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Unlike humans, who are usually hungry just hours after eating, a female mosquito that has been fed human blood will lose its appetite for several days. Because female mosquitoes do not consume blood, the movement of female mosquitoes is the means by which mosquito-transmitted infections are transmitted, the researchers hypothesized that reducing the number of female mosquitoes fed is a way to reduce the spread of the disease.
In a study published on February 7 in the journal Cell, researchers said they identified drugs that could reduce the blood thirst of mosquitoes. These compounds act on the hormonal pathways that signal to a mosquito that it is full.
"We are starting to run out of ideas for treating insects that spread diseases, and this is a totally new way of thinking about insect control," said lead author Leslie Vosshall, a researcher at the Howard Hughes Medical Institute and Laboratory. of Neurogenetics and Behavior of Rockefeller University. "Insecticides fail because of resistance, we have not found a way to make better repellents, and we do not have enough effective vaccines against most mosquito-borne diseases yet."
The new research has used Aedes aegypti mosquitoes, which spread pathogenic viruses such as yellow fever, dengue, Zika and chikungunya. Woman Ae. aegypti feeds on human blood to feed its growing eggs. Because a woman Ae. The mosquito aegypti has several broods during her life, she needs several meals. This cycling behavior offers many opportunities to transmit an infectious virus from one human to another.
But after eating a meal that doubles its weight, the female mosquito loses the desire to eat again for at least four days. The Vosshall laboratory has hypothesized that some neuropeptide hormones are responsible for the attraction of a mosquito to humans and that the diet has disabled these pathways. "We know that these pathways are important in human hunger.As they are conserved during the course of evolution, we have made the decision to use drugs for human nutrition to see if they would suppress the mosquitoes' appetite, "she says. "Finding that the pathways work the same way in mosquitoes gave us the confidence to continue this research."
His lab has identified a receptor called the neuropeptide receptor type Y 7 (NPYLR7) as one that tells the female mosquito if she is hungry or not. They then performed a high-throughput screening in tissue culture cells of more than 265,000 compounds to determine which would activate the NPYLR7 receptor.
Once they identified the best candidates, they tested 24 of them, among mosquitoes, and found that compound 18 worked better. The drug was able to inhibit the bite and feeding behaviors when the mosquitoes were exposed to the scent of a human being or to a source of warm blood. "When they are hungry, these mosquitoes are highly motivated.They fly to the scent of a human being in the same way that we could approach a chocolate cake," says Vosshall. "But after receiving the drug, they lost interest."
More work needs to be done before a compound can be developed for mosquito control. Researchers need to better understand the basic biology of the receptor and the best way to exploit it. In addition, future studies will need to focus on the best way to transmit the drugs to mosquitoes. An idea is a food that would attract women to come to drink the drug rather than drink blood.
Vosshall notes that if the techniques prove effective, they will likely work with other types of mosquitoes, such as those that spread malaria, as well as other arthropods that feed on human blood, including ticks that spread Lyme disease.
"Another benefit of this approach is that the effects of the drug are not permanent," she concludes. "This reduces appetite for a few days, which will naturally reduce reproduction as well, but it does not seek to eradicate mosquitoes, an approach that could have many other unintended consequences."
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Material provided by Cell press. Note: Content can be changed for style and length.
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