Degree

Doctor of Philosophy (PhD)

Department

Pathobiological Sciences

Document Type

Dissertation

Abstract

Previously, it was shown that the deletion of 38 amino acids from the N terminal end of glycoprotein K (gK) prevents the Herpes Simplex virus Type-1 (HSV-1McKrae ∆gK31-68) from entering into the axons of neurons. Herein, we showed for the first time that this modification in gK disrupts the ability of the virus to carry out a fusion of the viral envelope with the cellular plasma membrane and forces the virus to enter via endocytosis in epithelial cells and neuronal cell bodies. We showed that HSV-1 McKrae infection triggers cellular calcium signaling, Akt activation, and flipping of Akt to the external membrane surface, which facilitates interaction between Akt and HSV-1McKrae glycoprotein B (gB). However, the gK mutant virus fails to trigger calcium signaling and Akt-gB interaction and, therefore, utilizes endocytosis as an alternative to fusion-mediated entry. Following the entry into cells, the HSV-1tegument and capsid proteins utilize cellular motor machinery to mediate capsid transport to the nucleus where the virus replicates its genome. Herein, we showed that the inner tegument protein (UL37) of HSV-1 McKrae interacts with motor protein dynein, and the capsid ICP5 protein interacts with motor accessory proteins, for example, dynactin and EB1. Hence, knocking out selected motor accessory proteins reduced the HSV-1 capsid transport towards the nucleus in human neuroblastoma (SK-N-SH) cells. Interestingly, HSV-1 McKrae altered several cellular regulatory pathways during virus entry and capsid transport. For example, MAP kinases (MAPK) and phosphokinase C (PKC) pathways. Although the virus activates MAPK, this activation does not appear to play essential roles in virus entry and intracellular capsid transport. In contrast, inhibition of PKC inhibited virus entry indicating that this kinase is involved in virus entry and possibly in intracellular capsid transport. The results obtained in these studies suggest that HSV-1 regulates downstream neuronal signaling to facilitate virus entry and intracellular retrograde transport toward the nucleus of infected cells.

Date

11-1-2019

Committee Chair

Kousoulas, Konstantin Gus

Included in

Virology Commons

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