The reason why there are so many mosquitoes has been found. Does the virus attract mosquitoes by regulating skin bacteria to produce "mosquito attractants"?

Great scientific discovery!

Mosquitoes can actually locate humans through viruses! Chinese scientists have discovered for the first time that specific viruses can regulate the abundance of microorganisms on the host's skin and release mosquito-attracting gases.

The reason why humans are attractive to mosquitoes is that the decanal and undecanal present in human sebum can excite mosquitoes.

Some viruses transmitted by mosquitoes, after infecting the host, can actually affect the host's skin microbial community by regulating the expression of antibacterial proteins in the host's skin, causing specific microorganisms to multiply in large numbers and release odors that attract mosquitoes.

The researchers first infected mice with the Zika virus (ZIKV) and then observed whether Aedes mosquitoes preferred mice infected with Zika or mice that were not infected.

The results showed that mosquitoes indeed preferred mice infected with Zika virus:

70% of mosquitoes were attracted to infected mice, and the remaining 30% went to uninfected mice. This ratio is enough to explain the problem.

When Zika virus was replaced with dengue virus (DENV2), the results were the same, suggesting that mosquitoes do prefer hosts infected by mosquito-borne viruses.

Only acetophenone replicated the previous 70% to 30% experimental results. Moreover, acetophenone applied to human hands also attracted more mosquitoes. Dengue patients released much higher levels of acetophenone than healthy volunteers.

However, an important problem is that there is no enzyme in the genome of mammals that synthesizes acetophenone, including humans. In this case, the only target is human microorganisms. It is useless to eliminate digestive tract microorganisms alone, and it does not affect the preference of mosquitoes for infected mice;

Infected mice that had cleared their skin bacteria were much less attractive to mosquitoes, suggesting that the skin microbiota is key.

Subsequent analysis revealed that the number of Bacillus producing acetophenone had increased.

How does viral infection affect the abundance of Bacillus in the skin? The results are surprising! It turns out that mosquito-borne viruses inhibit the production of antimicrobial proteins (RELMa) in the skin, leading to the proliferation of bacteria that can produce acetophenone on the host's skin.

This co-evolution between mosquito-borne viruses and mosquitoes is truly fascinating.

According to the data, this trick of the mosquito-borne virus can double the number of mosquitoes surrounding the host!

This is the first time scientists have discovered that a mosquito-borne virus can promote its spread among people in this way.

So is there any way to change this situation?

The researchers found that giving infected mice a vitamin A derivative, isotretinoin, boosted the production of antimicrobial proteins in the mouse skin and inhibited the proliferation of acetophenone-producing bacteria.

Experiments on mice also showed that when isotretinoin was added to the food of infected mice, mosquitoes became equally fond of infected and uninfected mice.

Cell 2022, 185, 2510–2522.

doi.org/10.1016/j.cell.2022.05.016