Degree

Doctor of Philosophy (PhD)

Department

Pathobiological Sciences

Document Type

Dissertation

Abstract

Bovine herpesvirus-1 (BoHV-1) is the causative agent of infectious bovine rhinotracheitis and a component of the bovine respiratory disease complex. BoHV-1 is a significant burden on the cattle industry in the United States causing severe respiratory disease, abortions, loss of calves (“shipping fever”). BoHV-1 belongs to the alphaherpesvirus subfamily of Herpesviridae. Alphaherpesviruses enter axons of sensory nerves and establish life-long latency in trigeminal and dorsal root ganglionic neurons after primary infection of the oronasal or genital epithelium respectively. Modified live attenuated vaccines for BoHV-1 are commercially available but are limited in their protection while retaining the ability to establish latency in neurons and are increasingly recognized as causing disease in vaccinated animals. BoHV-1 viruses containing mutations in proteins conserved among alphaherpesviruses involved in entry or transport at various stages of neuroinvasion have been created throughout this project. A virus with a deletion of amino acids 31-84 encompassing two N-glycosylation sites at the amino terminus of glycoprotein K (gK) involved in the modulation of fusion machinery alters entry rendering the mutant virus reliant on clathrin-mediated endocytosis as demonstrated by inhibition of entry into MDBK cells in the presence of Pitstop-2. Viral tegument proteins released into the cytoplasm following fusion ultimately enable invasion of neurons by aiding transport of viral capsids or muting early innate responses. A virus containing a deletion of the amino terminal portion of tegument protein UL37 has been generated, a region identified in other alphaherpesvirus as essential for retrograde neuronal transport, and this mutant effects egress and productive infection in neurons. ICP0 is a virus tegument protein which degrades IRF3 thereby inhibiting type I interferon responses. Of two BoHV-1 viruses with deletions in predicted nuclear localization signals of ICP0, deletion of amino acids 620- 629 prevents replication in differentiated FBBC-1 neuronal cells. In addition, Cell lines of bovine origin have been used to characterize entry mechanisms, to visualize transport and provide a system for capsid tracking in neurons with the aim of informing the creation of safer vaccines and vaccine vector candidates for BoHV-1 and other pathogens of cattle.

Date

11-13-2021

Committee Chair

Kousoulas, Konstantin G.

Available for download on Monday, November 04, 2024

Share

COinS