Johns Hopkins scientists genetically engineer a malaria-resistant mosquitoes

Anopheles gambiae mosquito being injected with hemolymph for malaria research. (NIAID)

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Mosquitoes are bad news when it comes to the spread of malaria, a deadly disease that kills hundreds of thousands of people per year. We have previously covered a range of approaches to crack down on this problem, ranging from the apps that track disease-carrying mosquitoes by listening to their buzz to have a plan for the release of genetically engineered killer mosquitoes hunt their disease-with wild conspecifics.

Now, researchers from the Johns Hopkins University may have a different approach, and the CRISPR/Cas9 gene editing. Specifically, they have engineered mosquitoes that are resistant to the malaria parasite, by removing a gene called FREP1 that helps malaria to survive in the intestine of the mosquito.

“A big problem with the control of malaria is a disease of the poor in developing countries and requires an active compliance and participation of the indigenous population,” George Dimopoulos, a professor at the Johns Hopkins Bloomberg School of Public Health, told Digital Trends.

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The problem with this is that active compliance and participation means that people taking malaria medication, the removal of larval breeding sites and use of mosquito nets, all the things that are not always possible in areas where resources are scarce. Johns Hopkins’ genetically modified (GM) mosquito, on the other hand, is a suitable solution, because it does not require such active participation.

In trials in which the new FREP1-modified mosquitoes, the researchers demonstrated that the malaria parasite was unable to survive long enough to mature to a stage where it acts as a warning for the man. “The efficacy of the parasite to block in the GM mutant mosquitoes is such that it most probably would have an epidemiological impact if one could replace, a natural wild-type mosquito population with our GM mutants,” Dimopoulos continued.

Unfortunately, for now, there is a hitch in the plan: The GM-mosquitoes develop more slowly than ordinary mosquitoes, are less inclined to feed on blood, and lay fewer eggs. All those things may sound good from a human perspective, but they also mean that the mosquitoes are less likely to pass their genes — and that would be the wind on the wrong side of natural selection.

“The problem is that these GM mutants have a fitness cost,” Dimopoulos said. “The current studies are addressing this issue, and try to find ways for these mosquitoes as competitive as the wild-type. A way perhaps to do this is to inactivate the parasite-host-factor, FREP1, in the adult female gut only, in contrast to the entire mosquito in all stages of development. One can also see the integration of our strategy with a so-called gene drive to more effectively drive the changes in a mosquito population.”

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