Mosquitoes’ Ability to Carry Viruses Without Getting Sick Explained
Researchers have uncovered a key mechanism explaining how mosquitoes can carry viruses like those that cause yellow fever without becoming infected themselves. The discovery, published recently, could lead to modern strategies for controlling the spread of mosquito-borne diseases.
For years, scientists have understood that mosquitoes transmit viruses, but the specific process of how they do so – and why they don’t get sick in the process – remained a mystery. Traditional thinking suggested viruses traveled freely within the mosquito’s body. Still, a team led by Professor Cheng Gong at Tsinghua University’s School of Basic Medical Sciences has identified a protective mechanism at play.
Approximately five years ago, while conducting supporting data tests for mosquito-borne viruses, the team noticed that the hemolymph – the equivalent of blood in insects – of several key vector mosquito species, including Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus, was acidic. “However, virus particles would rapidly become inactivated and lose their ability to infect in this environment,” explained Professor Gong. “This finding suggests that mosquitoes carry a large number of viruses, but their bodies do not provide an environment suitable for the survival of virus particles.”
Further research revealed that the “transmission vector” isn’t the virus particles themselves, but rather the mosquito’s own extracellular vesicles. According to the study, these vesicles encapsulate the virus, shielding it from the acidic environment and allowing it to persist within the mosquito. This explains the phenomenon of asymptomatic viral carriage in mosquitoes.
To pinpoint how viruses enter these extracellular vesicles, the team systematically investigated over 100 proteins, ultimately identifying a crucial protein that determines a mosquito’s susceptibility to different viruses. Professor Gong stated that with this long-standing mystery solved, it may be possible to precisely regulate key host factors in mosquitoes to block the transmission pathways of mosquito-borne infectious diseases such as dengue fever and Japanese encephalitis.
This research offers a new understanding of mosquito biology and could pave the way for innovative public health interventions to combat the global burden of mosquito-borne illnesses. The findings could guide future strategies for controlling the spread of these diseases.
