical data.
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Affiliation(s)
- Daniel Gonçalves
- CLINAM Foundation for Nanomedicine, University of Basel, Basel, Switzerland.
| | - Patrick Hunziker
- CLINAM Foundation for Nanomedicine, University of Basel, Basel, Switzerland.
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15
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Pollitt LC, Bram JT, Blanford S, Jones MJ, Read AF. Existing Infection Facilitates Establishment and Density of Malaria Parasites in Their Mosquito Vector. PLoS Pathog 2015; 11:e1005003. [PMID: 26181518 PMCID: PMC4504473 DOI: 10.1371/journal.ppat.1005003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 06/04/2015] [Indexed: 02/06/2023] Open
Abstract
Very little is known about how vector-borne pathogens interact within their vector and how this impacts transmission. Here we show that mosquitoes can accumulate mixed strain malaria infections after feeding on multiple hosts. We found that parasites have a greater chance of establishing and reach higher densities if another strain is already present in a mosquito. Mixed infections contained more parasites but these larger populations did not have a detectable impact on vector survival. Together these results suggest that mosquitoes taking multiple infective bites may disproportionally contribute to malaria transmission. This will increase rates of mixed infections in vertebrate hosts, with implications for the evolution of parasite virulence and the spread of drug-resistant strains. Moreover, control measures that reduce parasite prevalence in vertebrate hosts will reduce the likelihood of mosquitoes taking multiple infective feeds, and thus disproportionally reduce transmission. More generally, our study shows that the types of strain interactions detected in vertebrate hosts cannot necessarily be extrapolated to vectors.
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Affiliation(s)
- Laura C. Pollitt
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
- * E-mail:
| | - Joshua T. Bram
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Simon Blanford
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Matthew J. Jones
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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16
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Wu Y, Sinden RE, Churcher TS, Tsuboi T, Yusibov V. Development of malaria transmission-blocking vaccines: from concept to product. ADVANCES IN PARASITOLOGY 2015; 89:109-52. [PMID: 26003037 DOI: 10.1016/bs.apar.2015.04.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Despite decades of effort battling against malaria, the disease is still a major cause of morbidity and mortality. Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. In the 1950s, Huff et al. first demonstrated the induction of transmission-blocking immunity in chickens by repeated immunizations with Plasmodium gallinaceum-infected red blood cells. Since then, significant progress has been made in identification of parasite antigens responsible for transmission-blocking activity. Recombinant technologies accelerated evaluation of these antigens as vaccine candidates, and it is possible to induce effective transmission-blocking immunity in humans both by natural infection and now by immunization with recombinant vaccines. This chapter reviews the efforts to produce TBVs, summarizes the current status and advances and discusses the remaining challenges and approaches.
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Affiliation(s)
- Yimin Wu
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
| | | | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Takafumi Tsuboi
- Division of Malaria Research, Ehime University, Matsuyama, Ehime, Japan
| | - Vidadi Yusibov
- Fraunhofer USA Center for Molecular Biotechnology, Newark, DE, USA
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17
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Landscape Epidemiology Modeling Using an Agent-Based Model and a Geographic Information System. LAND 2015. [DOI: 10.3390/land4020378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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18
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Saeed S, Tremp AZ, Dessens JT. Biogenesis of the crystalloid organelle in Plasmodium involves microtubule-dependent vesicle transport and assembly. Int J Parasitol 2015; 45:537-47. [PMID: 25900212 PMCID: PMC4459735 DOI: 10.1016/j.ijpara.2015.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/27/2015] [Accepted: 03/04/2015] [Indexed: 12/20/2022]
Abstract
Malaria parasites possess unique subcellular structures and organelles. One of these is the crystalloid, a multivesicular organelle that forms during the parasite's development in vector mosquitoes. The formation and function of these organelles remain poorly understood. A family of six conserved and modular proteins named LCCL-lectin adhesive-like proteins (LAPs), which have essential roles in sporozoite transmission, localise to the crystalloids. In this study we analyse crystalloid formation using transgenic Plasmodium berghei parasites expressing GFP-tagged LAP3. We show that deletion of the LCCL domain from LAP3 causes retarded crystalloid development, while knockout of LAP3 prevents formation of the organelle. Our data reveal that the process of crystalloid formation involves active relocation of endoplasmic reticulum-derived vesicles to common assembly points via microtubule-dependent transport. Inhibition of microtubule-dependent cargo transport disrupts this process and replicates the LCCL domain deletion mutant phenotype in wildtype parasites. These findings provide the first clear insight into crystalloid biogenesis, demonstrating a fundamental role for the LAP family in this process, and identifying the crystalloid and its formation as potential targets for malaria transmission control.
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Affiliation(s)
- Sadia Saeed
- Pathogen Molecular Biology Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Annie Z Tremp
- Pathogen Molecular Biology Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Johannes T Dessens
- Pathogen Molecular Biology Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
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19
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Gambhir M, Singh BK, Michael E. The Allee effect and elimination of neglected tropical diseases: a mathematical modelling study. ADVANCES IN PARASITOLOGY 2015; 87:1-31. [PMID: 25765192 DOI: 10.1016/bs.apar.2014.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Elimination and control programmes for neglected tropical diseases (NTDs) are underway around the world, yet they are generally informed by epidemiological modelling only to a rudimentary degree. Chief among the modelling-derived predictors of disease emergence or controllability is the basic reproduction number R0. The ecological systems of several of the NTDs include density-dependent processes--which alter the rate of e.g. parasite establishment or fecundity--that complicate the calculation of R0. Here we show how the forms of the density-dependent functions for a model of the NTD lymphatic filariasis affect the effective reproduction number Reff. We construct infection transmission models containing various density-dependent functions and show how they alter the shape of the Reff profile, affecting two important epidemiological outcome variables that relate to elimination and control programmes: the parasite transmission breakpoint (or extinction threshold) and the reproduction fitness, as measured by Reff. The current drive to control, eliminate or eradicate several parasitic infections would be substantially aided by the existence of ecological Allee effects. For these control programmes, the findings of this paper are encouraging, since a single positive density dependency (DD) can introduce a reasonable chance of achieving elimination; however, there are diminishing returns to additional positive DDs.
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Affiliation(s)
- Manoj Gambhir
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia
| | - Brajendra K Singh
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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20
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Akinosoglou KA, Bushell ESC, Ukegbu CV, Schlegelmilch T, Cho JS, Redmond S, Sala K, Christophides GK, Vlachou D. Characterization of Plasmodium developmental transcriptomes in Anopheles gambiae midgut reveals novel regulators of malaria transmission. Cell Microbiol 2015; 17:254-68. [PMID: 25225164 PMCID: PMC4371638 DOI: 10.1111/cmi.12363] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 08/27/2014] [Accepted: 09/08/2014] [Indexed: 12/24/2022]
Abstract
The passage through the mosquito is a major bottleneck for malaria parasite populations and a target of interventions aiming to block disease transmission. Here, we used DNA microarrays to profile the developmental transcriptomes of the rodent malaria parasite Plasmodium berghei in vivo, in the midgut of Anopheles gambiae mosquitoes, from parasite stages in the midgut blood bolus to sporulating oocysts on the basal gut wall. Data analysis identified several distinct transcriptional programmes encompassing genes putatively involved in developmental processes or in interactions with the mosquito. At least two of these programmes are associated with the ookinete development that is linked to mosquito midgut invasion and establishment of infection. Targeted disruption by homologous recombination of two of these genes resulted in mutant parasites exhibiting notable infection phenotypes. GAMER encodes a short polypeptide with granular localization in the gametocyte cytoplasm and shows a highly penetrant loss-of-function phenotype manifested as greatly reduced ookinete numbers, linked to impaired male gamete release. HADO encodes a putative magnesium phosphatase with distinctive cortical localization along the concave ookinete periphery. Disruption of HADO compromises ookinete development leading to significant reduction of oocyst numbers. Our data provide important insights into the molecular framework underpinning Plasmodium development in the mosquito and identifies two genes with important functions at initial stages of parasite development in the mosquito midgut.
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Affiliation(s)
| | | | | | | | - Jee-Sun Cho
- Department of Life Sciences, Imperial College LondonLondon, UK
| | - Seth Redmond
- Department of Life Sciences, Imperial College LondonLondon, UK
| | - Katarzyna Sala
- Department of Life Sciences, Imperial College LondonLondon, UK
| | - George K Christophides
- Department of Life Sciences, Imperial College LondonLondon, UK
- The Cyprus InstituteNicosia, Cyprus
| | - Dina Vlachou
- Department of Life Sciences, Imperial College LondonLondon, UK
- The Cyprus InstituteNicosia, Cyprus
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21
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Da DF, Churcher TS, Yerbanga RS, Yaméogo B, Sangaré I, Ouedraogo JB, Sinden RE, Blagborough AM, Cohuet A. Experimental study of the relationship between Plasmodium gametocyte density and infection success in mosquitoes; implications for the evaluation of malaria transmission-reducing interventions. Exp Parasitol 2014; 149:74-83. [PMID: 25541384 DOI: 10.1016/j.exppara.2014.12.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 12/10/2014] [Accepted: 12/15/2014] [Indexed: 11/29/2022]
Abstract
The evaluation of transmission reducing interventions (TRI) to control malaria widely uses membrane feeding assays. In such assays, the intensity of Plasmodium infection in the vector might affect the measured efficacy of the candidates to block transmission. Gametocyte density in the host blood is a determinant of the infection success in the mosquito, however, uncertain estimates of parasite densities and intrinsic characteristics of the infected blood can induce variability. To reduce this variation, a feasible method is to dilute infectious blood samples. We describe the effect of diluting samples of Plasmodium-containing blood samples to allow accurate relative measures of gametocyte densities and their impact on mosquito infectivity and TRI efficacy. Natural Plasmodium falciparum samples were diluted to generate a wide range of parasite densities, and fed to Anopheles coluzzii mosquitoes. This was compared with parallel dilutions conducted on Plasmodium berghei infections. We examined how blood dilution influences the observed blocking activity of anti-Pbs28 monoclonal antibody using the P. berghei/Anopheles stephensi system. In the natural species combination P. falciparum/An. coluzzii, blood dilution using heat-inactivated, infected blood as diluents, revealed positive near linear relationships, between gametocyte densities and oocyst loads in the range tested. A similar relationship was observed in the P. berghei/An. stephensi system when using a similar dilution method. In contrast, diluting infected mice blood with fresh uninfected blood dramatically increases the infectiousness. This suggests that highly infected mice blood contains inhibitory factors or reduced blood moieties, which impede infection and may in turn, lead to misinterpretation when comparing individual TRI evaluation assays. In the lab system, the transmission blocking activity of an antibody specific for Pbs28 was confirmed to be density-dependent. This highlights the need to carefully interpret evaluations of TRI candidates, regarding gametocyte densities in the P. berghei/An. stephensi system.
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Affiliation(s)
- Dari F Da
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France
| | - Thomas S Churcher
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Rakiswendé S Yerbanga
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Bienvenue Yaméogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Ibrahim Sangaré
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France
| | - Jean Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Robert E Sinden
- Division of Cell and Molecular Biology, Imperial College London, London, United Kingdom; The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Andrew M Blagborough
- Division of Cell and Molecular Biology, Imperial College London, London, United Kingdom
| | - Anna Cohuet
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France.
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How effective is integrated vector management against malaria and lymphatic filariasis where the diseases are transmitted by the same vector? PLoS Negl Trop Dis 2014; 8:e3393. [PMID: 25501002 PMCID: PMC4263402 DOI: 10.1371/journal.pntd.0003393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/05/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The opportunity to integrate vector management across multiple vector-borne diseases is particularly plausible for malaria and lymphatic filariasis (LF) control where both diseases are transmitted by the same vector. To date most examples of integrated control targeting these diseases have been unanticipated consequences of malaria vector control, rather than planned strategies that aim to maximize the efficacy and take the complex ecological and biological interactions between the two diseases into account. METHODOLOGY/PRINCIPAL FINDINGS We developed a general model of malaria and LF transmission and derived expressions for the basic reproductive number (R0) for each disease. Transmission of both diseases was most sensitive to vector mortality and biting rate. Simulating different levels of coverage of long lasting-insecticidal nets (LLINs) and larval control confirms the effectiveness of these interventions for the control of both diseases. When LF was maintained near the critical density of mosquitoes, minor levels of vector control (8% coverage of LLINs or treatment of 20% of larval sites) were sufficient to eliminate the disease. Malaria had a far greater R0 and required a 90% population coverage of LLINs in order to eliminate it. When the mosquito density was doubled, 36% and 58% coverage of LLINs and larval control, respectively, were required for LF elimination; and malaria elimination was possible with a combined coverage of 78% of LLINs and larval control. CONCLUSIONS/SIGNIFICANCE Despite the low level of vector control required to eliminate LF, simulations suggest that prevalence of LF will decrease at a slower rate than malaria, even at high levels of coverage. If representative of field situations, integrated management should take into account not only how malaria control can facilitate filariasis elimination, but strike a balance between the high levels of coverage of (multiple) interventions required for malaria with the long duration predicted to be required for filariasis elimination.
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Malaria parasites prepare for flight. Trends Parasitol 2014; 30:551-3. [DOI: 10.1016/j.pt.2014.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 10/17/2014] [Indexed: 01/22/2023]
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Moreno-García M, Recio-Tótoro B, Claudio-Piedras F, Lanz-Mendoza H. Injury and immune response: applying the danger theory to mosquitoes. FRONTIERS IN PLANT SCIENCE 2014; 5:451. [PMID: 25250040 PMCID: PMC4158974 DOI: 10.3389/fpls.2014.00451] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 08/20/2014] [Indexed: 05/28/2023]
Abstract
The insect immune response can be activated by the recognition of both non-self and molecular by-products of tissue damage. Since pathogens and tissue damage usually arise at the same time during infection, the specific mechanisms of the immune response to microorganisms, and to tissue damage have not been unraveled. Consequently, some aspects of damage caused by microorganisms in vector-borne arthropods have been neglected. We herein reassess the Anopheles-Plasmodium interaction, incorporating Matzinger's danger/damage hypothesis and George Salt's injury assumptions. The invasive forms of the parasite cross the peritrophic matrix and midgut epithelia to reach the basal lamina and differentiate into an oocyst. The sporozoites produced in the oocyst are released into the hemolymph, and from there enter the salivary gland. During parasite development, wounds to midgut tissue and the basement membrane are produced. We describe the response of the different compartments where the parasite interacts with the mosquito. In the midgut, the response includes the expression of antimicrobial peptides, production of reactive oxygen species, and possible activation of midgut regenerative cells. In the basal membrane, wound repair mainly involves the production of molecules and the recruitment of hemocytes. We discuss the susceptibility to damage in tissues, and how the place and degree of damage may influence the differential response and the expression of damage associated molecular patterns (DAMPs). Knowledge about damage caused by parasites may lead to a deeper understanding of the relevance of tissue damage and the immune response it generates, as well as the origins and progression of infection in this insect-parasite interaction.
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Affiliation(s)
- Miguel Moreno-García
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud PúblicaCuernavaca, México
| | - Benito Recio-Tótoro
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud PúblicaCuernavaca, México
- Instituto de Biotecnología, Posgrado en Ciencias Bioquímicas, Universidad Nacional Autónoma de MéxicoCuernavaca, México
| | - Fabiola Claudio-Piedras
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud PúblicaCuernavaca, México
- Facultad de Medicina, Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de MéxicoMéxico City, México
| | - Humberto Lanz-Mendoza
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud PúblicaCuernavaca, México
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Carter LM, Kafsack BF, Llinás M, Mideo N, Pollitt LC, Reece SE. Stress and sex in malaria parasites. EVOLUTION MEDICINE AND PUBLIC HEALTH 2013; 2013:135-47. [PMID: 24481194 PMCID: PMC3854026 DOI: 10.1093/emph/eot011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
For vector-borne parasites such as malaria, how within- and between-host processes interact to shape transmission is poorly understood. In the host, malaria parasites replicate asexually but for transmission to occur, specialized sexual stages (gametocytes) must be produced. Despite the central role that gametocytes play in disease transmission, explanations of why parasites adjust gametocyte production in response to in-host factors remain controversial. We propose that evolutionary theory developed to explain variation in reproductive effort in multicellular organisms, provides a framework to understand gametocyte investment strategies. We examine why parasites adjust investment in gametocytes according to the impact of changing conditions on their in-host survival. We then outline experiments required to determine whether plasticity in gametocyte investment enables parasites to maintain fitness in a variable environment. Gametocytes are a target for anti-malarial transmission-blocking interventions so understanding plasticity in investment is central to maximizing the success of control measures in the face of parasite evolution.
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Affiliation(s)
- Lucy M. Carter
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
- *Corresponding author. Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. Tel: +44 131 650 7706; Fax: +44 131 650 6564; E-mail:
| | - Björn F.C. Kafsack
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Manuel Llinás
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Nicole Mideo
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Laura C. Pollitt
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Sarah E. Reece
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Department of Molecular Biology, 246 Carl Icahn Lab, Washington Road, Princeton University, Princeton, NJ, USA; Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, Millennium Science Complex, University Park, PA, USA and Centre for Immunity, Infection & Evolution. Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
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Pollitt LC, Churcher TS, Dawes EJ, Khan SM, Sajid M, Basáñez MG, Colegrave N, Reece SE. Costs of crowding for the transmission of malaria parasites. Evol Appl 2013; 6:617-29. [PMID: 23789029 PMCID: PMC3684743 DOI: 10.1111/eva.12048] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 12/13/2012] [Accepted: 12/13/2012] [Indexed: 01/03/2023] Open
Abstract
The utility of using evolutionary and ecological frameworks to understand the dynamics of infectious diseases is gaining increasing recognition. However, integrating evolutionary ecology and infectious disease epidemiology is challenging because within-host dynamics can have counterintuitive consequences for between-host transmission, especially for vector-borne parasites. A major obstacle to linking within- and between-host processes is that the drivers of the relationships between the density, virulence, and fitness of parasites are poorly understood. By experimentally manipulating the intensity of rodent malaria (Plasmodium berghei) infections in Anopheles stephensi mosquitoes under different environmental conditions, we show that parasites experience substantial density-dependent fitness costs because crowding reduces both parasite proliferation and vector survival. We then use our data to predict how interactions between parasite density and vector environmental conditions shape within-vector processes and onward disease transmission. Our model predicts that density-dependent processes can have substantial and unexpected effects on the transmission potential of vector-borne disease, which should be considered in the development and evaluation of transmission-blocking interventions.
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Affiliation(s)
- Laura C Pollitt
- Institute of Evolutionary Biology, University of Edinburgh Edinburgh, UK ; Center for Infectious Disease Dynamics, Pennsylvania State University University Park, PA, USA
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Sinden RE, Blagborough AM, Churcher T, Ramakrishnan C, Biswas S, Delves MJ. The design and interpretation of laboratory assays measuring mosquito transmission of Plasmodium. Trends Parasitol 2012; 28:457-65. [DOI: 10.1016/j.pt.2012.07.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/20/2012] [Accepted: 07/24/2012] [Indexed: 12/14/2022]
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Sinden RE, Carter R, Drakeley C, Leroy D. The biology of sexual development of Plasmodium: the design and implementation of transmission-blocking strategies. Malar J 2012; 11:70. [PMID: 22424474 PMCID: PMC3315749 DOI: 10.1186/1475-2875-11-70] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/16/2012] [Indexed: 12/15/2022] Open
Abstract
A meeting to discuss the latest developments in the biology of sexual development of Plasmodium and transmission-control was held April 5-6, 2011, in Bethesda, MD. The meeting was sponsored by the Bill & Melinda Gates Foundation and the National Institutes of Health, National Institute of Allergy and Infectious Diseases (NIH/NIAID) in response to the challenge issued at the Malaria Forum in October 2007 that the malaria community should re-engage with the objective of global eradication. The consequent rebalancing of research priorities has brought to the forefront of the research agenda the essential need to reduce parasite transmission. A key component of any transmission reduction strategy must be methods to attack the parasite as it passes from man to the mosquito (and vice versa). Such methods must be rationally based on a secure understanding of transmission from the molecular-, cellular-, population- to the evolutionary-levels. The meeting represented a first attempt to draw together scientists with expertise in these multiple layers of understanding to discuss the scientific foundations and resources that will be required to provide secure progress toward the design and successful implementation of effective interventions.
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Affiliation(s)
- Robert E Sinden
- The Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK.
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Dong Y, Das S, Cirimotich C, Souza-Neto JA, McLean KJ, Dimopoulos G. Engineered anopheles immunity to Plasmodium infection. PLoS Pathog 2011; 7:e1002458. [PMID: 22216006 PMCID: PMC3245315 DOI: 10.1371/journal.ppat.1002458] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Accepted: 11/09/2011] [Indexed: 01/07/2023] Open
Abstract
A causative agent of human malaria, Plasmodium falciparum, is transmitted by Anopheles mosquitoes. The malaria parasite is under intensive attack from the mosquito's innate immune system during its sporogonic development. We have used genetic engineering to create immune-enhanced Anopheles stephensi mosquitoes through blood meal-inducible expression of a transgene encoding the IMD pathway-controlled NF-kB Rel2 transcription factor in the midgut and fat-body tissue. Transgenic mosquitoes showed greater resistance to Plasmodium and microbial infection as a result of timely concerted tissue-specific immune attacks involving multiple effectors. The relatively weak impact of this genetic modification on mosquito fitness under laboratory conditions encourages further investigation of this approach for malaria control.
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Affiliation(s)
- Yuemei Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Suchismita Das
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Chris Cirimotich
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jayme A. Souza-Neto
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kyle J. McLean
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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