Neutering Insect-borne Pestilences using CRISPR

You hear them buzzing in the dark.  They are seen crawling in the corners.  They latch onto your skin when you hike the woods.  Insects are everywhere.  They’ve lived amongst humans since time immemorial.  Some insects are important to humans.  For example, bees are needed to pollinate plants for agricultural purposes, in addition to producing honey and beeswax.  Silk is produced from silk worms.  Certain insects, like the Carpet beetles are used like vultures that eat up anything organic to clean skeletons!

However, insects are also the cause of many diseases that kill people, animals and plants.  For example, the annoying mosquito spreads many diseases like malaria, West Nile, yellow fever, Zika etc. all over the world.  Heartworm is a parasitic worm that is spread through mosquitos in pets.  Locusts ravage farmland in Africa and Asia causing economic losses and starvation. Traditional methods use pesticides to kill insects, however these chemicals themselves cause harm to the environment. Morever, insects become resistent to these pesticides and are harder to kill.

I learned about a new way of elimintating these dangerous insects while attending a webinar on “Medical Entomology” by Rutgers University professor, Dr. Chloe Hawkings. This promising technology called “gene drive” uses gene editing technology like CRISPR to edit insect genes that cause it to carry dieases. By modifying the genes of these insects and releasing them in the wild, they would mate with wild insects spreading the genetically modified genes throughout the insect population, thereby controling the population (Hawkings, C., 2020). This reduces the need for harmful pesticides, prevents pesticide resistance and reduces the harm to the environment. Gene drives can also help beneficial insects like bees which are being killed by various diseases.

One example of an engineered gene drive targets the mosquito genome to prevent malaria. The Anopheles gambiae or the African malaria mosquito spreads malaria by carrying a protozoan parasite that causes malaria which is then transmitted to the host while the female mosquito feeds on the host’s blood. Scientists are targeting the fertility gene called doublesex. By modifying this gene using CRISPR, it prevents the female offsprings from biting or laying eggs, preventing the transmission of the parasite (Nature Editorial, 2019). Similarly, modifying the genes of honey bees can make them resistant to bacteria or fungus that kills hives.

There are some potential drawbacks to the gene drive concept. It is not known if the modified gene will mutate into something more dangerous. It is also not known if the modified gene might enter another organism and mutate its genes. In fact the team that’s working on the doublesex gene is building reversal gene drives to control the spread of the gene drive within the target population (Nature Editorial, 2019). But it is interesting to see what CRISPR and other gene editing techniques can accomplish in non-medical fields for the betterment of humanity.

References

Hawkings, C. (2020, November 12) Medical Entomology [Webinar]. Rutgers University School of Biochemistry and Microbiology.

Nature Editorial. (2019, July 9). Self-destructing mosquitoes and sterilized rodents: the promise of gene drives. Nature. https://www.nature.com/articles/d41586-019-02087-5?error=cookies_not_supported&code=aee6b209-1c68-4697-84cb-d65856955e52

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