Dengue and Zica viruses make us more palatable to mosquitoes

An international team of researchers has found that when humans become infected with the dengue or the Zikasecrete a substance that makes them more attractive to mosquitoeswhich are the transmission vector of these virus.

The finding, published in the journal Cell, has helped scientists design a treatment based on a commercial acne medication that reduces the release of this substance in mice and thereby reduces mosquito bites.

Dengue, spread by mosquitoes in tropical areas around the world, causes fever, rash, pain, and sometimes bleeding and death.

Each year there are more than 50 million cases of dengue and about 20,000 deaths, most of them children, according to data from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health (NIH) of the United States.

Zika, transmitted by mosquitoes in the same family as dengue, does not usually cause serious illness in adults, but it does cause serious malformations in the fetuses of infected pregnant women.

Both viruses depend on mosquitoes for survival: when healthy mosquitoes bite an infected host, they can become infected themselves and spread the viruses to other animals. This is how these pathogens survive.

“Mosquitoes rely on their sense of smell to detect hosts. At the beginning of the study, we saw that they preferred to feed on mice infected with dengue and Zika”, explains Gong Cheng, lead scientist of the project at Tsinghua University who has led the research.

To find out why, the team analyzed odor samples from infected mice and humans and found that the culprit behind making them smell the most “delicious” was acetophenone, a compound also found in many fruits and cheeses, which was at an abnormally high level. in infected individuals.

“We found that flaviviruses [como el dengue y el Zika] they can use the increased release of acetophenone to help themselves achieve their life cycles more effectively, making their hosts more attractive to vector mosquitoes,” says Cheng.

Cheng and colleagues then investigated how dengue and Zika viruses manage to increase the level of acetophenone, describing it as “a sophisticated interaction between the skin microbiota of hosts, flaviviruses, and mosquitoes.”

When a flavivirus invades a host, the virus and the host’s body cells scramble to control the level of a key protein that regulates the composition of the skin’s microbiome. If the cells win, the microbiome keeps the acetophenone-producing bacteria at bay, but if the virus wins, the bacteria overreplicate and produce more acetophenone.

The result is that sick individuals smell as good to mosquitoes as a tray of freshly baked cookies, according to the authors.

Armed with this information, the team set out to find a way to help cells win the fight and decided to test whether isotretinoin – a vitamin A derivative commonly used as an acne medication – could suppress acetophenone production.

After feeding the mice isotretinoin and putting them in a cage with mosquitoes, the authors found that the mosquitoes fed equally on the isotretinoin-infected and uninfected mice.

Cheng and his team now plan to test their findings in the real world: “We want to administer isotretinoin in dengue patients to reduce acetophenone-mediated mosquito activity,” says Cheng.