Insects are common vectors for devastating human viruses such as Zika and Dengue. A novel strategy preventing the transmission of vector-borne viruses exploits the bacterium Wolbachia. Wolbachia is estimated to infect 70% of insect species and provides host insects with resistance to many viruses. Therefore, the replacement of insect populations with those infected by Wolbachia can be used to drive down vector-borne virus transmission. To ensure the success of this replacement strategy, the interactions between Wolbachia and insect hosts need to be understood. For my thesis, I focused on two aspects of Wolbachia-host interaction: which host cellular compartments harbor Wolbachia, and how host systems affect Wolbachia load dynamics. To address these questions, I used the Wolbachia/Drosophila model that provides a genetically tractable system for studying host-pathogen interactions. First, using serial focused ion beam electron microscopy I found the Wolbachia intracellular niche to be of host endoplasmic reticulum origin. Second, I used a Wolbachia-infected Drosophila cell line JW18 to perform an unbiased Drosophila whole genome RNAi screen taking advantage of a novel high-throughput fluorescence in situ hybridization (FISH) assay to detect changes in Wolbachia levels. 1117 genes altered Wolbachia levels when silenced by RNAi of which 329 genes increased and 788 genes decreased the level of Wolbachia. Validation of hits included in depth secondary screening using in vitro and in vivo RNAi, Drosophila mutants, and qPCR. A diverse set of host gene networks were identified to regulate Wolbachia levels including transcription, epigenetic modification, protein anabolism and catabolism, translation and cell cycle. I focused on an unexpected role of host proteasome and host translation factors such as the ribosome and translation initiation factors in suppressing Wolbachia levels both in vitro and in vivo. Preliminary results suggest that these interactions may have implications in the Wolbachia-mediated antiviral response in hosts. This screen provides the most comprehensive analysis of Wolbachia-host interactions to date and can serve as a basis for future research in understanding the molecular mechanisms that govern this unique symbiotic relationship.
|Commitee:||Cadwell, Ken H., Ernst, Joel D., Nance, Jeremy F.|
|School:||New York University|
|Department:||Basic Medical Science|
|School Location:||United States -- New York|
|Source:||DAI-B 79/08(E), Dissertation Abstracts International|
|Subjects:||Cellular biology, Microbiology|
|Keywords:||Drosophila, Host-pathogen interaction, RNAi screening, Wolbachia|
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