On localizing the effects CRISPR Gene-Drives and safeguarding our shared future

Abstract

Through advances in homing endonuclease engineering and the advent of the CRISPR class RNA-guided endonucleases, the construction, testing, and field deployment of gene drive technology have moved rapidly from theory into practice in laboratories around the world. As with any new technology, these advances bring about both benefits, as well as a slew of new concerns over the technology’s potential for catastrophic accidents, dual use, and long-term environmental impact. Thus, it is imperative to develop methods which limit the endless nature of classical gene drive designs, which will not only expand the utility and benefits of gene drive applications through localization of deployment, but also reduce the potential impact of an accidental escape during laboratory research. This project sets out to define and explore the possibility of containing, or localizing, a gene drive deployment by simultaneously introducing weaknesses into the self-propagating elements of a gene drive, and taking advantage of bottlenecks in matting populations to limit the spread of a given gene drive to a local gene pool. This is accomplished by breaking up components of a gene into several interdependent, self-driving elements, forming the daisy-chain gene drive system. In such a system, one of the essential components of the drive will not be self-driving, thus allowed to be diluted through repeated mating events with wild-type. To further expand on this idea, one can seed multiple copies of the non-driving element throughout an organism’s entire genome, allowing for further control over the number of times generations the drive is allowed to copy itself through a technique called daisyfield gene drive. Finally, daisy-quorum drives are where drive elements are inserted directly into and replace the function of essential, haploinsufficient genes in the genome, reducing the viability, and the evolutionary fitness, of hybrid offspring which result from mating events with wild-type organisms. Based on these techniques, a new generation of gene drives can be engineered and deployed that are limited in their ability to spread and pose a significantly lower risk of permanently altering the genome of the global population of an entire species. Combined with the research safety techniques outlined in this project, it is my hope iii that the techniques outlined in this work can improve the safety of future gene drive research and pave the way for eventual deployment.