Genomic surveillance of a vector control trial

From the Anopheles gambiae 1000 Genomes project we have identified numerous candidate insecticide resistance loci, some of which are causally associated with resistance in wild populations. Many variants confer resistance multiple classes of insecticide. Recently, the CRISPR/Cas9 endonuclease system was adapted for transformation of Anopheles mosquitoes. This transformation system can be used to introduce mutations or entire transgenes into the mosquito genome in a site-specific manner. Through homology-directed repair, individual mutations can be introduced into mosquitoes without any additional exogenous DNA sequences. In addition, large transgene cassettes carrying both regulatory and protein coding sequences can be introduced. Using this tool we will introduce, individually, the target-site (eg Vgsc-1575Y; Vgsc-1874F) and metabolic (eg Gste2-114T; Cyp4j5; Cyp6m2) insecticide resistance-associated mutations we have identified into a fully susceptible strain of An. gambiae. By having lines with a standard genetic background we will be able to quantify the impact of individual mutations on susceptibility to a range of insecticides. We will be able to generate, with high fidelity, super-resistant lines which may be used by IVCC partners to test the efficacy of new and repurposed insecticides. This will enable industry to rationally market insecticides, reducing the chances of widespread distribution of potentially ineffective insecticides. The work will be beneficial to both discovery and development scientists, and will enable scientists / disease programme staff to have a clear understanding of the likely impacts of resistance, empowering them to develop insecticide resistance management strategies. Furthermore, policy makers will have access to normative testing procedures and a strong evidence base to support control decisions.