Date of Award

5-2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Microbiology

Major Professor

Tim Sparer

Committee Members

Sarah Lebeis, Todd Reynolds, Barry Rouse

Abstract

Human cytomegalovirus (HCMV) is a ubiquitious herpes virus and a serious pathogen within immunocompromised populations. HCMV is the leading cause of infectious congenital disease. Without an effective vaccine much work is put into designing alternative treatment approaches. Current HCMV treatments include nucleoside analogues and recently the terminase inhibitor, letermovir. These treatments have unwanted side effects and HCMV can become resistant to them. This fact mandates production of alternative treatment approaches. In chapter two we use antiviral peptides to inhibit cytomegalovirus infection. Our peptides are highly efficient at inhibiting in vitro derived CMV, but they lack efficacy in vivo. The ineffectiveness is due to the inability to inhibit cell-to-cell spread. We must stop cell-to-cell spread to stop CMV. Cell-to-cell spread is the major mechanism by which CMV disseminates throughout the body. Innate immune cells mediate the CMV dissemination process, reviewed in chapter one. Interestingly, HCMV has evolved immunomodulatory proteins that enhance innate immune cell trafficking to infection sites. One protein of interest is the viral chemokine vCXCL-1. This protein is known to attract immune cells in vitro, but in vivo the function is unknown. Using the mouse model and murine cytomegalovirus (MCMV) we investigate vCXCL-1's in vivo functions. In chapter three we report that mice infected with a recombinant MCMV expressing vCXCL-1 at high levels had attenuated viral dissemination. We speculated this was due to abnormal vCXCL-1 expression. In chapter four we engineer a new recombinant MCMV expressing vCXCL-1 under control of the murine chemokine promoter MCK2, ensuring relatively normal physiological expression of vCXCL-1. This recombinant virus has increased viral dissemination kinetics compared to wild type viruses and altered inflammatory profiles. Increased dissemination is slightly reliant on the murine neutrophil which we report is able to harbor, transfer, and replicate MCMV. This work supports the hypothesis that vCXCL-1 is a virulence factor. Infection of immune compromised mice with our new recombinant MCMV was lethal in more than 50% of infected animals, while all animals infected with parental virus survived. This work sheds light on important aspects of CMV entry and dissemination, which could prove vital when designing future HCMV treatments.

Orcid ID

http://orcid.org/0000-0003-1572-6907

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