Gene drives for invasive pest management

In agriculture and wildlife, invasive pests are well known: rabbits and cane toads in Australia, grey squirrel in the UK, and the omnipresent infestation of rodents around the globe. Invasive vertebrate pests impact the environment, economy and society. Current control methods are costly and largely inadequate, and they often lead to unwanted suffering in target and non-target species. Gene drives that enable super-mendelian inheritance of a transgene may offer a more cost-effective, humane and species-specific alternative than current methods. We set out to develop and test a safe-guarded gene drive system, known as a split gene drive, that aims to spread female infertility through a laboratory-contained mouse population. Using mouse embryonic stem cell technology, we developed a CRISPR-Cas9 split gene drive which disrupts an essential female fertility gene and confers a recessive female-infertility phenotype. Split drive harbouring embryonic stem cells were developed using plasmid donor-DNA and a combination of SpCas9 ribonucleic protein and plasmid-based AsCas12a endonuclease. Engineered cells were validated using PCR, digital PCR and Sanger sequencing. A breeding population of split gene drive mice is being established to study the transmission frequency and phenotypic impact of the drive system in a model mouse population. The findings could help guide the development of safe gene drive systems for vertebrate pest management.