Patients infected with dengue fever release a higher amount of acetophenone, and the acetophenone in the odor component is highly attractive to mosquitoes. (Photo: Provided by Health Medical Network)
Although the dengue fever epidemic has slowed down slightly since autumn, the number of dengue fever cases remains high in some areas. Chen Xiuxi, a professor at the School of Public Health at National Taiwan University, led a team in “Healthy and smart living circle》Live program to explore the impact of microbiota on the prevalence and prevention of dengue fever. Research has found that “acetophenone” is strongly attractive to mosquitoes, and vitamin A derivatives can help reduce acetophenone-producing bacteria and reduce viruses. Transmission, therefore it is extremely important to prevent and control dengue fever by changing microbial bacteria.
Changing odor reduces Aedes aegypti bites
The dengue fever epidemic in Taiwan and internationally is more serious this year. Possible factors include climate and environmental factors that affect the microbial phase of mosquitoes, which increases the transmission ability of mosquito bites and intensifies the epidemic. How to prevent and control dengue fever by changing microbial bacteria is extremely important.
Chen Xiuxi explained that there is evidence that increasing mRELMα enzyme by ingesting vitamin A derivatives can effectively inhibit the microbial phase of the skin, thereby reducing the substance “acetophenone” that is easy to bite Aedes aegypti mosquitoes, and effectively reducing dengue fever infections. In addition to human microbial flora affecting the prevalence of dengue fever, mosquito commensal microorganisms also affect mosquito transmission capabilities by secreting chemicals and enzymes, inducing immune responses, and changing the mosquito’s biochemical environment.
In a study in the well-known journal “CELL”, experiments were conducted on experimental mice and human arms to explore the pattern mosquitoes use to find hosts. Research has found that “acetophenone” appears in the microbial flora of mice infected with dengue fever. The odor produced by it is strongly attractive to mosquitoes, making dengue fever patients susceptible to mosquito bites. When mosquitoes bite other people, the pathogenic bacteria are transmitted.
In addition, studies have found that experimental mice taking vitamin A derivatives have an increase in the mRELMα enzyme in the body, which can effectively inhibit skin infection by pathogenic bacteria. Therefore, when the body lacks vitamin A, the mechanism of inhibiting pathogenic bacterial infection in the body disappears, causing bacterial proliferation to release acetophenone. , and attract mosquito bites, so it should reduce the possibility of the body producing acetophenone.
Although current research shows that changing odor can effectively reduce mosquito bites, in the future, whether people will no longer need to use anti-mosquito products containing chemical substances, remove acetophenone from the body by bathing, or whether supplementing with vitamin A derivatives can effectively prevent mosquito bites? All need to be further experimentally confirmed by scientists. However, in the future, it is still conceivable to control the dengue fever epidemic through changes in human intestinal bacteria, and to use the technology industry to make biological control more complete.
“Microbiota” Unravels the Mystery of Aedes Aegypti Mosquito Bites
Why do odors attract bites from Aedes aegypti mosquitoes? The National Taiwan University Public Health Team analyzed the mechanism behind the operation:
◎Why are Aedes aegypti mosquitoes more likely to bite mice infected with dengue fever?
Dr. Lin Tingyu said that regarding this issue, a three-cage olfactometer experiment can be conducted, dividing healthy and infected mice into two groups, and then placing Aedes aegypti mosquitoes in the cages to observe which group they prefer to fly to. The results showed that there was no significant difference in the selection of Aedes aegypti mosquitoes in the first 2 days of the experiment, but after 4 to 6 days, Aedes aegypti mosquitoes were significantly more likely to choose mice infected with dengue fever. Further explore whether this is affected by odor? Therefore, a deodorizing device was added to the device, and it was found that there was no significant difference in the selection of Aedes aegypti mosquitoes after deodorization, indicating that the odor of the infected group indeed dominates the mosquito selection preference.
◎What odor components are strongly attractive to mosquitoes?
After collecting and analyzing the odor of infected mice, it was found that acetophenone can cause a strong antennal reaction in mosquitoes. Experiments were conducted by applying acetophenone on mouse skin and human skin, and it was found that it has a significant impact on mosquito selection preferences. At the same time, infection was also observed Patients with dengue fever have higher levels of acetophenone release, indicating that acetophenone in the odor component is highly attractive to mosquitoes.
◎Will destroying intestinal microorganisms or skin microorganisms affect the production of acetophenone?
From the experimental results, it can be found that after removing skin microorganisms, the release rate of acetophenone is significantly reduced, which means that skin microorganisms have a significant impact on the release of acetophenone. Among them, Bacillus campylobacter, Bacillus megaterium, Bacillus proteolytica, and Verde Bacillus manganese has a high influence on the production of acetophenone.
◎What biological mechanism does dengue virus affect acetophenone?
In living organisms, mRELMα is an important antibacterial protein that can effectively inhibit skin infection by pathogenic bacteria. However, patients infected with dengue fever lack this enzyme, indicating that dengue virus promotes the proliferation of acetophenone-producing bacteria by destroying mRELMα.
◎How to reduce the production of acetophenone?
Vitamin A derivatives restore mRELMα, reduce acetophenone-producing bacteria, and reduce viral transmission. (Hong Zhang et al., Cell, 2022)
Mosquito symbiotic microbiota
Regarding the microbiota in the mosquito, for example: the surface of the mosquito body contains entomopathogenic fungi, which are pathogenic fungi, such as Beauveria, Metarhizium, Lagenidium and Coelomomyces, which can infect and cause mosquito death; the midgut contains symbiotic fungi, including yeasts such as : Candida, Pichia, and Penicillium; somatic cells contain viruses that can replicate in mosquitoes, including: Flavivirus, Togaviridae, Bunyaviridae, Densovirinae, and Mesoniviridae; and reproductive organs contain intracellular symbiotic bacteria (Wolbachia). (Gao et al, Trends in Parasitology 2020)
▲Mosquitoes contain entomopathogenic fungi on their body surfaces, viruses in their body cells, and intracellular symbiotic bacteria in their reproductive organs. (Provided by National Taiwan University Public Health Team)
Professor Yan Mingfang explained that a study explored whether mosquito intestinal microbiota (Gut Microbiota) affects epidemic transmission and found that the mosquito intestinal microbiota can directly affect its transmission ability, such as: secreting chemicals and enzymes that inhibit viruses and Plasmodium, inducing Immune response, changes in mosquito midgut barrier or biochemical environment, etc. Mosquito intestinal microorganisms have other effects on mosquitoes, including: regulating reproductive behavior and reproduction rate, ultimately affecting vector density, producing pheromones that attract mosquitoes to mate during the mating process, changing mating preferences, and affecting mosquito reproduction. Past studies have found that In Culex pipiens, reintroduction of Bacillus and Staphylococcus into antibiotic-treated mosquitoes enhanced their reproductive capacity.
Regarding Wolbachia-induced cell incompatibility and blocking of pathogenic mechanisms, studies have found that female and male mosquitoes infected with Wolbachia can lay eggs after mating with Wolbachia. In addition, Wolbachia competes with viruses and pathogens for nutrients, activating the ability to fight against viruses and pathogens. immune response. (Huicheng Shi, et al. Protein & Cell, 2023)
Reprinted with permission from “Health Medical Network”/Reported by reporter Zheng Yifen
2023-11-13 01:13:50
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