1
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Naidoo K, Oliver SV. Gene drives: an alternative approach to malaria control? Gene Ther 2024:10.1038/s41434-024-00468-8. [PMID: 39039203 DOI: 10.1038/s41434-024-00468-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/14/2024] [Accepted: 07/18/2024] [Indexed: 07/24/2024]
Abstract
Genetic modification for the control of mosquitoes is frequently touted as a solution for a variety of vector-borne diseases. There has been some success using non-insecticidal methods like sterile or incompatible insect techniques to control arbovirus diseases. However, control by genetic modifications to reduce mosquito populations or create mosquitoes that are refractory to infection with pathogens are less developed. The advent of CRISPR-Cas9-mediated gene drives may advance this mechanism of control. In this review, use and progress of gene drives for vector control, particularly for malaria, is discussed. A brief history of population suppression and replacement gene drives in mosquitoes, rapid advancement of the field over the last decade and how genetic modification fits into the current scope of vector control are described. Mechanisms of alternative vector control by genetic modification to modulate mosquitoes' immune responses and anti-parasite effector molecules as part of a combinational strategy to combat malaria are considered. Finally, the limitations and ethics of using gene drives for mosquito control are discussed.
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Affiliation(s)
- Kubendran Naidoo
- SAMRC/Wits Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- National Health Laboratory Service, Johannesburg, South Africa.
- Wits Research Institute for Malaria, Faculty of Health Sciences, National Health Laboratory Service, University of the Witwatersrand, Johannesburg, South Africa.
- Infectious Diseases and Oncology Research Institute (IDORI), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Shüné V Oliver
- Wits Research Institute for Malaria, Faculty of Health Sciences, National Health Laboratory Service, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
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2
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Liang J, Kang L, Michalak P, Sharakhov IV. Hybridization between Aedes aegypti and Aedes mascarensis mosquitoes leads to disruption of male sex determination. Commun Biol 2024; 7:886. [PMID: 39039226 PMCID: PMC11263339 DOI: 10.1038/s42003-024-06560-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 07/05/2024] [Indexed: 07/24/2024] Open
Abstract
Understanding the sex determination pathway and its disruptions in mosquitoes is critical for the effective control of disease vectors through genetic manipulations based on sex separation. When male hybrids of Aedes aegypti females and Ae. mascarensis males are backcrossed to Ae. aegypti females, a portion of the backcross progeny manifests as males with abnormal sexual differentiation. We discovered a significant correlation between pupal abnormalities and the feminization of subsequent adults exemplified by the relative abundance of ovarian and testicular tissues. All intersex individuals were genetic males as they expressed a male determining factor, Nix. Further, our analysis of the sex-specific splicing of doublesex and fruitless transcripts demonstrated the presence of both male and female splice variants indicating that sex determination is disrupted. A comparative transcriptomic analysis revealed similar expression levels of most female-associated genes in reproductive organs and carcasses between intersexual males and normal females. Moreover, intersexes had largely normal gene expression in testes but significant gene downregulation in male accessory glands when compared with normal males. We conclude that evolving hybrid incompatibilities between Ae. aegypti and Ae. mascarensis involve disruption of sex determination and are accompanied by changes in gene expression associated with sexual differentiation.
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Affiliation(s)
- Jiangtao Liang
- Department of Entomology, Virginia Polytechnic and State University, Blacksburg, VA, USA
- Fralin Life Science Institute, Virginia Polytechnic and State University, Blacksburg, VA, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic and State University, Blacksburg, VA, USA
| | - Lin Kang
- Department of Biomedical Research, Edward Via College of Osteopathic Medicine, Monroe, LA, USA
- College of Pharmacy, University of Louisiana Monroe, Monroe, LA, USA
- Center for One Health Research, VA-MD College of Veterinary Medicine, Blacksburg, VA, USA
| | - Pawel Michalak
- Department of Biomedical Research, Edward Via College of Osteopathic Medicine, Monroe, LA, USA
- Center for One Health Research, VA-MD College of Veterinary Medicine, Blacksburg, VA, USA
- Institute of Evolution, University of Haifa, Haifa, Israel
| | - Igor V Sharakhov
- Department of Entomology, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Fralin Life Science Institute, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Department of Genetics and Cell Biology, Tomsk State University, Tomsk, Russia.
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3
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Aldridge RL, Gibson S, Linthicum KJ. Aedes aegypti Controls AE. Aegypti: SIT and IIT-An Overview. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2024; 40:32-49. [PMID: 38427588 DOI: 10.2987/23-7154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
The sterile insect technique (SIT) and the incompatible insect technique (IIT) are emerging and potentially revolutionary tools for controlling Aedes aegypti (L.), a prominent worldwide mosquito vector threat to humans that is notoriously difficult to reduce or eliminate in intervention areas using traditional integrated vector management (IVM) approaches. Here we provide an overview of the discovery, development, and application of SIT and IIT to Ae. aegypti control, and innovations and advances in technology, including transgenics, that could elevate these techniques to a worldwide sustainable solution to Ae. aegypti when combined with other IVM practices.
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4
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Weng SC, Masri RA, Akbari OS. Advances and challenges in synthetic biology for mosquito control. Trends Parasitol 2024; 40:75-88. [PMID: 38000957 PMCID: PMC11064511 DOI: 10.1016/j.pt.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023]
Abstract
Mosquito-borne illnesses represent a significant global health peril, resulting in approximately one million fatalities annually. West Nile, dengue, Zika, and malaria are continuously expanding their global reach, driven by factors that escalate mosquito populations and pathogen transmission. Innovative control measures are imperative to combat these catastrophic ailments. Conventional approaches, such as eliminating breeding sites and using insecticides, have been helpful, but they face challenges such as insecticide resistance and environmental harm. Given the mounting severity of mosquito-borne diseases, there is promise in exploring innovative approaches using synthetic biology to bolster mosquitoes' resistance to pathogens, or even eliminate the mosquito vectors, as a means of control. This review outlines current strategies, future goals, and the importance of gene editing for global health defenses against mosquito-borne diseases.
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Affiliation(s)
- Shih-Che Weng
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Reem A Masri
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S Akbari
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA.
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5
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Wong ML, Zulzahrin Z, Vythilingam I, Lau YL, Sam IC, Fong MY, Lee WC. Perspectives of vector management in the control and elimination of vector-borne zoonoses. Front Microbiol 2023; 14:1135977. [PMID: 37025644 PMCID: PMC10070879 DOI: 10.3389/fmicb.2023.1135977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/28/2023] [Indexed: 04/08/2023] Open
Abstract
The complex transmission profiles of vector-borne zoonoses (VZB) and vector-borne infections with animal reservoirs (VBIAR) complicate efforts to break the transmission circuit of these infections. To control and eliminate VZB and VBIAR, insecticide application may not be conducted easily in all circumstances, particularly for infections with sylvatic transmission cycle. As a result, alternative approaches have been considered in the vector management against these infections. In this review, we highlighted differences among the environmental, chemical, and biological control approaches in vector management, from the perspectives of VZB and VBIAR. Concerns and knowledge gaps pertaining to the available control approaches were discussed to better understand the prospects of integrating these vector control approaches to synergistically break the transmission of VZB and VBIAR in humans, in line with the integrated vector management (IVM) developed by the World Health Organization (WHO) since 2004.
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Affiliation(s)
- Meng Li Wong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Zulhisham Zulzahrin
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - I-Ching Sam
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Wenn-Chyau Lee
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- *Correspondence: Wenn-Chyau Lee,
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6
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Bui M, Dalla Benetta E, Dong Y, Zhao Y, Yang T, Li M, Antoshechkin IA, Buchman A, Bottino-Rojas V, James AA, Perry MW, Dimopoulos G, Akbari OS. CRISPR mediated transactivation in the human disease vector Aedes aegypti. PLoS Pathog 2023; 19:e1010842. [PMID: 36656895 PMCID: PMC9888728 DOI: 10.1371/journal.ppat.1010842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 01/31/2023] [Accepted: 12/28/2022] [Indexed: 01/20/2023] Open
Abstract
As a major insect vector of multiple arboviruses, Aedes aegypti poses a significant global health and economic burden. A number of genetic engineering tools have been exploited to understand its biology with the goal of reducing its impact. For example, current tools have focused on knocking-down RNA transcripts, inducing loss-of-function mutations, or expressing exogenous DNA. However, methods for transactivating endogenous genes have not been developed. To fill this void, here we developed a CRISPR activation (CRISPRa) system in Ae. aegypti to transactivate target gene expression. Gene expression is activated through pairing a catalytically-inactive ('dead') Cas9 (dCas9) with a highly-active tripartite activator, VP64-p65-Rta (VPR) and synthetic guide RNA (sgRNA) complementary to a user defined target-gene promoter region. As a proof of concept, we demonstrate that engineered Ae. aegypti mosquitoes harboring a binary CRISPRa system can be used to effectively overexpress two developmental genes, even-skipped (eve) and hedgehog (hh), resulting in observable morphological phenotypes. We also used this system to overexpress the positive transcriptional regulator of the Toll immune pathway known as AaRel1, which resulted in a significant suppression of dengue virus serotype 2 (DENV2) titers in the mosquito. This system provides a versatile tool for research pathways not previously possible in Ae. aegypti, such as programmed overexpression of endogenous genes, and may aid in gene characterization studies and the development of innovative vector control tools.
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Affiliation(s)
- Michelle Bui
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Elena Dalla Benetta
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Yuemei Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yunchong Zhao
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Ting Yang
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Ming Li
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Igor A. Antoshechkin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Anna Buchman
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - Vanessa Bottino-Rojas
- Department of Microbiology & Molecular Genetics, University of California Irvine, Irvine, California, United States of America
| | - Anthony A. James
- Department of Microbiology & Molecular Genetics, University of California Irvine, Irvine, California, United States of America
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Michael W. Perry
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Omar S. Akbari
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, San Diego, California, United States of America
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7
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Garrood WT, Cuber P, Willis K, Bernardini F, Page NM, Haghighat-Khah RE. Driving down malaria transmission with engineered gene drives. Front Genet 2022; 13:891218. [PMID: 36338968 PMCID: PMC9627344 DOI: 10.3389/fgene.2022.891218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 09/13/2022] [Indexed: 11/26/2022] Open
Abstract
The last century has witnessed the introduction, establishment and expansion of mosquito-borne diseases into diverse new geographic ranges. Malaria is transmitted by female Anopheles mosquitoes. Despite making great strides over the past few decades in reducing the burden of malaria, transmission is now on the rise again, in part owing to the emergence of mosquito resistance to insecticides, antimalarial drug resistance and, more recently, the challenges of the COVID-19 pandemic, which resulted in the reduced implementation efficiency of various control programs. The utility of genetically engineered gene drive mosquitoes as tools to decrease the burden of malaria by controlling the disease-transmitting mosquitoes is being evaluated. To date, there has been remarkable progress in the development of CRISPR/Cas9-based homing endonuclease designs in malaria mosquitoes due to successful proof-of-principle and multigenerational experiments. In this review, we examine the lessons learnt from the development of current CRISPR/Cas9-based homing endonuclease gene drives, providing a framework for the development of gene drive systems for the targeted control of wild malaria-transmitting mosquito populations that overcome challenges such as with evolving drive-resistance. We also discuss the additional substantial works required to progress the development of gene drive systems from scientific discovery to further study and subsequent field application in endemic settings.
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Affiliation(s)
- William T. Garrood
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Piotr Cuber
- Department of Molecular Biology, Core Research Laboratories, Natural History Museum, London, United Kingdom
| | - Katie Willis
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Federica Bernardini
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Nicole M. Page
- Department of Life Sciences, Imperial College London, London, United Kingdom
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8
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Dilani PVD, Dassanayake RS, Tyagi BK, Gunawardene YINS. The impact of transgenesis on mosquito fitness: A review. FRONTIERS IN INSECT SCIENCE 2022; 2:957570. [PMID: 38468772 PMCID: PMC10926467 DOI: 10.3389/finsc.2022.957570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/05/2022] [Indexed: 03/13/2024]
Abstract
Transgenic mosquitoes developed by genetic manipulation, offer a promising strategy for the sustainable and effective control of mosquito-borne diseases. This strategy relies on the mass release of transgenic mosquitoes into the wild, where their transgene is expected to persist in the natural environment, either permanently or transiently, within the mosquito population. In such circumstances, the fitness of transgenic mosquitoes is an important factor in determining their survival in the wild. The impact of transgene expression, insertional mutagenesis, inbreeding depression related to laboratory adaptation, and the hitchhiking effect involved in developing homozygous mosquito lines can all have an effect on the fitness of transgenic mosquitoes. Therefore, real-time estimation of transgene-associated fitness cost is imperative for modeling and planning transgenic mosquito release programs. This can be achieved by directly comparing fitness parameters in individuals homozygous or hemizygous for the transgene and their wild-type counterparts, or by cage invasion experiments to monitor the frequency of the transgenic allele over multiple generations. Recent advancements such as site-specific integration systems and gene drives, provide platforms to address fitness issues in transgenic mosquitoes. More research on the fitness of transgenic individuals is required to develop transgenic mosquitoes with a low fitness cost.
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Affiliation(s)
| | | | - Brij Kishore Tyagi
- Sponsored Research & Industrial Centre, VIT University, Vellore (TN), India
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9
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Kojin BB, Compton A, Adelman ZN, Tu Z. Selective targeting of biting females to control mosquito-borne infectious diseases. Trends Parasitol 2022; 38:791-804. [PMID: 35952630 PMCID: PMC9372635 DOI: 10.1016/j.pt.2022.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
Abstract
Mosquitoes are vectors for a number of infectious diseases. Only females feed on blood to provision for their embryos and, in doing so, transmit pathogens to the associated vertebrate hosts. Therefore, sex is an important phenotype in the context of genetic control programs, both for sex separation in the rearing facilities to avoid releasing biting females and for ways to distort the sex ratio towards nonbiting males. We review recent progress in the fundamental knowledge of sex determination and sex chromosomes in mosquitoes and discuss new methods to achieve sex separation and sex ratio distortion to help control mosquito-borne infectious diseases. We conclude by suggesting a few critical areas for future research.
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Affiliation(s)
- Bianca B Kojin
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, TX, USA
| | - Austin Compton
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA; Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA, USA
| | - Zach N Adelman
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, TX, USA.
| | - Zhijian Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA; Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA, USA.
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10
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Melesse Vergara M, Labbé J, Tannous J. Reflection on the Challenges, Accomplishments, and New Frontiers of Gene Drives. BIODESIGN RESEARCH 2022; 2022:9853416. [PMID: 37850135 PMCID: PMC10521683 DOI: 10.34133/2022/9853416] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/19/2022] [Indexed: 10/19/2023] Open
Abstract
Ongoing pest and disease outbreaks pose a serious threat to human, crop, and animal lives, emphasizing the need for constant genetic discoveries that could serve as mitigation strategies. Gene drives are genetic engineering approaches discovered decades ago that may allow quick, super-Mendelian dissemination of genetic modifications in wild populations, offering hopes for medicine, agriculture, and ecology in combating diseases. Following its first discovery, several naturally occurring selfish genetic elements were identified and several gene drive mechanisms that could attain relatively high threshold population replacement have been proposed. This review provides a comprehensive overview of the recent advances in gene drive research with a particular emphasis on CRISPR-Cas gene drives, the technology that has revolutionized the process of genome engineering. Herein, we discuss the benefits and caveats of this technology and place it within the context of natural gene drives discovered to date and various synthetic drives engineered. Later, we elaborate on the strategies for designing synthetic drive systems to address resistance issues and prevent them from altering the entire wild populations. Lastly, we highlight the major applications of synthetic CRISPR-based gene drives in different living organisms, including plants, animals, and microorganisms.
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Affiliation(s)
| | - Jesse Labbé
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Invaio Sciences, Cambridge, MA 02138USA
| | - Joanna Tannous
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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11
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Kojin BB, Jakes E, Biedler JK, Tu Z, Adelman ZN. Partial masculinization of Aedes aegypti females by conditional expression of Nix. PLoS Negl Trop Dis 2022; 16:e0010598. [PMID: 35776760 PMCID: PMC9307153 DOI: 10.1371/journal.pntd.0010598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 07/22/2022] [Accepted: 06/20/2022] [Indexed: 11/18/2022] Open
Abstract
Background
Aedes aegypti, the main vector of dengue, yellow fever, and other arboviruses thrives in tropical and subtropical areas around the globe putting half of the world’s population at risk. Despite aggressive efforts to control the transmission of those viruses, an unacceptable number of cases occur every year, emphasizing the need to develop new control strategies. Proposals for vector control focused on population suppression could offer a feasible alternative method to reduce disease transmission. The induction of extreme male-biased sex ratios has been hypothesized to be able to suppress or collapse a population, with previous experiments showing that stable expression of the male determining factor Nix in A. aegypti is sufficient to convert females into fertile males.
Methodology/Principal findings
Here, we report on the conditional expression of Nix in transgenic A. aegypti under the control of the tetracycline-dependent (Tet-off) system, with the goal of establishing repressible sex distortion. A masculinization phenotype was observed in three of the seven transgenic lines with females exhibiting male-like long maxillary palps and most importantly, the masculinized females were unable to blood feed. Doxycycline treatment of the transgenic lines only partially restored the normal phenotype from the masculinized transgenic lines, while RT-qPCR analysis of early embryos or adults showed no correlation between the level of masculinization and ectopic Nix expression.
Conclusions/Significance
While the conditional expression of Nix produced intersex phenotypes, the level of expression was insufficient to program full conversion. Modifications that increase both the level of activation (no tet) and the level of repression (with tet) will be necessary, as such this study represents one step forward in the development of genetic strategies to control vector-borne diseases via sex ratio distortion.
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Affiliation(s)
- Bianca B. Kojin
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, Texas, United States of America
| | - Emma Jakes
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, Texas, United States of America
| | - James K. Biedler
- Department of Biochemistry and Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Zhijian Tu
- Department of Biochemistry and Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Zach N. Adelman
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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12
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Transgenic expression of Nix converts genetic females into males and allows automated sex sorting in Aedes albopictus. Commun Biol 2022; 5:210. [PMID: 35256751 PMCID: PMC8901906 DOI: 10.1038/s42003-022-03165-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/13/2022] [Indexed: 12/16/2022] Open
Abstract
Aedes albopictus is a major vector of arboviruses. Better understanding of its sex determination is crucial for developing mosquito control tools, especially genetic sexing strains. In Aedes aegypti, Nix is the primary gene responsible for masculinization and Nix-expressing genetic females develop into fertile, albeit flightless, males. In Ae. albopictus, Nix has also been implicated in masculinization but its role remains to be further characterized. In this work, we establish Ae. albopictus transgenic lines ectopically expressing Nix. Several are composed exclusively of genetic females, with transgenic individuals being phenotypic and functional males due to the expression of the Nix transgene. Their reproductive fitness is marginally impaired, while their flight performance is similar to controls. Overall, our results show that Nix is sufficient for full masculinization in Ae. albopictus. Moreover, the transgene construct contains a fluorescence marker allowing efficient automated sex sorting. Consequently, such strains constitute valuable sexing strains for genetic control. Nix expression with a fluorescent marker in genetically female Ae. albopictus causes masculinization with minimal effects to reproductive fitness and flight performance.
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13
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Ang JXD, Nevard K, Ireland R, Purusothaman DK, Verkuijl SAN, Shackleford L, Gonzalez E, Anderson MAE, Alphey L. Considerations for homology-based DNA repair in mosquitoes: Impact of sequence heterology and donor template source. PLoS Genet 2022; 18:e1010060. [PMID: 35180218 PMCID: PMC8893643 DOI: 10.1371/journal.pgen.1010060] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 03/03/2022] [Accepted: 01/28/2022] [Indexed: 12/23/2022] Open
Abstract
The increasing prevalence of insecticide resistance and the ongoing global burden of vector-borne diseases have encouraged new efforts in mosquito control. For Aedes aegypti, the most important arboviral vector, integration rates achieved in Cas9-based knock-ins so far have been rather low, highlighting the need to understand gene conversion patterns and other factors that influence homology-directed repair (HDR) events in this species. In this study, we report the effects of sequence mismatches or donor template forms on integration rates. We found that modest sequence differences between construct homology arms [DNA sequence in the donor template which resembles the region flanking the target cut] and genomic target comprising 1.2% nucleotide dissimilarity (heterology) significantly reduced integration rates. While most integrations (59–88%) from plasmid templates were the result of canonical [on target, perfect repair] HDR events, no canonical events were identified from other donor types (i.e. ssDNA, biotinylated ds/ssDNA). Sequencing of the transgene flanking region in 69 individuals with canonical integrations revealed 60% of conversion tracts to be unidirectional and extend up to 220 bp proximal to the break, though in three individuals bidirectional conversion of up to 725 bp was observed. The field of genetic control of mosquito vectors has progressed rapidly in recent years, especially in Cas9-based control systems, due to its robustness to elicit a species-specific and dispersive control of mosquito population. To generate a Cas9-based integration, Cas9 and sgRNA are used to cleave a chromosomal locus while a plasmid DNA donor, containing a genetic cargo flanked by sequences homologous to the chromosomal locus, is supplied as a repair template. This results in the cargo being copied into the genome through HDR. This form of integration, however, is currently one of the major bottlenecks for researchers as it involves a laborious process of microinjecting mosquito embryos and has rather low integration rates. In this study, we assessed the effects of homologous sequence mismatches and various donor template forms (i.e. plasmid, ssDNA, biotinylated ds/ssDNA) on HDR. We found that sequence mismatches and non-plasmid donors reduced the efficiency and integrity of integration, respectively. By analysing the direction and length of homologous sequence that was copied into the genome concurrently with the cargo, we inferred the mechanism responsible for the integrations observed in our study. These findings will be useful to guide future construct designs for optimal HDR rates in mosquitoes.
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Affiliation(s)
| | | | | | | | - Sebald A. N. Verkuijl
- The Pirbright Institute, Pirbright, Woking, United Kingdom
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, United Kingdom
| | | | | | | | - Luke Alphey
- The Pirbright Institute, Pirbright, Woking, United Kingdom
- * E-mail: (MAEA); (LA)
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14
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Li M, Yang T, Bui M, Gamez S, Wise T, Kandul NP, Liu J, Alcantara L, Lee H, Edula JR, Raban R, Zhan Y, Wang Y, DeBeaubien N, Chen J, Sánchez C HM, Bennett JB, Antoshechkin I, Montell C, Marshall JM, Akbari OS. Suppressing mosquito populations with precision guided sterile males. Nat Commun 2021; 12:5374. [PMID: 34508072 PMCID: PMC8433431 DOI: 10.1038/s41467-021-25421-w] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/23/2021] [Indexed: 01/06/2023] Open
Abstract
The mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner. A. aegypti is the principal vector for arboviruses that impact on human health and wellbeing. Here the authors use precision guided sterile insect technique—pgSIT—to suppress or eliminate mosquito populations in multigeneration cage experiments.
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Affiliation(s)
- Ming Li
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Ting Yang
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Michelle Bui
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Stephanie Gamez
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Tyler Wise
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Nikolay P Kandul
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Junru Liu
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Lenissa Alcantara
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Haena Lee
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Jyotheeswara R Edula
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA.,Tata Institute for Genetics and Society, La Jolla, CA, USA.,Tata Institute for Genetics and Society (TIGS), TIGS Center at inStem, GKVK Campus, Bangalore, Karnataka, India
| | - Robyn Raban
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Yinpeng Zhan
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Yijin Wang
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Nick DeBeaubien
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Jieyan Chen
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Héctor M Sánchez C
- Divisions of Epidemiology & Biostatistics, School of Public Health, University of California, Berkeley, CA, USA
| | - Jared B Bennett
- Divisions of Epidemiology & Biostatistics, School of Public Health, University of California, Berkeley, CA, USA.,Biophysics Graduate Group, University of California, Berkeley, CA, USA
| | - Igor Antoshechkin
- Division of Biology and Biological Engineering (BBE), California Institute of Technology, Pasadena, CA, USA
| | - Craig Montell
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - John M Marshall
- Divisions of Epidemiology & Biostatistics, School of Public Health, University of California, Berkeley, CA, USA.,Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA. .,Tata Institute for Genetics and Society, La Jolla, CA, USA.
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