Don't bite me to "Come and bite me"!Cell: The "antidote" of the mosquito was found

Text ｜ "China Science News" trainee reporter Liu Runan

Since reading blogging, Cheng Gong has been on the mosquito and mosquito media virus for nearly 15 years.

He has studied more than 100,000 mosquitoes, and he has always had a problem to linger in his heart: why they can spread viruses so fast.

Mosquitoes can quickly spread diseases such as malaria, dengue fever, and encephalitis, and can make a city's epidemic rampant in just half a year.

Viruses transmitted through mosquitoes around the world can even lead to one billion people infected each year.

Recently, Cheng Gong, a professor at the School of Medicine of Tsinghua University, finally found the answer: human smell is a key factor in regulating mosquito behavior.

For mosquitoes, the unique smell of the infected person seems to be labeled "to bite me" to help it lock the target in the vast sea of ​​people. Once he completes blood -sucking and digestion, mosquitoes will quickly become a new source of infection.

Fortunately, Cheng Gong and others also discovered the "antidote" to deal with it: by regulating the skin microorganisms and reshaping the smell of the infected person, thereby affecting the sense of smell of mosquito. Recently, the study has appeared in the "Cell" magazine.

Once the mosquito stops, scientific researchers quickly put them into the pocket with mosquito absorbers. Zhu Yibin's picture

Plants are more "sweet" after being infected with viruses

People have studied mosquito media viruses for hundreds of years, but they are still not ideal for prevention and control through drugs and vaccines.

For example, dengue vaccine has an ADE (antibody dependency enhancement) effect -after the vaccine can not only prevent virus infections, but also leads to worsening infection symptoms.

"In this case, we want to focus on blocking the transmission pathway. This does not need to develop vaccines for each virus, and we can also control the transmission of all mosquito media viruses, and once and for all solve the problem of infection." Cheng Gong said.

But for a long time, this idea only stayed at the conjecture stage, without substantial progress. Until 2019, in order to prepare for the annual invitation of the "Viruses Yearbook", Cheng Gong had a new discovery after consulting a large number of literature and materials.

He deeply learned that although the plants cannot move, they still suffer from various infectious diseases. 80%of plant viruses are spread by insects, which is consistent with the process of human and animals.

Once the plant is infected by the virus, its smell will change, exuding a more "sweet" taste than normal plants, attracting more insects to eat.

At that time, Zhang Hongxin, a postdoctoral school of Tsinghua University, joined the laboratory.

Earlier, she had done many beetles to eat leaves and found that beetles were masters looking for food through odor.

Is there such an interactive effect between mosquito and bite objects? "The two who may not be related to the two have some coincidence in the underworld." Cheng Gong told the China Science News.

Seeking blood can't, "mouse flavor temptation"

Do mosquitoes that spread a series of viruses only love to find people and drink blood? the answer is negative.

At present, there are more than 3600 kinds of mosquitoes, only Egyptian mosquito, white -patterned Iraqi mosquito (commonly known as "flower spots mosquito") and other loved human blood. Others prefer poultry blood, beef blood, sparrow blood, etc. Have love. "

In this way, Egyptian Mosquito and white -patterned and mosquitoes have naturally become the most ideal experimental object of scientific researchers.

In Cheng Gong's laboratory, a staff member who specializes in mosquitoes can contribute to the laboratory every day to contribute thousands of Egyptian and Iraqi mosquitoes.

How do I solve so many mosquitoes? Do you want the staff to donate blood? Of course, for a few days, the mouse blood became its beauty meal.

Cheng Gong and others established a three cage olfactory measurement device and the armed smell measurement device, and used mice as bait.

In the three cages olfactory measurement device, the left box is full of the "mice" of healthy mice, and the box on the right is full of the smell of dengue virus or Zika virus infection with mice. Researchers put 60 sets of mosquitoes a group of mosquitoes. In the middle box, in less than 20 minutes, they flew into the box on the right.

These mosquitoes also have the same performance in the arms olfactory measurement device.

The mosquitoes in the laboratory alone are not enough to explain the problem, and it is necessary to find wild mosquitoes to assist in verification. And this can only be caught by "human taste".

In the jungle with high temperature and humidity in the wild, I saw a staff member who was tightly wrapped in a small piece of skin on his arms, sitting and waiting for mosquitoes.

Once the mosquito stops, the people next to them quickly put them into the pocket with mosquito suction guns.

This method is not broken. A little hesitant hesitated, and the mosquito's mouth was stabbed.

After the skills are pure, they can catch dozens or even hundreds of mosquitoes a day.

Studies have shown that "mice infected by dengue virus and Zika virus are significantly more attractive to Egyptian mosquito, white -patterned and mosquito. Story changes are the decisive factor that causes the host to attract mosquitoes. "Cheng Gong said.

Further research shows that after mosquito media infection, a large number of volatile small molecules, phenyl, can effectively activate the olfactory nervous system of mosquito and help mosquito to quickly discover the goals.

How to remove the label of "Bite me"?

Animal experiment is done, is the same in human body?

At this time, Cheng Gong ushered in the biggest difficulty in the research: in 2020, the new crown pneumonia epidemic was outbreak and the border was blocked.

As a typical input infectious disease, domestic infected people basically come from immigrants from tropical regions.

Where to find patients? This caused Cheng Gong's headache.

He contacted the doctors in the county and city of Yunnan, and planned to "keep the plant and treat rabbits". This defensive was half a year. It was not until May that Dehong Prefecture waited for a small amount of infection. What do you want to collect "people" directly to attract mosquitoes directly to attract mosquitoes?

They have developed a convenient and effective method for this: with cylindrical magnetic beads, covering materials that can adsorb odors (polymond methallaxane), which are under the three of the patient's armpits, necks, and arms. The most prone to sweat is rolled for 10 minutes, and then immersed in the orthopedic solution, and the "human flavor" is transferred to the liquid.

At the same time, they also selected healthy people living in the local area as the control group.

The test results are satisfactory: dengue fever patients are more attractive to mosquitoes.

Subsequent mechanism research shows that dengue virus and Zika virus infection can inhibit the expression of RELM-ALPHA/RETN in the host's skin, so that the excessive proliferation of skin spores that were originally suppressed, resulting in the infected host "to bite me" and "come to bite me". Tag -release phenylthone.

Based on this, researchers have found that feeding a drug to infected mice -different vitamin acid, which can effectively help them eliminate this label.

"This means that after oral drugs, mosquitoes cannot locate and discover the infection of the host through the phenylone released by the host, thereby blocking the transmission cycle of the virus." Cheng Gong told the China Science News.

Change "blocking" to "sparse"

Unfortunately, the skin microorganisms collected by the researchers failed to cultivate in the laboratory.

Therefore, data such as changes in skin microorganisms infected are not presented in research papers.

Due to the repetition of the domestic new crown epidemic, in recent years, the number of entry and exit has continued to be low, and there are very few patients with dengue fever.

In Malaysia, Singapore, Vietnam, Myanmar and other countries, there have been many patients with an epidemic, with many patients.

"At present, we have completed the study of microorganisms in the skin of the infected and non -infected people in Malaysia. Next month, the clinical trial of alienation is about to be carried out. If it is smooth, it may be promoted in the future." Peronic acid has long been approved drugs, and this study is equivalent to adding an indication to it.

In order to calculate, from inspiration, animal experiments, human trials to future clinical trials, Cheng Gong needs to pay at least six or seven years of effort. This is not the breeding stage of asking questions and thinking directions in the early stage.

Change the research and prevention of mosquito media virus and change "blocking" into "sparse" is why he persisted.

"Over the years, when a mosquito media infection occurs in a region, most of us are limited to the description of public health, such as the statistical infection rate and number of people. The solution is 'destroying it'. The large -scale use of insects did not reduce mosquito media virus, but instead intensified. In the past 40 years, the incidence of dengue fever has increased by 30 times. "He said.

"So we need to truly understand the basic principle of the mosquito media virus in nature, and why it spreads and why it can spread quickly. The complex interconnection between the virus has many mysteries to be solved. "

It is these complex effects and mysteries that make Cheng Gong very fascinating. In his opinion, mosquitoes can live steadily without being "keen" to spread viruses to humans, which is the best picture in the future.

Related thesis information:

https://dx.doi.org/10.1016/j.cell.20222.05.016

"China Science News" (2022-07-08 The first edition of the original title "The Secret of Cracking Mosquito" Come to Bite Me ")

Edit | Zhao Lu

Capture | Guo Gang

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