Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 70-85). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 70-85). Also available on the Internet.

Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 77-88).

Sensitivity of spirochetes from Borrelia burgdorferi sensu lato complex to serum complement of humans of different age and sex was analyzed. Complement-mediated Borrelia killing was observed in different combination of serum and selected Borrelia genospecies. The obtained results confirmed that age itself does not influence the sensitivity of human to Borrelia infection. However, the females seem to be more vulnerable to it. Each of ten tested Borrelia species was proved to be potentially infective for human in different ratio. The clear separation of all ten checked Borrelia species into two groups was revealed after the reaction with human sera: species with low sensitivity to human serum complement (mortality below 1 percent) and species with higher sensitivity (mortality over 3-4 percent).

abstract: Borrelia burgdorferi (Bb), the causative agent of Lyme disease, is a unique pathogen, with a complex genome and unique immune evasion tactics. It lacks genes encoding proteins involved in nutrient synthesis and typical metabolic pathways, and therefore relies on the host for nutrients. The Bb genome encodes both an unusually high number of predicted outer surface lipoproteins of unknown function but with multiple complex roles in pathogenesis, and an unusually low number of predicted outer membrane proteins, given the necessity of bringing in the required nutrients for pathogen survival. Cellular processing of bacterial membrane proteins is complex, and structures of proteins from Bb have all been solved without the N-terminal signal sequence that directs the protein to proper folding and placement in the membrane. This dissertation presents the first membrane-directed expression in E. coli of several Bb proteins involved in the pathogenesis of Lyme disease. For the first time, I present evidence that the predicted lipoprotein, BBA57, forms a large alpha-helical homo-multimeric complex in the OM, is soluble in several detergents, and purifiable. The purified BBA57 complex forms homogeneous, 10 nm-diameter particles, visible by negative stain electron microscopy. Two-dimensional class averages from negative stain images reveal the first low-resolution particle views, comprised of a ring of subunits with a plug on top, possibly forming a porin or channel. These results provide the first evidence to support our theories that some of the predicted lipoproteins in Bb form integral-complexes in the outer membrane, and require proper membrane integration to form functional proteins. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2020

No description available.

The Western Fence Lizard (Sceloporus occidentalis) is a major host of juvenile stages of the Western Black-legged Tick (Ixodes pacificus), which is the vector for the Lyme disease causative spirochete bacterium Borrelia burgdorferi in the western United States. Because S. occidentalis is reservoir incompetent and capable of eliminating spirochetes from infected ticks, it has been implicated as a major factor in the ecology of Lyme disease in the West. Although complement proteins in lizard blood have been established as the borreliacidal factor, no studies have examined intraspecific variability in host lizard borreliacidal capacity. In Chapter 1 of this thesis, we introduce the complexity of the Borrelia burgdorferi transmission cycle and it’s implications for transmission risk. In Chapter 2 we tested the hypothesis that host lizard physiological condition impacts their borreliacidal capacity. Blood plasma of lizards in varying physiological conditions was challenged against cultured B. burgdorferi, and the complement-mediated inactivation of spirochetes was quantified. Adult lizards had higher bactericidal activity than first-year juveniles, suggesting that complement-mediated inactivation develops with maturity and/or exposure to spirochete antigens. Also, bactericidal activity was positively associated with lizard tick load and body condition. Adult lizard sex did not significantly affect spirochete mortality. Lizards from an inland site with little exposure to ticks had higher bactericidal activity than lizards from a coastal population that is heavily parasitized by ticks.

No description available.

Lyme disease is a common tick borne disease in the US. Lyme disease emerged from the Northeast and in the past decade, Virginia has been witnessing a rapidly increasing trend in incidence. This thesis uses land cover projection data as a basis to look at the potential future trend of Lyme disease incidence in Virginia for the IPCC (Intergovernmental Panel on Climate change) scenarios of A1B and A2, which indicate a global and regional focus respectively. This study is a continuation of previous work done by an NSF funded research team at Virginia Tech, in exploring the variables affecting Lyme disease in Virginia. A Poisson point process is implemented in this thesis with land cover parameters (implemented land, water bodies, and edge metrics) and demographic parameters (population percentage and per capita income) as the spatial covariates. Lyme disease incidence data obtained from the Virginia Department of Health was used for model validation. The overall model was implemented using Python and its associated libraries while ArcGIS software was used for preliminary covariate analysis and data visualization. This thesis generates risk maps for A1B and A2 scenarios for each decade from 2010 through 2060. Spatial occurrence of disease incidence has been generated by the Poisson point process and the risk level of each county in Virginia has been calculated based on the incidence count predicted for it. Population and area at risk under each scenario for each decade was calculated. Results show that in A1B scenario 22.1% and 42.9% of the total population of Virginia are under high risk and in the A2 scenario, 21% and 33% of the total population of Virginia are under high risk of Lyme disease in 2010 and 2060 respectively. In terms of the area, A1B scenario has 28% under high risk in 2010 and 66% of the total area under high risk in 2060, while A2 scenarGIS, Lyme disease, Land cover projections, IPCC scenariosio has 22.4% under high risk of Lyme disease in 2010 62.7% of the total area in Virginia is under high risk in 2060. / Master of Science

The bacterial pathogen responsible for Lyme disease ¬— Borrelia burgdorferi— is an atypical Gram-negative spirochete that is transmitted to humans via the bite of an infected Ixodes tick. Like all Gram-negative bacteria the structural portion of the cell envelope known as peptidoglycan (PG) is sandwiched between the inner and outer membranes. Unlike virtually all bacteria, this PG layer is unique in B. burgdorferi in that the amino acid structure differs from most Gram-negative and Gram-positive bacteria by the addition of an Ornithine residue to the third amino acid location in the crosslinking structure. This unique motif is hypothesized to be responsible for the unusual clinical manifestations seen in Lyme disease, specifically Lyme arthritis, the most common late stage symptom of the disease in the United States. Peptidoglycan is only one component of the cell envelope in B. burgdorferi though; other portions of the cell envelope remain understudied specifically when viewed through the lens of the immune response they may elicit in addition to that of PG. The combined immunological effect of the unique bacterial antigen found in B. burgdorferi PG, as well as other potentially associated proteins contained within the cell wall, are explored here. These studies further our understanding of the B. burgdorferi cell envelope and provide critical information that underlies the elusive pathogenesis of Lyme disease. / Master of Science in Life Sciences / Lyme disease is a growing health concern, namely for the countries in the Northern Hemisphere. The bacterium responsible for this illness is Borrelia burgdorferi. B. burgdorferi can survive in the human body and is a threat in that as it replicates in the human host, it sheds pro-inflammatory fragments of its unique cell wall into the environment. This thesis will explore the consequences of this cell wall shedding and how the human immune response differs from the response seen in other more common bacteria. Additionally, I have found that the cell envelope fragments shed from B. burgdorferi may contain more than meets the eye. There is evidence here to support the discovery of a moonlighting protein that is bound to a portion of the cell wall in B. burgdorferi. This protein acts to bolster the structural integrity of the cell while also acting to modulate the host immune response.