Efficient population modification gene-drive rescue system in the malaria mosquito Anopheles stephensi

Cas9/gRNA-mediated gene-drive systems have advanced development of genetic technologies for controlling vector-borne pathogen transmission. These technologies include population suppression approaches, genetic analogs of insecticidal techniques that reduce the number of insect vectors, and population modification (replacement/alteration) approaches, which interfere with competence to transmit pathogens. Here, we develop a recoded gene-drive rescue system for population modification of the malaria vector, Anopheles stephensi, that relieves the load in females caused by integration of the drive into the kynurenine hydroxylase gene by rescuing its function. Non-functional resistant alleles are eliminated via a dominantly-acting maternal effect combined with slower-acting standard negative selection, and rare functional resistant alleles do not prevent drive invasion. Small cage trials show that single releases of gene-drive males robustly result in efficient population modification with >= 95% of mosquitoes carrying the drive within 5-11 generations over a range of initial release ratios. Gene drives may be impeded by the generation of resistant alleles following NHEJ. Here the authors develop a recoded gene-drive rescue system for the malaria mosquito, Anopheles stephensi, that targets the drive to the kynurenine hydroxylase gene for negative selection against mutated alleles.