Dissertation
DISCOVERY AND CHARACTERIZATION OF AN INTERGENIC SRNA IN THE LYME DISEASE PATHOGEN WITH A REGULATORY ROLE IN DISSEMINATED MAMMALIAN INFECTION
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/111342
Abstract
Lyme disease is a tick-borne infectious disease caused by bacterial species in the Borrelia genus. Borrelia burgdorferi, the primary pathogen in North America, is maintained in nature through an enzootic cycle consisting of ticks and mammals. These disparate environments require significant changes in bacterial gene expression for transmission to a host and subsequent infection to occur. One contributor to this requirement is the immune system of the host, which is abruptly encountered by tick-resident spirochetes at the outset of transmission. Through selective pressure and complex regulatory mechanisms, spirochetes can evade immune clearance, infect, and disseminate throughout the host, often causing chronic debilitating disease in susceptible animals like humans. Expanding our understanding of these regulatory mechanisms is critical for the effort to develop new interventions against Lyme disease.While some components of the B. burgdorferi genome are indispensable for host infectivity, others are only required for dissemination and maximum fitness in the host. One such genetic region is an intergenic sequence previously called bbd07, now known as ittB. Chapter two contains research which yielded the discovery of this important element and illustrates how its deletion results in attenuation of tissue colonization and pathogenesis. Molecular analysis of in vivo antigen expression is also reported and shows that the sequence likely encodes a regulatory factor.\nChapter three of this dissertation intends to provide supporting evidence and rational for the hypothesis that the bbd07/ittB locus encodes a small regulatory RNA (sRNA) instead of a protein. Outcomes of bbd07/ittB ¬overexpression were then investigated and found to lead to abatement of murine infectivity regardless of the presence of an adaptive immune response. Lastly, the effects of bbd07/ittB deletion on the B. burgdorferi transcriptome in vitro were assessed. Since it had already been observed that bbd07/ittB exerts regulatory control over expression levels of antigenic proteins during infection, it seemed possible that the same would be observable for mRNA levels between the wild type and mutant. Indeed, differential gene expression was observed, further implicating the gene product as a regulatory element. Further study is required to decipher the mechanism of action of bbd07/ittB.
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Details
- Title
- DISCOVERY AND CHARACTERIZATION OF AN INTERGENIC SRNA IN THE LYME DISEASE PATHOGEN WITH A REGULATORY ROLE IN DISSEMINATED MAMMALIAN INFECTION
- Creators
- Michael A Crowley
- Contributors
- Troy Bankhead (Advisor)Kelly Brayton (Committee Member)Leigh Knodler (Committee Member)Anders Omsland (Committee Member)Viveka Vadyvaloo (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Veterinary Medicine, College of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 113
- Identifiers
- 99900581609501842
- Language
- English
- Resource Type
- Dissertation