Development of Molecular Tools and Elucidation of Antiviral Pathways in Culex Mosquitoes
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Authors
Walsh, Elizabeth
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
Alternative Title
Abstract
Mosquitoes are major vectors of disease-causing pathogens that threaten human and animal health worldwide. Culex quinquefasciatus, in particular, transmits
a variety of arboviruses, yet the molecular mechanisms underlying its antiviral
immunity remain poorly understood. This dissertation investigates key antiviral
pathways in Culex species mosquitoes, focusing on RNA interference (RNAi) and
novel immune factors that influence virus replication. In Chapter 2, we examined the role of PIWI proteins in antiviral defense. We identified Piwi4 as an antiviral factor against negative-sense RNA viruses in Culex
derived cells. Additionally, we found that all PIWI proteins have a modest impact on
virus-derived piRNA generation. In Chapter 3, to develop genetic tools for studying antiviral responses, we
generated Cx. quinquefasciatus-derived Hsu Cas9 knock-in cells. This system enables
targeted gene editing and serves as a platform for functional studies of immune
pathways. In Chapter 4, we studied Bravo, a novel antiviral protein with broad activity
against multiple arboviruses. Based on its conserved domains, we hypothesized that
Bravo is an RNA-binding protein important to the antiviral immune response in Cx.
quinquefasciatus mosquitoes. We confirmed its antiviral activity against three
different arboviruses and used truncation mutations to narrow down the antiviral
protein domains.Together, this work advances our understanding of Culex mosquito immune
responses and establishes new molecular tools for studying mosquito antiviral
defenses. By identifying key antiviral factors and improving functional genetic
approaches in Culex mosquitoes, this research contributes to broader efforts to
understand vector-virus interactions and inform strategies for mosquito-borne disease
control.