Featured Articles
Efficacy of Wolbachia-Infected Mosquito Deployments for the Control of Dengue
17300A. Utarini, C. Indriani, R. A. Ahmad, W. Tantowijoyo, E. Arguni, M. R. Ansari, E. Supriyati, D. S. Wardana, Y. Meitika, I. Ernesia, I. Nurhayati, E. Prabowo, B. Andari, B. R. Green, L. Hodgson, Z. Cutcher, E. Rancès, P. A. Ryan, S. L. O’Neill, S. M. Dufau, New England Journal of Medicine, 384:2177-2186. 2021-06-10 11:05:41.
BACKGROUND Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia pipientis are less susceptible than wild-type A. aegypti to dengue virus infection. METHODS We conducted a cluster-randomized trial involving releases of wMel-infected A. aegypti mosquitoes for the control of dengue in Yogyakarta, Indonesia. We randomly assigned 12 geographic clusters to receive deployments of wMel-infected A. aegypti (intervention clusters) and 12 clusters to receive no deployments (control clusters). All clusters practiced local mosquito-control measures as usual. A test-negative design was used to assess the efficacy of the intervention. Patients with acute undifferentiated fever who presented to local primary care clinics and were 3 to 45 years of age were recruited. Laboratory testing was used to identify participants who had virologically confirmed dengue (VCD) and those who were test-negative controls. The primary end point was symptomatic VCD of any severity caused by any dengue virus serotype. RESULTS After successful introgression of wMel into the intervention clusters, 8144 participants were enrolled; 3721 lived in intervention clusters, and 4423 lived in control clusters. In the intention-to-treat analysis, VCD occurred in 67 of 2905 participants (2.3%) in the intervention clusters and in 318 of 3401 (9.4%) in the control clusters (aggregate odds ratio for VCD, 0.23; 95% confidence interval [CI], 0.15 to 0.35; P=0.004). The protective efficacy of the intervention was 77.1% (95% CI, 65.3 to 84.9) and was similar against the four dengue virus serotypes. The incidence of hospitalization for VCD was lower among participants who lived in intervention clusters (13 of 2905 participants [0.4%]) than among those who lived in control clusters (102 of 3401 [3.0%]) (protective efficacy, 86.2%; 95% CI, 66.2 to 94.3).
Guidance framework for testing of genetically modified mosquitoes, second edition
17049WHO, WHO-TDR, 2021-05-19 10:41:03.
For more than 2 decades, scientists have been working to harness the promise of molecular biology to develop genetically modified mosquitoes (GMMs) for use as public health tools to prevent the transmission of vector-borne diseases. Responding to a need for additional standards and guidance, the WHO Special Programme for Research and Training in Tropical Diseases (WHO-TDR) and the Foundation for the National Institutes of Health (FNIH) published in 2014 the first WHO Guidance framework for testing genetically modified mosquitoes. This revised version takes into account the technical progress made and lessons learned in this rapidly advancing field of research. Like the original guidance framework, it is intended to provide standards that foster quality and consistency in the processes for developing, testing and regulating these new genetic technologies. Best practices recommended in the 2021 guidance framework will further contribute to the comparability of results and credibility of conclusions in order to facilitate decision-making by countries interested in the potential use of GMMs as public health tools for the control of vector-borne diseases.
Selection of Sites for Field Trials of Genetically Engineered Mosquitoes with Gene Drive
16932G. C. Lanzaro, M. Campos, M. Crepeau, A. Cornel, A. Estrada, H. Gripkey, Z. Haddad, A. Kormos, S. Palomares and W. Sharpee, bioRxiv, 2021.04.28.441877. 2021-04-28 15:53:05.
Novel malaria control strategies using genetically engineered mosquitoes (GEMs) are on the horizon. Population modification is one approach wherein mosquitoes are engineered with genes rendering them refractory to the malaria parasite coupled with a low-threshold, Cas9-based gene drive. When released into a wild vector population, GEMs preferentially transmit these beneficial genes to their offspring, ultimately modifying a vector population into a non-vector one. Deploying this technology awaits evaluation including ecologically contained field trials. Here, we consider a process for site selection, the first critical step in designing a trial. Our goal is to identify a site that maximizes prospects for success, minimizes risk, and serves as a fair, valid, and convincing test of efficacy and impacts of a GEM product intended for large-scale deployment in Africa. We base site selection on geographical, geological, and biological, rather than social or legal, criteria. We recognize the latter as critically important but not preeminent. We propose physical islands as being the best candidates for a GEM field trial and present an evaluation of 22 African islands. We consider geographic and genetic isolation, biological complexity, island size, topography, and identify two island groups that satisfy key criteria for ideal GEM field trial sites.Competing Interest StatementThe authors have declared no competing interest.
Ecological Relationships of Mosquito Disease Vectors: Anticipating Risk Assessment of Gene Drive Technologies
16707Stephanie James, Hector Quemada and David O'Brochta, GeneConvene Global Collaborative, 2021-04-14 17:54:18.
An often-raised concern for the development of genetically modified mosquito technologies, particularly those involving gene drive, as tools to prevent disease transmission is the limitation of our understanding of the roles these species may play within the ecosystem. This series of webinars begins to explore what is known about the ecological relationships of mosquito vectors with regard to major types of species interactions. The speakers also will describe some of the methods by which potential interactions that may impact human or animal health and the environment can be examined in the context of case-by-case risk assessment and safety testing.
US Gene Drive Governance: A Special Feature in Health Security
16685L. Warmbrod, A. Kobokovich, R. West, G. K. Gronvall and M. Montague, Health Security, 19:131-132. 2021-04-08 14:51:20.
The novel potential of gene drives and related genetic pest control measures highlights a gap in the oversight of products using such technologies in the United States. The US Coordinated Framework for Regulation of Biotechnology, as applied by US Environmental Protection Agency, the US Food and Drug Administration, and US Department of Agriculture, may not fully encompass modern synthetic biology techniques that have significantly expanded the scope of genetic modification technology applications.
Systematic identification of plausible pathways to potential harm via problem formulation for investigational releases of a population suppression gene drive to control the human malaria vector Anopheles gambiae in West Africa
16668J. B. Connolly, J. D. Mumford, S. Fuchs, G. Turner, C. Beech, A. R. North and A. Burt, Malaria Journal, 20:170. 2021-03-29 18:49:26.
Population suppression gene drive has been proposed as a strategy for malaria vector control. A CRISPR-Cas9-based transgene homing at the doublesex locus (dsxFCRISPRh) has recently been shown to increase rapidly in frequency in, and suppress, caged laboratory populations of the malaria mosquito vector Anopheles gambiae. Here, problem formulation, an initial step in environmental risk assessment (ERA), was performed for simulated field releases of the dsxFCRISPRh transgene in West Africa.
GeneConvene Webinar Series on: Ecological Modeling in Risk Assessment of Gene Drives
16435Hector Quemada and David O'Brochta, 2021-02-23 16:59:25.
Unlike non-gene drive organisms, which can be limited in time and space and therefore provide data in small scale tests that can be relevant to large scale releases, the potential for large-scale spread from a limited release, even in well-isolated trials, means that reliance on models will be a more important tool for risk assessors. To date, this work has only started to receive attention. This series of four presentations deals with the development and use of models in ecology generally. Some of these presentations will also deal with the use of models specifically to assess the ecological impacts of gene drive organisms.
Making gene drive biodegradable
15687J. Zapletal, N. Najmitabrizi, M. Erraguntla, M. A. Lawley, K. M. Myles and Z. N. Adelman, Philosophical Transactions of the Royal Society B: Biological Sciences, 376:20190804. 2020-12-28 15:02:10.
Here, we consider the inclusion of self-elimination mechanisms into the design of homing-based gene drive transgenes. This approach not only caused the excision of the gene drive transgene, but also generates a transgene-free allele resistant to further action by the gene drive. Strikingly, our models suggest that this mechanism, acting at a modest rate (10%) as part of a single-component system, would be sufficient to cause the rapid reversion of even the most robust homing-based gene drive transgenes, without the need for further remediation.
Core commitments for field trials of gene drive organisms
15161K. C. Long, L. Alphey, G. J. Annas, C. S. Bloss, K. J. Campbell, J. Champer, C.-H. Chen, A. Choudhary, G. M. Church, J. P. Collins, K. L. Cooper, J. A. Delborne, O. R. Edwards, C. I. Emerson, K. Esvelt, S. W. Evans, R. M. Friedman, V. M. Gantz, F. Gould,, Science, 370:1417-1419. 2020-12-17 20:01:12.
While field trials of gene drive organisms (GDOs) ultimately will depend on public policy decisions, those engaged in GDO work can play critical roles in support of these decisions by generating evidence and developing evaluation strategies in fair and effective partnerships with relevant authorities and other stakeholders. The authorship of this statement reflects the current reality that GDO development is occurring primarily in high-income countries. However, fair partnership with counterparts and communities in low- and middle-income countries where many GDOs have the highest potential for positive impact, as well as recognition of the need for capacity-building and global cooperation, underlies each of our commitments.
Adequacy and sufficiency evaluation of existing EFSA guidelines for the molecular characterisation, environmental risk assessment and post-market environmental monitoring of genetically modified insects containing engineered gene drives
15043E. Panel o. G. M. Organisms, H. Naegeli, J.-L. Bresson, T. Dalmay, I. C. Dewhurst, M. M. Epstein, P. Guerche, J. Hejatko, F. J. Moreno, E. Mullins, F. Nogué, N. Rostoks, J. J. Sánchez Serrano, G. Savoini, E. Veromann, F. Veronesi, M. B. Bonsall, J. Mumfor, EFSA Journal, 18:e06297. 2020-11-12 19:24:46.
As a proactive measure, the European Food Safety Authority (EFSA) has been requested by the European Commission to review whether its previously published guidelines for the risk assessment of genetically modified animals (EFSA, 2012 and 2013), including insects (GMIs), are adequate and sufficient for GDMIs, primarily disease vectors, agricultural pests and invasive species, for deliberate release into the environment. Under this mandate, EFSA was not requested to develop risk assessment guidelines for GDMIs. In this Scientific Opinion, the Panel on Genetically Modified Organisms (GMO) concludes that EFSA's guidelines are adequate, but insufficient for the molecular characterisation (MC), environmental risk assessment (ERA) and post-market environmental monitoring (PMEM) of GDMIs. While the MC,ERA and PMEM of GDMIs can build on the existing risk assessment framework for GMIs that do not contain engineered gene drives, there are specific areas where further guidance is needed for GDMIs.
NIH NExTRAC (Novel and Exceptional Technology and Research Advisory Committee) | Workshop
15015NIH Office of Science Policy, National Institutes of Health (NIH), 2020-11-09 19:56:25.
NExTRAC provides advice to the Director of the National Institutes of Health (NIH) on matters related to the conduct and oversight of research involving emerging technologies in biomedical science. NExTRAC also makes recommendations on research involving the use of, and developments in, emerging biotechnologies and will address scientific, safety, ethical, and social issues associated with areas of emerging biotechnology research for which the NIH requests advice or guidance. One of the technologies this committee is considering is gene drive. The November 2020 meeting was a workshop: GENE DRIVES: BIOSAFETY GUIDANCE AND CONDITIONS FOR FIELD RELEASE RESEARCH
Evaluation of genetically modified mosquitoes for the control of vector-borne diseases
14661Global Malaria Programme, WHO - Position Statement, 2020-10-13 15:58:38.
In the spirit of fostering innovation, WHO takes the position that all potentially beneficial new technologies, including GMMs, should be investigated to determine whether they could be useful in the continued fight against diseases of public health concern. Such research should be conducted in steps and be supported by clear governance mechanisms to evaluate the health, environmental and ecological implications
A home and rescue gene drive forces its inheritance stably persisting in populations
14006N. P. Kandul, J. Liu, J. B. Bennett, J. M. Marshall and O. Akbari, bioRxiv, 2020.08.21.261610. 2020-08-23 17:46:58.
We demonstrate that HomeR can achieve nearly ~100% transmission enabling it to persist at genotypic fixation in several multi-generational population cage experiments, underscoring its long term stability.
Modelling the suppression of a malaria vector using a CRISPR-Cas9 gene drive to reduce female fertility
13724A. R. North, A. Burt and H. C. J. Godfray, BMC Biology, 18:98. 2020-08-11 12:23:41.
Gene drives based on CRISPR-Cas9 technology are increasingly being considered as tools for reducing the capacity of mosquito populations to transmit malaria, and one of the most promising options is driving endonuclease genes that reduce the fertility of female mosquitoes. Here, we use simulation modelling to understand the factors affecting the spread of this type of gene drive over a one million-square kilometre area of West Africa containing substantial environmental and social heterogeneity.
Genomic analyses of a livestock pest, the New World screwworm, find potential targets for genetic control programs
13618M. J. Scott, J. B. Benoit, R. J. Davis, S. T. Bailey, V. Varga, E. O. Martinson, P. V. Hickner, Z. Syed, G. A. Cardoso, T. T. Torres, M. T. Weirauch, E. H. Scholl, A. M. Phillippy, A. Sagel, M. Vasquez, G. Quintero and S. R. Skoda, Nature Communications, 3:424. 2020-08-04 12:56:38.
We identify and analyze the expression of genes that are likely important for host-seeking behavior (chemosensory), development of larvae in open wounds in warm-blooded animals (heat shock protein, immune response) and for building transgenic strains for genetic control programs including gene drive (sex determination, germline). This study will underpin future experiments aimed at understanding the parasitic lifestyle of the screwworm fly and greatly facilitate future development of strains for efficient systems for genetic control of screwworm.
The potential for a CRISPR gene drive to eradicate or suppress globally invasive social wasps
13486P. J. Lester, M. Bulgarella, J. W. Baty, P. K. Dearden, J. Guhlin and J. M. Kean, Scientific Reports, 10:12398. 2020-07-24 17:41:41.
P. J. Lester, M. Bulgarella, J. W. Baty, P. K. Dearden, J. Guhlin and J. M. Kean (2020). Scientific Reports. doi: 10.1038/s41598-020-69259-6 Gene drives have potential for widespread and cost-efficient pest control, but are highly controversial. We examined a potential gene drive targeting spermatogenesis to control the invasive common wasp (Vespula vulgaris) in New Zealand.
Position Paper on Integrated Vector Management: Strengthening AU Members’ Regulatory Capacities for Responsible Research Towards Elimination of Malaria in Africa
12743African Union Development Agency - NEPAD, AUDA-NEPAD, 2020-06-01 13:48:16.
Africa continues to bear a heavy brunt of the malaria which is a disease transmitted by the female Anopheles mosquito. Thousands of lives, mostly of young children, are lost every year; which undermines efforts deployed at various levels for increased life expectancy and improved wellbeing for the socio-economic transformation of the continent. Accelerated changes and complementary tools are urgently needed to ensure effective elimination of malaria on the continent. Genetic engineering has been identified as one of such promising tools when applied to mosquito populations to reduce the transmission of the malaria parasite. The African Union Development Agency – NEPAD (AUDA-NEPAD), based on recommendations from the African Union High-Level Panel on Emerging Technologies (APET), continues to provide African Union Members States with the necessary support to ensure that research on and development of new genetically-based vector control tools are conducted in a responsible manner and in full compliance with safety requirements for human health and the environment for the benefit of African communities.
Gene Drives: Pursuing opportunities, minimizing risk
11966K. L. Warmbrod, A. Kobokovich, R. West, G. Ray, M. Trotochaud and M. Montague, Center for Health Security, 2020-05-18 18:14:50.
This study analyzed the current state of gene drive technologies, the ways in which they might be deployed in the field, and the state of regulatory policy governing their development.
Toward the definition of efficacy and safety criteria for advancing gene drive-modified mosquitoes to field testing
7971S. L. James, J. M. Marshall, G. K. Christophides, F. O. Okumu and T. Nolan, Vector Borne and Zoonotic Diseases, 20:237. 2020-03-09 14:54:00.
Mosquitoes containing gene drive systems are being developed as complementary tools to prevent transmission of malaria and other mosquito-borne diseases. As with any new tool, decision makers and other stakeholders will need to balance risks (safety) and benefits (efficacy) when considering the rationale for testing and deploying gene drive-modified mosquito products. Developers will benefit from standards for judging whether an investigational gene drive product meets acceptability criteria for advancing to field trials. Such standards may be formalized as preferred product characteristics and target product profiles, which describe the desired attributes of the product category and of a particular product, respectively. This report summarizes discussions from two scientific workshops aimed at identifying efficacy and safety characteristics that must be minimally met for an investigational gene drive-modified mosquito product to be deemed viable to move from contained testing to field release and the data that will be needed to support an application for first field release.
Pathway to deployment of gene drive mosquitoes as a potential biocontrol tool for elimination of malaria in sub-Saharan Africa: Recommendations of a scientific working group
3982James, SC, Frank H.; Welkhoff, Philip A.; Emerson, Claudia; Godfray, H. Charles J.; Gottlieb, Michael; Greenwood, Brian; Lindsay, Steve W.; Mbogo, Charles M.; Okumu, Fredros O.; Quemada, Hector; Savadogo, Moussa; Singh, Jerome A.; Tountas, Karen H.; Touré, American Journal of Tropical Medicine and Hygiene, 98:1-49. 2018-01-20 00:00:00.
Gene drive technology offers the promise for a high-impact, cost-effective, and durable method to control malaria transmission that would make a significant contribution to elimination. Gene drive systems, such as those based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein, have the potential to spread beneficial traits through interbreeding populations of malaria mosquitoes. However, the characteristics of this technology have raised concerns that necessitate careful consideration of the product development pathway. A multidisciplinary working group considered the implications of low-threshold gene drive systems on the development pathway described in the World Health Organization Guidance Framework for testing genetically modified (GM) mosquitoes, focusing on reduction of malaria transmission by Anopheles gambiae s.l. mosquitoes in Africa as a case study. The group developed recommendations for the safe and ethical testing of gene drive mosquitoes, drawing on prior experience with other vector control tools, GM organisms, and biocontrol agents. These recommendations are organized according to a testing plan that seeks to maximize safety by incrementally increasing the degree of human and environmental exposure to the investigational product. As with biocontrol agents, emphasis is placed on safety evaluation at the end of physically confined laboratory testing as a major decision point for whether to enter field testing. Progression through the testing pathway is based on fulfillment of safety and efficacy criteria, and is subject to regulatory and ethical approvals, as well as social acceptance. The working group identified several resources that were considered important to support responsible field testing of gene drive mosquitoes.
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