Dengue and Zika virus with smell to attract mosquitoes

Dengue and Zika virus are transmitted by 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. Lack of treatment means many affected areas have high rates of morbidity and mortality. The new study, published in the journal Cellfound a way to reduce the release of this substance in mice and reduce the frequency of mosquito bites: treatment with a commercial acne medications.

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 have a behavior looking for guests, which may 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 feel to detect their guests”, explains Gong Chengresearcher at Tsinghua University (Beijing) and lead author of the paper, “At the start of the study, we found that these insect vectors preferred to search for and feed on infected mice, compared to healthy mice.”

A sophisticated strategy to increase infection

To determine why mosquitoes preferred infected hosts, the team analyzed samples of skin odor mice and infected humans to examine odor molecules in the epidermis. The researchers observed that the acetophenonea substance that was present at an abnormally high level on the skin of infected individuals, 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 this produces a antimicrobial protein –called RELMalfa– which keeps bacillus populations at bay.

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

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

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

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. researchers mice were fed 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 in animals infected with a flavivirus reduces the production of acetophenone because it remodels the bacteria populations on the host’s skin.

Similar mechanisms in other viruses

“Although we do not have data on other flaviviruses, such as yellow fever or West Nile virus, we believe it is quite possible that other of these viruses share similar mechanisms manipulate the smell of its 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 patientsin order to find out if this compound reduces the production of acetophenone in humans, as it does in mice”, indicates the researcher.

The authors also envisage a line of study on mosquitoes: “We want to identify olfactory receptors specific acetophenone in these insects and suppress 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.