Understanding the evolutionary space for the development of insecticide resistance

Insecticides have been the single most important tool in the effort to reduce the burden of malaria since the millennium, which resulted in halving the annual death rate for this disease.

However, selection on natural variation in genes that encode the molecular targets of insecticides can lead to the rapid proliferation of alleles that confer insecticide resistance and are selected in wild mosquito populations where insecticide use is the mainstay of mosquito control. Well documented examples of resistance to some insecticides widely used in mosquito control programmes have been shown to be conferred by variation of the ‘target site’ of mosquito proteins ordinarily bound, and blocked, by the insecticide molecule. This is referred to as target site resistance.

Extensive new genome resequencing studies of wild caught mosquitoes across sub-Saharan have revealed regions of the genome that appear to be under strong selection because they confer target site resistance. Additionally, protein modelling has been used to make predictions about how insecticide molecules interact with their target.

To complement these studies, this project looks to develop a form of accelerated evolution in vivo, to actively generate as wide a range of target site variants as possible, through the use of CRISPR genome editing tools, active in the germline of the mosquito. Mutations induced by this system will be subjected to an insecticide-based selection regime that should determine the effect of the various mutations on the resistance profile of the mosquito, allowing an accurate picture of the interaction between insecticide and mosquito ligand and potentially informing new or modified insecticide design.

Where does the project lie on the Translational Pathway?

T1 (Basic Research) – T2 (Human/Clinical Research)

Expected Outputs

The project will produce high quality REF returnable 3*/4* publications and will provide the evidence base for large scale research council, philanthropic (e.g. OP and Gates) and industry funding – in particular an industrial partnership award

Training Opportunities

Mosquito transgenesis, embryo microinjection, CRISPR, genome editing, bioinformatics, DNA cloning

Skills Required

Desirable skills to include:- Bioinformatic and/or quantitative biology; molecular biology; aptitude for DNA cloning; nsectary experience; population genetics

Key Publications associated with this project

Halperin, S.O., Tou, C.J., Wong, E.B. et al. CRISPR-guided DNA polymerases enable diversification of all nucleotides in a tunable window. Nature 560, 248–252 (2018). https://doi.org/10.1038/s41586-018-0384-8

A Hammond, R Galizi, K Kyrou, A Simoni, C Siniscalchi, D Katsanos, M Gribble, D Baker, E Marois, S Russell, A Burt, N Windbichler, A Crisanti and T Nolan. A CRISPR-based Gene Drive System Targeting Female Reproduction in the Malaria Mosquito. Nature Biotechnology 34,78–83 (2016

A Hammond, K Kyrou, M Bruttini, A North, R Galizi, X Karlsson, F Carpi, R D’Aurizio, A Crisanti and T Nolan The dynamics of creation and selection of mutations resistant to a gene drive over multiple generations in the malaria mosquito PLoS Genetics 2017, Oct 9

Hanna, R.E., Doench, J.G. Design and analysis of CRISPR–Cas experiments. Nat Biotechnol 38, 813–823 (2020). https://doi.org/10.1038/s41587-020-0490-7

Natural diversity of the malaria vector Anopheles gambiae (2017) The Anopheles gambiae 1000 Genomes Consortium.  Nature 552,  96–100 (2017)

Deadline: Thursday 11th February 2021; 12:00 noon GMT

Further details on the MRC/DTP and CASE programmes and application guidance and process can be found here