Date of Award

1-1-2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Biomedical Sciences

Content Description

1 online resource (xiii, 144 pages) : illustrations (some color)

Dissertation/Thesis Chair

Nicholas J Mantis

Committee Members

Janice D Pata, Kathleen McDonough, Klemen Strle, Timothy J LaRocca

Keywords

Antibodies, Borrelia, Lyme, Borrelia burgdorferi, Lyme disease, Antigenic determinants, Molecular immunology

Subject Categories

Immunology of Infectious Disease | Microbiology

Abstract

Borrelia burgdorferi (B. burgdorferi) is the causative agent of Lyme disease in the United States and Europe, which remains a major threat to public health. While currently no human Lyme disease vaccine is available, a previously licensed OspA-based vaccine was shown to effectively prevent transmission of B. burgdorferi from ticks to mammalian hosts. Concerning the vaccines mechanism of action, OspA antibodies enter the bloodmeal of a feeding tick and engage with B. burgdorferi producing OspA on their outer surface in a manner that impairs migration of the spirochete to the host; however exact antibody-spirochete interaction is unknown, despite the importance of OspA antibodies in protection. A notable OspA antibody interaction with B. burgdorferi reported three decades ago and never since been evaluated systematically, is antibody-mediated spirochete agglutination. The goal of my dissertation was three-fold: (1) Characterize the response of live B. burgdorferi to protective OspA MAbs in the absence of complement; (2) Identify determinants that promote OspA antibody-mediated agglutination of B. burgdorferi; and (3) Determine the consequences of OspA antibody-mediated agglutination on B. burgdorferi. To characterize the response of live B. burgdorferi to protective OspA MAbs, I utilized the OspA MAb LA-2 as a prototype over a range of doses. In combination with quantitative and qualitative methods, I demonstrate in Chapter 3 that established transmission-blocking human OspA-specific MAbs, alone and in combination, promote dose-dependent and epitope-specific agglutination of B. burgdorferi, which in turn, induces outer membrane stress that is restricted to aggregates. The significance of the studies presented in my dissertation is that I have potentially identified OspA antibody-mediated agglutination as a possible mechanism of protection. Furthermore, I have developed tools to quantify these interactions in vitro, discussed in Chapter 3, and in Appendix 2 and Appendix 3, generated the tools to visualize by fluorescent microscopy the interaction between protective OspA MAbs and B. burgdorferi during the transmission in the tick midgut. Collectively, the data presented in this dissertation reveal a possible mechanism by which protective OspA antibodies may entrap B. burgdorferi within the tick midgut.

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