Scientists Use CRISPR to Genetically Modify Sterile Malaria-Carrying Mosquitos

Tuesday, 08 December 2015 - 10:16AM
Genetic Engineering
Tuesday, 08 December 2015 - 10:16AM
Scientists Use CRISPR to Genetically Modify Sterile Malaria-Carrying Mosquitos
Could we see a cure to malaria in the near future? Two recent studies have demonstrated that "gene drives" using the gene editing tool CRISPR can genetically modify carrier mosquitos in order to prevent the spread of the disease.

Gene drives refer to the practice of proliferating a certain gene throughout populations at a rapid speed, usually in insect populations. They involve replacing a specific gene with another gene, along with a genetic mechanism for copying the gene many times in the genome, virtually ensuring that it will be passed onto the offspring. They've been theorized for many years, and now with the advent of CRISPR, scientists finally have a genetic modification tool that is precise enough to modify the genome in a specific place and make gene drives feasible in real life.
In the new study from researchers in London, a team of scientists altered a species of carrier mosquitos in order to make them sterile. Last month, a team of scientists at the University of California announced that they had successfully modified a type of carrier mosquito in order to prevent it from transmitting the disease through its bite. But where the UC study involved mosquitos that cause about 100,000 cases per year, this new study modified mosquitos that are responsible for about 100 million, so "this latest study is a much bigger deal," according to Kevin Esvelt of Harvard's Wyss Institute for Biologically Inspired Engineering, a pioneer in the gene drive technology.

But either way, both groups of scientists are "probably no more than a year away from something that could conceivably be released in the wild and expected to work," said Esvelt.

The one-year timeline refers to the technology being ready, but the world won't be ready for longer than that. More lab research as well as practical trials are necessary before implementing the technique, it "will be at least 10 more years before gene-drive malaria mosquitoes could be a working intervention," said Austin Burt of Imperial College London, a co-author of the new study.

In addition, there are wider concerns involving the gene drive technology, particularly that it could theoretically also be used to quickly proliferate a deadly bioweapon. By engineering a few rapidly reproducing insects, like mosquitos, with a gene for producing a toxin and arming them with a gene drive, the disease would soon spread across the mosquito population, and they would, in turn, infect humans with the poison. The FBI recently met with biology researchers at the National Academy of Sciences in order to discuss gene drives, and discussed the possibility of "entomological warfare."

But still, a potential method for reducing malaria is nothing to sneeze at, and once the sterility gene drive is implemented, it could drastically reduce or even eliminate local populations of the mosquito "within a few years."

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"All successful malaria control programs to date have relied on [mosquito] control through population suppression," said lead author Tony Nolan, but "there is no reason to think the approaches are incompatible. Finding new tools to fight malaria should mean that we look at all possible options."
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