Every time a mosquito is lured to the scent of your skin, you're at risk of contracting malaria, dengue fever, West Nile virus, or another deadly disease. A study published by Cell Press December 5th in the journal Cell has revealed an important class of neurons responsible for a mosquito's attraction to human skin odor, as well as odors that stimulate and inhibit the activity of these neurons. The findings could lead to a new generation of repellants and traps for effective mosquito control worldwide.
"These findings open up very realistic possibilities of developing ways to use simple, natural, affordable, and pleasant odors to prevent mosquitoes from finding humans," says senior study author Anandasankar Ray of the University of California, Riverside. "The powerful experimental approaches we have developed will help us find potential solutions that we could use not only here in the United States but also in Africa, Asia, and South America, where affordability is key in the war against these diseases."
Mosquitoes are attracted to our skin odor as well as plumes of carbon dioxide that we exhale. In previous studies, scientists found that mosquitoes have olfactory cells called cpA neurons that are responsible for detecting carbon dioxide. But until now, the identities of the neurons required for attraction to skin odor were a mystery.
In the new study, Ray and his team discovered that carbon-dioxide-sensitive cpA neurons are also sensitive detectors of human skin odor. This knowledge simplifies the challenge of blocking the mosquitoes' detection system, as there is only one class of neurons to eliminate both attractive triggers. In light of this research, developing drugs to inhibit the receptors could also be much simpler, as the cell-surface molecule that detects CO2 is a relatively stable structure, whereas odor molecules can take an almost infinite variety of molecular structures. Mosquitoes' attraction to human foot odor was strongly diminished when the insects were first exposed to a compound that inhibits the activity of these neurons by targeting the CO2 receptor.
The researchers then screened about half a million compounds and identified several that inhibit and activate cpA neurons. These compounds could be used in a complementary manner in safe and environmentally friendly repellants or traps to prevent mosquitoes from transmitting deadly diseases. "The insect olfactory system is an excellent target to manipulate their attraction to humans and other prey," Ray says. "We believe that this study will be the foundation for the discovery of a new generation of mosquito-behavior-modifying approaches."
Cell, Tauxe et al.: "Targeting a dual detector of skin and CO2 to modify mosquito host seeking."
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