Genetically Engineered Pests: Ultimate Solution or Too Much Power?

September 16, 2015 | Sarah Tse

close-up of mosquito biting human skin.
Photo credit: Gilles San Martin/Flickr/CC BY-SA 2.0

A Google executive dreams of genetically engineering mosquitoes to eradicate diseases like malaria and dengue fever. But this technique could have unforeseen and dangerous consequences.

Imagine a world without mosquitoes, one where you could enjoy balmy summer evenings without having to worry about waking up the next morning covered in those itchy red bumps—it’s basically a dream come true.

In areas where mosquitoes carry deadly diseases, the blood-sucking insects are more than just a nuisance. Reducing the mosquito population or somehow making them less infectious would save hundreds of thousands of lives, and also improve socio-economic conditions in regions that are crippled by such diseases.

In Africa, one child dies from malaria every minute. Although mortality rates have dropped about 60% since 2000, the disease caused by Plasmodium parasites continues to ravage the continent. Dengue fever, on the other hand, is caused by a virus and has no cure or specific treatment other than rest and clinical care. The disease has become an epidemic in recent decades, with about 500,000 cases requiring hospitalization each year. Using genetic engineering to handicap mosquitoes and prevent them from spreading disease is a highly tantalizing prospect to anyone hoping to make an impact on human health.

That’s exactly what Linus Upson, a senior executive at Google, hopes to accomplish. According to a report at The Information, he has an idea for a project that he’s mentioned to his colleagues. Although he hasn’t officially announced the project, we can assume the initiative would fall under a new life-sciences division of Google’s re-organized corporate structure.

So how exactly would one go about genetically engineering mosquitoes? Upson has yet to elaborate on the specifics of his idea, but recent advances in genetic technology point to potential solutions.

One way to manage mosquito populations is the Sterile Insect Technique. This system sterilizes insects by engineering a self-limiting gene that shortens lifespan so the mosquitos never reach reproductive age. Scientists can suppress the gene in their lab-raised insects and release them to mate with wild insects. Like a sleeper agent, the gene is only activated when it’s inherited by offspring at which point it interferes with development and prevents them from ever reproducing on their own.

Scientists have already successfully used this method on mosquitoes in the Cayman Islands, resulting in an 80-95 percent reduction in population. But this system requires constant maintenance by reintroducing engineered mosquitoes every few generations to keep the self-limiting gene circulating. Plus, the remaining 20 percent of the mosquito population could still continue infecting people.

The revolutionary CRISPR gene-editing tool offers a more permanent solution. Based on an existing mechanism used by bacteria to defend against viruses, CRISPR allows scientists to precisely edit a gene — and it’s cheaper and easier than with any previous method. They can also ensure that the edited genes are passed on to all offspring using the gene-drive system, which hijacks normal cell division to pass on certain genes more frequently. Using these technologies, scientists could completely infiltrate a population of mosquitoes with, perhaps, an edited gene that keeps them from transmitting disease.

While this technology seems like a magic bullet — not only to eliminate malaria and dengue fever, but also to solve all kinds of health, agricultural, and even energy related problems — Upson may run into a few obstacles if he tries to implement CRISPR and gene-drive in his project.

Both technologies are incredibly new and still untested. We have no idea what long-term effects this kind of gene-editing may cause, or what happens when edited genes spread throughout a population. Once you release a modified individual into the wild, the edited gene will eventually alter the entire species—and there’s no way to undo it.

That’s why some scientists have banded together to issue a call for caution as research on gene-editing moves forward. Any lethal side-effects of CRISPR could have catastrophic ramifications since mosquitoes comprise a fundamental level in the food-chain. Before we can use the technology to eliminate these infectious diseases, we have to make sure we won’t inadvertently create worse problems for the entire eco-system. No matter how annoying mosquitoes are, we probably can’t survive without them.

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