June 2010

Document Type


Degree Name



Dept. of Science & Engineering


Oregon Health & Science University


Upon infection a virus elicits a great number of responses from the host cell, and in order for a successful infection to occur, the virus must employ various mechanisms to evade these immune responses. One such immune evasion method of Kaposi’s sarcoma-associated herpesvirus (KSHV) is the viral E3 ubiquitin ligase, K5. K5 is known to downregulate the major histocompatability complex (MHC) class one, which is part of the immune response. Another possible target for downregulation by K5, BST-2, had been suggested. BST-2 has been shown to inhibit viral egress of some enveloped viruses by tethering nascent virions to the surface of the cell. Here the relationship of K5 and BST-2, and that of BST-2 and KSHV infection, is examined. It is determined that K5 has the ability to downregulate BST-2, alone or in the context of KSHV infection. The lysines on the cytoplasmic N-terminal tail of BST-2 are ubiquitinated by K5 after BST-2 leaves the ER, after which, BST-2 is then destined for the lysosome for degradation. In addition to this, it is demonstrated that BST-2 has the ability to restrict KSHV viral release in the absence of K5. By showing that BST-2 is a bona fide substrate of K5, the importance of K5 in overcoming the innate immune response is further elucidated.




Div. of Environmental & Biomolecular Systems


School of Medicine



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