Genetic Engineering Alters Mosquitoes' Sense of Smell

In one of the first successful attempts at genetically engineering mosquitoes, HHMI researchers have altered the way the insects respond to odors, including the smell of humans and the insect repellant DEET.

The research not only demonstrates that mosquitoes can be genetically altered using the latest research techniques, but paves the way to understanding why the insect is so attracted to humans, and how to block that attraction. The time has come now to do genetics in these important disease-vector insects.

I think our new work is a great example that you can do it," says Leslie Vosshall, an HHMI investigator at The Rockefeller University who led the new research. Vosshall's first target: a gene called orco, which her lab had deleted in genetically engineered flies 10 years earlier. "We knew this gene was important for flies to be able to respond to the odors they respond to," says 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."

When given a choice between a human and any other animal, normal Aedes aegypti will reliably buzz toward the human. But the mosquitoes with orco mutations showed reduced preference for the smell of humans over guinea pigs, even in the presence of carbon dioxide, which is thought to help mosquitoes respond to human scent. "By disrupting a single gene, we can fundamentally confuse the mosquito from its task of seeking humans," says Vosshall.