Dengue and Zika viruses alter the smell of their hosts to attract mosquitoes

Dengue and Zika viruses are transmitted through mosquito bites. Now, a study by researchers in China shows that when humans and mice are infected with these viruses, they secrete a chemical that makes them more attractive to virus-spreading mosquitoes.

Nearly half of the world’s population lives in a dengue risk area. The lack of treatment means that many affected regions have high morbidity and mortality rates. The new study, published in the magazine Cellfound a way to reduce the release of this substance in mice and reduce the frequency of mosquito bites: treatment with a commercial acne drug.

The two viruses, of the genus flavivirus they depend on these insects to survive in the wild. When a healthy mosquito bites an infected host, it can contract the infection and then transmit it to other individuals through its bites.

Work shows that mosquitoes of the genus Aedes they have a host-seeking behavior, which can be motivated by the smell of animals infected with these viruses. The species Temples of the Egyptians there Aedes albopictus They are vectors of transmission of Zika and dengue fever.

Mosquitoes of the genus “Aedes” have a host-seeking behavior, which can be motivated by the smell of infected animals.

“Mosquitoes rely on their sense of smell to detect their hosts,” explains Gong Cheng, a researcher at Tsinghua University (Beijing) and lead author of the paper, “At the start of the study, we found that these insect vectors preferred research and feeding of infected mice, compared to other healthy mice”.

A sophisticated strategy to increase infection

To determine why mosquitoes preferred infected hosts, the team analyzed skin odor samples from infected mice and humans to examine the odor molecules in the epidermis. Researchers have found that acetophenone, a substance present at abnormally high levels in the skin of infected people, is particularly attractive to mosquitoes.

In humans and mice, acetophenone is produced by certain bacteria of the genus Bacillus that grow on the skin. Normally, it produces an antimicrobial protein – called RELmalfa – which keeps bacilli populations at bay.

“Dengue virus and Zika virus promote the proliferation of acetophenone-generating skin bacteria by suppressing the expression of RELMalfa,” says Cheng. As a result, some bacteria replicate excessively and produce more acetophenone, making these diseased individuals more attractive to mosquitoes.

“Ultimately, the virus can manipulate the skin microbiome of its hosts to attract more mosquitoes and thus spread faster,” says Penghua Wang, immunologist at UConn Health University Medical Center (Connecticut, USA) and co- author of the study.

Dengue-infected people were more attractive to mosquitoes and showed more acetophenone on their skin than healthy people

Once the identity of the chemical compound was revealed, the researchers found that when mice infected with dengue were given isotretinoin (an acne drug), they emitted less acetophenone, which reduced their attractiveness to humans. mosquitoes.

This medicine is a derivative of vitamin A, which is known to increase the production of antimicrobial peptide in the skin.

The experience was simple. The researchers fed the mice isotretinoin and put them in a cage with mosquitoes. They found that mosquitoes did not feed on infected mice treated with the anti-acne drug more than those that fed on uninfected animals.

As Cheng explains at SINC, “The administration of isotretinoin through the diet of animals infected with flaviviruses reduces acetophenone production because it remodels bacteria populations on the host’s skin.”

Similar mechanisms in other viruses

“Although we do not have data for other flaviviruses, such as yellow fever or West Nile virus, we believe there is a strong possibility that other of these viruses share similar mechanisms for manipulate the smell of their host. For this reason, we will analyze other mosquito-borne flaviviruses and alphaviruses, under the same experimental conditions,” Cheng continues.

In the future, the team plans to apply their findings in the real world. “We plan to administer isotretinoin in the diet of dengue fever patients, to find out if this compound reduces the production of acetophenone in humans, as it does in mice,” explains the researcher.

The authors also plan a line of study in mosquitoes: “We want to identify specific olfactory receptors for acetophenone in these insects and knock out genes from the mosquito population using gene drive technology,” says Cheng.

Without the receptors, mosquitoes will no longer be able to sense the skin molecule they love so much, possibly mitigating the spread of dengue fever and other flaviviruses, the authors conclude.

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