The sci-fi technology tackling malarial mosquitos

Environmental campaigner Liz O’Neill doesn’t mince her words about gene drives – the next generation of genetic modification (GM) technology.

“It is extremely worrying,” says the director of UK anti-GM pressure group, GM Freeze. “To release something that has been specifically created in a laboratory in order to outfight nature, and spread without exception within wild populations, is extraordinary arrogant.

“And once the genie is out of the bottle, you cannot put it back in.

The way gene drives work sounds like something from a science fiction novel, but they are already being used in laboratory tests. It is complicated stuff, but here is a simple explanation.

While standard GM introduces a new, lab-tweaked gene into a organism, gene drive technology goes one stage further. It introduces a gene drive – a lab-created gene that can also automatically replicate itself – that targets and removes a specific natural gene.

This is how it works: if an animal (parent A) that contains a gene drive mates with one that doesn’t (parent B), then in the forming embryo that starts to combine their genetic material, parent A’s gene drive immediately gets to work.

It recognises the natural gene version of itself in the opposite chromosome from parent B, and destroys it, by cutting it out of the DNA chain. Parent B’s chromosome then repairs itself – but does so, by copying parent A’s gene drive.

So, the embryo, and the resulting offspring, are all but guaranteed to have the gene drive, rather than a 50% chance with standard GM – because an embryo takes half its genes from each parent.

Gene drives are created by adding something called Crispr, a programmable DNA sequence, to a gene. This tells it to target the natural version of itself in the DNA of the other parent in the new embryo. The gene drive also contains an enzyme that does the actual cutting.

So, what is the point of such complex technology? It is hoped that gene drives can be used to greatly reduce the numbers of malarial mosquitos, and other pests or invasive species.

This process is more effective than standard DNA because as every single offspring has the introduced gene trait it spreads much faster and further.

One organisation at the forefront of this is Target Malaria, which has developed gene drives that stop mosquitos from producing female offspring. This is important for two reasons – only the females bite, and without females, mosquito numbers will plummet.

The core aim is to greatly reduce the number of people who die from malaria – of which there were sadly 627,000 in 2020, according to the World Health Organization.

It could also slash the economic impact of the disease. With 241 million cases in 2020, mostly in Africa, malaria is estimated to cost the continent $12bn (£9.7bn) in reduced economic output every year.

The financial effect of invasive species – everything from cane toads, to lionfish, brown snakes, fruit flies, zebra muscles, and Japanese knotweed – is even higher. They cost the US and Canada $26bn (£21bn) a year, according to the US Department of Agriculture’s National Invasive Species Information Center. Globally, it puts the impact at $1.29tn over the past 50 years.

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