Genetically-Engineered Mosquitoes Can't Smell A Human

Mosquitoes are rumored to have killed half the humans that ever lived, and their notorious reputation doesn't seem to be slowing down. In an effort to fight off one of the most threatening insects to humans, scientists have engineered a mosquito with a lessened appetite for human blood. 

Researchers from the Howard Hughes Medical Institute (HHMI) honed in on a mosquito's scent for human blood in order to counter the pest. Lead researcher on the study Leslie Vosshall chose to focus on a very specific gene: orco, a gene that affected olfactory responses in flies.

"We knew this gene was important for flies to be able to respond to the odors they respond to," said Vosshall. "And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes."

The team selected the mosquito species Aedes aegypti as the test subject. Aedes aegypti has an affinity for human blood - to the extent the skeeter will reliably buzz its way toward a human if given the choice between a human or another animal - and is responsible for transmitting deadly diseases like dengue fever and yellow fever. Vosshall and fellow HHMI investigators used zinc-finger nucleases to mutate the orco gene. The results were encouraging.

"By disrupting a single gene, we can fundamentally confuse the mosquito from its task of seeking humans," says Vosshall.

Mosquito-related illnesses affect millions worldwide, and the team hopes that insights into mosquito behavior could lead to more effective methods of disease prevention than hiding behind nets. Malaria alone was responsible for over half a million deaths worldwide in 2019, of which 86 percent were children, according to the CDC and World Health Organization.

"We want to know what it is about these mosquitoes that makes them so specialized for humans," Vosshall explained.. "And if we can also provide insights into how existing repellants are working, then we can start having some ideas about what a next-generation repellant would look like." 

You can read the full published study in the journal Nature.