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Anderson MAE, Gonzalez E, Edgington MP, Ang JXD, Purusothaman DK, Shackleford L, Nevard K, Verkuijl SAN, Harvey-Samuel T, Leftwich PT, Esvelt K, Alphey L. A multiplexed, confinable CRISPR/Cas9 gene drive can propagate in caged Aedes aegypti populations. Nat Commun 2024; 15:729. [PMID: 38272895 PMCID: PMC10810878 DOI: 10.1038/s41467-024-44956-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/11/2024] [Indexed: 01/27/2024] Open
Abstract
Aedes aegypti is the main vector of several major pathogens including dengue, Zika and chikungunya viruses. Classical mosquito control strategies utilizing insecticides are threatened by rising resistance. This has stimulated interest in new genetic systems such as gene drivesHere, we test the regulatory sequences from the Ae. aegypti benign gonial cell neoplasm (bgcn) homolog to express Cas9 and a separate multiplexing sgRNA-expressing cassette inserted into the Ae. aegypti kynurenine 3-monooxygenase (kmo) gene. When combined, these two elements provide highly effective germline cutting at the kmo locus and act as a gene drive. Our target genetic element drives through a cage trial population such that carrier frequency of the element increases from 50% to up to 89% of the population despite significant fitness costs to kmo insertions. Deep sequencing suggests that the multiplexing design could mitigate resistance allele formation in our gene drive system.
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Affiliation(s)
- Michelle A E Anderson
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Estela Gonzalez
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- Animal and Plant Health Agency, Woodham Lane, Addlestone, Surrey, KT15 3NB, UK
| | - Matthew P Edgington
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Joshua X D Ang
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Deepak-Kumar Purusothaman
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- MRC-University of Glasgow Centre for Virus Research, Henry Wellcome Building, 464 Bearsden Road, Glasgow, G61 1QH, UK
| | - Lewis Shackleford
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Katherine Nevard
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
| | - Sebald A N Verkuijl
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- Department of Biology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | | | - Philip T Leftwich
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK
| | - Kevin Esvelt
- Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Luke Alphey
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0HN, UK.
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
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Anderson MAE, Gonzalez E, Ang JXD, Shackleford L, Nevard K, Verkuijl SAN, Edgington MP, Harvey-Samuel T, Alphey L. Closing the gap to effective gene drive in Aedes aegypti by exploiting germline regulatory elements. Nat Commun 2023; 14:338. [PMID: 36670107 PMCID: PMC9860013 DOI: 10.1038/s41467-023-36029-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 01/13/2023] [Indexed: 01/22/2023] Open
Abstract
CRISPR/Cas9-based homing gene drives have emerged as a potential new approach to mosquito control. While attempts have been made to develop such systems in Aedes aegypti, none have been able to match the high drive efficiency observed in Anopheles species. Here we generate Ae. aegypti transgenic lines expressing Cas9 using germline-specific regulatory elements and assess their ability to bias inheritance of an sgRNA-expressing element (kmosgRNAs). Four shu-Cas9 and one sds3-Cas9 isolines can significantly bias the inheritance of kmosgRNAs, with sds3G1-Cas9 causing the highest average inheritance of ~86% and ~94% from males and females carrying both elements outcrossed to wild-type, respectively. Our mathematical model demonstrates that sds3G1-Cas9 could enable the spread of the kmosgRNAs element to either reach a higher (by ~15 percentage point) maximum carrier frequency or to achieve similar maximum carrier frequency faster (by 12 generations) when compared to two other established split drive systems.
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Affiliation(s)
- Michelle A E Anderson
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Estela Gonzalez
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Joshua X D Ang
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Lewis Shackleford
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Katherine Nevard
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Sebald A N Verkuijl
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- Mathematical Ecology Research Group, Department of Biology, University of Oxford, 11a Mansfield Road, Oxford, OX13SZ, UK
| | - Matthew P Edgington
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Tim Harvey-Samuel
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK
| | - Luke Alphey
- Arthropod Genetics, The Pirbright Institute, Ash Road, Pirbright, GU24 0NF, UK.
- The Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
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Leftwich PT, Spurgin LG, Harvey-Samuel T, Thomas CJE, Paladino LC, Edgington MP, Alphey L. Genetic pest management and the background genetics of release strains. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190805. [PMID: 33357053 DOI: 10.1098/rstb.2019.0805] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Genetic pest management (GPM) methods involve releasing modified versions of a pest species to mate with wild pests in the target area. Proposed for a wide range of applications in public health, agriculture and conservation, most progress has been made with pest insects. Offspring of the released modified insects and wild pests carry the modification-which might be transgenes, artificially introduced Wolbachia or genetic damage from radiation, for example-but they also carry a complete haploid genome from their laboratory-reared parent, as well as one from their wild parent. Unless these F1 hybrids are completely unable to reproduce, further mating will lead to introgression of DNA sequences from the release strain into the wild population. We discuss issues around strain selection and the potential consequences of such introgression. We conclude that such introgression is probably harmless in almost all circumstances, and could, in theory, provide specific additional benefits to the release programme. We outline population monitoring approaches that could be used, going forward, to determine how background genetics may affect GPM. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Philip T Leftwich
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK
| | - Lewis G Spurgin
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK
| | | | | | | | | | - Luke Alphey
- Arthropod Genetics, The Pirbright Institute, Pirbright GU24 0NF, UK
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4
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Abstract
A wide range of gene drive mechanisms have been proposed that are predicted to increase in frequency within a population even when they are deleterious to individuals carrying them. This also allows associated desirable genetic material ("cargo genes") to increase in frequency. Gene drives have garnered much attention for their potential use against a range of globally important problems including vector borne disease, crop pests and invasive species. Here we propose a novel gene drive mechanism that could be engineered using a combination of toxin-antidote and CRISPR components, each of which are already being developed for other purposes. Population genetics mathematical models are developed here to demonstrate the threshold-dependent nature of the proposed system and its robustness to imperfect homing, incomplete penetrance of toxins and transgene fitness costs, each of which are of practical significance given that real-world components inevitably have such imperfections. We show that although end-joining repair mechanisms may cause the system to break down, under certain conditions, it should persist over time scales relevant for genetic control programs. The potential of such a system to provide localised population suppression via sex ratio distortion or female-specific lethality is also explored. Additionally, we investigate the effect on introduction thresholds of adding an extra CRISPR base element, showing that this may either increase or decrease dependent on parameter context.
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Affiliation(s)
| | - Tim Harvey-Samuel
- The Pirbright Institute, Ash Road, Woking, Surrey, Pirbright, GU24 0NF, UK
| | - Luke Alphey
- The Pirbright Institute, Ash Road, Woking, Surrey, Pirbright, GU24 0NF, UK
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Abstract
Sequencing technologies have fuelled a rapid rise in descriptions of microbial communities associated with hosts, but what is often harder to ascertain is the evolutionary significance of these symbioses. Here, we review the role of vertical (VT), horizontal (HT), environmental acquisition and mixed modes of transmission (MMT), in the establishment of animal host–microbe associations. We then model four properties of gut microbiota proposed as key to promoting animal host–microbe relationships: modes of transmission, host reproductive mode, host mate choice and host fitness. We found that: (i) MMT led to the highest frequencies of host–microbe associations, and that some environmental acquisition or HT of microbes was required for persistent associations to form unless VT was perfect; (ii) host reproductive mode (sexual versus asexual) and host mate choice (for microbe carriers versus non-carriers) had little impact on the establishment of host–microbe associations; (iii) host mate choice did not itself lead to reproductive isolation, but could reinforce it; and (iv) changes in host fitness due to host–microbe associations had a minimal impact upon the formation of co-associations. When we introduced a second population, into which host–microbe carriers could disperse but in which environmental acquisition did not occur, highly efficient VT was required for host–microbe co-associations to persist. Our study reveals that transmission mode is of key importance in establishing host–microbe associations.
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Affiliation(s)
- Philip T Leftwich
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | | | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
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Edgington MP, Harvey‐Samuel T, Alphey L. Population-level multiplexing: A promising strategy to manage the evolution of resistance against gene drives targeting a neutral locus. Evol Appl 2020; 13:1939-1948. [PMID: 32908596 PMCID: PMC7463328 DOI: 10.1111/eva.12945] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/19/2020] [Accepted: 02/25/2020] [Indexed: 01/30/2023] Open
Abstract
CRISPR-based gene drives bias inheritance in their favour by inducing double-stranded breaks (DSBs) at wild-type homologous loci and using the drive transgene as a repair template-converting drive heterozygotes into homozygotes. Recent studies have shown that alternate end-joining repair mechanisms produce cut-resistant alleles that rapidly induce drive failure. Multiplexing-simultaneously targeting multiple sites at the wild-type locus-is commonly assumed to overcome this issue since resistance would need to develop at all target sites for the system to fail. This may work for some population suppression drives targeting essential (e.g. viability or fertility) genes if careful design can ensure cut-resistant alleles themselves have low fitness. However, here, models are used to demonstrate that this approach will be ineffective when targeting neutral loci. We then go on to compare the performance of four alternative population-level multiplexing approaches with standard individual-level multiplexing. Two of these approaches have mechanisms preventing them from becoming linked, thus avoiding multiple simultaneous DSBs and giving a large improvement. Releasing multiple unlinked drives gives a modest improvement, while releasing multiple drives that may become linked over time produces a decrease in performance under the conditions tested here. Based on performance and technical feasibility, we then take one approach forward for further investigation, demonstrating its robustness to different performance parameters and its potential for controlling very large target populations.
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Edgington MP, Alphey LS. Modeling the mutation and reversal of engineered underdominance gene drives. J Theor Biol 2019; 479:14-21. [PMID: 31260669 PMCID: PMC6699728 DOI: 10.1016/j.jtbi.2019.06.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 06/24/2019] [Accepted: 06/27/2019] [Indexed: 01/31/2023]
Abstract
A range of gene drive systems have been proposed that are predicted to increase their frequency and that of associated desirable genetic material even if they confer a fitness cost on individuals carrying them. Engineered underdominance (UD) is such a system and, in one version, is based on the introduction of two independently segregating transgenic constructs each carrying a lethal gene, a suppressor for the lethal at the other locus and a desirable genetic "cargo". Under this system individuals carrying at least one copy of each construct (or no copies of either) are viable whilst those that possess just one of the transgenic constructs are non-viable. Previous theoretical work has explored various properties of these systems, concluding that they should persist indefinitely in absence of resistance or mutation. Here we study a population genetics model of UD gene drive that relaxes past assumptions by allowing for loss-of-function mutations in each introduced gene. We demonstrate that mutations are likely to cause UD systems to break down, eventually resulting in the elimination of introduced transgenes. We then go on to investigate the potential of releasing "free suppressor" carrying individuals as a new method for reversing UD gene drives and compare this to the release of wild-types; the only previously proposed reversal strategy for UD. This reveals that while free suppressor carrying individuals may represent an inexpensive reversal strategy due to extremely small release requirements, they are not able to return a fully wild-type population as rapidly as the release of wild-types.
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Affiliation(s)
| | - Luke S Alphey
- The Pirbright Institute, Ash Road, Woking, Surrey GU24 0NF, UK
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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: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Edgington MP, Alphey LS. Population dynamics of engineered underdominance and killer-rescue gene drives in the control of disease vectors. PLoS Comput Biol 2018; 14:e1006059. [PMID: 29570717 PMCID: PMC5884568 DOI: 10.1371/journal.pcbi.1006059] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 04/04/2018] [Accepted: 02/27/2018] [Indexed: 12/12/2022] Open
Abstract
A number of different genetics-based vector control methods have been proposed. Two approaches currently under development in Aedes aegypti mosquitoes are the two-locus engineered underdominance and killer-rescue gene drive systems. Each of these is theoretically capable of increasing in frequency within a population, thus spreading associated desirable genetic traits. Thus they have gained attention for their potential to aid in the fight against various mosquito-vectored diseases. In the case of engineered underdominance, introduced transgenes are theoretically capable of persisting indefinitely (i.e. it is self-sustaining) whilst in the killer-rescue system the rescue component should initially increase in frequency (while the lethal component (killer) is common) before eventually declining (when the killer is rare) and being eliminated (i.e. it is temporally self-limiting). The population genetics of both systems have been explored using discrete generation mathematical models. The effects of various ecological factors on these two systems have also been considered using alternative modelling methodologies. Here we formulate and analyse new mathematical models combining the population dynamics and population genetics of these two classes of gene drive that incorporate ecological factors not previously studied and are simple enough to allow the effects of each to be disentangled. In particular, we focus on the potential effects that may be obtained as a result of differing ecological factors such as strengths of larval competition; numbers of breeding sites; and the relative fitness of transgenic mosquitoes compared with their wild-type counterparts. We also extend our models to consider population dynamics in two demes in order to explore the effects of dispersal between neighbouring populations on the outcome of UD and KR gene drive systems.
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Affiliation(s)
| | - Luke S. Alphey
- The Pirbright Institute, Pirbright, Woking, Surrey, United Kingdom
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10
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Abstract
We undertake a detailed mathematical analysis of a recent nonlinear ordinary differential equation (ODE) model describing the chemotactic signalling cascade within an Escherichia coli cell. The model includes a detailed description of the cell signalling cascade and an average approximation of the receptor activity. A steady-state stability analysis reveals the system exhibits one positive real steady state which is shown to be asymptotically stable. Given the occurrence of a negative feedback between phosphorylated CheB (CheB-P) and the receptor state, we ask under what conditions the system may exhibit oscillatory-type behaviour. A detailed analysis of parameter space reveals that whilst variation in kinetic rate parameters within known biological limits is unlikely to lead to such behaviour, changes in the total concentration of the signalling proteins do. We postulate that experimentally observed overshoot behaviour can actually be described by damped oscillatory dynamics and consider the relationship between overshoot amplitude, total cell protein concentration and the magnitude of the external ligand stimulus. Model reductions in the full ODE model allow us to understand the link between phosphorylation events and the negative feedback between CheB-P and receptor methylation, as well as elucidate why some mathematical models exhibit overshoot and others do not. Our paper closes by discussing intercell variability of total protein concentration as a means of ensuring the overall survival of a population as cells are subjected to different environments.
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Affiliation(s)
- Matthew P Edgington
- Department of Mathematics and Statistics, University of Reading, Whiteknights, PO Box 220, Reading, RG6 6AX, UK.,The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK
| | - Marcus J Tindall
- Department of Mathematics and Statistics, University of Reading, Whiteknights, PO Box 220, Reading, RG6 6AX, UK. .,Institute for Cardiovascular and Metabolic Research, University of Reading, Whiteknights, PO Box 218, Reading, RG6 6AA, UK.
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [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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12
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Edgington MP, Tindall MJ. Understanding the link between single cell and population scale responses of Escherichia coli in differing ligand gradients. Comput Struct Biotechnol J 2015; 13:528-38. [PMID: 26693274 PMCID: PMC4660157 DOI: 10.1016/j.csbj.2015.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 11/30/2022] Open
Abstract
We formulate an agent-based population model of Escherichia coli cells which incorporates a description of the chemotaxis signalling cascade at the single cell scale. The model is used to gain insight into the link between the signalling cascade dynamics and the overall population response to differing chemoattractant gradients. Firstly, we consider how the observed variation in total (phosphorylated and unphosphorylated) signalling protein concentration affects the ability of cells to accumulate in differing chemoattractant gradients. Results reveal that a variation in total cell protein concentration between cells may be a mechanism for the survival of cell colonies across a wide range of differing environments. We then study the response of cells in the presence of two different chemoattractants. In doing so we demonstrate that the population scale response depends not on the absolute concentration of each chemoattractant but on the sensitivity of the chemoreceptors to their respective concentrations. Our results show the clear link between single cell features and the overall environment in which cells reside.
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Affiliation(s)
- Matthew P Edgington
- Department of Mathematics & Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX, UK
| | - Marcus J Tindall
- Department of Mathematics & Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX, UK ; Institute for Cardiovascular and Metabolic Research, University of Reading, Whiteknights, PO Box 218, Reading RG6 6AA, UK
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Edgington MP, Tindall MJ. Fold-change detection in a whole-pathway model of Escherichia coli chemotaxis. Bull Math Biol 2014; 76:1376-95. [PMID: 24809945 DOI: 10.1007/s11538-014-9965-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 04/15/2014] [Indexed: 10/25/2022]
Abstract
There has been recent interest in sensory systems that are able to display a response which is proportional to a fold change in stimulus concentration, a feature referred to as fold-change detection (FCD). Here, we demonstrate FCD in a recent whole-pathway mathematical model of Escherichia coli chemotaxis. FCD is shown to hold for each protein in the signalling cascade and to be robust to kinetic rate and protein concentration variation. Using a sensitivity analysis, we find that only variations in the number of receptors within a signalling team lead to the model not exhibiting FCD. We also discuss the ability of a cell with multiple receptor types to display FCD and explain how a particular receptor configuration may be used to elucidate the two experimentally determined regimes of FCD behaviour. All findings are discussed in respect of the experimental literature.
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Affiliation(s)
- Matthew P Edgington
- Department of Mathematics & Statistics, University of Reading, Whiteknights, PO Box 220, Reading, RG6 6AX, UK,
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