Freie Universiẗat, Diss., 2004--Berlin. / Dateiformat: zip, Dateien im PDF-Format. Erscheinungsjahr an der Haupttitelstelle: 2004.

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.

Lyme disease is the most significant vector-borne disease in the United States. Its southward advance over the last several decades has been quantified, and previous research has examined the potential role of climate change on the disease's expansion, but no research has considered the role of future land cover patterns upon its distribution. This research examines Lyme disease risk in the southeastern United States based on estimated land cover projections under four different Intergovernmental Panel on Climate Change Special Report Emissions Scenarios (IPCC-SRES) A1B, A2, B1, and B2. Results are aggregated to census tracts which are the basic unit of analysis for this study. This study applied previously established relationships between Lyme disease and land cover in Virginia to the projected land cover layers under each scenario. The study area, the southeastern United States, was defined from Level III Ecoregions that are present in Virginia and extend throughout the Southeast. Projected land cover data for each scenario were obtained from the USGS. The projected land cover datasets are compatible with the National Land Cover Dataset (NLCD) categories and had seventeen land cover categories. The raster datasets were reclassified to four broad land cover types: Water, Developed, Forest, and Herbaceous areas and the relationship between certain landscape configurations were analyzed using FRAGSTATS 4.2. Significant variables established in previous research were used to develop a spatial Poisson regression model to project Lyme disease incidence for each decade to the year 2100. Results indicated that potential land cover suitability for Lyme disease transmission will increase under two scenarios (A1B and A2) while potential land cover suitability for Lyme disease transmission was predicted to decrease under the other two scenarios (B1 and B2). Total area under the highest category of potential land cover suitability Lyme disease transmission was calculated for each year under each scenario. The A2 scenario experiences the most rapid acceleration of potential land cover suitability for Lyme disease transmission, with an average increase of 16,163.95 km² per decade, while the A1B scenario was projected to show an average increase of 3,458.47 km² per decade. Conversely, the B1 scenario showed an average decrease of 595.7 km² per decade and the B2 scenario showed the largest decrease of potential land cover suitability for Lyme disease transmission with an average decrease of 2,006.83 km² per decade. This study examined the potential spatial distribution of potential land cover suitability for Lyme disease transmission in the southeastern United States under four different future land cover scenarios. The results indicate geographic regions of the study area that are at greatest risk of potential land cover suitability for Lyme disease transmission under four different predictive scenarios developed by the IPCC. The A1B and A2 land cover projections are predicted to have an overall increase in areas where the Lyme disease transmission cycle will be enhanced by 2100 and the scenarios have a primary focus on economic development. Economic concerns outweigh environmental concerns for the A1B scenario, in addition to a high standard of living. The A2 scenario describes rapid population growth which results in high rates of land cover conversion to developed land; in addition, this scenario describes a reduction of environmental protection. The B1 and B2 land cover projections are predicted to have an overall decrease in areas of high Lyme disease transmission by 2100 and these scenarios have a central focus on environmental sustainability. The B1 scenario is characterized by a high environmental awareness which results in lower demand for forest products. A common theme for the B1 scenario is restoration and forest protection. Finally, the B2 scenario is described as improving local and regional environmental value which results in a high demand for biofuels and repossession of degraded lands, and an overall increase of forest cover. This study was the first to predict potential land cover suitability for Lyme disease risk and geographic distribution using projected land cover in the southeastern United States, and the results of this research can aid in the reduction of Lyme disease as it continues to expand in the south. / Master of Science

A doença de Lyme é uma doença causada pelas bactérias do complexo Borrelia burgdorferi sensu lato que são transmitidas por carrapatos do complexo Ixodes ricinus. A distribuição geográfica dessas bactérias é confirmada no Hemisfério Norte (America do Norte, Europa e Ásia). Suspeita-se que uma enfermidade, compatível com doença de Lyme no Brasil, esteja provavelmente relacionada a uma espécie de Borrelia diferente das espécies causadoras de doença de Lyme no hemisfério Norte e que o vetor sejam carrapatos do gênero Amblyomma. Por estas razões, a doença brasileira passou a ser chamada de Doença de Lyme-Símile (DLS). A borreliose aviária é causada pela Borrelia anserina, que apresenta distribuição cosmopolita. É transmitida por carrapatos argasideos do gênero Argas. O presente trabalho foi dividido em dois capítulos: o primeiro investigou a presença de Borrelia spp em áreas onde foram relatados casos humanos de DLS no Estado de São Paulo. No segundo capítulo, é relatado o primeiro isolamento em meio BSK e a caracterização molecular de uma cepa de espiroqueta aviária presumidamente identificada como B. anserina, no Brasil. Para o primeiro capítulo, foram processados um total de 349 carrapatos Amblyomm cajennense adultos coletados em áreas com suspeita de DLS, nove amostras de sangue ou tecidos de pacientes humanos com diagnóstico clínico e sorológico de DLS, duas amostras de caldas de meio BSK previamente inoculado com tecidos ou sangue de pacientes com suspeita de DLS, e três amostras de caldas de meio BSK previamente inoculado com carrapatos coletados de áreas com suspeita de DLS. Essas amostras tiveram seu DNA extraído e testado pela nested-PCR com primers específicos para porções do gene flagelina B (flaB), aptos a amplificar porções deste gene de qualquer espécie de Borrelia. Todas as amostras foram negativas pela nested-PCR, não evidenciando a presença de Borrelia sp nas amostras avaliadas. Para o segundo capítulo, foi utilizada uma amostra de espiroqueta aviária originária de carrapatos Argas miniatus, colhidos em um galinheiro no Município de Pedro Leopoldo, MG. O isolamento in vitro e caracterização molecular da espiroqueta aviária foi feito a partir da inoculação de soro infectado, contendo espiroquetas viáveis, em meio BSK. O soro, baço, fígado e o próprio cultivo foram utilizado para amplificação na PCR para os genes rrs e flaB, seguido de seqüenciamento dos mesmos. O isolamento da espiroqueta foi obtido com sucesso, com várias passagens realizadas. A análise genética das seqüências do isolado mostrou 99.8% (483 de 484-bp) e 98.7% (754 de 764-bp) de similaridade às seqüências correspondentes dos genes rrs e flaB de B. anserina, respectivamente, disponíveis no GenBank. Pela análise filogenética inferida pela seqüência parcial do gene flaB, a cepa Brasileira agrupou-se com a seqüência de B. anserina dos EUA. Os resultados indicam a cepa brasileira estudada, designada de cepa PL, pertence à espécie B.anserina. / Lyme disease is caused by bacteria belonging to the complex Borrelia burgdorferi sensu lato, which are transmitted by ticks of the Ixodes ricinus complex. The distribution of these bacteria are restricted to the northern hemisphere (North America, Europe, and Asia). Lyme disease-like cases have been reported in Brazil, but it is possible that another Borrelia species is involved in these cases, and ticks of the genus Amblyomma have been implicated as vectors. Due to these reasons, the disease in Brazil has been referred as Lyme Disease-Simile (LDS). Borrelia anserina, the agent of avian spirochetosis, has a wordwide distribution, where it is transmitted primarily by ticks of the genus Argas. The present study was divided in two chapters: the first one evaluated the presence of Borrelia spp in areas of the state of São Paulo where LDS have been reported. The second chapter reports the first in vitro isolation in BSK medium and molecular characterization of a spirochete strain from Brazil, presumably identified as B. anserina. For the first chapter, a total of 349 adult ticks (Amblyomma cajennense) collected in areas where LDS cases have been reported were processed. In addition, nine human blood or tissue samples from patients with clinical and serological diagnostic of LDS, two samples from BSK medium previously inoculated with samples of skin or blood of LDS patients, and three samples of BSK medium previously inoculated with tick samples were also processed. All these samples were processed for DNA extraction and then tested by nested-PCR employing primers targeting a portion of the flagelin B gene (flaB),which amplify a flaB fragment in all known Borrelia species. All samples were negative by this nested-PCR, showing no evidence of Borrelia sp in the tested samples. The second chapter evaluated an avian spirochete strain originated from Argas miniatus ticks from Pedro Leopoldo municipality, state of Minas Gerais. DNA fragments of the rrs (16S rRNA) and flab genes were amplified by PCR and sequenced to determine phylogenetic similarities. The resulting sequences were 99.8% (483 of 484) and 98.7% (754 of 764) similar to GenBank corresponding sequences of B. anserina rrs and flaB genes, respectively. By neighbor-joining phylogenetic analysis, the flaB sequence of the Brazilian strain clustered in a monophyletic group with the sequence of B. anserina under 100% bootstrap support. The isolate was successfully isolated in BSK medium, with seven passages performed. The spirochete crude antigen, fixed in glass slides, showed strong immunfluorescence reactivity with sera from chickens previously inoculated with the isolate. The spirochete strain isolated in the present study was genetically identified as B. anserina, labeled as strain PL.