Lare mosquitoes Aedes terrorize much of the planet. Their bites maintain worldwide epidemics as formidable as those of yellow fever, dengue fever, Zika or even chikungunya. By successively attacking a person who is already infected and then a healthy person, they – or rather they since only females bite – constitute the sole vectors of these diseases.
With several tens of thousands of deaths to its credit each year, and millions of patients, the genre Aedes and its various species (aegypti, albopictus…) are on the podium of the worst listed killers, behind the anopheles, mosquito vectors of malaria.
Yet theAedes could plead not guilty. In January 2022, a team from the Institute for Research and Development (IRD, Mivegec) in Montpellier, led by Julien Pompon, showed that once infected with the dengue virus, the animal lost part of its reason. It multiplies attacks, bites and transplants the same hosts, increasing the risk of transmission of the pathogen. Abolition or at least attenuation of discernment, could advance the defense.
Altered body odor
An article published on June 30 in the journal Cell will offer his lawyers a new argument: manipulation. A Chinese team has just demonstrated that flaviviruses (responsible for dengue fever and Zika), when they infect a human or a mouse, modify their body odor and make them irresistible to insects. No murder, therefore, just a crime of passion.
To demonstrate this, Chinese scientists first proposed to different species ofAedes to choose between an infected mouse and a healthy mouse. Without hesitation, all opted for diseased rodents, dengue as Zika. The same result was observed with blotters impregnated with human sweat.
Chinese team found that in diseased mice, peptides are rarer and bacteria thrive
The researchers then tried to understand its origin. They therefore compared the volatile compounds present on the two types of skin, infected or not. Several molecules proved to be overabundant on the affected epidermis. All were then presented to mosquitoes. To listen to the researchers, one of them literally “freaked out”.
Chosen in spite of itself, acetophenone is produced by bacteria present on the skin. On healthy epidermis, bacilli are fought by antimicrobial peptides called RELMα. The Chinese team found that in diseased mice, peptides are rarer and bacteria thrive. “By suppressing RELMα, the virus allows the proliferation of bacteria, and therefore of acetophenone which will attract mosquitoes”summarizes Professor Dong Cheng, of the Tsinghua School of Medicine, who coordinated the research.
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