James, A. A. | bioRxiv Science

bioRxiv2020

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

The development of Cas9/gRNA-mediated gene-drive systems has bolstered the advancement of genetic technologies for controlling vector-borne pathogen transmission. These include population suppression approaches, genetic analogs of insecticidal techniques that reduce the number of vector insects, and population modification (replacement/alteration) approaches, which interfere with competence to transmit pathogens. We developed a recoded gene-drive rescue system for population modification in 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 a functional resistant allele does 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.

genetics↗

bioRxiv2019

Cas9-mediated gene-editing in the malaria mosquito Anopheles stephensi by ReMOT Control

Innovative tool development is essential for continued advancement in malaria control and depends on a deeper understanding of the molecular mechanisms that govern transmission of malaria parasites by Anopheles mosquitoes. Targeted disruption of genes in mosquito vectors is a powerful method to uncover the underlying biology of vector-pathogen interactions, and genome manipulation technologies can themselves form the basis of mosquito and pathogen control strategies. However, the embryo injection methods used to genetically manipulate mosquitoes, and in particular Anopheles species, are difficult and inefficient, particularly for non-specialist laboratories. We have adapted a strategy called ReMOT Control (Receptor-mediated Ovary Transduction of Cargo) to deliver the Cas9 ribonucleoprotein complex to adult mosquito ovaries and generate targeted and heritable mutations in the malaria vector Anopheles stephensi. We found that gene editing by ReMOT Control in Anopheles mosquitoes was comparable to the technique in Ae. aegypti and as efficient in editing as standard embryo injections. The adaptation of this technology to Anopheles mosquitoes opens up the power of reverse genetics to malaria vector labs that do not have the equipment or technical expertise to perform embryo injections and establishes the flexibility of ReMOT Control for gene-editing in non-Aedes species.

genetics↗