Doctor of Philosophy / Department of Division of Biology / Rollie J. Clem / Mosquitoes are carriers of a variety of harmful human pathogens, including viruses. In
order to be successfully transmitted, a virus must evade mosquito immune responses. In this
work, the innate immune role of apoptosis in mosquito-virus interactions was examined utilizing
the disease vector Aedes aegypti and Sindbis virus. Ae. aegypti is the main vector for yellow
fever and dengue virus, which result in over 100 million infections per year. Sindbis virus
(Togaviridae) can be transmitted to vertebrates by Ae. aegypti in the laboratory. Sindbis is also
well characterized molecularly, making it a good model system for understanding virus-vector
interactions.
Sindbis MRE-16 recombinant virus clones were utilized to express either an antiapoptotic
or pro-apoptotic gene during virus replication. Mosquitoes were infected with
recombinant virus clones during a blood meal or by intrathoracic injection. Midgut tissue and
whole body samples were analyzed for virus infection and dissemination. Virus was also
quantified in saliva and mosquito survival was assayed. Decreased infection in the midgut and
delayed virus replication were observed in mosquitoes that were infected with virus expressing a
pro-apoptotic gene. Infection with this virus clone also resulted in less virus in the saliva and
reduced survival of infected mosquitoes. In addition, negative selection against pro-apoptotic
gene expression during virus replication was observed. Collectively, these data suggest that
apoptosis can serve as an antiviral defense in Ae. aegypti and may potentially be exploited to
control virus transmission.
An additional study included in this dissertation focused on zebrafish development and
migration of somitic precursors from the tailbud. The tailbud consists of a population of stem
cells at the posterior tip of the embryonic tail. The exit of these stem cells from the tailbud is required for the formation of tail somites. A novel double mutant was identified that lacked the t-box transcription factor spadetail and the BMP inhibitor chordin. Double mutants completely lacked somites and had an enlarged tailbud due to accumulation of stem cells that were unable to exit the tailbud. This study indicates the importance of BMP inhibition and spadetail expression in the proper exit of muscle precursors from the tailbud.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/15378 |
| Date | January 1900 |
| Creators | O'Neill, Katelyn Leigh |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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