Thesis Defense Announcement
To: The George Mason University Community
Candidate: Forrest Keck
Program: M.S. in Biology
Date: Friday, April 17, 2015
Time: 10:00 AM
Place: George Mason University
Prince William Campus
Bull Run Hall, Room 247
Title: "Characterizing the Effect of Bortezomib on Rift Valley Fever Virus Multiplication"
Thesis Director: Dr. Aarthi Narayanan
Thesis Committee: Dr. Ramin Hakami, Dr. Anne Verhoeven
A copy of the thesis will be available in the Mercer Library. All are invited to attend the defense.
This thesis investigates the FDA-approved cancer drug Bortezomib; characterizing its use as a novel application in Bunyavirus antiviral therapy. Rift Valley Fever virus (RVFV) belongs to the family Bunyaviridae and is a known cause of epizootics and epidemics in Africa and the Middle East. With no FDA approved therapeutics available to treat RVFV infection, understanding the interactions between the virus and the infected host is crucial to developing novel therapeutic strategies. Here, we investigated the requirement of the ubiquitin-proteasome system (UPS) for the establishment of a productive RVFV infection. It was previously shown that the UPS plays a central role in RVFV multiplication involving degradation of PKR and p62 subunit of TFIIH. Using the FDA-approved proteasomal inhibitor Bortezomib, we observed robust inhibition of intracellular and extracellular viral loads. Bortezomib treatment did not affect the nuclear/cytoplasmic distribution of the non-structural protein NSs; however, the ability of NSs to form nuclear filaments was abolished as a result of Bortezomib treatment. In silico ubiquitination prediction analysis predicted that known NSs interactors (SAP30, YY1, and mSin3A) have multiple putative ubiquitination sites, while NSs itself was not predicted to be ubiquitinated. Immunoprecipitation studies indicated a decrease in interaction between SAP30 – NSs, and mSin3A – NSs in the context of Bortezomib treatment. This decrease in association between SAP30 - NSs also correlated with a decrease in the ubiquitination status of SAP30 with Bortezomib treatment. Bortezomib treatment, however; resulted in increased ubiquitination of mSin3A, suggesting that Bortezomib dynamically affects the ubiquitination status of host proteins that interact with NSs. Finally, we observed that expression of interferon beta (IFN-â) was increased in Bortezomib treated cells which indicated that the cellular antiviral mechanism was revived as a result of treatment and may contribute to control of viral multiplication.