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

TLDR

Cas9/gRNA gene‑drive systems have enabled genetic control of vector‑borne disease, including suppression and population‑modification strategies that alter pathogen transmission competence. The authors designed a recoded gene‑drive rescue system for *Anopheles stephensi* that restores kynurenine hydroxylase function to mitigate female fitness costs. The system employs a dominantly‑acting maternal effect and standard negative selection to eliminate non‑functional resistant alleles, while functional resistant alleles do not impede drive spread. Cage trials demonstrate that a single release of gene‑drive males achieves ≥95 % drive frequency in the population within 5–11 generations across various release ratios.

Abstract

Abstract 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.