Researchers at the University of Missouri have found viruses spread in the bodies of mosquitoes much quicker than previously thought.

"Previously, the common understanding was that when a mosquito has picked up a virus, it first needs some time to build up inside the mid-gut, or stomach, before infecting other tissues in the mosquito," said Alexander Franz, an assistant professor in the Department of Veterinary Pathobiology in the MU College of Veterinary Medicine and the study’s corresponding author. "However, our observations show that this process occurs at a much faster pace; in fact, there is only a narrow window of 32 to 48 hours between the initial infection and the virus leaving the mosquito’s stomach. For this field of research, that revelation is eye opening."

Franz and others believe this knowledge eventually could lead to the prevention of mosquito-transmitted diseases.

In this study, the researchers observed a mosquito infected with the chikungunya virus, which originates in Africa and was first found in people in the Americas in 2013. There is no vaccine to prevent or treat this virus. The most common symptoms include fever and joint pain, which can be severe and disabling.

The researchers used three separate electron microscopes to view the virus traveling through the mosquito, beginning with its mid-gut. The first two microscopes provided different two-dimensional views of a single layer of tissue in the mosquito’s stomach. The third, a focused ion-beam electron microscope, allowed researchers to see multiple layers of tissue.

"We’re now visualizing a real virus with a three-dimensional model, at scale," said DeAna Grant, a researcher with the Electron Microscopy Core Facility at the University of Missouri and a co-author on the study. "We can take a three-dimensional image showing the inside of a mosquito’s stomach and say that this dot is a virus particle. There is no guessing to what that dot is. In addition, with this technology we were able to track in three-dimension the virus traveling through the mosquito at 24-, 32- and 48-hour intervals, and within 48 hours or less, we could see the virus particles leaving the mosquito’s mid-gut."

These researchers hope to one day inhibit the genes involved with the release of the virus from within the mosquito’s stomach to prevent future transmission of mosquito-borne diseases.

The study, “Ultrastructural analysis of chikungunya virus dissemination from the midgut of the yellow fever mosquito, Aedes aegypti,” was published in Viruses.

Source: Missouri University College of Veterinary Medicine