All ETDs from UAB

Advisory Committee Chair

William J Britt

Advisory Committee Members

Terje Dokland

Ilya Frolov

Zsuzsanna Bebok

John Kappes

Document Type

Dissertation

Date of Award

2016

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Human cytomegalovirus (HCMV) is the largest and most structurally complex of all the herpesviruses. HCMV is an important human pathogen that results in significant morbidity and disease in immunocompromised individuals. The assembly of herpesviruses is complex and involves a nuclear and cytoplasmic phase. The nuclear events of capsid assembly and genome incorporation as well as nuclear egress are believed to be similar in all herpesviruses and as such, are more clearly defined then the cytoplasmic phase; including the process of tegument and envelope acquisition. Human Cytomegalovirus induces the reorganization of the cellular secretory pathway including the Golgi apparatus and membranes from the endosomal system to form its AC. The AC has been defined as a concentrated area of tegument and viral glycoproteins, along with endosomal membranes; surrounded by a concentric ring by Golgi apparatus membranes. Interruption in the trafficking of structural components of the virion to the AC reduces the production of infectious virus showing that the AC is important for the process of tegument acquisition and envelopment. Although the function of the AC in the assembly of HCMV particles has been well studied, how the virus induces its formation including the reorganization of the Golgi apparatus is still to be elucidated. In this study we determined the kinetics of Golgi disassembly relative to the progression of infection and found that it correlated with the cytoplasmic detection of the tegument protein pp65 (UL83). We identified a mechanism of Golgi apparatus disassembly associated with the phosphorylation of the cis-Golgi protein Grasp65. We determined that expression of a phospho-negative Grasp65, Grasp65-7A, reduced Golgi fragmentation and the efficiency of AC formation; resulting in a 1-2 log decrease in the production of infectious particles; that was secondary to a defect in assembly. Interestingly, we found that the incorporation of the glycoprotein gH (an envelope protein that is required for attachment and to induce gB mediated fusion) was significantly reduced. Finally, we provide data that suggests Polo-like kinase 1 is involved in the reorganiziation of the Golgi induced by HCMV infection.

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