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Naidoo K, Oliver SV. Gene drives: an alternative approach to malaria control? Gene Ther 2024:10.1038/s41434-024-00468-8. [PMID: 39039203 DOI: 10.1038/s41434-024-00468-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/14/2024] [Accepted: 07/18/2024] [Indexed: 07/24/2024]
Abstract
Genetic modification for the control of mosquitoes is frequently touted as a solution for a variety of vector-borne diseases. There has been some success using non-insecticidal methods like sterile or incompatible insect techniques to control arbovirus diseases. However, control by genetic modifications to reduce mosquito populations or create mosquitoes that are refractory to infection with pathogens are less developed. The advent of CRISPR-Cas9-mediated gene drives may advance this mechanism of control. In this review, use and progress of gene drives for vector control, particularly for malaria, is discussed. A brief history of population suppression and replacement gene drives in mosquitoes, rapid advancement of the field over the last decade and how genetic modification fits into the current scope of vector control are described. Mechanisms of alternative vector control by genetic modification to modulate mosquitoes' immune responses and anti-parasite effector molecules as part of a combinational strategy to combat malaria are considered. Finally, the limitations and ethics of using gene drives for mosquito control are discussed.
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Affiliation(s)
- Kubendran Naidoo
- SAMRC/Wits Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- National Health Laboratory Service, Johannesburg, South Africa.
- Wits Research Institute for Malaria, Faculty of Health Sciences, National Health Laboratory Service, University of the Witwatersrand, Johannesburg, South Africa.
- Infectious Diseases and Oncology Research Institute (IDORI), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Shüné V Oliver
- Wits Research Institute for Malaria, Faculty of Health Sciences, National Health Laboratory Service, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
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2
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Wyse AP, Dos Santos AJB, Azevedo JDS, Meneses ACD, Santos VMDC. Mathematical modeling of the performance of wild and transgenic mosquitoes in malaria transmission. PLoS One 2023; 18:e0285000. [PMID: 37115773 PMCID: PMC10146568 DOI: 10.1371/journal.pone.0285000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
A mathematical model that simulates malaria transmission under the influence of transgenic mosquitoes refractory to malaria is presented in this paper. The zygosity of transgenic mosquitoes is taken into account and, consequently, the total population of mosquitoes is comprised of wild type and heterozygous and homozygous transgenic mosquitoes. These three mosquito varieties interact by mating and competition, and the genetic characteristics of their resulting offspring are in accordance with Mendelian genetics or the mutagenic chain reaction (MCR) technique. Although the incorporation of transgenic mosquitoes into the ecosystem reduces the incidence of malaria, the model also takes into account the importance of completing treatment in individuals with confirmed infection and the imminent risk of increased environmental temperature.
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Affiliation(s)
- Ana Paula Wyse
- Department of Scientific Computing, Informatics Center, Federal University of Paraíba, João Pessoa, Paraíba, Brazil
| | | | - Juarez Dos Santos Azevedo
- Institute of Science, Technology and Innovation, Federal University of Bahia, Camaçari, Bahia, Brazil
| | - Aline Costa de Meneses
- Graduate Program in Mathematical and Computational Modeling, Informatics Center, Federal University of Paraíba, João Pessoa, Paraíba, Brazil
| | - Victor Matheus Da Cunha Santos
- Graduate Program in Mathematical and Computational Modeling, Informatics Center, Federal University of Paraíba, João Pessoa, Paraíba, Brazil
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3
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Bottino-Rojas V, James AA. Use of Insect Promoters in Genetic Engineering to Control Mosquito-Borne Diseases. Biomolecules 2022; 13:16. [PMID: 36671401 PMCID: PMC9855440 DOI: 10.3390/biom13010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Mosquito transgenesis and gene-drive technologies provide the basis for developing promising new tools for vector-borne disease prevention by either suppressing wild mosquito populations or reducing their capacity from transmitting pathogens. Many studies of the regulatory DNA and promoters of genes with robust sex-, tissue- and stage-specific expression profiles have supported the development of new tools and strategies that could bring mosquito-borne diseases under control. Although the list of regulatory elements available is significant, only a limited set of those can reliably drive spatial-temporal expression. Here, we review the advances in our ability to express beneficial and other genes in mosquitoes, and highlight the information needed for the development of new mosquito-control and anti-disease strategies.
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Affiliation(s)
- Vanessa Bottino-Rojas
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
| | - Anthony A. James
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
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4
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Garrood WT, Cuber P, Willis K, Bernardini F, Page NM, Haghighat-Khah RE. Driving down malaria transmission with engineered gene drives. Front Genet 2022; 13:891218. [PMID: 36338968 PMCID: PMC9627344 DOI: 10.3389/fgene.2022.891218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 09/13/2022] [Indexed: 11/26/2022] Open
Abstract
The last century has witnessed the introduction, establishment and expansion of mosquito-borne diseases into diverse new geographic ranges. Malaria is transmitted by female Anopheles mosquitoes. Despite making great strides over the past few decades in reducing the burden of malaria, transmission is now on the rise again, in part owing to the emergence of mosquito resistance to insecticides, antimalarial drug resistance and, more recently, the challenges of the COVID-19 pandemic, which resulted in the reduced implementation efficiency of various control programs. The utility of genetically engineered gene drive mosquitoes as tools to decrease the burden of malaria by controlling the disease-transmitting mosquitoes is being evaluated. To date, there has been remarkable progress in the development of CRISPR/Cas9-based homing endonuclease designs in malaria mosquitoes due to successful proof-of-principle and multigenerational experiments. In this review, we examine the lessons learnt from the development of current CRISPR/Cas9-based homing endonuclease gene drives, providing a framework for the development of gene drive systems for the targeted control of wild malaria-transmitting mosquito populations that overcome challenges such as with evolving drive-resistance. We also discuss the additional substantial works required to progress the development of gene drive systems from scientific discovery to further study and subsequent field application in endemic settings.
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Affiliation(s)
- William T. Garrood
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Piotr Cuber
- Department of Molecular Biology, Core Research Laboratories, Natural History Museum, London, United Kingdom
| | - Katie Willis
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Federica Bernardini
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Nicole M. Page
- Department of Life Sciences, Imperial College London, London, United Kingdom
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5
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Dilani PVD, Dassanayake RS, Tyagi BK, Gunawardene YINS. The impact of transgenesis on mosquito fitness: A review. FRONTIERS IN INSECT SCIENCE 2022; 2:957570. [PMID: 38468772 PMCID: PMC10926467 DOI: 10.3389/finsc.2022.957570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/05/2022] [Indexed: 03/13/2024]
Abstract
Transgenic mosquitoes developed by genetic manipulation, offer a promising strategy for the sustainable and effective control of mosquito-borne diseases. This strategy relies on the mass release of transgenic mosquitoes into the wild, where their transgene is expected to persist in the natural environment, either permanently or transiently, within the mosquito population. In such circumstances, the fitness of transgenic mosquitoes is an important factor in determining their survival in the wild. The impact of transgene expression, insertional mutagenesis, inbreeding depression related to laboratory adaptation, and the hitchhiking effect involved in developing homozygous mosquito lines can all have an effect on the fitness of transgenic mosquitoes. Therefore, real-time estimation of transgene-associated fitness cost is imperative for modeling and planning transgenic mosquito release programs. This can be achieved by directly comparing fitness parameters in individuals homozygous or hemizygous for the transgene and their wild-type counterparts, or by cage invasion experiments to monitor the frequency of the transgenic allele over multiple generations. Recent advancements such as site-specific integration systems and gene drives, provide platforms to address fitness issues in transgenic mosquitoes. More research on the fitness of transgenic individuals is required to develop transgenic mosquitoes with a low fitness cost.
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Affiliation(s)
| | | | - Brij Kishore Tyagi
- Sponsored Research & Industrial Centre, VIT University, Vellore (TN), India
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6
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Adelman ZN, Kojin BB. Malaria-Resistant Mosquitoes (Diptera: Culicidae); The Principle is Proven, But Will the Effectors Be Effective? JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:1997-2005. [PMID: 34018548 DOI: 10.1093/jme/tjab090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Indexed: 06/12/2023]
Abstract
Over the last few decades, a substantial number of anti-malarial effector genes have been evaluated for their ability to block parasite infection in the mosquito vector. While many of these approaches have yielded significant effects on either parasite intensity or prevalence of infection, just a few have been able to completely block transmission. Additionally, many approaches, while effective against the parasite, also disrupt or alter important aspects of mosquito physiology, leading to corresponding changes in lifespan, reproduction, and immunity. As the most promising approaches move towards field-based evaluation, questions of effector gene robustness and durability move to the forefront. In this forum piece, we critically evaluate past effector gene approaches with an eye towards developing a deeper pipeline to augment the current best candidates.
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Affiliation(s)
- Zach N Adelman
- Department of Entomology and AgriLife Research, Texas A&M University, College Station, TX, USA
| | - Bianca B Kojin
- Department of Entomology and AgriLife Research, Texas A&M University, College Station, TX, USA
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7
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Dong S, Dong Y, Simões ML, Dimopoulos G. Mosquito transgenesis for malaria control. Trends Parasitol 2021; 38:54-66. [PMID: 34483052 DOI: 10.1016/j.pt.2021.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/01/2021] [Accepted: 08/03/2021] [Indexed: 12/14/2022]
Abstract
Malaria is one of the deadliest diseases. Because of the ineffectiveness of current malaria-control methods, several novel mosquito vector-based control strategies have been proposed to supplement existing control strategies. Mosquito transgenesis and gene drive have emerged as promising tools for preventing the spread of malaria by either suppressing mosquito populations by self-destructing mosquitoes or replacing mosquito populations with disease-refractory populations. Here we review the development of mosquito transgenesis and its application for malaria control, highlighting the transgenic expression of antiparasitic effector genes, inactivation of host factor genes, and manipulation of miRNAs and lncRNAs. Overall, from a malaria-control perspective, mosquito transgenesis is not envisioned as a stand-alone approach; rather, its use is proposed as a complement to existing vector-control strategies.
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Affiliation(s)
- Shengzhang Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Yuemei Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Maria L Simões
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
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8
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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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9
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James SL, Marshall JM, Christophides GK, Okumu FO, Nolan T. Toward the Definition of Efficacy and Safety Criteria for Advancing Gene Drive-Modified Mosquitoes to Field Testing. Vector Borne Zoonotic Dis 2020; 20:237-251. [PMID: 32155390 PMCID: PMC7153640 DOI: 10.1089/vbz.2019.2606] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mosquitoes containing gene drive systems are being developed as complementary tools to prevent transmission of malaria and other mosquito-borne diseases. As with any new tool, decision makers and other stakeholders will need to balance risks (safety) and benefits (efficacy) when considering the rationale for testing and deploying gene drive-modified mosquito products. Developers will benefit from standards for judging whether an investigational gene drive product meets acceptability criteria for advancing to field trials. Such standards may be formalized as preferred product characteristics and target product profiles, which describe the desired attributes of the product category and of a particular product, respectively. This report summarizes discussions from two scientific workshops aimed at identifying efficacy and safety characteristics that must be minimally met for an investigational gene drive-modified mosquito product to be deemed viable to move from contained testing to field release and the data that will be needed to support an application for first field release.
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Affiliation(s)
- Stephanie L James
- Foundation for the National Institutes of Health, North Bethesda, Maryland
| | | | | | | | - Tony Nolan
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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10
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Abstract
The inexorable emergence of mosquito-borne arboviruses and the failure of traditional vector control methods to prevent their transmission have triggered the development of alternative entomological interventions to render mosquito populations incapable of carrying arboviruses. Here, we use a theoretical framework to argue that decreasing mosquito tolerance to arbovirus infection could be a more evolutionarily sustainable disease control strategy than increasing mosquito resistance. Increasing resistance is predicted to select for mutant arboviruses escaping resistance, whereas reducing tolerance should lead to the death of infected vectors and thus select for mosquito-attenuated arbovirus variants that are less transmissible.
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Affiliation(s)
- Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions Unit, Department of Virology, UMR2000, CNRS, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, UMR3569, CNRS, 75015 Paris, France.
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11
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Abstract
Vector control programs based on population reduction by matings with mass-released sterile insects require the release of only male mosquitoes, as the release of females, even if sterile, would increase the number of biting and potentially disease-transmitting individuals. While small-scale releases demonstrated the applicability of sterile males releases to control the yellow fever mosquito Aedes aegypti, large-scale programs for mosquitoes are currently prevented by the lack of efficient sexing systems in any of the vector species.Different approaches of sexing are pursued, including classical genetic and mechanical methods of sex separation. Another strategy is the development of transgenic sexing systems. Such systems already exist in other insect pests. Genome modification tools could be used to apply similar strategies to mosquitoes. Three major tools to modify mosquito genomes are currently used: transposable elements, site-specific recombination systems, and genome editing via TALEN or CRISPR/Cas. All three can serve the purpose of developing sexing systems and vector control strains in mosquitoes in two ways: first, via their use in basic research. A better understanding of mosquito biology, including the sex-determining pathways and the involved genes can greatly facilitate the development of sexing strains. Moreover, basic research can help to identify other regulatory elements and genes potentially useful for the construction of transgenic sexing systems. Second, these genome modification tools can be used to apply the gained knowledge to build and test mosquito sexing strains for vector control.
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Affiliation(s)
- Irina Häcker
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany.
| | - Marc F Schetelig
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
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12
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Wyse AP, dos Santos AJB, Azevedo JDS, de Lima JS, de Faria JR. Modeling the spreading and interaction between wild and transgenic mosquitoes with a random dispersal. PLoS One 2018; 13:e0205879. [PMID: 30379965 PMCID: PMC6209212 DOI: 10.1371/journal.pone.0205879] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/03/2018] [Indexed: 11/18/2022] Open
Abstract
Due to recent advances in genetic manipulation, transgenic mosquitoes may be a viable alternative to reduce some diseases. Feasibility conditions are obtained by simulating and analyzing mathematical models that describe the behavior of wild and transgenic populations living in the same geographic area. In this paper, we present a reaction-diffusion model in which the reaction term is a nonlinear function that describes the interaction between wild and transgenic mosquitoes, considering the zygosity, and the diffusive term that represents a nonuniform spatial spreading characterized by a random diffusion parameter. The resulting nonlinear system of partial differential equations is numerically solved using the sequential operator splitting technique, combining the finite element method and Runge-Kutta method. This scheme is numerically implemented considering uncertainty in the diffusion parameters of the model. Several scenarios simulating spatial release strategies of transgenic mosquitoes are analyzed, demonstrating an intrinsic association between the transgene frequency in the total population and the strategy adopted.
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Affiliation(s)
- Ana Paula Wyse
- Department of Scientific Computing, Informatic Center, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
- * E-mail:
| | | | - Juarez dos Santos Azevedo
- Exact and Technology Sciences Center, Universidade Federal do Recôncavo of Bahia, Cruz das Almas, Bahia, Brazil
| | - Josenildo Silva de Lima
- Graduate Program in Mathematical and Computational Modeling, Informatic Center, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Jairo Rocha de Faria
- Department of Scientific Computing, Informatic Center, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
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13
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Abstract
Technologies for controlling mosquito vectors based on genetic manipulation and the release of genetically modified mosquitoes (GMMs) are gaining ground. However, concrete epidemiological evidence of their effectiveness, sustainability, and impact on the environment and nontarget species is lacking; no reliable ecological evidence on the potential interactions among GMMs, target populations, and other mosquito species populations exists; and no GMM technology has yet been approved by the WHO Vector Control Advisory Group. Our opinion is that, although GMMs may be considered a promising control tool, more studies are needed to assess their true effectiveness, risks, and benefits. Overall, several lines of evidence must be provided before GMM-based control strategies can be used under the integrated vector management framework.
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Affiliation(s)
- André B B Wilke
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - John C Beier
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Giovanni Benelli
- Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto 80, 56124 Pisa, Italy; The BioRobotics Institute, Sant'Anna School of Advanced Studies, viale Rinaldo Piaggio 34, 56025 Pontedera, Pisa, Italy.
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14
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Jupatanakul N, Sim S, Angleró-Rodríguez YI, Souza-Neto J, Das S, Poti KE, Rossi SL, Bergren N, Vasilakis N, Dimopoulos G. Engineered Aedes aegypti JAK/STAT Pathway-Mediated Immunity to Dengue Virus. PLoS Negl Trop Dis 2017; 11:e0005187. [PMID: 28081143 PMCID: PMC5230736 DOI: 10.1371/journal.pntd.0005187] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/15/2016] [Indexed: 12/31/2022] Open
Abstract
We have developed genetically modified Ae. aegypti mosquitoes that activate the conserved antiviral JAK/STAT pathway in the fat body tissue, by overexpressing either the receptor Dome or the Janus kinase Hop by the blood feeding-induced vitellogenin (Vg) promoter. Transgene expression inhibits infection with several dengue virus (DENV) serotypes in the midgut as well as systemically and in the salivary glands. The impact of the transgenes Dome and Hop on mosquito longevity was minimal, but it resulted in a compromised fecundity when compared to wild-type mosquitoes. Overexpression of Dome and Hop resulted in profound transcriptome regulation in the fat body tissue as well as the midgut tissue, pinpointing several expression signatures that reflect mechanisms of DENV restriction. Our transcriptome studies and reverse genetic analyses suggested that enrichment of DENV restriction factor and depletion of DENV host factor transcripts likely accounts for the DENV inhibition, and they allowed us to identify novel factors that modulate infection. Interestingly, the fat body-specific activation of the JAK/STAT pathway did not result in any enhanced resistance to Zika virus (ZIKV) or chikungunya virus (CHIKV) infection, thereby indicating a possible specialization of the pathway’s antiviral role. Dengue has represented a significant public health burden for a number of decades, and given the lack of dengue-specific drugs and limited availability of licensed vaccine, new methods for prevention and control are urgently needed. Here, we investigated whether genetic manipulation of the mosquitoes’ native JAK/STAT pathway-mediated anti-DENV defense system could be used to render mosquitoes more resistant to infection. We generated Ae. aegypti mosquitoes overexpressing the JAK/STAT pathway components Dome and Hop under the control of a bloodmeal-inducible, fat body-specific vitellogenin (Vg) promoter. These genetically modified mosquitoes showed an increased resistance to DENV infection, likely because of higher expression of DENV restriction factors and lower expression of DENV host factors, as indicated by transcriptome analyses. Expression of the transgenes had a minimal impact on mosquito longevity; however, it significantly impaired the mosquitoes’ fecundity. Interestingly, bloodmeal-inducible fat body-specific overexpression of either Hop or Dome did not affect mosquito permissiveness to either ZIKV or CHIKV infection, suggesting a possible specialization of JAK/STAT pathway antiviral defenses. Thus, our study is the first to provide a proof-of-concept that genetic engineering of the mosquitoes’ JAK/STAT immune pathway can be used to render this host more resistant to DENV infection.
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Affiliation(s)
- Natapong Jupatanakul
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Shuzhen Sim
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yesseinia I. Angleró-Rodríguez
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jayme 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
| | - 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
| | - Kristin E. Poti
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Shannan L. Rossi
- Department of Pathology and Center of Biodefense and Emerging Infectious Diseases, Center for Tropical Diseases, Institute for Human Infections and Immunity, The University of Texas Medical Branch, Galveston TX, United States of America
| | - Nicholas Bergren
- Department of Pathology and Center of Biodefense and Emerging Infectious Diseases, Center for Tropical Diseases, Institute for Human Infections and Immunity, The University of Texas Medical Branch, Galveston TX, United States of America
| | - Nikos Vasilakis
- Department of Pathology and Center of Biodefense and Emerging Infectious Diseases, Center for Tropical Diseases, Institute for Human Infections and Immunity, The University of Texas Medical Branch, Galveston TX, 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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15
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Laboratory rearing of Anopheles arabiensis: impact on genetic variability and implications for Sterile Insect Technique (SIT) based mosquito control in northern Sudan. Malar J 2016; 15:432. [PMID: 27799066 PMCID: PMC5088653 DOI: 10.1186/s12936-016-1484-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/11/2016] [Indexed: 12/18/2022] Open
Abstract
Background Mosquito colony populations often show significant changes in their population genetic make-up compared to the field populations that were used as founding source. Most of the changes that have been reported are indicators of depletion in the overall genetic diversity of the colony populations. The Sterile Insect Techniques programme of mosquito control that is underway in Northern Sudan uses sterilized males produced from a laboratory-maintained colony population. The genetic diversity of an advanced generation of this colony population was quantitatively assessed and compared to the field population from which the colony was derived. Methods Anopheles arabiensis mosquito samples from the 13th generation of the colony, and from the locality that was the source of the first generation of the colony, were genotyped at 11 microsatellite loci distributed throughout the species’ genome. Standard population genetic analyses were carried out to quantify and compare their population genetic make-up and diversities. Results The colony samples showed significant reduction in the total number of alleles, the numbers of rare and private alleles, and the fractions of heterozygote individuals at all the loci. The pattern of change is consistent with the expected effect of the use of a small number of mosquitoes when the colony was established. Departure from Hardy–Weinberg equilibrium in the direction of homozygote excess was observed at some loci and attributed to the presence of null-alleles. Conclusions This study highlights the need for broad sampling when initiating colony populations and for ongoing assessment of the population genetic make-up of colony populations. Previous assessments of survivorship, dispersive behaviour and swarm formation indicate that the inbreeding and reduced genetic variability reported in this study may not have had direct fitness consequences yet. However, noting the lessons learned in other SIT programmes about the impact of colonization on male sexual behaviour and longevity, as well as other inbreeding related adverse effects, a systematic investigation of these potential effects is recommended because they have direct impact on the ultimate success of the programme.
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17
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Ng'habi KR, Lee Y, Knols BGJ, Mwasheshi D, Lanzaro GC, Ferguson HM. Colonization of malaria vectors under semi-field conditions as a strategy for maintaining genetic and phenotypic similarity with wild populations. Malar J 2015; 14:10. [PMID: 25604997 PMCID: PMC4340333 DOI: 10.1186/s12936-014-0523-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/20/2014] [Indexed: 11/12/2022] Open
Abstract
Background Malaria still accounts for an estimated 207 million cases and 627,000 deaths worldwide each year. One proposed approach to complement existing malaria control methods is the release of genetically-modified (GM) and/or sterile male mosquitoes. As opposed to laboratory colonization, this requires realistic semi field systems to produce males that can compete for females in nature. This study investigated whether the establishment of a colony of the vector Anopheles arabiensis under more natural semi-field conditions can maintain higher levels of genetic diversity than achieved by laboratory colonization using traditional methods. Methods Wild females of the African malaria vector An. arabiensis were collected from a village in southern Tanzania and used to establish new colonies under different conditions at the Ifakara Health Institute. Levels of genetic diversity and inbreeding were monitored in colonies of An. arabiensis that were simultaneously established in small cage colonies in the SFS and in a large semi-field (SFS) cage and compared with that observed in the original founder population. Phenotypic traits that determine their fitness (body size and energetic reserves) were measured at 10th generation and compared to founder wild population. Results In contrast to small cage colonies, the SFS population of An. arabiensis exhibited a higher degree of similarity to the founding field population through time in several ways: (i) the SFS colony maintained a significantly higher level of genetic variation than small cage colonies, (ii) the SFS colony had a lower degree of inbreeding than small cage colonies, and (iii) the mean and range of mosquito body size in the SFS colony was closer to that of the founding wild population than that of small cage colonies. Small cage colonies had significantly lower lipids and higher glycogen abundances than SFS and wild population. Conclusions Colonization of An. arabiensis under semi-field conditions was associated with the retention of a higher degree of genetic diversity, reduced inbreeding and greater phenotypic similarity to the founding wild population than observed in small cage colonies. Thus, mosquitoes from such semi-field populations are expected to provide more realistic representation of mosquito ecology and physiology than those from small cage colonies.
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Affiliation(s)
- Kija R Ng'habi
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Ifakara, Kilombero, Morogoro, United Republic of Tanzania.
| | - Yoosook Lee
- Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of Calfornia, Davis, USA.
| | - Bart G J Knols
- In2Care BV, Costerweg 5, 6702 AA, Wageningen, The Netherlands.
| | - Dickson Mwasheshi
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Ifakara, Kilombero, Morogoro, United Republic of Tanzania.
| | - Gregory C Lanzaro
- Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of Calfornia, Davis, USA.
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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18
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Arik AJ, Hun LV, Quicke K, Piatt M, Ziegler R, Scaraffia PY, Badgandi H, Riehle MA. Increased Akt signaling in the mosquito fat body increases adult survivorship. FASEB J 2014; 29:1404-13. [PMID: 25550465 DOI: 10.1096/fj.14-261479] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/30/2014] [Indexed: 11/11/2022]
Abstract
Akt signaling regulates diverse physiologies in a wide range of organisms. We examine the impact of increased Akt signaling in the fat body of 2 mosquito species, the Asian malaria mosquito Anopheles stephensi and the yellow fever mosquito Aedes aegypti. Overexpression of a myristoylated and active form of A. stephensi and Ae. aegypti Akt in the fat body of transgenic mosquitoes led to activation of the downstream signaling molecules forkhead box O (FOXO) and p70 S6 kinase in a tissue and blood meal-specific manner. In both species, increased Akt signaling in the fat body after blood feeding significantly increased adult survivorship relative to nontransgenic sibling controls. In A. stephensi, survivorship was increased by 15% to 45%, while in Ae. aegypti, it increased 14% to 47%. Transgenic mosquitoes fed only sugar, and thus not expressing active Akt, had no significant difference in survivorship relative to nontransgenic siblings. Expression of active Akt also increased expression of fat body vitellogenin, but the number of viable eggs did not differ significantly between transgenic and nontransgenic controls. This work demonstrates a novel mechanism of enhanced survivorship through increased Akt signaling in the fat bodies of multiple mosquito genera and provides new tools to unlock the molecular underpinnings of aging in eukaryotic organisms.
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Affiliation(s)
- Anam J Arik
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Lewis V Hun
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Kendra Quicke
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Michael Piatt
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Rolf Ziegler
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Patricia Y Scaraffia
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Hemant Badgandi
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Michael A Riehle
- *Department of Entomology, University of Arizona, Tucson, Arizona, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Department of Tropical Medicine, Vector-Borne Infectious Diseases Research Center, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, USA; and Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
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19
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Meza JS, Díaz-Fleischer F, Sánchez-Velásquez LR, Zepeda-Cisneros CS, Handler AM, Schetelig MF. Fitness cost implications of PhiC31-mediated site-specific integrations in target-site strains of the Mexican fruit fly, Anastrepha ludens (Diptera: Tephritidae). PLoS One 2014; 9:e109690. [PMID: 25303238 PMCID: PMC4193812 DOI: 10.1371/journal.pone.0109690] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 09/10/2014] [Indexed: 01/14/2023] Open
Abstract
Site-specific recombination technologies are powerful new tools for the manipulation of genomic DNA in insects that can improve transgenesis strategies such as targeting transgene insertions, allowing transgene cassette exchange and DNA mobilization for transgene stabilization. However, understanding the fitness cost implications of these manipulations for transgenic strain applications is critical. In this study independent piggyBac-mediated attP target-sites marked with DsRed were created in several genomic positions in the Mexican fruit fly, Anastrepha ludens. Two of these strains, one having an autosomal (attP_F7) and the other a Y-linked (attP_2-M6y) integration, exhibited fitness parameters (dynamic demography and sexual competitiveness) similar to wild type flies. These strains were thus selected for targeted insertion using, for the first time in mexfly, the phiC31-integrase recombination system to insert an additional EGFP-marked transgene to determine its effect on host strain fitness. Fitness tests showed that the integration event in the int_2-M6y recombinant strain had no significant effect, while the int_F7 recombinant strain exhibited significantly lower fitness relative to the original attP_F7 target-site host strain. These results indicate that while targeted transgene integrations can be achieved without an additional fitness cost, at some genomic positions insertion of additional DNA into a previously integrated transgene can have a significant negative effect. Thus, for targeted transgene insertions fitness costs must be evaluated both previous to and subsequent to new site-specific insertions in the target-site strain.
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Affiliation(s)
- José S. Meza
- Programa Moscafrut, SAGARPA-IICA, Metapa de Domínguez, Chiapas, México
- Instituto de Biotecnología y Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Xalapa, Veracruz, México
| | - Francisco Díaz-Fleischer
- Instituto de Biotecnología y Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Xalapa, Veracruz, México
| | - Lázaro R. Sánchez-Velásquez
- Instituto de Biotecnología y Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Xalapa, Veracruz, México
| | | | - Alfred M. Handler
- Center for Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, United States of America
| | - Marc F. Schetelig
- Center for Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, United States of America
- Justus-Liebig-University Giessen, Institute for Phytopathology and Applied Zoology, Giessen, Germany
- * E-mail:
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20
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Feasible introgression of an anti-pathogen transgene into an urban mosquito population without using gene-drive. PLoS Negl Trop Dis 2014; 8:e2827. [PMID: 24992213 PMCID: PMC4081001 DOI: 10.1371/journal.pntd.0002827] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 03/13/2014] [Indexed: 11/19/2022] Open
Abstract
Background Introgressing anti-pathogen constructs into wild vector populations could reduce disease transmission. It is generally assumed that such introgression would require linking an anti-pathogen gene with a selfish genetic element or similar technologies. Yet none of the proposed transgenic anti-pathogen gene-drive mechanisms are likely to be implemented as public health measures in the near future. Thus, much attention now focuses instead on transgenic strategies aimed at mosquito population suppression, an approach generally perceived to be practical. By contrast, aiming to replace vector competent mosquito populations with vector incompetent populations by releasing mosquitoes carrying a single anti-pathogen gene without a gene-drive mechanism is widely considered impractical. Methodology/Principal Findings Here we use Skeeter Buster, a previously published stochastic, spatially explicit model of Aedes aegypti to investigate whether a number of approaches for releasing mosquitoes with only an anti-pathogen construct would be efficient and effective in the tropical city of Iquitos, Peru. To assess the performance of such releases using realistic release numbers, we compare the transient and long-term effects of this strategy with two other genetic control strategies that have been developed in Ae. aegypti: release of a strain with female-specific lethality, and a strain with both female-specific lethality and an anti-pathogen gene. We find that releasing mosquitoes carrying only an anti-pathogen construct can substantially decrease vector competence of a natural population, even at release ratios well below that required for the two currently feasible alternatives that rely on population reduction. Finally, although current genetic control strategies based on population reduction are compromised by immigration of wild-type mosquitoes, releasing mosquitoes carrying only an anti-pathogen gene is considerably more robust to such immigration. Conclusions/Significance Contrary to the widely held view that transgenic control programs aimed at population replacement require linking an anti-pathogen gene to selfish genetic elements, we find releasing mosquitoes in numbers much smaller than those considered necessary for transgenic population reduction can result in comparatively rapid and robust population replacement. In light of this non-intuitive result, directing efforts to improve rearing capacity and logistical support for implementing releases, and reducing the fitness costs of existing recombinant technologies, may provide a viable, alternative route to introgressing anti-pathogen transgenes under field conditions. Dengue is transmitted by the Aedes aegypti mosquito. Releases of genetically sterile males have been shown to reduce wild mosquito numbers. An alternative approach is to release mosquitoes carrying genes blocking dengue transmission. It is often assumed that spreading such genes in mosquito populations requires using selfish genetic elements (SGEs - genes that are inherited at higher rates than other genes in the genome). Absent such techniques, the release numbers required to transform mosquito populations is seen as prohibitive. However, strategies that rely on SGEs or related technologies to spread anti-dengue genes are unlikely to be implemented in the near future as a public health response. Using a biologically detailed model of Aedes aegypti populations dynamics and genetics, we assess how many mosquitoes need to be released to spread an anti-pathogen gene in an urban environment without using an SGE. We compare release numbers with two other, currently feasible transgenic strategies: releasing mosquitoes with female-lethal genes, and mosquitoes carrying both female-lethal and anti-pathogen genes. We show that even without using SGEs, releasing mosquitoes in numbers much smaller than those considered necessary for transgenic population reduction can effectively reduce the ability of Aedes aegypti to spread dengue.
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21
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Pondeville E, Puchot N, Meredith JM, Lynd A, Vernick KD, Lycett GJ, Eggleston P, Bourgouin C. Efficient ΦC31 integrase-mediated site-specific germline transformation of Anopheles gambiae. Nat Protoc 2014; 9:1698-712. [PMID: 24945385 DOI: 10.1038/nprot.2014.117] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Current transgenic methodology developed for mosquitoes has not been applied widely to the major malaria vector Anopheles gambiae, which has proved more difficult to genetically manipulate than other mosquito species and dipteran insects. In this protocol, we describe ΦC31-mediated site-specific integration of transgenes into the genome of A. gambiae. The ΦC31 system has many advantages over 'classical' transposon-mediated germline transformation systems, because it allows integration of large transgenes at specific, characterized genomic locations. Starting from a general protocol, we have optimized steps from embryo collection to co-injection of transgene-containing plasmid and in vitro-produced ΦC31 integrase mRNA. We also provide tips for screening transgenic larvae. The outlined procedure provides robust transformation in A. gambiae, resulting in homozygous transgenic lines in ∼2-3 months.
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Affiliation(s)
- Emilie Pondeville
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Nicolas Puchot
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Janet M Meredith
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, UK
| | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Kenneth D Vernick
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Gareth J Lycett
- 1] Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK. [2]
| | - Paul Eggleston
- 1] Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, UK. [2]
| | - Catherine Bourgouin
- 1] Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France. [2]
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22
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Franz AWE, Sanchez-Vargas I, Raban RR, Black WC, James AA, Olson KE. Fitness impact and stability of a transgene conferring resistance to dengue-2 virus following introgression into a genetically diverse Aedes aegypti strain. PLoS Negl Trop Dis 2014; 8:e2833. [PMID: 24810399 PMCID: PMC4014415 DOI: 10.1371/journal.pntd.0002833] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 03/17/2014] [Indexed: 01/11/2023] Open
Abstract
In 2006, we reported a mariner (Mos1)-transformed Aedes aegypti line, Carb77, which was highly resistant to dengue-2 virus (DENV2). Carb77 mosquitoes expressed a DENV2-specific inverted-repeat (IR) RNA in midgut epithelial cells after ingesting an infectious bloodmeal. The IR-RNA formed double-stranded DENV2-derived RNA, initiating an intracellular antiviral RNA interference (RNAi) response. However, Carb77 mosquitoes stopped expressing the IR-RNA after 17 generations in culture and lost their DENV2-refractory phenotype. In the current study, we generated new transgenic lines having the identical transgene as Carb77. One of these lines, Carb109M, has been genetically stable and refractory to DENV2 for >33 generations. Southern blot analysis identified two transgene integration sites in Carb109M. Northern blot analysis detected abundant, transient expression of the IR-RNA 24 h after a bloodmeal. Carb109M mosquitoes were refractory to different DENV2 genotypes but not to other DENV serotypes. To further test fitness and stability, we introgressed the Carb109M transgene into a genetically diverse laboratory strain (GDLS) by backcrossing for five generations and selecting individuals expressing the transgene's EGFP marker in each generation. Comparison of transgene stability in replicate backcross 5 (BC5) lines versus BC1 control lines demonstrated that backcrossing dramatically increased transgene stability. We subjected six BC5 lines to five generations of selection based on EGFP marker expression to increase the frequency of the transgene prior to final family selection. Comparison of the observed transgene frequencies in the six replicate lines relative to expectations from Fisher's selection model demonstrated lingering fitness costs associated with either the transgene or linked deleterious genes. Although minimal fitness loss (relative to GDLS) was manifest in the final family selection stage, we were able to select homozygotes for the transgene in one family, Carb109M/GDLS.BC5.HZ. This family has been genetically stable and DENV2 refractory for multiple generations. Carb109M/GDLS.BC5.HZ represents an important line for testing proof-of-principle vector population replacement. Expression of a DENV2 sequence-derived IR RNA in the mosquito midgut initiates an antiviral intracellular RNAi response that efficiently blocks DENV2 infection and profoundly impairs vector competence for that virus in Aedes aegypti. DENV2-specific IR RNA expression in the Carb109M strain has maintained the RNAi-based, refractory phenotype for 33 generations in laboratory culture. The two transgene integration sites were stable after multiple generations and following introgression into a genetically-diverse (GDLS) Ae. aegypti population. Introgression of the transgene into the GDLS genetic background changed GDLS from a DENV2 susceptible phenotype to a DENV2 refractory phenotype. The DENV2 refractory homozygous line, Carb109M/GDLS.BC5.HZ, exhibits (relative to GDLS) minimal fitness loss associated with the transgene. This line could be a potential candidate for proof-of-principle field studies.
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Affiliation(s)
- Alexander W. E. Franz
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, United States of America
| | - Irma Sanchez-Vargas
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Robyn R. Raban
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - William C. Black
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Anthony A. James
- Departments of Microbiology and Molecular Genetics and Molecular Biology and Biochemistry, University of California, Irvine, California, United States of America
| | - Ken E. Olson
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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Harvey-Samuel T, Ant T, Gong H, Morrison NI, Alphey L. Population-level effects of fitness costs associated with repressible female-lethal transgene insertions in two pest insects. Evol Appl 2014; 7:597-606. [PMID: 24944572 PMCID: PMC4055180 DOI: 10.1111/eva.12159] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/17/2014] [Indexed: 11/29/2022] Open
Abstract
Genetic control strategies offer great potential for the sustainable and effective control of insect pests. These strategies involve the field release of transgenic insects with the aim of introducing engineered alleles into wild populations, either permanently or transiently. Their efficacy can therefore be reduced if transgene-associated fitness costs reduce the relative performance of released insects. We describe a method of measuring the fitness costs associated with transgenes by analyzing their evolutionary trajectories when placed in competition with wild-type alleles in replicated cage populations. Using this method, we estimated lifetime fitness costs associated with two repressible female-lethal transgenes in the diamondback moth and olive fly as being acceptable for field suppression programs. Furthermore, using these estimates of genotype-level fitness costs, we were able to project longer-term evolutionary trajectories for the transgenes investigated. Results from these projections demonstrate that although transgene-associated fitness costs will ultimately cause these transgenes to become extinct, even when engineered lethality is repressed, they may persist for varying periods of time before doing so. This implies that tetracycline-mediated transgene field persistence in these strains is unlikely and suggests that realistic estimates of transgene-associated fitness costs may be useful in trialing ‘uncoupled’ gene drive system components in the field.
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Affiliation(s)
- Tim Harvey-Samuel
- Department of Zoology, University of Oxford Oxford, UK ; Oxitec Ltd, Milton Park Oxford, UK
| | - Thomas Ant
- Department of Zoology, University of Oxford Oxford, UK ; Oxitec Ltd, Milton Park Oxford, UK
| | | | | | - Luke Alphey
- Department of Zoology, University of Oxford Oxford, UK ; Oxitec Ltd, Milton Park Oxford, UK
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24
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McArthur CC, Meredith JM, Eggleston P. Transgenic Anopheles gambiae expressing an antimalarial peptide suffer no significant fitness cost. PLoS One 2014; 9:e88625. [PMID: 24516671 PMCID: PMC3916423 DOI: 10.1371/journal.pone.0088625] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 01/10/2014] [Indexed: 01/11/2023] Open
Abstract
Mosquito-borne diseases present some of the greatest health challenges faced by the world today. In many cases, existing control measures are compromised by insecticide resistance, pathogen tolerance to drugs and the lack of effective vaccines. In light of these difficulties, new genetic tools for disease control programmes, based on the deployment of genetically modified mosquitoes, are seen as having great promise. Transgenic strains may be used to control disease transmission either by suppressing vector populations or by replacing susceptible with refractory genotypes. In practice, the fitness of the transgenic strain relative to natural mosquitoes will be a critical determinant of success. We previously described a transgenic strain of Anopheles gambiae expressing the Vida3 peptide into the female midgut following a blood-meal, which exhibited significant protection against malaria parasites. Here, we investigated the fitness of this strain relative to non-transgenic controls through comparisons of various life history traits. Experiments were designed, as far as possible, to equalize genetic backgrounds and heterogeneity such that fitness comparisons focussed on the presence and expression of the transgene cassette. We also employed reciprocal crosses to identify any fitness disturbance associated with inheritance of the transgene from either the male or female parent. We found no evidence that the presence or expression of the effector transgene or associated fluorescence markers caused any significant fitness cost in relation to larval mortality, pupal sex ratio, fecundity, hatch rate or longevity of blood-fed females. In fact, fecundity was increased in transgenic strains. We did, however, observe some fitness disturbances associated with the route of inheritance of the transgene. Maternal inheritance delayed male pupation whilst paternal inheritance increased adult longevity for both males and unfed females. Overall, in comparison to controls, there was no evidence of significant fitness costs associated with the presence or expression of transgenes in this strain.
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Affiliation(s)
- Clare C. McArthur
- Centre for Applied Entomology and Parasitology, Keele University, Keele, Staffordshire, United Kingdom
| | - Janet M. Meredith
- Centre for Applied Entomology and Parasitology, Keele University, Keele, Staffordshire, United Kingdom
| | - Paul Eggleston
- Centre for Applied Entomology and Parasitology, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
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25
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YANG CUIHONG, LI JIA. DYNAMICS OF INTERACTIVE MOSQUITO POPULATIONS WITH TWO TRANSGENES. J BIOL SYST 2014. [DOI: 10.1142/s0218339013400032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We formulate a continuous-time 3D model system for the interactive mosquito populations with two different transgenes. We assume that the transgenes are dominant over the wild gene and that one of the transgenes is dominant over the other transgene. Using transformations, we translate the model system to its topologically equivalent 2D system. Based on the investigations of the reduced two-dimensional system, we obtain conditions for the existence and stability of boundary and positive equilibria. We provide numerical examples to demonstrate the rich and complex dynamical features of the model system.
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Affiliation(s)
- CUIHONG YANG
- School of Mathematics and Statistics, Central China Normal University, Wuhan, P. R. China
| | - JIA LI
- Department of Mathematical Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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26
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Carter V, Underhill A, Baber I, Sylla L, Baby M, Larget-Thiery I, Zettor A, Bourgouin C, Langel Ü, Faye I, Otvos L, Wade JD, Coulibaly MB, Traore SF, Tripet F, Eggleston P, Hurd H. Killer bee molecules: antimicrobial peptides as effector molecules to target sporogonic stages of Plasmodium. PLoS Pathog 2013; 9:e1003790. [PMID: 24278025 PMCID: PMC3836994 DOI: 10.1371/journal.ppat.1003790] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/27/2013] [Indexed: 11/18/2022] Open
Abstract
A new generation of strategies is evolving that aim to block malaria transmission by employing genetically modified vectors or mosquito pathogens or symbionts that express anti-parasite molecules. Whilst transgenic technologies have advanced rapidly, there is still a paucity of effector molecules with potent anti-malaria activity whose expression does not cause detrimental effects on mosquito fitness. Our objective was to examine a wide range of antimicrobial peptides (AMPs) for their toxic effects on Plasmodium and anopheline mosquitoes. Specifically targeting early sporogonic stages, we initially screened AMPs for toxicity against a mosquito cell line and P. berghei ookinetes. Promising candidate AMPs were fed to mosquitoes to monitor adverse fitness effects, and their efficacy in blocking rodent malaria infection in Anopheles stephensi was assessed. This was followed by tests to determine their activity against P. falciparum in An. gambiae, initially using laboratory cultures to infect mosquitoes, then culminating in preliminary assays in the field using gametocytes and mosquitoes collected from the same area in Mali, West Africa. From a range of 33 molecules, six AMPs able to block Plasmodium development were identified: Anoplin, Duramycin, Mastoparan X, Melittin, TP10 and Vida3. With the exception of Anoplin and Mastoparan X, these AMPs were also toxic to an An. gambiae cell line at a concentration of 25 µM. However, when tested in mosquito blood feeds, they did not reduce mosquito longevity or egg production at concentrations of 50 µM. Peptides effective against cultured ookinetes were less effective when tested in vivo and differences in efficacy against P. berghei and P. falciparum were seen. From the range of molecules tested, the majority of effective AMPs were derived from bee/wasp venoms.
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Affiliation(s)
- Victoria Carter
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Ann Underhill
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Ibrahima Baber
- Malaria Research and Training Centre (MRTC), Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Lakamy Sylla
- Malaria Research and Training Centre (MRTC), Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Mounirou Baby
- Centre National de Transfusion Sanguine, Bamako, Mali
| | - Isabelle Larget-Thiery
- Institut Pasteur, Centre for Production and Infection of Anopheles (CEPIA), Parasitology and Mycology Department, Paris, France
| | - Agnès Zettor
- Institut Pasteur, Centre for Production and Infection of Anopheles (CEPIA), Parasitology and Mycology Department, Paris, France
| | - Catherine Bourgouin
- Institut Pasteur, Centre for Production and Infection of Anopheles (CEPIA), Parasitology and Mycology Department, Paris, France
| | - Ülo Langel
- Department of Neurochemistry Svante Arrhenius v. 21A, Stockholm University, Stockholm, Sweden
| | - Ingrid Faye
- Department of Molecular Bioscience, the Wenner-Gren Institute, Svante Arrhenius v. 20C, Stockholm University, Stockholm, Sweden
| | - Laszlo Otvos
- Temple University Department of Biology, Philadelphia, Pennsylvania, United States of America
| | - John D. Wade
- Howard Florey Research Laboratories, Florey Institute for Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Mamadou B. Coulibaly
- Malaria Research and Training Centre (MRTC), Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Sekou F. Traore
- Malaria Research and Training Centre (MRTC), Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Frederic Tripet
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Paul Eggleston
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
| | - Hilary Hurd
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
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Smith RC, Kizito C, Rasgon JL, Jacobs-Lorena M. Transgenic mosquitoes expressing a phospholipase A(2) gene have a fitness advantage when fed Plasmodium falciparum-infected blood. PLoS One 2013; 8:e76097. [PMID: 24098427 PMCID: PMC3788000 DOI: 10.1371/journal.pone.0076097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/20/2013] [Indexed: 11/18/2022] Open
Abstract
Background Genetically modified mosquitoes have been proposed as an alternative strategy to reduce the heavy burden of malaria. In recent years, several proof-of-principle experiments have been performed that validate the idea that mosquitoes can be genetically modified to become refractory to malaria parasite development. Results We have created two transgenic lines of Anophelesstephensi, a natural vector of Plasmodium falciparum, which constitutively secrete a catalytically inactive phospholipase A2 (mPLA2) into the midgut lumen to interfere with Plasmodium ookinete invasion. Our experiments show that both transgenic lines expressing mPLA2 significantly impair the development of rodent malaria parasites, but only one line impairs the development of human malaria parasites. In addition, when fed on malaria-infected blood, mosquitoes from both transgenic lines are more fecund than non-transgenic mosquitoes. Consistent with these observations, cage experiments with mixed populations of transgenic and non-transgenic mosquitoes show that the percentage of transgenic mosquitoes increases when maintained on Plasmodium-infected blood. Conclusions Our results suggest that the expression of an anti-Plasmodium effector gene gives transgenic mosquitoes a fitness advantage when fed malaria-infected blood. These findings have important implications for future applications of transgenic mosquito technology in malaria control.
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Affiliation(s)
- Ryan C. Smith
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Christopher Kizito
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jason L. Rasgon
- Department of Entomology, Center for Infectious Disease Dynamics and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Marcelo Jacobs-Lorena
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Dabire KR, Sawadodgo S, Diabate A, Toe KH, Kengne P, Ouari A, Costantini C, Gouagna C, Simard F, Baldet T, Lehmann T, Gibson G. Assortative mating in mixed swarms of the mosquito Anopheles gambiae s.s. M and S molecular forms, in Burkina Faso, West Africa. MEDICAL AND VETERINARY ENTOMOLOGY 2013; 27:298-312. [PMID: 23360106 DOI: 10.1111/j.1365-2915.2012.01049.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The molecular form composition of Anopheles gambiae Giles s.s. (Diptera: Culicidae) mating swarms and the associated mating pairs (copulae) were investigated during two rainy seasons (July to October, 2005 and July to November, 2006) in the villages of Soumousso and Vallée du Kou (VK7). Although the habitats of these villages differ markedly, sympatric populations of M and S molecular forms of An. gambiae s.s. occur in both places periodically. The main aim was to assess the degree to which these molecular forms mate assortatively. In Soumousso, a wooded savannah habitat, the majority of swarm samples consisted of only S-form males (21/28), although a few M-form males were found in mixed M- and S-form swarms. In VK7, a rice growing area, the majority of swarm samples consisted of only M-form males (38/62), until October and November 2006, when there were nearly as many mixed-form as single-form swarms. Overall, ∼60% of M- and S-form swarms were temporally or spatially segregated; the two forms were effectively prevented from encountering each other. Of the remaining 40% of swarms, however, only about half were single-form and the rest were mixed-form. Of the 33 copulae collected from mixed-form swarms, only four were mixed-form pairs, significantly fewer than expected by random pairing between forms (χ(2) = 10.34, d.f. = 2, P < 0.01). Finally, all specimens of inseminated females were of the same form as the sperm contained within their spermatheca (n = 91), even for the four mixed-form copulae. These findings indicate that assortative mating occurs within mixed-form swarms, mediated most probably by close-range mate recognition cues.
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Affiliation(s)
- K R Dabire
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa.
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Paton D, Underhill A, Meredith J, Eggleston P, Tripet F. Contrasted Fitness Costs of Docking and Antibacterial Constructs in the EE and EVida3 Strains Validates Two-Phase Anopheles gambiae Genetic Transformation System. PLoS One 2013; 8:e67364. [PMID: 23840679 PMCID: PMC3694017 DOI: 10.1371/journal.pone.0067364] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 05/16/2013] [Indexed: 01/25/2023] Open
Abstract
The deployment of transgenic mosquitoes carrying genes for refractoriness to malaria has long been seen as a futuristic scenario riddled with technical difficulties. The integration of anti-malarial effector genes and a gene-drive system into the mosquito genome without affecting mosquito fitness is recognized as critical to the success of this malaria control strategy. Here we conducted detailed fitness studies of two Anopheles gambiae s.s. transgenic lines recently developed using a two-phase targeted genetic transformation system. In replicated cage-invasion experiments, males and females of the EE Phase-1 docking strain and EVida3 Phase-2 strain loaded with an antimicrobial peptide (AMP) expressed upon blood-feeding, were mixed with individuals of a recently-colonized strain of the Mopti chromosomal form. The experimental design enabled us to detect initial strain reproductive success differences, assortative mating and hybrid vigor that may characterize mosquito release situations. In addition, the potential fitness costs of the unloaded Phase-1 and loaded Phase-2 genetic constructs, independent of the strains' original genetic backgrounds, were estimated between the 1(st) instar larvae, pupae and adult stages over 10 generations. The Phase-1 unloaded docking cassette was found to have significantly lower allelic fitness relative to the wild type allele during larval development. However, overall genotypic fitness was comparable to the wild type allele across all stages leading to stable equilibrium in all replicates. In contrast, the Phase-2 construct expressing EVida3 disappeared from all replicates within 10 generations due to lower fitness of hemi- and homozygous larvae, suggesting costly background AMP expression and/or of the DsRed2 marker. This is the first study to effectively partition independent fitness stage-specific determinants in unloaded and loaded transgenic strains of a Phase-1-2 transformation system. Critically, the high fitness of the Phase-1 docking strain makes it the ideal model system for measuring the genetic load of novel candidate anti-malarial molecules in vivo.
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Affiliation(s)
- Doug Paton
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Anne Underhill
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Janet Meredith
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Paul Eggleston
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Frederic Tripet
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
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Fitness of transgenic mosquito Aedes aegypti males carrying a dominant lethal genetic system. PLoS One 2013; 8:e62711. [PMID: 23690948 PMCID: PMC3653897 DOI: 10.1371/journal.pone.0062711] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 03/22/2013] [Indexed: 02/03/2023] Open
Abstract
OX513A is a transgenic strain of Aedes aegypti engineered to carry a dominant, non-sex-specific, late-acting lethal genetic system that is repressed in the presence of tetracycline. It was designed for use in a sterile-insect (SIT) pest control system called RIDL® (Release of Insects carrying a Dominant Lethal gene) by which transgenic males are released in the field to mate with wild females; in the absence of tetracycline, the progeny from such matings will not survive. We investigated the mating fitness of OX513A in the laboratory. Male OX513A were as effective as Rockefeller (ROCK) males at inducing refractoriness to further mating in wild type females and there was no reduction in their ability to inseminate multiple females. They had a lower mating success but yielded more progeny than the wild-type comparator strain (ROCK) when one male of each strain was caged with a ROCK female. Mating success and fertility of groups of 10 males—with different ratios of RIDL to ROCK—competing for five ROCK females was similar, but the median longevity of RIDL males was somewhat (18%) lower. We conclude that the fitness under laboratory conditions of OX513A males carrying a tetracycline repressible lethal gene is comparable to that of males of the wild-type comparator strain.
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Chen L, Zhu C, Zhang D. Naturally occurring incompatibilities between different Culex pipiens pallens populations as the basis of potential mosquito control measures. PLoS Negl Trop Dis 2013; 7:e2030. [PMID: 23383354 PMCID: PMC3561155 DOI: 10.1371/journal.pntd.0002030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/08/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Vector-borne diseases remain a threat to public health, especially in tropical countries. The incompatible insect technique has been explored as a potential control strategy for several important insect vectors. However, this strategy has not been tested in Culex pipiens pallens, the most prevalent mosquito species in China. Previous works used introgression to generate new strains that matched the genetic backgrounds of target populations while harboring a new Wolbachia endosymbiont, resulting in mating competitiveness and cytoplasmic incompatibility. The generation of these incompatible insects is often time-consuming, and the long-term stability of the newly created insect-Wolbachia symbiosis is uncertain. Considering the wide distribution of Cx. pipiens pallens and hence possible isolation of different populations, we sought to test for incompatibilities between natural populations and the possibility of exploiting these incompatibilities as a control strategy. METHODOLOGY/PRINCIPAL FINDINGS Three field populations were collected from three geographic locations in eastern China. Reciprocal cross results showed that bi-directional patterns of incompatibility existed between some populations. Mating competition experiments indicated that incompatible males could compete with cognate males in mating with females, leading to reduced overall fecundity. F1 offspring from incompatible crosses maintained their maternal crossing types. All three populations tested positive for Wolbachia. Removal of Wolbachia by tetracycline rendered matings between these populations fully compatible. CONCLUSIONS/SIGNIFICANCE Our findings indicate that naturally occurring patterns of cytoplasmic incompatibility between Cx. pipiens pallens populations can be the basis of a control strategy for this important vector species. The observed incompatibilities are caused by Wolbachia. More tests including field trials are warranted to evaluate the feasibility of this strategy as a supplement to other control measures.
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Affiliation(s)
- Lin Chen
- Department of Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
- Jiangsu Province Key Laboratory of Modern Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
| | - Changliang Zhu
- Department of Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
- Jiangsu Province Key Laboratory of Modern Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
| | - Donghui Zhang
- Department of Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
- Jiangsu Province Key Laboratory of Modern Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, P. R. China
- * E-mail:
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Open field release of genetically engineered sterile male Aedes aegypti in Malaysia. PLoS One 2012; 7:e42771. [PMID: 22970102 PMCID: PMC3428326 DOI: 10.1371/journal.pone.0042771] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/11/2012] [Indexed: 12/17/2022] Open
Abstract
Background Dengue is the most important mosquito-borne viral disease. In the absence of specific drugs or vaccines, control focuses on suppressing the principal mosquito vector, Aedes aegypti, yet current methods have not proven adequate to control the disease. New methods are therefore urgently needed, for example genetics-based sterile-male-release methods. However, this requires that lab-reared, modified mosquitoes be able to survive and disperse adequately in the field. Methodology/Principal Findings Adult male mosquitoes were released into an uninhabited forested area of Pahang, Malaysia. Their survival and dispersal was assessed by use of a network of traps. Two strains were used, an engineered ‘genetically sterile’ (OX513A) and a wild-type laboratory strain, to give both absolute and relative data about the performance of the modified mosquitoes. The two strains had similar maximum dispersal distances (220 m), but mean distance travelled of the OX513A strain was lower (52 vs. 100 m). Life expectancy was similar (2.0 vs. 2.2 days). Recapture rates were high for both strains, possibly because of the uninhabited nature of the site. Conclusions/Significance After extensive contained studies and regulatory scrutiny, a field release of engineered mosquitoes was safely and successfully conducted in Malaysia. The engineered strain showed similar field longevity to an unmodified counterpart, though in this setting dispersal was reduced relative to the unmodified strain. These data are encouraging for the future testing and implementation of genetic control strategies and will help guide future field use of this and other engineered strains.
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Caljon G, De Vooght L, Van Den Abbeele J. Options for the delivery of anti-pathogen molecules in arthropod vectors. J Invertebr Pathol 2012; 112 Suppl:S75-82. [PMID: 22841635 DOI: 10.1016/j.jip.2012.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/15/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
Blood feeding arthropods are responsible for the transmission of a large array of medically important infectious agents that include viruses, bacteria, protozoan parasites and helminths. The recent development of transgenic and paratransgenic technologies have enabled supplementing the immune system of these arthropod vectors with anti-pathogen effector molecules in view of compromising their vector competence for these microbial agents. The characteristics of the selected anti-pathogen compound will largely determine the efficacy and specificity of this approach. Low specificity will generally result in bystander effects, likely having a direct or indirect fitness cost for the arthropod. In contrast, the use of highly specific compounds from the adaptive immune system of vertebrates such as antibody derived fragments is more likely to enable highly specific effects without conferring a selective disadvantage to the (para)transgenic arthropods. Here, Nanobodies® are excellent candidates to increase the immune competence of arthropods. Moreover they were shown to exert a novel type of anti-pathogen activity that uniquely depends on their small size.
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Affiliation(s)
- Guy Caljon
- Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium.
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Abstract
The ability to manipulate the genomes of many insects has become a practical reality over the past 15 years. This has been led by the identification of several useful transposon vector systems that have allowed the identification and development of generalized, species-specific, and tissue-specific promoter systems for controlled expression of gene products upon introduction into insect genomes. Armed with these capabilities, researchers have made significant strides in both fundamental and applied transgenics in key model systems such as Bombyx mori, Tribolium casteneum, Aedes aegypti, and Anopheles stephensi. Limitations of transposon systems were identified, and alternative tools were developed, thus significantly increasing the potential for applied transgenics for control of both agricultural and medical insect pests. The next 10 years promise to be an exciting time of transitioning from the laboratory to the field, from basic research to applied control, during which the full potential of gene manipulation in insect systems will ultimately be realized.
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Affiliation(s)
- Malcolm J Fraser
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556-0369, USA.
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35
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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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36
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Low- and high-tech approaches to control Plasmodium parasite transmission by anopheles mosquitoes. J Trop Med 2011; 2011:891342. [PMID: 21876705 PMCID: PMC3157759 DOI: 10.1155/2011/891342] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 06/08/2011] [Indexed: 11/25/2022] Open
Abstract
Current efforts have proven inadequate to stop the transmission of Plasmodium parasites, and hence the spread of malaria, by Anopheles mosquitoes. Therefore, a novel arsenal of strategies for inhibiting Plasmodium infection of mosquitoes is urgently needed. In this paper, we summarize research on two approaches to malaria control, a low-tech strategy based on parasite inhibition by the mosquito's natural microflora, and a high-tech strategy using genetic modification of mosquitoes that renders them resistant to infection and discuss advantages and disadvantages for both approaches.
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Bargielowski I, Nimmo D, Alphey L, Koella JC. Comparison of life history characteristics of the genetically modified OX513A line and a wild type strain of Aedes aegypti. PLoS One 2011; 6:e20699. [PMID: 21698096 PMCID: PMC3117796 DOI: 10.1371/journal.pone.0020699] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 05/06/2011] [Indexed: 01/21/2023] Open
Abstract
The idea of implementing genetics-based insect control strategies modelled on the traditional SIT (Sterile Insect Technique), such as RIDL (Release of Insects carrying a Dominant Lethal), is becoming increasingly popular. In this paper, we compare a genetically modified line of Aedes aegypti carrying a tetracycline repressible, lethal positive feedback system (OX513A) with a genetically similar, unmodified counterpart and their respective responses to increasing larval rearing density using a constant amount of food per larva. The parameters that we examined were larval mortality, developmental rate (i.e., time to pupation), adult size and longevity. Analysis revealed some statistically significant differences between the life history traits we examined. The genetically modified OX513A line overall showed 5% lower larval survival as well as reduced adult longevity (20 vs 24 days mean lifespan) compared to the unmodified line. Furthermore, the OX513A line pupated about one day sooner, which could be advantageous in mass-rearing, but produced somewhat smaller adults than the unmodified line; this effect was more pronounced in females than in males. Increasing the larval rearing density delayed pupation, decreased adult longevity and reduced adult size in both lines. While the delay in pupation and the decrease in longevity were similar between the two lines, the decrease in adult size was more pronounced for OX513A males.Our study shows that in a controlled laboratory situation the transgenic sterile OX513A line may have somewhat reduced performance compared to its unmodified counterpart and that high rearing densities may further reduce performance. Laboratory-based cage trials as well as field trials are necessary to assess how the differences in life history traits documented here impact the males' success upon release. Furthermore, this paper highlights the potential value of optimisation of mass-rearing systems as optimised rearing methods may be able to alleviate performance issues associated with specific lines or with lab-adapted lines in general.
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Affiliation(s)
- Irka Bargielowski
- Division of Biology, Imperial College London, London, United Kingdom
- Oxitec Limited, Oxford, United Kingdom
| | | | - Luke Alphey
- Oxitec Limited, Oxford, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Jacob C. Koella
- Division of Biology, Imperial College London, London, United Kingdom
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Marshall JM, Pittman GW, Buchman AB, Hay BA. Semele: a killer-male, rescue-female system for suppression and replacement of insect disease vector populations. Genetics 2011; 187:535-51. [PMID: 21078687 PMCID: PMC3030495 DOI: 10.1534/genetics.110.124479] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 11/10/2010] [Indexed: 11/18/2022] Open
Abstract
Two strategies to control mosquito-borne diseases, such as malaria and dengue fever, are reducing mosquito population sizes or replacing populations with disease-refractory varieties. We propose a genetic system, Semele, which may be used for both. Semele consists of two components: a toxin expressed in transgenic males that either kills or renders infertile wild-type female recipients and an antidote expressed in females that protects them from the effects of the toxin. An all-male release results in population suppression because wild-type females that mate with transgenic males produce no offspring. A release that includes transgenic females results in gene drive since females carrying the allele are favored at high population frequencies. We use simple population genetic models to explore the utility of the Semele system. We find that Semele can spread under a wide range of conditions, all of which require a high introduction frequency. This feature is desirable since transgenic insects released accidentally are unlikely to persist, transgenic insects released intentionally can be spatially confined, and the element can be removed from a population through sustained release of wild-type insects. We examine potential barriers to Semele gene drive and suggest molecular tools that could be used to build the Semele system.
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Affiliation(s)
- John M Marshall
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, W2 1PG, United Kingdom.
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Koenraadt CJ, Kormaksson M, Harrington LC. Effects of inbreeding and genetic modification on Aedes aegypti larval competition and adult energy reserves. Parasit Vectors 2010; 3:92. [PMID: 20925917 PMCID: PMC2967506 DOI: 10.1186/1756-3305-3-92] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 10/06/2010] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Genetic modification of mosquitoes offers a promising strategy for the prevention and control of mosquito-borne diseases. For such a strategy to be effective, it is critically important that engineered strains are competitive enough to serve their intended function in population replacement or reduction of wild mosquitoes in nature. Thus far, fitness evaluations of genetically modified strains have not addressed the effects of competition among the aquatic stages and its consequences for adult fitness. We therefore tested the competitive success of combinations of wild, inbred and transgenic (created in the inbred background) immature stages of the dengue vector Aedes aegypti in the presence of optimal and sub-optimal larval diets. RESULTS The wild strain of Ae. aegypti demonstrated greater performance (based on a composite index of survival, development rate and size) than the inbred strain, which in turn demonstrated greater performance than the genetically modified strain. Moreover, increasing competition through lowering the amount of diet available per larva affected fitness disproportionately: transgenic larvae had a reduced index of performance (95-119%) compared to inbred (50-88%) and wild type larvae (38-54%). In terms of teneral energy reserves (glycogen, lipid and sugar), adult wild type mosquitoes had more reserves directly available for flight, dispersal and basic metabolic functions than transgenic and inbred mosquitoes. CONCLUSIONS Our study provides a detailed assessment of inter- and intra-strain competition across aquatic stages of wild type, inbred, and transgenic mosquitoes and the impact of these conditions on adult energy reserves. Although it is not clear what competitive level is adequate for success of transgenic strains in nature, strong gene drive mechanisms are likely to be necessary in order to overcome competitive disadvantages in the larval stage that carryover to affect adult fitness.
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White SM, Rohani P, Sait SM. Modelling pulsed releases for sterile insect techniques: fitness costs of sterile and transgenic males and the effects on mosquito dynamics. J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2010.01880.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Benedict M, Eckerstorfer M, Franz G, Gaugitsch H, Greiter A, Heissenberger A, Knols B, Kumschick S, Nentwig W, Rabitsch W. Defining Environment Risk Assessment Criteria for Genetically Modified Insects to be placed on the EU Market. ACTA ACUST UNITED AC 2010. [DOI: 10.2903/sp.efsa.2010.en-71] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Scolari F, Siciliano P, Gabrieli P, Gomulski LM, Bonomi A, Gasperi G, Malacrida AR. Safe and fit genetically modified insects for pest control: from lab to field applications. Genetica 2010; 139:41-52. [PMID: 20725766 DOI: 10.1007/s10709-010-9483-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 08/07/2010] [Indexed: 01/10/2023]
Abstract
Insect transgenesis is continuously being improved to increase the efficacy of population suppression and replacement strategies directed to the control of insect species of economic and sanitary interest. An essential prerequisite for the success of both pest control applications is that the fitness of the transformant individuals is not impaired, so that, once released in the field, they can efficiently compete with or even out-compete their wild-type counterparts for matings in order to reduce the population size, or to spread desirable genes into the target population. Recent research has shown that the production of fit and competitive transformants can now be achieved and that transgenes may not necessarily confer a fitness cost. In this article we review the most recent published results of the fitness assessment of different transgenic insect lines and underline the necessity to fulfill key requirements of ecological safety. Fitness evaluation studies performed in field cages and medium/large-scale rearing will validate the present encouraging laboratory results, giving an indication of the performance of the transgenic insect genotype after release in pest control programmes.
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Affiliation(s)
- F Scolari
- Department of Animal Biology, University of Pavia, Pavia, Italy
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Alphey L, Benedict M, Bellini R, Clark GG, Dame DA, Service MW, Dobson SL. Sterile-insect methods for control of mosquito-borne diseases: an analysis. Vector Borne Zoonotic Dis 2010; 10:295-311. [PMID: 19725763 PMCID: PMC2946175 DOI: 10.1089/vbz.2009.0014] [Citation(s) in RCA: 298] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Effective vector control, and more specifically mosquito control, is a complex and difficult problem, as illustrated by the continuing prevalence (and spread) of mosquito-transmitted diseases. The sterile insect technique and similar methods control certain agricultural insect pest populations in a species-specific, environmentally sound, and effective manner; there is increased interest in applying this approach to vector control. Such an approach, like all others in use and development, is not a one-size-fits-all solution, and will be more appropriate in some situations than others. In addition, the proposed release of pest insects, and more so genetically modified pest insects, is bound to raise questions in the general public and the scientific community as to such a method's efficacy, safety, and sustainability. This article attempts to address these concerns and indicate where sterile-insect methods are likely to be useful for vector control.
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Affiliation(s)
- Luke Alphey
- Oxitec Limited, Oxford, United
Kingdom
- Department of Zoology, University of Oxford, Oxford,
United Kingdom
| | - Mark Benedict
- Entomology Unit, International Atomic Energy Agency,
Vienna, Austria
| | - Romeo Bellini
- Centro Agricoltura Ambiente “G.Nicoli,”
Crevalcore, Italy
| | - Gary G. Clark
- Mosquito and Fly Research Unit, USDA-ARS-CMAVE,
Gainesville, Florida
| | | | - Mike W. Service
- Liverpool School of Tropical Medicine, Liverpool,
United Kingdom
| | - Stephen L. Dobson
- Department of Entomology, University of Kentucky,
Lexington, Kentucky
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O'Donnell D, Armbruster P. Inbreeding depression affects life-history traits but not infection by Plasmodium gallinaceum in the Asian tiger mosquito, Aedes albopictus. INFECTION GENETICS AND EVOLUTION 2010; 10:669-77. [PMID: 20359551 DOI: 10.1016/j.meegid.2010.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/21/2010] [Accepted: 03/23/2010] [Indexed: 10/19/2022]
Abstract
Emerging and re-emerging vector-borne diseases represent an increasingly significant public health challenge. While geographic variation among populations of vector species for susceptibility to pathogen infection and vector competence has been thoroughly documented, relatively little attention has been devoted to understanding the ultimate evolutionary causes of this intraspecific variation. Local genetic drift is known to influence genetic differentiation among populations for a variety of container-inhabiting mosquito species, including Aedes albopictus. Because genetic drift is expected to reduce genetic variation and lead to the accumulation of (partially) recessive deleterious alleles, we hypothesized that reduced genetic variation might affect susceptibility to pathogen infection in a model pathogen-vector system. We therefore created replicate inbred (two generations of full-sib mating, expected f=0.375) and control (expected f approximately 0.07) lines of Ae. albopictus and measured life-history traits including larval survivorship, adult longevity, and female wing length (body size) as well as susceptibility to infection by a model pathogen, Plasmodium gallinaceum. Inbred mosquitoes had significantly reduced larval survivorship and female adult longevity but inbreeding did not affect male adult longevity or female wing length (body size). Furthermore, there was no effect of inbreeding on susceptibility to infection by P. gallinaceum. Therefore, while our results did not support the hypothesis that reduced genetic variation influences susceptibility to pathogen infection in this system, we did find evidence for an effect of reduced genetic variation on female adult longevity, an important component of vectorial capacity. We suggest that additional research is needed to elucidate the genetic underpinnings of intraspecific variation in traits related to disease transmission and discuss the implications of our results for the efficacy of creating transgenic strains refractory to disease transmission.
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Affiliation(s)
- Deborah O'Donnell
- Department of Biology, Georgetown University, 37th and O Sts. NW, Washington, DC 20057, United States
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45
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Santos MN, Nogueira PM, Dias FBS, Valle D, Moreira LA. Fitness aspects of transgenic Aedes fluviatilis mosquitoes expressing a Plasmodium-blocking molecule. Transgenic Res 2010; 19:1129-35. [DOI: 10.1007/s11248-010-9375-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 02/01/2010] [Indexed: 12/19/2022]
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Gholizadeh S, Djadid ND, Basseri HR, Zakeri S, Ladoni H. Analysis of von Willebrand factor A domain-related protein (WARP) polymorphism in temperate and tropical Plasmodium vivax field isolates. Malar J 2009; 8:137. [PMID: 19549316 PMCID: PMC2709902 DOI: 10.1186/1475-2875-8-137] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 06/23/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The identification of key molecules is crucial for designing transmission-blocking vaccines (TBVs), among those ookinete micronemal proteins are candidate as a general class of malaria transmission-blocking targets. Here, the sequence analysis of an extra-cellular malaria protein expressed in ookinetes, named von Willebrand factor A domain-related protein (WARP), is reported in 91 Plasmodium vivax isolates circulating in different regions of Iran. METHODS Clinical isolates were collected from north temperate and southern tropical regions in Iran. Primers have been designed based on P. vivax sequence (ctg_6991) which amplified a fragment of about 1044 bp with no size variation. Direct sequencing of PCR products was used to determine polymorphism and further bioinformatics analysis in P. vivax sexual stage antigen, pvwarp. RESULTS Amplified pvwarp gene showed 886 bp in size, with no intron. BLAST analysis showed a similarity of 98-100% to P. vivax Sal-I strain; however, Iranian isolates had 2 bp mismatches in 247 and 531 positions that were non-synonymous substitution [T (ACT) to A (GCT) and R (AGA) to S (AGT)] in comparison with the Sal-I sequence. CONCLUSION This study presents the first large-scale survey on pvwarp polymorphism in the world, which provides baseline data for developing WARP-based TBV against both temperate and tropical P. vivax isolates.
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Affiliation(s)
- Saber Gholizadeh
- Biotechnology Research Center (BRC), Pasteur Institute of Iran (PII), Tehran, Iran.
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Schaffer WM, Bronnikova TV. Controlling malaria: competition, seasonality and 'slingshotting' transgenic mosquitoes into natural populations. JOURNAL OF BIOLOGICAL DYNAMICS 2009; 3:286-304. [PMID: 22880835 DOI: 10.1080/17513750802582621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Forty years after the World Health Organization abandoned its eradication campaign, malaria remains a public health problem of the first magnitude with worldwide infection rates on the order of 300 million souls. The present paper reviews potential control strategies from the viewpoint of mathematical epidemiology. Following MacDonald and others, we argue in Section 1 that the use of imagicides, i.e., killing, or at least repelling, adult mosquitoes, is inherently the most effective way of combating the pandemic. In Section 2, we model competition between wild-type (WT) and plasmodium-resistant, genetically modified (GM) mosquitoes. Under the assumptions of inherent cost and prevalence-dependant benefit to transgenics, GM introduction can never eradicate malaria save by stochastic extinction of WTs. Moreover, alternative interventions that reduce prevalence have the undesirable consequence of reducing the likelihood of successful GM introduction. Section 3 considers the possibility of using seasonal fluctuations in mosquito abundance and disease prevalence to 'slingshot' GM mosquitoes into natural populations. By introducing GM mosquitoes when natural populations are about to expand, one can 'piggyback' on the yearly cycle. Importantly, this effect is only significant when transgene cost is small, in which case the non-trivial equilibrium is a focus (damped oscillations), and piggybacking is amplified by the system's inherent tendency to oscillate. By way of contrast, when transgene cost is large, the equilibrium is a node and no such amplification is obtained.
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Affiliation(s)
- W M Schaffer
- Department of Ecology and Evolutionary Biology, The University of Arizona, AZ, USA.
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Marshall JM. The effect of gene drive on containment of transgenic mosquitoes. J Theor Biol 2009; 258:250-65. [PMID: 19490857 DOI: 10.1016/j.jtbi.2009.01.031] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 01/27/2009] [Accepted: 01/30/2009] [Indexed: 11/19/2022]
Abstract
Mosquito-borne diseases such as malaria and dengue fever continue to be a major health problem through much of the world. Several new potential approaches to disease control utilize gene drive to spread anti-pathogen genes into the mosquito population. Prior to a release, these projects will require trials in outdoor cages from which transgenic mosquitoes may escape, albeit in small numbers. Most genes introduced in small numbers are very likely to be lost from the environment; however, gene drive mechanisms enhance the invasiveness of introduced genes. Consequently, introduced transgenes may be more likely to persist than ordinary genes following an accidental release. Here, we develop stochastic models to analyze the loss probabilities for several gene drive mechanisms, including homing endonuclease genes, transposable elements, Medea elements, the intracellular bacterium Wolbachia, engineered underdominance genes, and meiotic drive. We find that Medea and Wolbachia present the best compromise between invasiveness and containment for the six gene drive systems currently being considered for the control of mosquito-borne disease.
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Affiliation(s)
- John M Marshall
- Department of Biomathematics, UCLA School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095-1766, USA.
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Dixit R, Sharma A, Mourya DT, Kamaraju R, Patole MS, Shouche YS. Salivary gland transcriptome analysis during Plasmodium infection in malaria vector Anopheles stephensi. Int J Infect Dis 2009; 13:636-46. [PMID: 19128996 DOI: 10.1016/j.ijid.2008.07.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 06/19/2008] [Accepted: 07/12/2008] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Understanding the tissue-specific molecular cross-talk mechanism during the mosquito-parasite interaction is of prime importance in the design of new strategies for malaria control. Because mosquito salivary glands are the final destination for the parasite maturation and transmission of vector-borne diseases, identification and characterization of salivary genes and their products are equally important in order to access their effect on the infectivity of the parasite. During the last five years there have been several studies on the sialomes of Anopheles mosquitoes, however very limited information is available on the changes in the salivary gland transcriptome in the presence of Plasmodium, and this information is limited to the mosquito Anopheles gambiae. METHODS In this study we aimed to explore and identify parasite-induced transcripts from the salivary glands of Anopheles stephensi, using a subtractive hybridization protocol. RESULTS Ninety-four percent of expressed sequence tags (ESTs) showed close homology to previously known families of mosquito salivary gland secretary proteins, representing the induced expression of alternative splicing and/or additional new members of the protein family. The remaining 6% of ESTs did not yield significant homology to any known proteins in the non-redundant database and thus may represent a class of unknown/novel salivary proteins. Primary analysis of the ESTs also revealed identification of several novel immune-related transcripts, including defensin and cecropins, probably involved in counter-activation of the antagonistic defense system. A comprehensive description of each family of proteins has been discussed in relation to the tissue-specific mosquito-parasite interaction. CONCLUSION This is the first report on the identification of new putative salivary genes, presumably activated during parasite infection.
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Affiliation(s)
- Rajnikant Dixit
- Molecular Biology Unit, National Center for Cell Science, Ganeshkhind, Pune, India.
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Ferguson HM, Ng'habi KR, Walder T, Kadungula D, Moore SJ, Lyimo I, Russell TL, Urassa H, Mshinda H, Killeen GF, Knols BG. Establishment of a large semi-field system for experimental study of African malaria vector ecology and control in Tanzania. Malar J 2008; 7:158. [PMID: 18715508 PMCID: PMC2543042 DOI: 10.1186/1475-2875-7-158] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Accepted: 08/20/2008] [Indexed: 01/08/2023] Open
Abstract
Background Medical entomologists increasingly recognize that the ability to make inferences between laboratory experiments of vector biology and epidemiological trends observed in the field is hindered by a conceptual and methodological gap occurring between these approaches which prevents hypothesis-driven empirical research from being conducted on relatively large and environmentally realistic scales. The development of Semi-Field Systems (SFS) has been proposed as the best mechanism for bridging this gap. Semi-field systems are defined as enclosed environments, ideally situated within the natural ecosystem of a target disease vector and exposed to ambient environmental conditions, in which all features necessary for its life cycle completion are present. Although the value of SFS as a research tool for malaria vector biology is gaining recognition, only a few such facilities exist worldwide and are relatively small in size (< 100 m2). Methods The establishment of a 625 m2 state-of-the-art SFS for large-scale experimentation on anopheline mosquito ecology and control within a rural area of southern Tanzania, where malaria transmission intensities are amongst the highest ever recorded, is described. Results A greenhouse frame with walls of mosquito netting and a polyethylene roof was mounted on a raised concrete platform at the Ifakara Health Institute. The interior of the SFS was divided into four separate work areas that have been set up for a variety of research activities including mass-rearing for African malaria vectors under natural conditions, high throughput evaluation of novel mosquito control and trapping techniques, short-term assays of host-seeking behaviour and olfaction, and longer-term experimental investigation of anopheline population dynamics and gene flow within a contained environment that simulates a local village domestic setting. Conclusion The SFS at Ifakara was completed and ready for use in under two years. Preliminary observations indicate that realistic and repeatable observations of anopheline behaviour are obtainable within the SFS, and that habitat and climatic features representative of field conditions can be simulated within it. As work begins in the SFS in Ifakara and others around the world, the major opportunities and challenges to the successful application of this tool for malaria vector research and control are discussed.
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Affiliation(s)
- Heather M Ferguson
- Division of Infection and Immunity, University of Glasgow, G128TA Glasgow, UK.
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