Swelling in Mosquito Bite May Contribute to Viral Replication

A new mouse study revealed that the itchy, red welts that appear on a spot bitten by a mosquito may boost the replication of any mosquito-borne viruses.

The study, published in the journal Immunology, suggests that the inflammatory response of the body to the bite site of mosquitoes may cause viral replication and make them more likely to cause a disease.

"Before we did this study, little was known about the events and processes that occur at mosquito bite sites," explained Clive McKimmie, a Research Fellow at the University of Leeds and senior author of the study, in a statement.

For the study, researchers used mouse models to analyze the bite of Aedes aegypti mosquito, known carrier of Zika, dengue and chikungunya. Researchers injected the mice with viruses into their skin with or without the presence of mosquito bite at the injection site. The researchers then compared the immune response between the injection with the bite and injection without the bite.

Mosquitoes injects saliva into the skin when they bite, triggering an immune response, in which white blood cells called neutrophils and myeloid cells rush to the site.

Surprisingly, researchers discovered that some of the immune cells that responded in the injection with mosquito bite got infected with the virus and involuntarily helped the replication of the virus. The researchers also found out that the presence of mosquito bite in the injection site resulted in order of magnitude higher levels of virus.

On the other hand, the injection without mosquito bite and its accompanying inflammation deter viral replication.

"This was a big surprise we didn't expect," McKimmie commented on a press release. These viruses are not known for infecting immune cells. And sure enough, when we stopped these immune cells from coming in, the bite did not enhance the infection anymore."

Their findings, although done in mouse models, may open new insights for combating life-threatening viruses.