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Dhole S, Lloyd AL, Gould F. Tethered homing gene drives: A new design for spatially restricted population replacement and suppression. Evol Appl 2019; 12:1688-1702. [PMID: 31462923 PMCID: PMC6708424 DOI: 10.1111/eva.12827] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 05/06/2019] [Accepted: 05/10/2019] [Indexed: 12/18/2022] Open
Abstract
Optimism regarding potential epidemiological and conservation applications of modern gene drives is tempered by concern about the possibility of unintended spread of engineered organisms beyond the target population. In response, several novel gene drive approaches have been proposed that can, under certain conditions, locally alter characteristics of a population. One challenge for these gene drives is the difficulty of achieving high levels of localized population suppression without very large releases in the face of gene flow. We present a new gene drive system, tethered homing (TH), with improved capacity for both localization and population suppression. The TH drive is based on driving a payload gene using a homing construct that is anchored to a spatially restricted gene drive. We use a proof-of-concept mathematical model to show the dynamics of a TH drive that uses engineered underdominance as an anchor. This system is composed of a split homing drive and a two-locus engineered underdominance drive linked to one part of the split drive (the Cas endonuclease). We use simple population genetic simulations to show that the tethered homing technique can offer improved localized spread of costly transgenic payload genes. Additionally, the TH system offers the ability to gradually adjust the genetic load in a population after the initial alteration, with minimal additional release effort. We discuss potential solutions for improving localization and the feasibility of creating TH drive systems. Further research with models that include additional biological details will be needed to better understand how TH drives would behave in natural populations, but the preliminary results shown here suggest that tethered homing drives can be a useful addition to the repertoire of localized gene drives.
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Affiliation(s)
- Sumit Dhole
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth Carolina
| | - Alun L. Lloyd
- Biomathematics Graduate Program and Department of MathematicsNorth Carolina State UniversityRaleighNorth Carolina
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNorth Carolina
| | - Fred Gould
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth Carolina
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNorth Carolina
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Lai HE, Canavan C, Cameron L, Moore S, Danchenko M, Kuiken T, Sekeyová Z, Freemont PS. Synthetic Biology and the United Nations. Trends Biotechnol 2019; 37:1146-1151. [PMID: 31257057 DOI: 10.1016/j.tibtech.2019.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/29/2019] [Accepted: 05/31/2019] [Indexed: 11/18/2022]
Abstract
Synthetic biology is a rapidly emerging interdisciplinary field of science and engineering that aims to redesign living systems through reprogramming genetic information. The field has catalysed global debate among policymakers and publics. Here we describe how synthetic biology relates to these international deliberations, particularly the Convention on Biological Diversity (CBD).
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Affiliation(s)
- Hung-En Lai
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK; Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK
| | - Caoimhe Canavan
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK; Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK
| | - Loren Cameron
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK; Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK
| | - Simon Moore
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK; Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK
| | - Monika Danchenko
- Institute of Virology, Biomedical Research Centre, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovak Republic
| | - Todd Kuiken
- Genetic Engineering and Society Center, North Carolina State University, Raleigh, NC 27695-7565, USA.
| | - Zuzana Sekeyová
- Institute of Virology, Biomedical Research Centre, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovak Republic.
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK; Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK.
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Two-By-One model of cytoplasmic incompatibility: Synthetic recapitulation by transgenic expression of cifA and cifB in Drosophila. PLoS Genet 2019; 15:e1008221. [PMID: 31242186 PMCID: PMC6594578 DOI: 10.1371/journal.pgen.1008221] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/30/2019] [Indexed: 01/22/2023] Open
Abstract
Wolbachia are maternally inherited bacteria that infect arthropod species worldwide and are deployed in vector control to curb arboviral spread using cytoplasmic incompatibility (CI). CI kills embryos when an infected male mates with an uninfected female, but the lethality is rescued if the female and her embryos are likewise infected. Two phage WO genes, cifAwMel and cifBwMel from the wMel Wolbachia deployed in vector control, transgenically recapitulate variably penetrant CI, and one of the same genes, cifAwMel, rescues wild type CI. The proposed Two-by-One genetic model predicts that CI and rescue can be recapitulated by transgenic expression alone and that dual cifAwMeland cifBwMel expression can recapitulate strong CI. Here, we use hatch rate and gene expression analyses in transgenic Drosophila melanogaster to demonstrate that CI and rescue can be synthetically recapitulated in full, and strong, transgenic CI comparable to wild type CI is achievable. These data explicitly validate the Two-by-One model in wMel-infected D. melanogaster, establish a robust system for transgenic studies of CI in a model system, and represent the first case of completely engineering male and female animal reproduction to depend upon bacteriophage gene products. Releases of Wolbachia-infected mosquitos are underway worldwide because Wolbachia block replication of Zika and Dengue viruses and spread themselves maternally through arthropod populations via cytoplasmic incompatibility (CI). The CI drive system depends on a Wolbachia-induced sperm modification that results in embryonic lethality when an infected male mates with an uninfected female, but this lethality is rescued when the female and her embryos are likewise infected. We recently reported that the phage WO genes, cifA and cifB, cause the sperm modification and cifA rescues the embryonic lethality caused by the wMel Wolbachia strain deployed in vector control. These reports motivated proposal of the Two-by-One model of CI whereby two genes cause lethality and one gene rescues it. Here we provide unequivocal support for the model in the Wolbachia strain used in vector control via synthetic methods that recapitulate CI and rescue in the absence of a Wolbachia infections. Our results reveal the set of phage WO genes responsible for this powerful genetic drive system, act as a proof-of-concept that these genes alone can induce gene drive like crossing patterns, and establish methodologies and hypotheses for future studies of CI in Drosophila. We discuss the implications of the Two-by-One model towards functional mechanisms of CI, the emergence of incompatibility between Wolbachia strains, vector control applications, and CI gene nomenclature.
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Bull JJ, Remien CH, Krone SM. Gene-drive-mediated extinction is thwarted by population structure and evolution of sib mating. EVOLUTION MEDICINE AND PUBLIC HEALTH 2019; 2019:66-81. [PMID: 31191905 PMCID: PMC6556056 DOI: 10.1093/emph/eoz014] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/18/2019] [Indexed: 11/12/2022]
Abstract
Background and objectives Genetic engineering combined with CRISPR technology has developed to the point that gene drives can, in theory, be engineered to cause extinction in countless species. Success of extinction programs now rests on the possibility of resistance evolution, which is largely unknown. Depending on the gene-drive technology, resistance may take many forms, from mutations in the nuclease target sequence (e.g. for CRISPR) to specific types of non-random population structures that limit the drive (that may block potentially any gene-drive technology). Methodology We develop mathematical models of various deviations from random mating to consider escapes from extinction-causing gene drives. A main emphasis here is sib mating in the face of recessive-lethal and Y-chromosome drives. Results Sib mating easily evolves in response to both kinds of gene drives and maintains mean fitness above 0, with equilibrium fitness depending on the level of inbreeding depression. Environmental determination of sib mating (as might stem from population density crashes) can also maintain mean fitness above 0. A version of Maynard Smith’s haystack model shows that pre-existing population structure can enable drive-free subpopulations to be maintained against gene drives. Conclusions and implications Translation of mean fitness into population size depends on ecological details, so understanding mean fitness evolution and dynamics is merely the first step in predicting extinction. Nonetheless, these results point to possible escapes from gene-drive-mediated extinctions that lie beyond the control of genome engineering. Lay summary Recent gene drive technologies promise to suppress and even eradicate pests and disease vectors. Simple models of gene-drive evolution in structured populations show that extinction-causing gene drives can be thwarted both through the evolution of sib mating as well as from purely demographic processes that cluster drive-free individuals.
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Affiliation(s)
- James J Bull
- Department of Integrative Biology, University of Texas, Austin, TX, USA
| | | | - Stephen M Krone
- Department of Mathematics, University of Idaho, Moscow, ID, USA
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Frieß JL, von Gleich A, Giese B. Gene drives as a new quality in GMO releases-a comparative technology characterization. PeerJ 2019; 7:e6793. [PMID: 31110918 PMCID: PMC6501761 DOI: 10.7717/peerj.6793] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/15/2019] [Indexed: 01/10/2023] Open
Abstract
Compared to previous releases of genetically modified organisms (GMOs) which were primarily plants, gene drives represent a paradigm shift in the handling of GMOs: Current regulation of the release of GMOs assumes that for specific periods of time a certain amount of GMOs will be released in a particular region. However, now a type of genetic technology arises whose innermost principle lies in exceeding these limits-the transformation or even eradication of wild populations. The invasive character of gene drives demands a thorough analysis of their functionalities, reliability and potential impact. But such investigations are hindered by the fact that an experimental field test would hardly be reversible. Therefore, an appropriate prospective assessment is of utmost importance for an estimation of the risk potential associated with the application of gene drives. This work is meant to support the inevitable characterization of gene drives by a comparative approach of prospective technology assessment with a focus on potential sources of risk. Therein, the hazard and exposure potential as well as uncertainties with regard to the performance of synthetic gene drives are addressed. Moreover, a quantitative analysis of their invasiveness should enable a differentiated evaluation of their power to transform wild populations.
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Affiliation(s)
- Johannes L. Frieß
- Institute for Safety/Security and Risk Sciences, University of Natural Resources and Life Sciences, Vienna (BOKU), Austria
| | - Arnim von Gleich
- Department of Technology Design and Development, Faculty of Production Engineering, University of Bremen, Germany
| | - Bernd Giese
- Institute for Safety/Security and Risk Sciences, University of Natural Resources and Life Sciences, Vienna (BOKU), Austria
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56
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Cerdá M, Keyes KM. Systems Modeling to Advance the Promise of Data Science in Epidemiology. Am J Epidemiol 2019; 188:862-865. [PMID: 30877289 DOI: 10.1093/aje/kwy262] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/13/2018] [Accepted: 11/14/2018] [Indexed: 12/18/2022] Open
Abstract
Systems science models use computer-based algorithms to model dynamic interactions between study units within and across levels and are characterized by nonlinear and feedback processes. They are particularly valuable approaches that complement the traditional epidemiologic toolbox in cases in which real data are not available and in cases in which traditional epidemiologic methods are limited by issues such as interference, spatial dependence, and dynamic feedback processes. In this commentary, we propose 2 key contributions that systems models can make to epidemiology: 1) the ability to test assumptions about underlying mechanisms that give rise to population distributions of disease; and 2) help in identifying the types of interventions that have the greatest potential to reduce population rates of disease in the future or in new sites where they have not yet been implemented. We discuss central challenges in the application of systems science approaches in epidemiology, propose potential solutions, and predict future developments in the role that systems science can play in epidemiology.
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Affiliation(s)
- Magdalena Cerdá
- Department of Population Health, New York University School of Medicine, New York, New York
| | - Katherine M Keyes
- Department of Epidemiology, Columbia University Mailman School of Public Health, New York, New York
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57
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Noble C, Min J, Olejarz J, Buchthal J, Chavez A, Smidler AL, DeBenedictis EA, Church GM, Nowak MA, Esvelt KM. Daisy-chain gene drives for the alteration of local populations. Proc Natl Acad Sci U S A 2019; 116:8275-8282. [PMID: 30940750 PMCID: PMC6486765 DOI: 10.1073/pnas.1716358116] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
If they are able to spread in wild populations, CRISPR-based gene-drive elements would provide new ways to address ecological problems by altering the traits of wild organisms, but the potential for uncontrolled spread tremendously complicates ethical development and use. Here, we detail a self-exhausting form of CRISPR-based drive system comprising genetic elements arranged in a daisy chain such that each drives the next. "Daisy-drive" systems can locally duplicate any effect achievable by using an equivalent self-propagating drive system, but their capacity to spread is limited by the successive loss of nondriving elements from one end of the chain. Releasing daisy-drive organisms constituting a small fraction of the local wild population can drive a useful genetic element nearly to local fixation for a wide range of fitness parameters without self-propagating spread. We additionally report numerous highly active guide RNA sequences sharing minimal homology that may enable evolutionarily stable daisy drive as well as self-propagating CRISPR-based gene drive. Especially when combined with threshold dependence, daisy drives could simplify decision-making and promote ethical use by enabling local communities to decide whether, when, and how to alter local ecosystems.
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Affiliation(s)
- Charleston Noble
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - John Min
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
| | - Jason Olejarz
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138
| | - Joanna Buchthal
- Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
| | - Alejandro Chavez
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114
| | - Andrea L Smidler
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115
| | | | - George M Church
- Department of Genetics, Harvard Medical School, Boston, MA 02115;
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
| | - Martin A Nowak
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138
- Department of Mathematics, Harvard University, Cambridge, MA 02138
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | - Kevin M Esvelt
- Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139;
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58
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Oberhofer G, Ivy T, Hay BA. Cleave and Rescue, a novel selfish genetic element and general strategy for gene drive. Proc Natl Acad Sci U S A 2019; 116:6250-6259. [PMID: 30760597 PMCID: PMC6442612 DOI: 10.1073/pnas.1816928116] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
There is great interest in being able to spread beneficial traits throughout wild populations in ways that are self-sustaining. Here, we describe a chromosomal selfish genetic element, CleaveR [Cleave and Rescue (ClvR)], able to achieve this goal. ClvR comprises two linked chromosomal components. One, germline-expressed Cas9 and guide RNAs (gRNAs)-the Cleaver-cleaves and thereby disrupts endogenous copies of a gene whose product is essential. The other, a recoded version of the essential gene resistant to cleavage and gene conversion with cleaved copies-the Rescue-provides essential gene function. ClvR enhances its transmission, and that of linked genes, by creating conditions in which progeny lacking ClvR die because they have no functional copies of the essential gene. In contrast, those who inherit ClvR survive, resulting in an increase in ClvR frequency. ClvR is predicted to spread to fixation under diverse conditions. To test these predictions, we generated a ClvR element in Drosophila melanogasterClvRtko is located on chromosome 3 and uses Cas9 and four gRNAs to disrupt melanogaster technical knockout (tko), an X-linked essential gene. Rescue activity is provided by tko from Drosophila virilisClvRtko results in germline and maternal carryover-dependent inactivation of melanogaster tko (>99% per generation); lethality caused by this loss is rescued by the virilis transgene; ClvRtko activities are robust to genetic diversity in strains from five continents; and uncleavable but functional melanogaster tko alleles were not observed. Finally, ClvRtko spreads to transgene fixation. The simplicity of ClvR suggests it may be useful for altering populations in diverse species.
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Affiliation(s)
- Georg Oberhofer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Tobin Ivy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Bruce A Hay
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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Prowse TA, Adikusuma F, Cassey P, Thomas P, Ross JV. A Y-chromosome shredding gene drive for controlling pest vertebrate populations. eLife 2019; 8:41873. [PMID: 30767891 PMCID: PMC6398975 DOI: 10.7554/elife.41873] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/13/2019] [Indexed: 11/16/2022] Open
Abstract
Self-replicating gene drives that modify sex ratios or infer a fitness cost could be used to control populations of invasive alien species. The targeted deletion of Y sex chromosomes using CRISPR technology offers a new approach for sex bias that could be incorporated within gene-drive designs. We introduce a novel gene-drive strategy termed Y-CHromosome deletion using Orthogonal Programmable Endonucleases (Y-CHOPE), incorporating a programmable endonuclease that ‘shreds’ the Y chromosome, thereby converting XY males into fertile XO females. Firstly, we demonstrate that the CRISPR/Cas12a system can eliminate the Y chromosome in embryonic stem cells with high efficiency (c. 90%). Next, using stochastic, individual-based models of a pest mouse population, we show that a Y-shredding drive that progressively depletes the pool of XY males could effect population eradication through mate limitation. Our molecular and modeling data suggest that a Y-CHOPE gene drive could be a viable tool for vertebrate pest control.
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Affiliation(s)
- Thomas Aa Prowse
- School of Mathematical Sciences, The University of Adelaide, Adelaide, Australia
| | - Fatwa Adikusuma
- School of Medicine, The University of Adelaide, Adelaide, Australia.,South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Phillip Cassey
- The Centre for Applied Conservation Science, The University of Adelaide, Adelaide, Australia.,School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Paul Thomas
- School of Medicine, The University of Adelaide, Adelaide, Australia.,South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Joshua V Ross
- School of Mathematical Sciences, The University of Adelaide, Adelaide, Australia
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60
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Promises and perils of gene drives: Navigating the communication of complex, post-normal science. Proc Natl Acad Sci U S A 2019; 116:7692-7697. [PMID: 30642954 DOI: 10.1073/pnas.1805874115] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
In November of 2017, an interdisciplinary panel discussed the complexities of gene drive applications as part of the third Sackler Colloquium on "The Science of Science Communication." The panel brought together a social scientist, life scientist, and journalist to discuss the issue from each of their unique perspectives. This paper builds on the ideas and conversations from the session to provide a more nuanced discussion about the context surrounding responsible communication and decision-making for cases of post-normal science. Deciding to use gene drives to control and suppress pests will involve more than a technical assessment of the risks involved, and responsible decision-making regarding their use will require concerted efforts from multiple actors. We provide a review of gene drives and their potential applications, as well as the role of journalists in communicating the extent of uncertainties around specific projects. We also discuss the roles of public opinion and online environments in public engagement with scientific processes. We conclude with specific recommendations about how to address current challenges and foster more effective communication and decision-making for complex, post-normal issues, such as gene drives.
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61
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Kandul NP, Liu J, Sanchez C HM, Wu SL, Marshall JM, Akbari OS. Transforming insect population control with precision guided sterile males with demonstration in flies. Nat Commun 2019; 10:84. [PMID: 30622266 PMCID: PMC6325135 DOI: 10.1038/s41467-018-07964-7] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 12/05/2018] [Indexed: 01/03/2023] Open
Abstract
The sterile insect technique (SIT) is an environmentally safe and proven technology to suppress wild populations. To further advance its utility, a novel CRISPR-based technology termed precision guided SIT (pgSIT) is described. PgSIT mechanistically relies on a dominant genetic technology that enables simultaneous sexing and sterilization, facilitating the release of eggs into the environment ensuring only sterile adult males emerge. Importantly, for field applications, the release of eggs will eliminate burdens of manually sexing and sterilizing males, thereby reducing overall effort and increasing scalability. Here, to demonstrate efficacy, we systematically engineer multiple pgSIT systems in Drosophila which consistently give rise to 100% sterile males. Importantly, we demonstrate that pgSIT-generated sterile males are fit and competitive. Using mathematical models, we predict pgSIT will induce substantially greater population suppression than can be achieved by currently-available self-limiting suppression technologies. Taken together, pgSIT offers to potentially transform our ability to control insect agricultural pests and disease vectors.
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Affiliation(s)
- Nikolay P Kandul
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, California, USA
| | - Junru Liu
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, California, USA
| | - Hector M Sanchez C
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA 94720, California, USA
| | - Sean L Wu
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA 94720, California, USA
| | - John M Marshall
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA 94720, California, USA
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, California, USA.
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, California, USA.
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62
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Abstract
Background Aedes aegypti is an important mosquito vector that transmits arboviruses that cause devastating diseases including Zika, dengue fever, yellow fever and chikungunya. Improved understanding of gene regulation in the early development of Ae. aegypti will facilitate genetic studies and help the development of novel control strategies of this important disease vector. Results In this study, we demonstrated through transgenic assays that the promoter of an endogenous early zygotic gene KLC2 could drive gene expression in the syncytial blastoderm and early cellular blastoderm, which is a stage that the developing germline and the rest of embryo are accessible to genetic manipulation. An unexpected expression of the reporter gene in transgenic male testes was also observed. Further analysis confirmed the expression of the endogenous KLC2 in the testes, which was not detected in the previous RNA sequencing data. Conclusions Our finding provided a new promoter element that can be used in future genetic studies and applications in Ae. aegypti. Moreover, our transgenic reporter assays showed that cautions are needed when interpreting RNA sequencing data as transient or tissue-specific transcription may go undetected by RNAseq. Electronic supplementary material The online version of this article (10.1186/s13071-018-3210-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wanqi Hu
- Department of Biochemistry, Virginia Tech, 303 Fralin, Blacksburg, VA, 24061, USA.,Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Zhijian Jake Tu
- Department of Biochemistry, Virginia Tech, 303 Fralin, Blacksburg, VA, 24061, USA. .,Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, 24061, USA.
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63
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Leftwich PT, Edgington MP, Harvey-Samuel T, Carabajal Paladino LZ, Norman VC, Alphey L. Recent advances in threshold-dependent gene drives for mosquitoes. Biochem Soc Trans 2018; 46:1203-1212. [PMID: 30190331 PMCID: PMC6195636 DOI: 10.1042/bst20180076] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 01/09/2023]
Abstract
Mosquito-borne diseases, such as malaria, dengue and chikungunya, cause morbidity and mortality around the world. Recent advances in gene drives have produced control methods that could theoretically modify all populations of a disease vector, from a single release, making whole species less able to transmit pathogens. This ability has caused both excitement, at the prospect of global eradication of mosquito-borne diseases, and concern around safeguards. Drive mechanisms that require individuals to be released at high frequency before genes will spread can therefore be desirable as they are potentially localised and reversible. These include underdominance-based strategies and use of the reproductive parasite Wolbachia Here, we review recent advances in practical applications and mathematical analyses of these threshold-dependent gene drives with a focus on implementation in Aedes aegypti, highlighting their mechanisms and the role of fitness costs on introduction frequencies. Drawing on the parallels between these systems offers useful insights into practical, controlled application of localised drives, and allows us to assess the requirements needed for gene drive reversal.
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Affiliation(s)
| | | | | | | | | | - Luke Alphey
- The Pirbright Institute, Pirbright, Woking, Surrey, U.K.
- Department of Zoology, University of Oxford, Oxford, U.K
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64
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Waters AJ, Capriotti P, Gaboriau DCA, Papathanos PA, Windbichler N. Rationally-engineered reproductive barriers using CRISPR & CRISPRa: an evaluation of the synthetic species concept in Drosophila melanogaster. Sci Rep 2018; 8:13125. [PMID: 30177778 PMCID: PMC6120925 DOI: 10.1038/s41598-018-31433-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/17/2018] [Indexed: 01/28/2023] Open
Abstract
The ability to erect rationally-engineered reproductive barriers in animal or plant species promises to enable a number of biotechnological applications such as the creation of genetic firewalls, the containment of gene drives or novel population replacement and suppression strategies for genetic control. However, to date no experimental data exist that explores this concept in a multicellular organism. Here we examine the requirements for building artificial reproductive barriers in the metazoan model Drosophila melanogaster by combining CRISPR-based genome editing and transcriptional transactivation (CRISPRa) of the same loci. We directed 13 single guide RNAs (sgRNAs) to the promoters of 7 evolutionary conserved genes and used 11 drivers to conduct a misactivation screen. We identify dominant-lethal activators of the eve locus and find that they disrupt development by strongly activating eve outside its native spatio-temporal context. We employ the same set of sgRNAs to isolate, by genome editing, protective INDELs that render these loci resistant to transactivation without interfering with target gene function. When these sets of genetic components are combined we find that complete synthetic lethality, a prerequisite for most applications, is achievable using this approach. However, our results suggest a steep trade-off between the level and scope of dCas9 expression, the degree of genetic isolation achievable and the resulting impact on fly fitness. The genetic engineering strategy we present here allows the creation of single or multiple reproductive barriers and could be applied to other multicellular organisms such as disease vectors or transgenic organisms of economic importance.
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Affiliation(s)
- Andrew J Waters
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Paolo Capriotti
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - David C A Gaboriau
- Facility for Imaging by Light Microscopy, NHLI, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Philippos Aris Papathanos
- Section of Genomics and Genetics, Department of Experimental Medicine, University of Perugia, 06132, Perugia, Italy
| | - Nikolai Windbichler
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington, London, SW7 2AZ, UK.
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65
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Gantz VM, Akbari OS. Gene editing technologies and applications for insects. CURRENT OPINION IN INSECT SCIENCE 2018; 28:66-72. [PMID: 30551769 PMCID: PMC6296244 DOI: 10.1016/j.cois.2018.05.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 05/09/2023]
Abstract
Initially discovered in bacteria, CRISPR-based genome editing endonucleases have proven remarkably amenable for adaptation to insects. To date, these endonucleases have been utilized in a plethora of both model and non-model insects including diverse flies, bees, beetles, butterflies, moths, and grasshoppers, to name a few, thereby revolutionizing functional genomics of insects. In addition to basic genome editing, they have also been invaluable for advanced genome engineering and synthetic biology applications. Here we explore the recent genome editing advancements in insects for generating site-specific genomic mutations, insertions, deletions, as well as more advanced applications such as Homology Assisted Genome Knock-in (HACK), potential to utilize DNA base editing, generating predictable reciprocal chromosomal translocations, and development gene drives to control the fate of wild populations.
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Affiliation(s)
- Valentino M Gantz
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92092, USA; Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92092, USA; Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA.
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66
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Burt A, Deredec A. Self-limiting population genetic control with sex-linked genome editors. Proc Biol Sci 2018; 285:rspb.2018.0776. [PMID: 30051868 PMCID: PMC6083257 DOI: 10.1098/rspb.2018.0776] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/28/2018] [Indexed: 12/30/2022] Open
Abstract
In male heterogametic species the Y chromosome is transmitted solely from fathers to sons, and is selected for based only on its impacts on male fitness. This fact can be exploited to develop efficient pest control strategies that use Y-linked editors to disrupt the fitness of female descendants. With simple population genetic and dynamic models we show that Y-linked editors can be substantially more efficient than other self-limiting strategies and, while not as efficient as gene drive approaches, are expected to have less impact on non-target populations with which there is some gene flow. Efficiency can be further augmented by simultaneously releasing an autosomal X-shredder construct, in either the same or different males. Y-linked editors may be an attractive option to consider when efficient control of a species is desired in some locales but not others.
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Affiliation(s)
- Austin Burt
- Life Sciences, Imperial College, Silwood Park, Ascot SL5 7PY, UK
| | - Anne Deredec
- UMR BIOGER, INRA AgroParisTech, Université Paris-Saclay, Avenue Lucien Bretignières, 78850 Thiverval-Grignon, France
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67
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Khamis D, El Mouden C, Kura K, Bonsall MB. Ecological effects on underdominance threshold drives for vector control. J Theor Biol 2018; 456:1-15. [PMID: 30040965 DOI: 10.1016/j.jtbi.2018.07.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 01/05/2023]
Abstract
Underdominance gene drives are frequency-dependent drives that aim to spread a desired homozygote genotype within a population. When the desired homozygote is released above a threshold frequency, heterozygote fitness disadvantage acts to drive the desired trait to fixation. Underdominance drives have been proposed as a way to control vector-borne disease through population suppression and replacement in a spatially contained and reversible way-benefits that directly address potential safety concerns with gene drives. Here, ecological and epidemiological dynamics are coupled to a model of mosquito genetics to investigate theoretically the impact of different types of underdominance gene drive on disease prevalence. We model systems with two engineered alleles carried either on the same pair of chromosomes at the same locus or homozygously on different pairs at different loci, genetic lethality that affects both sexes or only females, and bi-sex or male-only releases. Further, the different genetic and ecological fitness costs that can arise from genetic modification and artificial rearing are investigated through their effect on the population threshold frequency that is required to trigger the drive mechanism. We show that male-only releases must be significantly larger than bi-sex releases to trigger the underdominance drive. In addition, we find that female-specific lethality averts a higher percentage of disease cases over a control period than does bi-sex lethality. Decreases in the genetic fitness of the engineered homozygotes can increase the underdominance threshold substantially, but we find that the mating success of transgenic mosquitoes with wild-type females (influenced by a lack of competitiveness or the evolution of behavioural resistance in the form of active female mate preference) and the longevity of artificially-reared mosquitoes are vitally important to the success chances of underdominance based gene drive control efforts.
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Affiliation(s)
- Doran Khamis
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Claire El Mouden
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Klodeta Kura
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Michael B Bonsall
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
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68
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Turner G, Beech C, Roda L. Means and ends of effective global risk assessments for genetic pest management. BMC Proc 2018; 12:13. [PMID: 30079104 PMCID: PMC6069755 DOI: 10.1186/s12919-018-0112-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The development and use of genetic technologies is regulated by countries according to their national laws and governance structures. Legal frameworks require comprehensive technical evidence to be submitted by an applicant on the biology of the organism, its safety to human, animal health and the environment in which it will be released. Some countries also require information on socio-economic and trade impacts. One of the key elements that assists decision-making under those legal frameworks is the use of risk assessments. The risk assessment paradigm of problem formulation based on risk hypothesis, and the assessment of plausible scientific pathways leading to potential environmental and human harms being realised, has been used widely to assess potential risks of genetic technologies to human health and the environment, from crops to mosquitoes. This paper uses the case study of a genetically modified self-limiting olive fly (Bactrocera oleae) for a first deliberate release in Spain to examine the regulatory processes and stakeholders involved in the assessment of risk. It is anticipated that existing risk assessment frameworks are equally applicable to gene drive technologies that may spread and persist in the environment and cross-national borders, but it is the governance structures surrounding the involvement of civil society in regulatory processes that must be administered in a more transparent and defined manner.
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Affiliation(s)
- Geoff Turner
- 1Imperial College London, Silwood Park, Ascot, UK.,2Formerly Oxitec Ltd, Milton Park, Abingdon, UK
| | - Camilla Beech
- 2Formerly Oxitec Ltd, Milton Park, Abingdon, UK.,Cambea Consulting Ltd, 10 Beech Court, Hurst, Wokingham, UK
| | - Lucia Roda
- 4Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
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69
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Goold HD, Wright P, Hailstones D. Emerging Opportunities for Synthetic Biology in Agriculture. Genes (Basel) 2018; 9:E341. [PMID: 29986428 PMCID: PMC6071285 DOI: 10.3390/genes9070341] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 06/27/2018] [Accepted: 07/03/2018] [Indexed: 12/11/2022] Open
Abstract
Rapid expansion in the emerging field of synthetic biology has to date mainly focused on the microbial sciences and human health. However, the zeitgeist is that synthetic biology will also shortly deliver major outcomes for agriculture. The primary industries of agriculture, fisheries and forestry, face significant and global challenges; addressing them will be assisted by the sector’s strong history of early adoption of transformative innovation, such as the genetic technologies that underlie synthetic biology. The implementation of synthetic biology within agriculture may, however, be hampered given the industry is dominated by higher plants and mammals, where large and often polyploid genomes and the lack of adequate tools challenge the ability to deliver outcomes in the short term. However, synthetic biology is a rapidly growing field, new techniques in genome design and synthesis, and more efficient molecular tools such as CRISPR/Cas9 may harbor opportunities more broadly than the development of new cultivars and breeds. In particular, the ability to use synthetic biology to engineer biosensors, synthetic speciation, microbial metabolic engineering, mammalian multiplexed CRISPR, novel anti microbials, and projects such as Yeast 2.0 all have significant potential to deliver transformative changes to agriculture in the short, medium and longer term. Specifically, synthetic biology promises to deliver benefits that increase productivity and sustainability across primary industries, underpinning the industry’s prosperity in the face of global challenges.
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Affiliation(s)
- Hugh Douglas Goold
- Department of Molecular Sciences, Macquarie University, North Ryde, NSW 2109, Australia.
- New South Wales Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia.
| | - Philip Wright
- New South Wales Department of Primary Industries, Locked Bag 21, 161 Kite St, Orange, NSW 2800, Australia.
| | - Deborah Hailstones
- New South Wales Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia.
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70
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Dhole S, Vella MR, Lloyd AL, Gould F. Invasion and migration of spatially self-limiting gene drives: A comparative analysis. Evol Appl 2018; 11:794-808. [PMID: 29875820 PMCID: PMC5978947 DOI: 10.1111/eva.12583] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/27/2017] [Indexed: 12/14/2022] Open
Abstract
Recent advances in research on gene drives have produced genetic constructs that could theoretically spread a desired gene (payload) into all populations of a species, with a single release in one place. This attribute has advantages, but also comes with risks and ethical concerns. There has been a call for research on gene drive systems that are spatially and/or temporally self-limiting. Here, we use a population genetics model to compare the expected characteristics of three spatially self-limiting gene drive systems: one-locus underdominance, two-locus underdominance and daisy-chain drives. We find large differences between these gene drives in the minimum release size required for successfully driving a payload into a population. The daisy-chain system is the most efficient, requiring the smallest release, followed by the two-locus underdominance system, and then the one-locus underdominance system. However, when the target population exchanges migrants with a nontarget population, the gene drives requiring smaller releases suffer from higher risks of unintended spread. For payloads that incur relatively low fitness costs (up to 30%), a simple daisy-chain drive is practically incapable of remaining localized, even with migration rates as low as 0.5% per generation. The two-locus underdominance system can achieve localized spread under a broader range of migration rates and of payload fitness costs, while the one-locus underdominance system largely remains localized. We also find differences in the extent of population alteration and in the permanence of the alteration achieved by the three gene drives. The two-locus underdominance system does not always spread the payload to fixation, even after successful drive, while the daisy-chain system can, for a small set of parameter values, achieve a temporally limited spread of the payload. These differences could affect the suitability of each gene drive for specific applications.
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Affiliation(s)
- Sumit Dhole
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
| | - Michael R. Vella
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNCUSA
- Biomathematics Graduate ProgramDepartment of MathematicsNorth Carolina State UniversityRaleighNCUSA
| | - Alun L. Lloyd
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNCUSA
- Biomathematics Graduate ProgramDepartment of MathematicsNorth Carolina State UniversityRaleighNCUSA
| | - Fred Gould
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNCUSA
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71
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Buchman AB, Ivy T, Marshall JM, Akbari OS, Hay BA. Engineered Reciprocal Chromosome Translocations Drive High Threshold, Reversible Population Replacement in Drosophila. ACS Synth Biol 2018. [PMID: 29608276 DOI: 10.1101/088393] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Replacement of wild insect populations with transgene-bearing individuals unable to transmit disease or survive under specific environmental conditions using gene drive provides a self-perpetuating method of disease prevention. Mechanisms that require the gene drive element and linked cargo to exceed a high threshold frequency in order for spread to occur are attractive because they offer several points of control: they bring about local, but not global population replacement; and transgenes can be eliminated by reintroducing wildtypes into the population so as to drive the frequency of transgenes below the threshold frequency required for drive. Reciprocal chromosome translocations were proposed as a tool for bringing about high threshold population replacement in 1940 and 1968. However, translocations able to achieve this goal have only been reported once, in the spider mite Tetranychus urticae, a haplo-diploid species in which there is strong selection in haploid males for fit homozygotes. We report the creation of engineered translocation-bearing strains of Drosophila melanogaster, generated through targeted chromosomal breakage and homologous recombination. These strains drive high threshold population replacement in laboratory populations. While it remains to be shown that engineered translocations can bring about population replacement in wild populations, these observations suggest that further exploration of engineered translocations as a tool for controlled population replacement is warranted.
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Affiliation(s)
- Anna B Buchman
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Tobin Ivy
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - John M Marshall
- School of Public Health , University of California , Berkeley , California 94720 , United States
| | - Omar S Akbari
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Bruce A Hay
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
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72
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Buchman AB, Ivy T, Marshall JM, Akbari OS, Hay BA. Engineered Reciprocal Chromosome Translocations Drive High Threshold, Reversible Population Replacement in Drosophila. ACS Synth Biol 2018; 7:1359-1370. [PMID: 29608276 DOI: 10.1021/acssynbio.7b00451] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Replacement of wild insect populations with transgene-bearing individuals unable to transmit disease or survive under specific environmental conditions using gene drive provides a self-perpetuating method of disease prevention. Mechanisms that require the gene drive element and linked cargo to exceed a high threshold frequency in order for spread to occur are attractive because they offer several points of control: they bring about local, but not global population replacement; and transgenes can be eliminated by reintroducing wildtypes into the population so as to drive the frequency of transgenes below the threshold frequency required for drive. Reciprocal chromosome translocations were proposed as a tool for bringing about high threshold population replacement in 1940 and 1968. However, translocations able to achieve this goal have only been reported once, in the spider mite Tetranychus urticae, a haplo-diploid species in which there is strong selection in haploid males for fit homozygotes. We report the creation of engineered translocation-bearing strains of Drosophila melanogaster, generated through targeted chromosomal breakage and homologous recombination. These strains drive high threshold population replacement in laboratory populations. While it remains to be shown that engineered translocations can bring about population replacement in wild populations, these observations suggest that further exploration of engineered translocations as a tool for controlled population replacement is warranted.
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Affiliation(s)
- Anna B Buchman
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Tobin Ivy
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - John M Marshall
- School of Public Health , University of California , Berkeley , California 94720 , United States
| | - Omar S Akbari
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Bruce A Hay
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
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73
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Buchman A, Marshall JM, Ostrovski D, Yang T, Akbari OS. Synthetically engineered Medea gene drive system in the worldwide crop pest Drosophila suzukii. Proc Natl Acad Sci U S A 2018. [PMID: 29666236 DOI: 10.1101/162255] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
Synthetic gene drive systems possess enormous potential to replace, alter, or suppress wild populations of significant disease vectors and crop pests; however, their utility in diverse populations remains to be demonstrated. Here, we report the creation of a synthetic Medea gene drive system in a major worldwide crop pest, Drosophila suzukii We demonstrate that this drive system, based on an engineered maternal "toxin" coupled with a linked embryonic "antidote," is capable of biasing Mendelian inheritance rates with up to 100% efficiency. However, we find that drive resistance, resulting from naturally occurring genetic variation and associated fitness costs, can be selected for and hinder the spread of such a drive. Despite this, our results suggest that this gene drive could maintain itself at high frequencies in a wild population and spread to fixation if either its fitness costs or toxin resistance were reduced, providing a clear path forward for developing future such systems in this pest.
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Affiliation(s)
- Anna Buchman
- Department of Entomology, University of California, Riverside, CA 92521
- Center for Infectious Disease and Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093
| | - John M Marshall
- Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA 94720
| | - Dennis Ostrovski
- Department of Entomology, University of California, Riverside, CA 92521
- Center for Infectious Disease and Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
| | - Ting Yang
- Department of Entomology, University of California, Riverside, CA 92521
- Center for Infectious Disease and Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093
| | - Omar S Akbari
- Department of Entomology, University of California, Riverside, CA 92521;
- Center for Infectious Disease and Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093
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74
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Synthetically engineered Medea gene drive system in the worldwide crop pest Drosophila suzukii. Proc Natl Acad Sci U S A 2018; 115:4725-4730. [PMID: 29666236 PMCID: PMC5939061 DOI: 10.1073/pnas.1713139115] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here we describe a fully functional gene drive system constructed in a major worldwide crop pest, Drosophila suzukii. This system is composed of a synthetic Medea drive with a maternal miRNA “toxin” and a zygotic “antidote,” and we demonstrate that it can bias inheritance with 100% efficiency and can persist in a population given high release frequencies. We discuss how such a system may be used to suppress D. suzukii populations or render them harmless to target crops. Synthetic gene drive systems possess enormous potential to replace, alter, or suppress wild populations of significant disease vectors and crop pests; however, their utility in diverse populations remains to be demonstrated. Here, we report the creation of a synthetic Medea gene drive system in a major worldwide crop pest, Drosophila suzukii. We demonstrate that this drive system, based on an engineered maternal “toxin” coupled with a linked embryonic “antidote,” is capable of biasing Mendelian inheritance rates with up to 100% efficiency. However, we find that drive resistance, resulting from naturally occurring genetic variation and associated fitness costs, can be selected for and hinder the spread of such a drive. Despite this, our results suggest that this gene drive could maintain itself at high frequencies in a wild population and spread to fixation if either its fitness costs or toxin resistance were reduced, providing a clear path forward for developing future such systems in this pest.
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75
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Marshall JM, Akbari OS. Can CRISPR-Based Gene Drive Be Confined in the Wild? A Question for Molecular and Population Biology. ACS Chem Biol 2018; 13:424-430. [PMID: 29370514 DOI: 10.1021/acschembio.7b00923] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The recent discovery of CRISPR and its application as a gene editing tool has enabled a range of gene drive systems to be engineered with greater ease. In order for the benefits of this technology to be realized, in some circumstances drive systems should be developed that are capable of both spreading into populations to achieve their desired impact and being recalled in the event of unwanted consequences or public disfavor. We review the performance of three broad categories of drive systems at achieving these goals: threshold-dependent drives, homing-based drive and remediation systems, and temporally self-limiting systems such as daisy-chain drives.
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Affiliation(s)
- John M Marshall
- Divisions of Biostatistics and Epidemiology, School of Public Health, University of California , Berkeley, California 94720, United States
| | - Omar S Akbari
- Section of Cell and Developmental Biology, University of California, San Diego , La Jolla, California 92093, United States of America
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76
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Abstract
Drive is a process of accelerated inheritance from one generation to the next that allows some genes to spread rapidly through populations even if they do not contribute to-or indeed even if they detract from-organismal survival and reproduction. Genetic elements that can spread by drive include gametic and zygotic killers, meiotic drivers, homing endonuclease genes, B chromosomes, and transposable elements. The fact that gene drive can lead to the spread of fitness-reducing traits (including lethality and sterility) makes it an attractive process to consider exploiting to control disease vectors and other pests. There are a number of efforts to develop synthetic gene drive systems, particularly focused on the mosquito-borne diseases that continue to plague us.
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Affiliation(s)
- Austin Burt
- Life Sciences, Imperial College, Silwood Park, Ascot, SL5
7PY, United Kingdom
| | - Andrea Crisanti
- Life Sciences, Imperial College, South Kensington, London, SW7 2AZ, United Kingdom
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77
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Novak BJ, Maloney T, Phelan R. Advancing a New Toolkit for Conservation: From Science to Policy. CRISPR J 2018; 1:11-15. [PMID: 31021184 DOI: 10.1089/crispr.2017.0019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Climate change and non-native wildlife diseases are exacerbating persistent challenges to biodiversity such as habitat destruction, invasive species and over-harvesting. With these increasing threats there is a pressing need to expand the conservationists' toolbox. CRISPR-Cas9 genome editing (GE) offers a precise and potentially transformative tool to confront these challenges. Researchers, regulators, conservationists and the public are all needed to engage proactively in the thoughtful and responsible development and application of these new tools.
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Affiliation(s)
- Ben J Novak
- 1 Revive & Restore , Sausalito, California.,2 Department of Anatomy and Developmental Biology, Monash University , Clayton, Australia .,3 Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organization , Newcomb, Australia
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78
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Roy S, Saha TT, Zou Z, Raikhel AS. Regulatory Pathways Controlling Female Insect Reproduction. ANNUAL REVIEW OF ENTOMOLOGY 2018; 63:489-511. [PMID: 29058980 DOI: 10.1146/annurev-ento-020117-043258] [Citation(s) in RCA: 302] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The synthesis of vitellogenin and its uptake by maturing oocytes during egg maturation are essential for successful female reproduction. These events are regulated by the juvenile hormones and ecdysteroids and by the nutritional signaling pathway regulated by neuropeptides. Juvenile hormones act as gonadotropins, regulating vitellogenesis in most insects, but ecdysteroids control this process in Diptera and some Hymenoptera and Lepidoptera. The complex crosstalk between the juvenile hormones, ecdysteroids, and nutritional signaling pathways differs distinctly depending on the reproductive strategies adopted by various insects. Molecular studies within the past decade have revealed much about the relationships among, and the role of, these pathways with respect to regulation of insect reproduction. Here, we review the role of juvenile hormones, ecdysteroids, and nutritional signaling, along with that of microRNAs, in regulating female insect reproduction at the molecular level.
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Affiliation(s)
- Sourav Roy
- Department of Entomology, Institute for Integrative Genome Biology, and Center for Disease Vector Research, University of California, Riverside, California 92521, USA; , ,
| | - Tusar T Saha
- Department of Entomology, Institute for Integrative Genome Biology, and Center for Disease Vector Research, University of California, Riverside, California 92521, USA; , ,
| | - Zhen Zou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China;
| | - Alexander S Raikhel
- Department of Entomology, Institute for Integrative Genome Biology, and Center for Disease Vector Research, University of California, Riverside, California 92521, USA; , ,
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79
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Adelman ZN, Pledger D, Myles KM. Developing standard operating procedures for gene drive research in disease vector mosquitoes. Pathog Glob Health 2017; 111:436-447. [PMID: 29350584 PMCID: PMC6066849 DOI: 10.1080/20477724.2018.1424514] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Numerous arthropod species represent potential targets for gene-drive-based population suppression or replacement, including those that transmit diseases, damage crops, or act as deleterious invasive species. Containment measures for gene drive research in arthropods have been discussed in the literature, but the importance of developing safe and effective standard operating procedures (SOPs) for these types of experiments has not been adequately addressed. Concisely written SOPs link safe work practices, containment measures, institutional training, and research-specific protocols. Here we discuss information to be considered by principal investigators, biosafety officers, and institutional biosafety committees as they work together to develop SOPs for experiments involving gene drive in arthropods, and describe various courses of action that can be used to maintain the effectiveness of SOPs through evaluation and revision. The information provided herein will be especially useful to investigators and regulatory personnel who may lack extensive experience working with arthropods under containment conditions.
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Affiliation(s)
- Zach N. Adelman
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David Pledger
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Kevin M. Myles
- Department of Entomology, Texas A&M University, College Station, TX, USA
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80
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Abstract
The prospect of using genetic methods to target vector, parasite, and reservoir species offers tremendous potential benefits to public health, but the use of genome editing to alter the shared environment will require special attention to public perception and community governance in order to benefit the world. Public skepticism combined with the media scrutiny of gene drive systems could easily derail unpopular projects entirely, especially given the potential for trade barriers to be raised against countries that employ self-propagating gene drives. Hence, open and community-guided development of thoughtfully chosen applications is not only the most ethical approach, but also the most likely to overcome the economic, social, and diplomatic barriers. Here we review current and past attempts to alter ecosystems using biological methods, identify key determinants of social acceptance, and chart a stepwise path for developers towards safe and widely supported use.
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Affiliation(s)
- Devora A. Najjar
- Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Kevin M. Esvelt
- Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
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81
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Abstract
Self-propagating gene drive technologies have a number of desirable characteristics that warrant their development for the control of insect pest and vector populations, such as the malaria-transmitting mosquitoes. Theoretically easy to deploy and self-sustaining, these tools may be used to generate cost-effective interventions that benefit society without obvious bias related to wealth, age or education. Their species-specific design offers the potential to reduce environmental risks and aim to be compatible and complementary with other control strategies, potentially expediting the elimination and eradication of malaria. A number of strategies have been proposed for gene-drive based control of the malaria mosquito and recent demonstrations have shown proof-of-principle in the laboratory. Though several technical, ethical and regulatory challenges remain, none appear insurmountable if research continues in a step-wise and open manner.
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Affiliation(s)
| | - Roberto Galizi
- Department of Life Sciences, Imperial College London, London, UK
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82
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Abstract
Evolution in the form of selective breeding has long been harnessed as a useful tool by humans. However, rapid evolution can also be a danger to our health and a stumbling block for biotechnology. Unwanted evolution can underlie the emergence of drug and pesticide resistance, cancer, and weeds. It makes live vaccines and engineered cells inherently unreliable and unpredictable, and therefore potentially unsafe. Yet, there are strategies that have been and can possibly be used to stop or slow many types of evolution. We review and classify existing population genetics-inspired methods for arresting evolution. Then, we discuss how genome editing techniques enable a radically new set of approaches to limit evolution.
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83
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Edgington MP, Alphey LS. Conditions for success of engineered underdominance gene drive systems. J Theor Biol 2017; 430:128-140. [PMID: 28728996 PMCID: PMC5562440 DOI: 10.1016/j.jtbi.2017.07.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/20/2017] [Accepted: 07/15/2017] [Indexed: 12/02/2022]
Abstract
Engineered underdominance is one of a number of different gene drive strategies that have been proposed for the genetic control of insect vectors of disease. Here we model a two-locus engineered underdominance based gene drive system that is based on the concept of mutually suppressing lethals. In such a system two genetic constructs are introduced, each possessing a lethal element and a suppressor of the lethal at the other locus. Specifically, we formulate and analyse a population genetics model of this system to assess when different combinations of release strategies (i.e. single or multiple releases of both sexes or males only) and genetic systems (i.e. bisex lethal or female-specific lethal elements and different strengths of suppressors) will give population replacement or fail to do so. We anticipate that results presented here will inform the future design of engineered underdominance gene drive systems as well as providing a point of reference regarding release strategies for those looking to test such a system. Our discussion is framed in the context of genetic control of insect vectors of disease. One of several serious threats in this context are Aedes aegypti mosquitoes as they are the primary vectors of dengue viruses. However, results are also applicable to Ae. aegypti as vectors of Zika, yellow fever and chikungunya viruses and also to the control of a number of other insect species and thereby of insect-vectored pathogens.
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Affiliation(s)
| | - Luke S Alphey
- The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK
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84
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Macias VM, Ohm JR, Rasgon JL. Gene Drive for Mosquito Control: Where Did It Come from and Where Are We Headed? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:E1006. [PMID: 28869513 PMCID: PMC5615543 DOI: 10.3390/ijerph14091006] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 02/08/2023]
Abstract
Mosquito-borne pathogens place an enormous burden on human health. The existing toolkit is insufficient to support ongoing vector-control efforts towards meeting disease elimination and eradication goals. The perspective that genetic approaches can potentially add a significant set of tools toward mosquito control is not new, but the recent improvements in site-specific gene editing with CRISPR/Cas9 systems have enhanced our ability to both study mosquito biology using reverse genetics and produce genetics-based tools. Cas9-mediated gene-editing is an efficient and adaptable platform for gene drive strategies, which have advantages over innundative release strategies for introgressing desirable suppression and pathogen-blocking genotypes into wild mosquito populations; until recently, an effective gene drive has been largely out of reach. Many considerations will inform the effective use of new genetic tools, including gene drives. Here we review the lengthy history of genetic advances in mosquito biology and discuss both the impact of efficient site-specific gene editing on vector biology and the resulting potential to deploy new genetic tools for the abatement of mosquito-borne disease.
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Affiliation(s)
- Vanessa M Macias
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Johanna R Ohm
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
| | - Jason L Rasgon
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
- The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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85
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Macias VM, Jimenez AJ, Burini-Kojin B, Pledger D, Jasinskiene N, Phong CH, Chu K, Fazekas A, Martin K, Marinotti O, James AA. nanos-Driven expression of piggyBac transposase induces mobilization of a synthetic autonomous transposon in the malaria vector mosquito, Anopheles stephensi. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 87:81-89. [PMID: 28676355 PMCID: PMC5580807 DOI: 10.1016/j.ibmb.2017.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Transposons are a class of selfish DNA elements that can mobilize within a genome. If mobilization is accompanied by an increase in copy number (replicative transposition), the transposon may sweep through a population until it is fixed in all of its interbreeding members. This introgression has been proposed as the basis for drive systems to move genes with desirable phenotypes into target species. One such application would be to use them to move a gene conferring resistance to malaria parasites throughout a population of vector mosquitos. We assessed the feasibility of using the piggyBac transposon as a gene-drive mechanism to distribute anti-malarial transgenes in populations of the malaria vector, Anopheles stephensi. We designed synthetic gene constructs that express the piggyBac transposase in the female germline using the control DNA of the An. stephensi nanos orthologous gene linked to marker genes to monitor inheritance. Two remobilization events were observed with a frequency of one every 23 generations, a rate far below what would be useful to drive anti-pathogen transgenes into wild mosquito populations. We discuss the possibility of optimizing this system and the impetus to do so.
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Affiliation(s)
- Vanessa M Macias
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Alyssa J Jimenez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Bianca Burini-Kojin
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - David Pledger
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Nijole Jasinskiene
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Celine Hien Phong
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Karen Chu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Aniko Fazekas
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Kelcie Martin
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Osvaldo Marinotti
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Anthony A James
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States; Department of Microbiology and Molecular Genetics, B240 Med Sci Bldg., School of Medicine, University of California, Irvine, CA 92697-4025, United States.
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86
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Noble C, Olejarz J, Esvelt KM, Church GM, Nowak MA. Evolutionary dynamics of CRISPR gene drives. SCIENCE ADVANCES 2017; 3:e1601964. [PMID: 28435878 PMCID: PMC5381957 DOI: 10.1126/sciadv.1601964] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/10/2017] [Indexed: 05/28/2023]
Abstract
The alteration of wild populations has been discussed as a solution to a number of humanity's most pressing ecological and public health concerns. Enabled by the recent revolution in genome editing, clustered regularly interspaced short palindromic repeats (CRISPR) gene drives-selfish genetic elements that can spread through populations even if they confer no advantage to their host organism-are rapidly emerging as the most promising approach. However, before real-world applications are considered, it is imperative to develop a clear understanding of the outcomes of drive release in nature. Toward this aim, we mathematically study the evolutionary dynamics of CRISPR gene drives. We demonstrate that the emergence of drive-resistant alleles presents a major challenge to previously reported constructs, and we show that an alternative design that selects against resistant alleles could greatly improve evolutionary stability. We discuss all results in the context of CRISPR technology and provide insights that inform the engineering of practical gene drive systems.
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Affiliation(s)
- Charleston Noble
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- Department of Genetics, Harvard Medical School, Cambridge, MA 02138, USA
| | - Jason Olejarz
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138, USA
| | - Kevin M. Esvelt
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - George M. Church
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- Department of Genetics, Harvard Medical School, Cambridge, MA 02138, USA
| | - Martin A. Nowak
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138, USA
- Department of Mathematics, Harvard University, Cambridge, MA 02138, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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87
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Unckless RL, Clark AG, Messer PW. Evolution of Resistance Against CRISPR/Cas9 Gene Drive. Genetics 2017; 205:827-841. [PMID: 27941126 PMCID: PMC5289854 DOI: 10.1534/genetics.116.197285] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/01/2016] [Indexed: 11/18/2022] Open
Abstract
CRISPR/Cas9 gene drive (CGD) promises to be a highly adaptable approach for spreading genetically engineered alleles throughout a species, even if those alleles impair reproductive success. CGD has been shown to be effective in laboratory crosses of insects, yet it remains unclear to what extent potential resistance mechanisms will affect the dynamics of this process in large natural populations. Here we develop a comprehensive population genetic framework for modeling CGD dynamics, which incorporates potential resistance mechanisms as well as random genetic drift. Using this framework, we calculate the probability that resistance against CGD evolves from standing genetic variation, de novo mutation of wild-type alleles, or cleavage repair by nonhomologous end joining (NHEJ)-a likely by-product of CGD itself. We show that resistance to standard CGD approaches should evolve almost inevitably in most natural populations, unless repair of CGD-induced cleavage via NHEJ can be effectively suppressed, or resistance costs are on par with those of the driver. The key factor determining the probability that resistance evolves is the overall rate at which resistance alleles arise at the population level by mutation or NHEJ. By contrast, the conversion efficiency of the driver, its fitness cost, and its introduction frequency have only minor impact. Our results shed light on strategies that could facilitate the engineering of drivers with lower resistance potential, and motivate the possibility to embrace resistance as a possible mechanism for controlling a CGD approach. This study highlights the need for careful modeling of the population dynamics of CGD prior to the actual release of a driver construct into the wild.
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Affiliation(s)
- Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853
| | - Philipp W Messer
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853
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88
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Champer J, Buchman A, Akbari OS. Cheating evolution: engineering gene drives to manipulate the fate of wild populations. Nat Rev Genet 2016; 17:146-59. [PMID: 26875679 DOI: 10.1038/nrg.2015.34] [Citation(s) in RCA: 241] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Engineered gene drives - the process of stimulating the biased inheritance of specific genes - have the potential to enable the spread of desirable genes throughout wild populations or to suppress harmful species, and may be particularly useful for the control of vector-borne diseases such as malaria. Although several types of selfish genetic elements exist in nature, few have been successfully engineered in the laboratory thus far. With the discovery of RNA-guided CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated 9) nucleases, which can be utilized to create, streamline and improve synthetic gene drives, this is rapidly changing. Here, we discuss the different types of engineered gene drives and their potential applications, as well as current policies regarding the safety and regulation of gene drives for the manipulation of wild populations.
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Affiliation(s)
- Jackson Champer
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Anna Buchman
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Omar S Akbari
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
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89
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Adelman ZN, Tu Z. Control of Mosquito-Borne Infectious Diseases: Sex and Gene Drive. Trends Parasitol 2016; 32:219-229. [PMID: 26897660 DOI: 10.1016/j.pt.2015.12.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/01/2015] [Accepted: 12/04/2015] [Indexed: 01/23/2023]
Abstract
Sterile male releases have successfully reduced local populations of the dengue vector, Aedes aegypti, but challenges remain in scale and in separating sexes before release. The recent discovery of the first mosquito male determining factor (M factor) will facilitate our understanding of the genetic programs that initiate sexual development in mosquitoes. Manipulation of the M factor and possible intermediary factors may result in female-to-male conversion or female killing, enabling efficient sex separation and effective reduction of target mosquito populations. Given recent breakthroughs in the development of CRISPR-Cas9 reagents as a source of gene drive, more advanced technologies at driving maleness, the ultimate disease refractory phenotype, become possible and may represent efficient and self-limiting methods to control mosquito populations.
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Affiliation(s)
- Zach N Adelman
- Department of Entomology, Virginia Tech, Blacksburg, VA, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
| | - Zhijian Tu
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA; Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA.
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90
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Reid W, O'Brochta DA. Applications of genome editing in insects. CURRENT OPINION IN INSECT SCIENCE 2016; 13:43-54. [PMID: 27436552 DOI: 10.1016/j.cois.2015.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 09/23/2015] [Accepted: 11/01/2015] [Indexed: 05/14/2023]
Abstract
Insect genome editing was first reported 1991 in Drosophila melanogaster but the technology used was not portable to other species. Not until the recent development of facile, engineered DNA endonuclease systems has gene editing become widely available to insect scientists. Most applications in insects to date have been technical in nature but this is rapidly changing. Functional genomics and genetics-based insect control efforts will be major beneficiaries of the application of contemporary gene editing technologies. Engineered endonucleases like Cas9 make it possible to create powerful and effective gene drive systems that could be used to reduce or even eradicate specific insect populations. 'Best practices' for using Cas9-based editing are beginning to emerge making it easier and more effective to design and use but gene editing technologies still require traditional means of delivery in order to introduce them into somatic and germ cells of insects-microinjection of developing embryos. This constrains the use of these technologies by insect scientists. Insects created using editing technologies challenge existing governmental regulatory structures designed to manage genetically modified organisms.
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Affiliation(s)
- William Reid
- Institute for Bioscience and Biotechnology Research, Department of Entomology, University of Maryland, College Park, 9600 Gudelsky Drive, Rockville, MD 20850, United States
| | - David A O'Brochta
- Institute for Bioscience and Biotechnology Research, Department of Entomology, University of Maryland, College Park, 9600 Gudelsky Drive, Rockville, MD 20850, United States.
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91
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Abstract
On December 18, 2014, a yellow female fly quietly emerged from her pupal case. What made her unique was that she had only one parent carrying a mutant allele of this classic recessive locus. Then, one generation later, after mating with a wild-type male, all her offspring displayed the same recessive yellow phenotype. Further analysis of other such yellow females revealed that the construct causing the mutation was converting the opposing chromosome with 95% efficiency. These simple results, seen also in mosquitoes and yeast, open the door to a new era of genetics wherein the laws of traditional Mendelian inheritance can be bypassed for a broad variety of purposes. Here, we consider the implications of this fundamentally new form of "active genetics," its applications for gene drives, reversal and amplification strategies, its potential for contributing to cell and gene therapy strategies, and ethical/biosafety considerations associated with such active genetic elements. Also watch the Video Abstract.
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Affiliation(s)
- Valentino M Gantz
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
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92
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Akbari OS, Bellen HJ, Bier E, Bullock SL, Burt A, Church GM, Cook KR, Duchek P, Edwards OR, Esvelt KM, Gantz VM, Golic KG, Gratz SJ, Harrison MM, Hayes KR, James AA, Kaufman TC, Knoblich J, Malik HS, Matthews KA, O'Connor-Giles KM, Parks AL, Perrimon N, Port F, Russell S, Ueda R, Wildonger J. BIOSAFETY. Safeguarding gene drive experiments in the laboratory. Science 2015; 349:927-9. [PMID: 26229113 PMCID: PMC4692367 DOI: 10.1126/science.aac7932] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Multiple stringent confinement strategies should be used whenever possible
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Affiliation(s)
- Omar S Akbari
- Department of Entomology, Univ. of California, Riverside, CA 92507, USA. Center for Disease Vector Research, Institute for Integrative Genome Biology, Univ. of California, Riverside, CA 92507, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, Univ. of California, San Diego, La Jolla, CA 92095, USA.
| | - Simon L Bullock
- Division of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Austin Burt
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, Berks SL5 7PY, UK
| | - George M Church
- Wyss Institute for Biologically Inspired Engineering, Harvard Medical School, Boston, MA 02115, USA. Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Kevin R Cook
- Bloomington Drosophila Stock Center, Department of Biology, Indiana Univ., Bloomington, IN 47405, USA
| | - Peter Duchek
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Owain R Edwards
- CSIRO Centre for Environment and Life Sciences, Underwood Avenue, Floreat, WA 6014, Australia
| | - Kevin M Esvelt
- Wyss Institute for Biologically Inspired Engineering, Harvard Medical School, Boston, MA 02115, USA.
| | - Valentino M Gantz
- Section of Cell and Developmental Biology, Univ. of California, San Diego, La Jolla, CA 92095, USA
| | - Kent G Golic
- Department of Biology, Univ. of Utah, Salt Lake City, UT 84112, USA
| | - Scott J Gratz
- Laboratory of Genetics, Univ. of Wisconsin-Madison, Madison, WI 53706, USA
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, Univ. of Wisconsin-Madison, Madison, WI 53706, USA
| | - Keith R Hayes
- CSIRO Biosecurity Flagship, General Post Of ce Box 1538, Hobart, Tasmania, 7001, Australia
| | - Anthony A James
- Departments of Microbiology & Molecular Genetics and Molecular Biology & Biochemistry, Univ. of California at Irvine, Irvine, CA 92697, USA
| | - Thomas C Kaufman
- Bloomington Drosophila Stock Center, Department of Biology, Indiana Univ., Bloomington, IN 47405, USA
| | - Juergen Knoblich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Harmit S Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA. Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Kathy A Matthews
- Bloomington Drosophila Stock Center, Department of Biology, Indiana Univ., Bloomington, IN 47405, USA
| | - Kate M O'Connor-Giles
- Laboratory of Genetics, Univ. of Wisconsin-Madison, Madison, WI 53706, USA. Laboratory of Cell and Molecular Biology, Univ. of Wisconsin-Madison, Madison, WI 53706, USA
| | - Annette L Parks
- Bloomington Drosophila Stock Center, Department of Biology, Indiana Univ., Bloomington, IN 47405, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA. Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Fillip Port
- Division of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Steven Russell
- Department of Genetics, Univ. of Cambridge, Cambridge, Cambridgeshire CB2 3EH, UK
| | - Ryu Ueda
- Department of Genetics, Graduate Univ. for Advanced Studies, Mishima, Shizuoka 411-8540, Japan. NIG-Fly Stock Center, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Jill Wildonger
- Department of Biochemistry, Univ. of Wisconsin-Madison, Madison, WI 53706, USA
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93
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Bull JJ. Evolutionary decay and the prospects for long-term disease intervention using engineered insect vectors. EVOLUTION MEDICINE AND PUBLIC HEALTH 2015; 2015:152-66. [PMID: 26160736 PMCID: PMC4529661 DOI: 10.1093/emph/eov013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 06/19/2015] [Indexed: 02/03/2023]
Abstract
After a long history of applying the sterile insect technique to suppress populations of disease vectors and agricultural pests, there is growing interest in using genetic engineering both to improve old methods and to enable new methods. The two goals of interventions are to suppress populations, possibly eradicating a species altogether, or to abolish the vector’s competence to transmit a parasite. New methods enabled by genetic engineering include the use of selfish genes toward either goal as well as a variety of killer-rescue systems that could be used for vector competence reduction. This article reviews old and new methods with an emphasis on the potential for evolution of resistance to these strategies. Established methods of population suppression did not obviously face a problem from resistance evolution, but newer technologies might. Resistance to these newer interventions will often be mechanism-specific, and while it is too early to know where resistance evolution will become a problem, it is at least possible to propose properties of interventions that will be more or less effective in blocking resistance evolution.
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Affiliation(s)
- J J Bull
- Department of Integrative Biology; Department of Integrative Biology; Department of Integrative Biology;
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94
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Abstract
Sex chromosome drivers are selfish elements that subvert Mendel's first law of segregation and therefore are overrepresented among the products of meiosis. The sex-biased progeny produced then fuels an extended genetic conflict between the driver and the rest of the genome. Many examples of sex chromosome drive are known, but the occurrence of this phenomenon is probably largely underestimated because of the difficulty to detect it. Remarkably, nearly all sex chromosome drivers are found in two clades, Rodentia and Diptera. Although very little is known about the molecular and cellular mechanisms of drive, epigenetic processes such as chromatin regulation could be involved in many instances. Yet, its evolutionary consequences are far-reaching, from the evolution of mating systems and sex determination to the emergence of new species.
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Affiliation(s)
- Quentin Helleu
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, France and Université Paris-Sud, Orsay, France
| | - Pierre R Gérard
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, France and Université Paris-Sud, Orsay, France
| | - Catherine Montchamp-Moreau
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, France and Université Paris-Sud, Orsay, France
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95
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Abstract
Recent advances in genetic engineering are bringing new promise for controlling mosquito populations that transmit deadly pathogens. Here we discuss past and current efforts to engineer mosquito strains that are refractory to disease transmission or are suitable for suppressing wild disease-transmitting populations.
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Affiliation(s)
| | - Andrea Smidler
- />Department of Immunology and Infectious Diseases, Harvard School of Public Health, Avenue Louis Pasteur, Boston, MA 021155 USA
- />Department of Genetics, Harvard Medical School, Avenue Louis Pasteur, Boston, MA 02115 USA
| | - Flaminia Catteruccia
- />Department of Immunology and Infectious Diseases, Harvard School of Public Health, Avenue Louis Pasteur, Boston, MA 021155 USA
- />Department of Microbiology, Perugia University, Perugia, 06100 Italy
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96
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Medusa: a novel gene drive system for confined suppression of insect populations. PLoS One 2014; 9:e102694. [PMID: 25054803 PMCID: PMC4108329 DOI: 10.1371/journal.pone.0102694] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 06/23/2014] [Indexed: 01/03/2023] Open
Abstract
Gene drive systems provide novel opportunities for insect population suppression by driving genes that confer a fitness cost into pest or disease vector populations; however regulatory issues arise when genes are capable of spreading across international borders. Gene drive systems displaying threshold properties provide a solution since they can be confined to local populations and eliminated through dilution with wild-types. We propose a novel, threshold-dependent gene drive system, Medusa, capable of inducing a local and reversible population crash. Medusa consists of four components - two on the X chromosome, and two on the Y chromosome. A maternally-expressed, X-linked toxin and a zygotically-expressed, Y-linked antidote results in suppression of the female population and selection for the presence of the transgene-bearing Y because only male offspring of Medusa-bearing females are protected from the effects of the toxin. At the same time, the combination of a zygotically-expressed, Y-linked toxin and a zygotically-expressed, X-linked antidote selects for the transgene-bearing X in the presence of the transgene-bearing Y. Together these chromosomes create a balanced lethal system that spreads while selecting against females when present above a certain threshold frequency. Simple population dynamic models show that an all-male release of Medusa males, carried out over six generations, is expected to induce a population crash within 12 generations for modest release sizes on the order of the wild population size. Re-invasion of non-transgenic insects into a suppressed population can result in a population rebound; however this can be prevented through regular releases of modest numbers of Medusa males. Finally, we outline how Medusa could be engineered with currently available molecular tools.
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97
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Reeves RG, Bryk J, Altrock PM, Denton JA, Reed FA. First steps towards underdominant genetic transformation of insect populations. PLoS One 2014; 9:e97557. [PMID: 24844466 PMCID: PMC4028297 DOI: 10.1371/journal.pone.0097557] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 04/08/2014] [Indexed: 11/18/2022] Open
Abstract
The idea of introducing genetic modifications into wild populations of insects to stop them from spreading diseases is more than 40 years old. Synthetic disease refractory genes have been successfully generated for mosquito vectors of dengue fever and human malaria. Equally important is the development of population transformation systems to drive and maintain disease refractory genes at high frequency in populations. We demonstrate an underdominant population transformation system in Drosophila melanogaster that has the property of being both spatially self-limiting and reversible to the original genetic state. Both population transformation and its reversal can be largely achieved within as few as 5 generations. The described genetic construct {Ud} is composed of two genes; (1) a UAS-RpL14.dsRNA targeting RNAi to a haploinsufficient gene RpL14 and (2) an RNAi insensitive RpL14 rescue. In this proof-of-principle system the UAS-RpL14.dsRNA knock-down gene is placed under the control of an Actin5c-GAL4 driver located on a different chromosome to the {Ud} insert. This configuration would not be effective in wild populations without incorporating the Actin5c-GAL4 driver as part of the {Ud} construct (or replacing the UAS promoter with an appropriate direct promoter). It is however anticipated that the approach that underlies this underdominant system could potentially be applied to a number of species.
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Affiliation(s)
- R. Guy Reeves
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
- * E-mail:
| | - Jarosław Bryk
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Philipp M. Altrock
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Jai A. Denton
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Floyd A. Reed
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
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98
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Gokhale CS, Reeves RG, Reed FA. Dynamics of a combined Medea-underdominant population transformation system. BMC Evol Biol 2014; 14:98. [PMID: 24884575 PMCID: PMC4068157 DOI: 10.1186/1471-2148-14-98] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 04/28/2014] [Indexed: 01/16/2023] Open
Abstract
Background Transgenic constructs intended to be stably established at high frequencies in
wild populations have been demonstrated to “drive” from low
frequencies in experimental insect populations. Linking such population
transformation constructs to genes which render them unable to transmit pathogens
could eventually be used to stop the spread of vector-borne diseases like malaria
and dengue. Results Generally, population transformation constructs with only a single transgenic
drive mechanism have been envisioned. Using a theoretical modelling approach we
describe the predicted properties of a construct combining autosomal Medea and
underdominant population transformation systems. We show that when combined they
can exhibit synergistic properties which in broad circumstances surpass those of
the single systems. Conclusion With combined systems, intentional population transformation and its reversal can
be achieved readily. Combined constructs also enhance the capacity to
geographically restrict transgenic constructs to targeted populations. It is
anticipated that these properties are likely to be of particular value in
attracting regulatory approval and public acceptance of this novel technology.
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Affiliation(s)
- Chaitanya S Gokhale
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August Thienemann Str-2, 24306 Plön, Germany.
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99
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Calla B, Hall B, Hou S, Geib SM. A genomic perspective to assessing quality of mass-reared SIT flies used in Mediterranean fruit fly (Ceratitis capitata) eradication in California. BMC Genomics 2014; 15:98. [PMID: 24495485 PMCID: PMC3923235 DOI: 10.1186/1471-2164-15-98] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/31/2014] [Indexed: 02/07/2023] Open
Abstract
Background Temperature sensitive lethal (tsl) mutants of the tephritid C. capitata are used extensively in control programs involving sterile insect technique in California. These flies are artificially reared and treated with ionizing radiation to render males sterile for further release en masse into the field to compete with wild males and disrupt establishment of invasive populations. Recent research suggests establishment of C. capitata in California, despite the fact that over 250 million sterile flies are released weekly as part of the state’s preventative program. In this project, genome-level quality assessment was performed, measured as expression differences between the Vienna-7 tsl mutants used in SIT programs and wild flies. RNA-seq was performed to provide a genome-wide map of the messenger RNA populations in C. capitata, and to investigate significant expression changes in Vienna-7 mass reared flies. Results Flies from the Vienna-7 colony showed a markedly reduced abundance of transcripts related to visual and chemical responses, including light stimuli, neural development and signaling pathways when compared to wild flies. In addition, genes associated with muscle development and locomotion were shown to be reduced. This suggests that the Vienna-7 line may be less competitive in mating and host plant finding where these stimuli are utilized. Irradiated flies showed several transcripts representing stress associated with irradiation. Conclusions There are significant changes at the transcriptome level that likely alter the competitiveness of mass reared flies and provide justification for pursuing methods for strain improvement, increasing competitiveness of mass-reared flies, or exploring alternative SIT approaches to increase the efficiency of eradication programs.
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Affiliation(s)
| | | | | | - Scott M Geib
- Tropical Crop and Commodity Protection Research Unit, USDA-ARS Pacific Basin Agricultural Research Center, Hilo, HI 96720, USA.
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100
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Akbari OS, Papathanos PA, Sandler JE, Kennedy K, Hay BA. Identification of germline transcriptional regulatory elements in Aedes aegypti. Sci Rep 2014; 4:3954. [PMID: 24492376 PMCID: PMC3912481 DOI: 10.1038/srep03954] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/16/2014] [Indexed: 12/18/2022] Open
Abstract
The mosquito Aedes aegypti is the principal vector for the yellow fever and dengue viruses, and is also responsible for recent outbreaks of the alphavirus chikungunya. Vector control strategies utilizing engineered gene drive systems are being developed as a means of replacing wild, pathogen transmitting mosquitoes with individuals refractory to disease transmission, or bringing about population suppression. Several of these systems, including Medea, UD(MEL), and site-specific nucleases, which can be used to drive genes into populations or bring about population suppression, utilize transcriptional regulatory elements that drive germline-specific expression. Here we report the identification of multiple regulatory elements able to drive gene expression specifically in the female germline, or in the male and female germline, in the mosquito Aedes aegypti. These elements can also be used as tools with which to probe the roles of specific genes in germline function and in the early embryo, through overexpression or RNA interference.
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Affiliation(s)
- Omar S Akbari
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Philippos A Papathanos
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Jeremy E Sandler
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Katie Kennedy
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bruce A Hay
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
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