Identifier

etd-07082008-083329

Degree

Master of Science (MS)

Department

Veterinary Medical Sciences - Pathobiological Sciences

Document Type

Thesis

Abstract

HSV-1 acquires its final envelope by budding into cytoplasmic vesicles thought to be derived from Trans-Golgi Network (TGN) membranes. This process is facilitated by interactions among the carboxyl termini of viral glycoproteins and tegument proteins. To investigate the relative importance of different viral glycoproteins in cytoplasmic virion morphogenesis, a set of recombinant viruses were constructed silencing expression of the glycoprotein E (ΔgE), the carboxyl terminus of glycoprotein D (gDΔcp), and the membrane protein UL20 (ΔUL20). In addition, recombinant viruses were constructed having the ΔgE+gDΔcp, and the ΔgE+ΔgM (glycoprotein M) deletions. These recombinant viruses were constructed using the double-red, site-directed mutagenesis system implemented on the HSV-1 genome cloned into a bacterial artificial chromosome (bac). The ΔgE, ΔgE+ΔgM, and gDΔcp viruses produced viral plaques that were approximately 50% smaller to those produced by the wild-type virus HSV-1(F strain). The gDΔcp+ΔgE recombinant virus produced viral plaques that were on the average 50% smaller to those produced by either the ΔgE, ΔgE+ΔgM, or the gDΔcp viruses. However, these viral plaques were substantially larger than those produced by previously constructed UL20-null or gK-null viruses. Kinetics of viral replication revealed that all recombinant viruses appeared to produce similar viral titers at late times post infection. However, both the gDΔcp and the ΔgE+gDΔcp viruses appeared to replicate slower than the wild-type virus or the ΔgE and ΔgE+ΔgM viruses. Electron microscopy revealed that all viruses regardless of their different gene mutations produced enveloped virions that were secreted outside, with no apparent accumulation of unenveloped capsids in the cytoplasm of infected cells. These results suggest that the gD and gE carboxyl termini, either alone or in a redundant manner, are not essential in cytoplasmic virion envelopment and egress from infected cells. Furthermore, the results show that gK/UL20 complex serves preeminent roles among all viral glycoproteins in cytoplasmic virion morphogenesis and egress.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Konstantin Gus Kousoulas

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