A discovery by a Washington State University-led research team could inhibit the spread of West Nile and Zika and Dengue viruses.
In a study published today in the journal Cell Reports, researchers have been able to show that mammalian insulin activates an antiviral immunity pathway in mosquitoes and increases the ability of insects to suppress the virus.
Mosquito bites are the most common form of infection of people with flaviviruses, a virus family that includes West Nile, dengue fever and Zika. Both West Nile and Dengue fever can cause serious illness or even death in humans. Zika has been linked to birth defects when pregnant women are infected.
"It's really important that we have some sort of protection against these diseases, because we do not have treatments right now, and if we can stop the infection at the mosquito level, people would not get the virus." said Laura Ahlers, principal author of the study and recently a graduate of WSU, Ahlers is now a postdoctoral fellow at the National Institutes of Health in Bethesda, Maryland.
Ahlers and her colleagues initially worked with fruit flies that have a similar immune response to mosquitoes and identified an insulin-like receptor in the insects that, when activated, inhibits the replication of West Nile virus in the flies. The researchers then triggered the same reaction in mosquitoes by feeding them blood containing elevated levels of insulin. Subsequent tests have shown that activation of this receptor also causes the suppression of dengue and Zika in insect cells.
While it was already known that insulin enhances the immune response to mosquitoes, it has for the first time identified the association of insulin with a specific immune response pathway called JAK / STAT. This is a significant step towards the long-term goal of intervention, said Alan Goodman, WSU Assistant Professor and author of the paper.
"If we can activate this arm of immunity through the insulin receptor in the mosquito, we can reduce the overall viral load in the mosquito population," said Goodman. "If the mosquitoes carry fewer viruses, they will transmit fewer viruses and there is a better chance that you will not get the disease."
Insulin Can Increase The Immunity of Mosquitoes To The West Nile VirusLaura R.H. Ahlers, Chasity E. Trammell, Grace F. Carrell, Sophie Mackinnon, Brandi K. Torrevillas, Clement Y. Chow, Shirley Luckhart, Alan G. Goodman. Insulin Potentiates JAK/STAT Signaling to Broadly Inhibit Flavivirus Replication in Insect Vectors. Cell Reports, 2019; 29 (7): 1946 DOI: 10.1016/j.celrep.2019.10.029