Functional Analyses of West Nile virus-Host Interactions

  • Author / Creator
    Xu, Zaikun
  • West Nile virus (WNV) is a neurotropic, blood-borne flavivirus that can cause serious neurological disease in humans and animals. While significant progress has been made in identifying virus-encoded pathogenic determinants, very little is known regarding how these viral proteins interact with host cell proteins. Recent evidence suggests that in addition to its structural role in packaging genomic RNA, the WNV capsid protein plays important roles in virus host interactions and therefore, characterizing the interactions between capsid and cellular proteins should contribute to our understanding of WNV disease and may even reveal targets for antiviral therapy. Through an extensive yeast two-hybrid screen, I identified DDX56, a novel WNV capsid-interacting nucleolar RNA helicase. Experimental analyses revealed DDX56 is not required for production of viral RNA or proteins, however, WNV virions secreted from DDX56-depleted cells are 100 times less infectious than those produced in normal cells. Collectively, these data suggest that DDX56 is critical for assembly of infectious WNV virions possibly by facilitating the packaging of viral RNA. I also investigated how WNV infection affects tight junctions in polarized cells with the goal of understanding how the virus breaches the blood-brain barrier to gain access to the central nervous system. While a number of recent studies have documented that WNV infection negatively impacts the barrier function of tight junctions, the intracellular mechanism by which this occurs is poorly understood. Using a coordinated approach to understand the direct effects of WNV infection on tight junction proteins in both epithelial and endothelial cells, I discovered that WNV infection results in endocytosis of a specific subset of tight junction membrane proteins including claudin-1 and JAM-1 followed by microtubule-based transport to and degradation in lysosomes. Further studies into this process could lead to therapeutic treatments that block viral spread and/or design of attenuated vaccine strains.

  • Subjects / Keywords
  • Graduation date
    Fall 2013
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Wozniak, Richard (Cell Biology)
    • Russell, Rodney (BioMedical Sciences)
    • Smiley, Jim (Medical Microbiology & Immunology)
    • Marchant, David (Medical Microbiology & Immunology)