Janina Krambrich: A Mosquito's Guide to Viral Emergence: Unveiling Mosquito-Borne Virus Transmission Dynamics, Vector Competence, and Genetic Evolution

Abstract

In the complex world of disease transmission, mosquitoes often take centre stage as unwitting actors in the spread of viruses that threaten human and animal health. Imagine this: a tiny mosquito, often overlooked in the grand scheme of nature, carrying within it the potential to cause widespread disease, earning it the title of the world's deadliest animal. This doctoral thesis explores the captivating realm of mosquito-borne viruses, shedding light on their emergence, transmission dynamics, and evolutionary development.Arboviruses such as Japanese encephalitis virus (JEV), Usutu virus (USUV) and chikungunya virus (CHIKV) pose a significant global health problem given their increasing spread, particularly in growing urban areas, and amid today’s climate variations and change. It is important to understand the transmission dynamics of these viruses. In particular, USUV, which is transmitted by Culex mosquitoes, is increasingly being reported in Europe. This warrants an understanding of the vector competence of different European mosquito species to predict and manage potential outbreaks. Similarly, JEV is widespread in Asia and, given the climatic similarities, warrants an investigation into the vector competence of European mosquito species. CHIKV with its different lineages emphasises the need to understand its evolutionary history in order to predict and contain future outbreaks.This work has three objectives. To determine the abundance of JEV vector mosquitoes in Hanoi, Vietnam, to assess the vector competence of Swedish mosquitoes for USUV and JEV, and to analyse the factors that contributed to the 2018 CHIKV outbreak in Thailand. Field collections in Vietnam analysed Culex populations and correlated seasonal abundance with disease incidence. Vector competence experiments revealed USUV transmission potential and emphasised the inability of JEV transmission by Swedish Cx. pipiens. A genomic analysis of CHIKV traced its evolutionary development and provided insight into the dynamics of the 2018 outbreak.The historical context of mosquito-borne viruses emphasises their evolutionary origins and highlights the need for a comprehensive understanding. The results of the thesis contribute to insights into vector abundance dynamics, vector competence, and viral evolution, all critical aspects for disease surveillance and control. Future research approaches include assessing the competence of additional mosquito species, investigating environmental influences on transmission and exploring the immune responses of mosquitoes.Continuous surveillance, molecular epidemiology and innovative methods of vector control are crucial for containing the spread of viruses. Interdisciplinary collaboration and a "One Health" approach are essential for comprehensive disease prevention and control strategies. By improving our understanding of the dynamics of mosquito-borne viruses, we can better protect public health in the face of emerging infectious diseases.