Defining the antiviral basis for Wolbachia-mediated biocontrol.

Abstract 

Billions of people live at risk of mosquito-borne viruses such as dengue and Zika. The World Mosquito Program (WMP, Monash University) has developed a novel biocontrol tool to address this unmet need. Introduction of the endosymbiotic bacterium Wolbachia into Aedes aegypti, the main vector of dengue and Zika, renders the mosquito resistant to viral transmission. Since 2011 WMP has introgressed Wolbachia into Ae. aegypti populations in 10 countries covering ~5.5 million people and is now scaling up to protect 75 million people by 2025. Importantly, dengue disease is significantly reduced in areas where Wolbachia-Ae. aegypti are established.  

Despite the rapid global uptake and implementation of this technology, we do not fully understand how Wolbachia inhibits viral transmission in mosquitoes. Our research is focussed on identifying the specific host changes that occur when antiviral Wolbachia strains are present. To do this, we have developed a novel panel of mosquito lines that carry Wolbachia strains that do or do not inhibit viral transmission. This presentation will describe some of our recent findings, including changes to mosquito gene expression profiles that may contribute to the antiviral state. In addition, in collaboration with Oxford University Clinical Research Unit, Vietnam, we have utilised human dengue patient blood to determine the importance of Wolbachia tissue distribution in preventing viral infection, dissemination and transmission in the mosquito. 

These findings contribute to our understanding of the molecular bases for Wolbachia-mediated viral inhibition and may support the uptake and longevity of this promising technology. 

Biography

Johanna Fraser is based at the Institute of Vector-borne Disease, Monash University. She leads a research program investigating the antiviral effects of the symbiotic bacterium, Wolbachia in Aedes aegypti mosquitoes.  

Dr. Fraser completed her PhD at the Burnet Institute in 2011, where she characterised the biochemical triggers that drive hepatitis C virus entry into host cells. Her first post-doctoral role at Monash University involved screening for and characterising dengue antiviral drugs and included a stint at DUKE NUS in Singapore under the guidance of Prof. Vasudevan.  

In 2016 she joined the Institute of Vector-borne Disease, home of the World Mosquito Program, which utilises Wolbachia-infected Ae. aegypti mosquitoes to reduce the disease burden caused by arboviruses including dengue and Zika. Dr Fraser’s research aims to build the evidence base and support the long-term success of Wolbachia-based biocontrol programs. Her work has included characterisation of a panel of novel Wolbachia strains for antiviral effects and host fitness impacts. She currently has an active NHMRC Ideas grant as CIA investigating the risk of dengue virus developing resistance towards Wolbachia.