title: Medusa: a novel gene drive system for confined suppression of insect populations.
abstract: Gene drive systems provide novel opportunities for insect population suppression by driving genes that confer a fitness cost into pest or disease vector populations; however regulatory issues arise when genes are capable of spreading across international borders. Gene drive systems displaying threshold properties provide a solution since they can be confined to local populations and eliminated through dilution with wild-types. We propose a novel, threshold-dependent gene drive system, Medusa, capable of inducing a local and reversible population crash. Medusa consists of four components--two on the X chromosome, and two on the Y chromosome. A maternally-expressed, X-linked toxin and a zygotically-expressed, Y-linked antidote results in suppression of the female population and selection for the presence of the transgene-bearing Y because only male offspring of Medusa-bearing females are protected from the effects of the toxin. At the same time, the combination of a zygotically-expressed, Y-linked toxin and a zygotically-expressed, X-linked antidote selects for the transgene-bearing X in the presence of the transgene-bearing Y. Together these chromosomes create a balanced lethal system that spreads while selecting against females when present above a certain threshold frequency. Simple population dynamic models show that an all-male release of Medusa males, carried out over six generations, is expected to induce a population crash within 12 generations for modest release sizes on the order of the wild population size. Re-invasion of non-transgenic insects into a suppressed population can result in a population rebound; however this can be prevented through regular releases of modest numbers of Medusa males. Finally, we outline how Medusa could be engineered with currently available molecular tools.
authors: Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.
authors: John M
authors: JM
authors: Marshall
authors: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America.
authors: Bruce A
authors: BA
authors: Hay
mesh_terms: D000465:Algorithms; D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics*; D000931:Antidotes / Q000378:metabolism*; D059006:Chromosomes, Insect / Q000235:genetics; D005260:Female; D005818:Genetic Engineering / Q000379:methods*; D005828:Genetics, Population / Q000379:methods; D040582:Inheritance Patterns; D007300:Insect Control / Q000379:methods*; D008297:Male; D008957:Models, Genetic; D013997:Time Factors; D014118:Toxins, Biological / Q000235:genetics*; D019076:Transgenes / Q000235:genetics; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics
chemical_list: D000931:Antidotes; D014118:Toxins, Biological