Chinese Study Discovers Bacteria that Fights Dengue and Zika in Mosquitoes

By introducing the bacterium into mosquito populations in dengue-endemic areas, scientists hope to reduce the spread of these dangerous diseases.

April 20, 2024
Editor-in-Chief, The China Academy

Hold on to your bug zappers, folks, because we’re about to witness the ultimate disinfectant operation – and it’s going down in the guts of mosquitoes! That’s right, these pesky blood-suckers have a secret weapon hiding inside them, and it’s about to unleash a sanitation storm like no other.

Meet Rosenbergiella_YN46, the gut bacteria that’s about to give mosquitoes a serious case of squeaky-clean blues. This gutsy little bacterium has been biding its time, waiting for its moment to shine as the ultimate mosquito decontamination unit. And now, it’s time for this sanitation superhero to work its magic.

When these mosquitoes chow down on their next blood meal, Rosenbergiella_YN46 springs into action, secreting a special enzyme that rapidly acidifies the insect’s gut. It’s like a cleaning crew gone wild, scrubbing that tummy until it’s so inhospitable that dengue, Zika, and any other disease-causing stowaways don’t stand a chance. Talk about a deep clean!

This is the genius idea of researchers from the Tsinghua University-Peking University Joint Center for Life Sciences in Beijing. They have got their inspiration from mosquitoes in Yunnan Province, China. Yunnan Province is known for having diseases spread by mosquitoes, like dengue fever. But here’s the interesting twist: in different areas of Yunnan Province where the climate and number of mosquitoes are similar, the outbreaks of dengue fever are different.

So the scientists wanted to know why some places have more dengue fever than others. They also wanted to understand why mosquitoes from different areas can spread the virus differently. To figure it out, the scientists went to four places in Yunnan Province starting from 2020. They caught thousands of female mosquitoes that like to suck blood and studied them.

From 2020, the researchers studied mosquitoes in southwestern China, where they collected specimens before adding bacterium to water where mosquito eggs were laid. They say the results offer the potential for a nature-based method to stop worldwide mosquito-borne diseases caused by flaviviruses.

The scientists looked closely at the bacteria in the mosquitoes’ guts. They did this because when mosquitoes get infected with the virus, it usually happens in their gut. In earlier studies, the scientists already saw a connection between the bacteria in the gut and the virus mosquitoes carry. They wanted to see if the gut bacteria were different in mosquitoes from different places.

And guess what? The gut bacteria were indeed different in mosquitoes from different areas. The bacteria in the gut of mosquitoes can be influenced by the environment they live in. Some of the bacteria come from the water where mosquitoes breed, and some come from the sap of plants or the sweet liquid in flowers.

Out of all the bacteria they found, Rosenbergiella_YN46 caught their attention. This bacterium was found in the guts of mosquitoes in Wenshan and Pu’er but not so much in Xishuangbanna and Lincang. It seems that the presence of Rosenbergiella_YN46 is linked to the places where dengue fever outbreaks happen in Yunnan Province.

So, are the mosquitoes in Wenshan and Pu’er less likely to get sick or spread viruses because they have more of a specific bacterium called Rosenbergiella_YN46 in their guts? To check if this is true, scientists did an experiment where they put this bacteria into the guts of other mosquitoes.

They tried this with two common types of mosquitoes that can spread diseases: Aedes albopictus and Aedes aegypti. It worked! The mosquitoes that had Rosenbergiella_YN46 in their guts were much less likely to get infected with diseases like dengue or Zika when they bit someone.

But why does this happen? It turns out that Rosenbergiella_YN46 produces a special enzyme called RyGDH. This enzyme makes the mosquito’s gut become more acidic, changing its environment. Previous studies have shown that the envelope protein of mosquito-borne viruses like dengue virus is sensitive to acidic signals. When the virus enters the super acidic environment (pH less than 6.5) in the mosquito’s gut, something amazing happens to its outer coating, called the envelope protein. The acid completely changes the structure of this protein, permanently disabling its function.

With its envelope protein broken, the virus particle is left completely powerless and unable to infect anything. It’s like the virus showed up to the party without its costume – the bouncer (the acidic gut) just turns it away at the door. This acidic defense system in the mosquito’s gut ends up significantly reducing the mosquito’s susceptibility to the virus.

Having found the “good bacteria”, the research team came up with a plan: to have more mosquitoes in the wild carry this bacteria and become “good mosquitoes” that do not transmit the virus.

Their approach involved introducing Rosenbergiella_YN46 bacteria into the water where mosquitoes lay eggs and hatch. The experiment showed that when the eggs of wild Aedes albopictus mosquitoes captured in Xishuangbanna hatched in such water environments, successful gut colonization occurred, and the mosquitoes became less susceptible to virus infection.

The scientists were really excited because this method worked not only in the lab but also in a real area where there was an outbreak of the disease. They built a big greenhouse and used the local environment to grow local mosquitoes. Then, they added the Rosenbergiella_YN46 bacteria to the water in the greenhouse. When they tested these mosquitoes, they found that fewer of them were infected with the virus compared to before.

These findings, published in the journal Science, suggest that Rosenbergiella_YN46 could be a potential biocontrol agent for reducing flavivirus transmission and prevalence. By introducing the bacterium into mosquito populations in dengue-endemic areas, scientists hope to reduce the spread of these dangerous diseases. This approach could offer a safer and more environmentally friendly alternative to traditional mosquito control methods.


Editor-in-Chief, The China Academy
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