Thesis (Ph. D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Vita. Bibliography: 284-323.

The aim of the study was to analyze the infectious potential of the newly described species, B. americana and B. carolinensis, studied on the laboratory model mammals mice. Our goal was to analyze and compare the vectorial capacity of two different tick vectors, Amblyomma americanum and Ixodes ricinus, in acquiring and transmition of both spirochete species to the host. The results of this study confirmed that ticks A. americanum and I. ricinus are capable to maintain and transmit B. americana and B.carolinensis.We confirmed that both analysed spirochete species, B. carolinensis and B. americana, showed the potential to develop the disease in laboratory model mammal, which indirectly support the fact that both spirochete species might be concidered as the risk factors in the area where they are distributed. Our results shows that A. americanum is able to transmit both spirochete species, which increases that risk of acquiring the Lyme disease to human population in the area of distribution of A. americanum

abstract: Glycosaminoglycans (GAGs) are a class of complex biomolecules comprised of linear, sulfated polysaccharides whose presence on cell surfaces and in the extracellular matrix involve them in many physiological phenomena as well as in interactions with pathogenic microbes. Decorin binding protein A (DBPA), a Borrelia surface lipoprotein involved in the infectivity of Lyme disease, is responsible for binding GAGs found on decorin, a small proteoglycan present in the extracellular matrix. Different DBPA strains have notable sequence heterogeneity that results in varying levels of GAG-binding affinity. In this dissertation, the structures and GAG-binding mechanisms for three strains of DBPA (B31 and N40 DBPAs from B. burgdorferi and PBr DBPA from B. garinii) are studied to determine why each strain has a different affinity for GAGs. These three strains have similar topologies consisting of five α-helices held together by a hydrophobic core as well as two long flexible segments: a linker between helices one and two and a C-terminal tail. This structural arrangement facilitates the formation of a basic pocket below the flexible linker which is the primary GAG-binding epitope. However, this GAG-binding site can be occluded by the flexible linker, which makes the linker a negative regulator of GAG-binding. ITC and NMR titrations provide KD values that show PBr DBPA binds GAGs with higher affinity than B31 and N40 DBPAs, while N40 binds with the lowest affinity of the three. Work in this thesis demonstrates that much of the discrepancies seen in GAG affinities of the three DBPAs can be explained by the amino acid composition and conformation of the linker. Mutagenesis studies show that B31 DBPA overcomes the pocket obstruction with the BXBB motif in its linker while PBr DBPA has a retracted linker that exposes the basic pocket as well as a secondary GAG-binding site. N40 DBPA, however, does not have any evolutionary modifications to its structure to enhance GAG binding which explains its lower affinity for GAGs. GMSA and ELISA assays, along with NMR PRE experiments, confirm that structural changes in the linker do affect GAG-binding and, as a result, the linker is responsible for regulating GAG affinity. / Dissertation/Thesis / Doctoral Dissertation Biochemistry 2015

I describe procedures for the introduction of Borrelia burgdorferi, the spirochetal agent of Lyme disease, into larval and nymphal stage of the tick vector, Ixodes ricinus. The goal of this Mgr. Thesis is to find an optima system, that would reliably and reproducibly allow the infection of large numbers of ticks with the Lyme disease spirochete.

The aim of present master’s thesis was to compare the results of serological methods for diagnosing borreliosis that are commonly used in Spadia laboratories (ELISA, immunoblots) in terms of recommendation on how and when to indicate and interpret them. The theoretical part is focusing on the characteristics and history of borreliosis, microbiological description of Borrelia, immune system and pathogenesis of the disease as well as the therapy and prevention. The experimental part is focusing on the analysis of results obtained from common examinations of antibodies to Borrelia made in Spadia Lab laboratories from January 1st 2014 to December 31st 2015. Screening of antibodies to Borrelia made by ELISA in IgM and IgG was done for all samples according to recommendation of CDC. In 2014 the ELISA screening was done using ELISA kits from Euroimmun and Evolis sample processors whereas in 2015 it was done using DiaSorin’s CLIA kits on Liaison analyser. Positive results were then confirmed by Westernblot or lineblot alternatively if the physician did not ask otherwise. It must be remembered that ELISA and Westernblot belong among serological methods that are using antibodies, i.e. substances produced by the immune system. The immune system plays the key role in protecting the body against infection and the antibodies are its important tool. Serological methods belong among immunoassay methods, which is still not standardized. Diagnosis of infections cann‘t be based only on antibody testing. It is necessary to assess the results in the context of the entire clinical picture, history and in the case of antibodies it is recommended retesting with an interval.

Although Lyme disease is the most frequently reported vector-borne illness in the United States, recent evidence from the CDC suggests that Lyme disease incidence in the United States may be much higher than reported. Lyme disease symptoms can be mistaken for a wide variety of diseases, which can complicate the diagnosis. To date, no diagnostic criteria analysis has been conducted examining the association between sociodemographic variables (sex and age) and seasonality of infection with the severity and symptomology found in Lyme disease cases. Using the CDC's outbreak investigation model, a primary case/control study was conducted using the ROSS Scale to collect data. Comparisons were made between a Lyme disease-diagnosed group (n = 203) and a convenience sample of non-Lyme disease patients (n = 388). Novel symptom patterns were found to significantly predict a diagnosis of Lyme disease. Odds ratio results revealed a positive association between musculoskeletal (OR = 11; 95% CI), neurological (OR = 12; 95% CI), cognitive (OR = 10; 95% CI), and cutaneous (OR = 144; 95% CI) symptoms frequency and severity and the diagnosis of Lyme disease. In addition, overall symptom frequency and severity scores displayed significant differences between cases and controls, between males and females, and among certain age groups. No correlation was found between symptom frequency and severity with the seasonality of infection. Current diagnostic tools search for antibodies to the Borrelia bacteria, but antibody production takes a few weeks. The results of this study help identify at-risk patients based on the presentation and severity of Lyme disease symptoms when antibodies are not present in measureable quantities in the blood stream, allowing for earlier diagnosis.

Indiana University-Purdue University Indianapolis (IUPUI) / Lyme disease is a multi-system inflammatory disorder that is currently the fastest growing arthropod-borne disease in the United States. The Lyme disease pathogen, Borrelia burgdorferi, exists within an enzootic cycle consisting of Ixodes tick vectors and a variety of vertebrate hosts. Borrelia lies within a distinct clade of microorganisms known as spirochetes which exhibit a unique spiral morphology. The underlying genetic mechanisms controlling for borrelial morphologies are still being discovered. One flagellar protein, FlaB, has been indicated to affect both spiral shape and motility of the organisms and significantly impacts the organism’s ability to establish infection. Due to the potential connection between morphological characteristics and pathogenesis, we sought to screen and identify morphological mutants in an attempt to identify genes associated with morphological phenotypes of Borrelia burgdorferi. Among Borrelia’s unique features is the presence of abundant lipoproteins making up its cellular membrane as opposed to the typical lipopolysaccharides. These proteins confer a wide variety of functions to the microorganism, among which include the abilities to circulate between widely differing hosts and to establish infection. Two important outer surface proteins, OspC and OspA, are found to be inversely expressed throughout the borrelial life cycle. OspC, in particular, becomes highly expressed during tick-feeding and transmission to the mammalian host. It has been found to be essential for establishment of infection. A global regulatory pathway has been shown to control for OspC, however there are missing links in this pathway between the external stimuli (such as temperature, pH, and cell density) and the regulatory pathway. We have performed a screening process to identify OspC expression mutants in order to identify novel genes associated with this pathway.

The use of the periplasmic alkaline phosphatase (PhoA) reporter protein from E. coli has been critical for definition of the topology of transmembrane proteins of multiple bacterial species. This report demonstrates development of a PhoA reporter system in B. burgdorferi. Codon usage of the E. coli phoA in B. burgdorferi was analyzed and an optimized version of the gene was obtained. In order to assess the differential activity of the reporter system, two optimized PhoA-fusion construct using B. burgdorferi proteins were engineered: one using the periplasmic protein OppAIV and one using the cytoplasmic protein PncA. The activity of PhoA requires periplasmic localization. The periplasmic OppAIV-PhoA fusion as well as the cytoplasmic PncA-PhoA fusion produced detectable PhoA protein in E. coli and in B. burgdorferi. The periplasmic fusion construct, but not the cytoplasmic fusion construct, resulted in functional alkaline phosphatase (AP) activity in E. coli, as observed by blue colonies on agar plates containing a chromogenic substrate for AP. In contrast, both of the fusion constructs produced limited detectable levels of functional alkaline phosphatase activity in B. burgdorferi, as observed by yellow color change in liquid protein lysate containing a chromogenic substrate for AP. Development of a PhoA fusion reporter system for use in B. burgdorferi will provide a new molecular genetics tool for analyzing the topology of B. burgdorferi transmembrane proteins. These types of studies are critical for understanding the function of B. burgdorferi transport systems and may identify novel molecular approaches for the treatment of Lyme disease.

Lyme borreliosis, more commonly referred to as Lyme disease, is the fastest growing zoonotic disease in North America with approximately 30,000 confirmed cases and 300,000 estimated infections per year. In nature, the causative agent of Lyme disease, the bacterium Borrelia burgdorferi, cycles between Ixodes sp. ticks and small mammals. Humans become infected with Lyme disease after being bitten by an infected tick. The primary indicator of a Borrelia burgdorferi infection is a bull’s eye rash typically followed by flu-like symptoms with treatment consisting of a 2-4 week course of antibiotics. If not treated, later stages of the disease can result in arthritis, cardiovascular and neurological symptoms. Diagnosis of Lyme disease is challenging and currently requires a complex laboratory diagnostic using indirect detection of host-generated antibodies by a two-tiered approach consisting of an enzyme linked immunosorbent assay (ELISA) followed by IgM and IgG immunoblots. Although two-tier testing has provided an adequate approach for Lyme disease diagnosis, it has weaknesses including subjective analysis, complex protocols and lack of reagent standardization. Immuno-PCR (iPCR) is a method that combines ELISA-based detection specificity with the sensitivity of PCR signal amplification and has demonstrated increased sensitivity for many applications such as detection of disease biomarkers but has yet to be applied for diagnosis of Lyme disease. Herein, using iPCR and recombinant B. burgdorferi antigens, an assay for both the direct and the indirect detection of Lyme disease was developed iv and demonstrated improved sensitivity for detection of B. burgdorferi antibodies using a murine model. Moreover, we present evidence using human Lyme disease patient serum samples that iPCR using both multiple antigens and a unique single hybrid antigen is capable of achieving increased sensitivity and specificity compared to existing methodology. These data represent the first demonstration of iPCR for Lyme disease diagnosis and support the replacement of two-tier testing with a more simplified and objective approach.

The Lyme disease spirochete Borrelia burgdorferi is the only known human pathogen that directly activates invariant natural killer T (iNKT) cells. The number and activation kinetics of iNKT cells vary greatly among different strains of mice. Here, we report the role of the iNKT cell response in the pathogenesis of Lyme disease using C57BL/6 (B6) mice, a strain with optimal iNKT cell activation that is resistant to the development of spirochetal-induced inflammation. During experimental infection of B6 mice with B. burgdorferi , iNKT cells localize to the inflamed heart where they are activated by CD1d-expressing macrophages. Activation of iNKT cells in vivo results in the production of IFNγ, which we demonstrate controls the severity of murine Lyme carditis by at least two mechanisms. First, IFNγ greatly enhances the recognition of B. burgdorferi by macrophages, leading to increased phagocytosis of the spirochete. Secondly, IFNγ activation of macrophages increases the surface expression of CD1d, thereby facilitating further iNKT activation. Collectively, our data demonstrate that in the resistant background, B6, iNKT cells modulate acute murine Lyme carditis through the action of IFNγ, which appears to self-renew through a positive feedback loop during infection. Inflammation during infection with B. burgdorferi is dependent on the ability of the spirochete to evade local mechanisms of clearance. Even though macrophages are the main infiltrating cell during Lyme carditis, the identification of a receptor capable of mediating phagocytosis of B. burgdorferi has been elusive. Here, we demonstrate that the integrin CR3 is able to mediate binding to the spirochete and facilitate phagocytosis in a complement-dependent and independent manner. Expression of CR3, but not CR4, in CHO cells markedly enhanced their capacity to interact with B. burgdorferi , in the absence and presence of complement opsonization. Furthermore, the interaction between CR3 and B. burgdorferi is dependent on the metal-ion-dependent adhesion site (MIDAS) and could be blocked with EDTA. Inhibition of CR3 with blocking antibody was able to completely abrogate phagocytosis of B. burgdorferi by the macrophage-like RAW264.7 cells and partially block uptake by bone marrow-derived macrophages (BMMs), a finding that was recapitulated with CD11b-deficient BMMs. We further show that activation with recombinant IFNγ increases the transcription of CD11b and CD18, which correlates with increased surface expression of CR3, and that the effect of IFNγ on the phagocytosis of B. burgdorferi is circumscribed to CR3 activity, because inhibition of CR3 is able to completely diminish the effect of IFNγ on the phagocytosis of the B. burgdorferi . Lastly, our results demonstrate that CR3 is a negative regulator of proinflammatory cytokine induction in macrophages responding to B. burgdorferi . Overall, our data demonstrate roles for CR3 in the binding, phagocytosis and proinflammatory cytokine elicited by B. burgdorferi and shed light on the role of IFNγ in mediating the clearance of the spirochete during Lyme disease.