March 4, 2021

expert reaction to a paper suggesting that gene drives could be used to help control grey squirrel numbers in the UK

A paper published in Scientific Reports looks at a novel combination of CRISPR‑based gene drives to control invasive grey squirrel in the UK.

Prof Luke Alphey, Group Leader in Arthropod Genetics, The Pirbright Institute, said:

“This study assesses the prospects for using a gene drive to control invasive grey squirrels in the UK. This is a modelling study exploring the potential for such an approach – no such gene drives currently exist and developing them for grey squirrels would be quite a long-term project. Invasive species are a major problem for biodiversity and conservation; in many cases there are no adequate methods for control. Genetic methods may provide new options, potentially both more effective and with fewer off-target effects. Most work on gene drives has focused on mosquitoes; this study is unusual in focusing on a vertebrate (grey squirrel), though there has also been interest in targeting invasive populations of mice and rats on islands.

“‘Gene drive’ is a broad term covering many systems with varying properties. The authors consider several leading designs, settling on a variant that is ‘local’, i.e. will not spread far beyond the populations into which it is released, along with other desirable properties. As with any modelling study, there are a number of assumptions in the models, but these are carefully explained by the authors. The authors conclude that such gene drives could potentially be very effective if they could be built, and provide some pointers as to how to build them, though that remains a significant challenge. Regulatory approval and public acceptance would obviously be essential before any actual use of such technology – that is a long way off, but this paper indicates that gene drives could be a valuable tool in the conservation toolbox.”

Dr Tony Nolan, Senior Lecturer, Liverpool School of Tropical Medicine (LSTM), said:

“This is a theoretical study that is interesting for the way in which it combines different elements of gene drives that have previously been proposed, in ways that could reduce the likelihood of resistance developing to the gene drive, and could provide a way of localising its spread. The challenge will be in translating these elements from theory into practical testing in the laboratory, which will be no trivial exercise. Demonstration of its practical feasibility would be a significant milestone. In the meantime, studies like this are useful for informing conversation about the relative merits of gene drive for controlling grey squirrels, and more broadly as a potential new conservation tool to protect endangered species.”

‘Novel combination of CRISPR‑based gene drives eliminates resistance and localises spread’ by Nicky Faber et al. will be published in Scientific Reports at 16:00 UK time on Thursday 4^th March 2021, which is also when the embargo will lift.

DOI: 10.1038/s41598-021-83239-4

Declared interests

None others received.