{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/139934"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/139934","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Leveraging <i>Borrelia burgdorferi</i> peptidoglycan chemistry to understand Lyme disease symptom progression","abstract":"With an estimated 476,000 cases each year, Lyme disease (LD) is fast becoming an epidemic in the Northeastern and Midwestern United States. Caused by the spirochete Borrelia burgdorferi, LD is characterized by a wide variety of disease manifestations such as the bull's eye rash or erythema migrans despite the lack of classical virulence factors like lipopolysaccharide, toxins, or secretion systems to transport them. More debilitating late-stage symptoms include Lyme arthritis (LA), acrodermatitis chronica atrophicans, and neuroborreliosis, each strongly associated with particular species of Borrelia. The bacterial peptidoglycan component of the cell wall has been recognized as an antigen in numerous other studies of human pathogens. Indeed, previous studies have shown that the peptidoglycan component of the cell wall alone is sufficient to induce severe LA in a murine model in a matter of days. Furthermore, it has been demonstrated that B. burgdorferi PG persists in host tissue and in the synovial fluid of LA patients, and the unique structure of B. burgdorferi PG may play a key role in that. As B. burgdorferi lacks the machinery to recycle shed PG fragments, the bacterium sheds nearly 50% of its cell wall every generation. All this taken as a whole, investigations into how PG mediates its diverse manifestations are warranted. In this dissertation, a D-Alanyl-D-Alanine carboxypeptidase in an infectious model of B. burgdorferi was characterized and disrupted, causing an alteration of PG chemistry. Using a murine model, we demonstrate that this subsequently results in the near total attenuation of LA, which we confirmed through visual tracking of LA progression and histopathology, and changes in tissue tropism. In addition, this change in PG chemistry causes a change in the binding of peptidoglycan associated proteins (PAPs), particularly P83/100. P83/100 was previously shown to drastically affect bacterial burden in a murine model, and using immunofluorescence, we established that our mutant strain exhibits low abundance of this protein. With this as impetus, we were interested as to whether different pathogenic Borrelia species have distinct PG structural motifs that may explain their different disease manifestations. We employed an -omics approach to analyzing liquid chromatography–mass spectrometry (LCMS) data and have observed that despite conserved amino acids, the PG varies significantly. With currently approved LD diagnostics leaving much to be desired, especially in the detection of early-stage Lyme disease, we sought to leverage the unique PG chemistry of B. burgdorferi and have screened a panel of high affinity and specific antibodies against it which may be the first step in the development of reliable LD diagnostics. We have made an endeavor to leverage Borrelia PG and have provided unique insights into how it may possibly mediate disease progression. Further understanding these mechanisms may potentially reveal novel targets for the specific treatment of LD.","abstract_html":"With an estimated 476,000 cases each year, Lyme disease (LD) is fast becoming an epidemic in the Northeastern and Midwestern United States. Caused by the spirochete Borrelia burgdorferi, LD is characterized by a wide variety of disease manifestations such as the bull&#x27;s eye rash or erythema migrans despite the lack of classical virulence factors like lipopolysaccharide, toxins, or secretion systems to transport them. More debilitating late-stage symptoms include Lyme arthritis (LA), acrodermatitis chronica atrophicans, and neuroborreliosis, each strongly associated with particular species of Borrelia. The bacterial peptidoglycan component of the cell wall has been recognized as an antigen in numerous other studies of human pathogens. Indeed, previous studies have shown that the peptidoglycan component of the cell wall alone is sufficient to induce severe LA in a murine model in a matter of days. Furthermore, it has been demonstrated that B. burgdorferi PG persists in host tissue and in the synovial fluid of LA patients, and the unique structure of B. burgdorferi PG may play a key role in that. As B. burgdorferi lacks the machinery to recycle shed PG fragments, the bacterium sheds nearly 50% of its cell wall every generation. All this taken as a whole, investigations into how PG mediates its diverse manifestations are warranted. In this dissertation, a D-Alanyl-D-Alanine carboxypeptidase in an infectious model of B. burgdorferi was characterized and disrupted, causing an alteration of PG chemistry. Using a murine model, we demonstrate that this subsequently results in the near total attenuation of LA, which we confirmed through visual tracking of LA progression and histopathology, and changes in tissue tropism. In addition, this change in PG chemistry causes a change in the binding of peptidoglycan associated proteins (PAPs), particularly P83/100. P83/100 was previously shown to drastically affect bacterial burden in a murine model, and using immunofluorescence, we established that our mutant strain exhibits low abundance of this protein. With this as impetus, we were interested as to whether different pathogenic Borrelia species have distinct PG structural motifs that may explain their different disease manifestations. We employed an -omics approach to analyzing liquid chromatography–mass spectrometry (LCMS) data and have observed that despite conserved amino acids, the PG varies significantly. With currently approved LD diagnostics leaving much to be desired, especially in the detection of early-stage Lyme disease, we sought to leverage the unique PG chemistry of B. burgdorferi and have screened a panel of high affinity and specific antibodies against it which may be the first step in the development of reliable LD diagnostics. We have made an endeavor to leverage Borrelia PG and have provided unique insights into how it may possibly mediate disease progression. Further understanding these mechanisms may potentially reveal novel targets for the specific treatment of LD.","abstract_has_math":false,"creators":["Ahmad, Saadman Seraj"],"institution":"Virginia Tech","degree_name":"Doctor of Philosophy","degree_level":"doctoral","degree_discipline":"Biochemistry","degree_department":"Biochemistry","school":null,"contributors":[],"advisors":[],"committee_chairs":["Jutras, Brandon L."],"committee_members":["Helm, Richard F.","Caswell, Clayton Christopher","Tu, Zhijian"],"year":2025,"date_issued":"2025-12-16","date_published":"2025-12-16","updated_at":"2026-07-22T22:20:29Z","subjects":["Borrelia burgdorferi","Lyme disease","peptidoglycan","arthritis"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45178"],"render_values":[{"text":"vt_gsexam:45178","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/139934","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Jutras, Brandon L."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Helm, Richard F.","Caswell, Clayton Christopher","Tu, Zhijian"]},{"key":"dc:contributor.department","label":"Department","values":["Biochemistry"]},{"key":"dc:creator","label":"Author","values":["Ahmad, Saadman Seraj"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-12-17T09:00:28Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-12-17T09:00:28Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-12-16"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biochemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Borrelia burgdorferi","Lyme disease","peptidoglycan","arthritis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45178"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/139934"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["With an estimated 476,000 cases each year, Lyme disease (LD) is fast becoming an epidemic in the Northeastern and Midwestern United States. Caused by the spirochete Borrelia burgdorferi, LD is characterized by a wide variety of disease manifestations such as the bull's eye rash or erythema migrans despite the lack of classical virulence factors like lipopolysaccharide, toxins, or secretion systems to transport them. More debilitating late-stage symptoms include Lyme arthritis (LA), acrodermatitis chronica atrophicans, and neuroborreliosis, each strongly associated with particular species of Borrelia. The bacterial peptidoglycan component of the cell wall has been recognized as an antigen in numerous other studies of human pathogens. Indeed, previous studies have shown that the peptidoglycan component of the cell wall alone is sufficient to induce severe LA in a murine model in a matter of days. Furthermore, it has been demonstrated that B. burgdorferi PG persists in host tissue and in the synovial fluid of LA patients, and the unique structure of B. burgdorferi PG may play a key role in that. As B. burgdorferi lacks the machinery to recycle shed PG fragments, the bacterium sheds nearly 50% of its cell wall every generation. All this taken as a whole, investigations into how PG mediates its diverse manifestations are warranted. In this dissertation, a D-Alanyl-D-Alanine carboxypeptidase in an infectious model of B. burgdorferi was characterized and disrupted, causing an alteration of PG chemistry. Using a murine model, we demonstrate that this subsequently results in the near total attenuation of LA, which we confirmed through visual tracking of LA progression and histopathology, and changes in tissue tropism. In addition, this change in PG chemistry causes a change in the binding of peptidoglycan associated proteins (PAPs), particularly P83/100. P83/100 was previously shown to drastically affect bacterial burden in a murine model, and using immunofluorescence, we established that our mutant strain exhibits low abundance of this protein. With this as impetus, we were interested as to whether different pathogenic Borrelia species have distinct PG structural motifs that may explain their different disease manifestations. We employed an -omics approach to analyzing liquid chromatography–mass spectrometry (LCMS) data and have observed that despite conserved amino acids, the PG varies significantly. With currently approved LD diagnostics leaving much to be desired, especially in the detection of early-stage Lyme disease, we sought to leverage the unique PG chemistry of B. burgdorferi and have screened a panel of high affinity and specific antibodies against it which may be the first step in the development of reliable LD diagnostics. We have made an endeavor to leverage Borrelia PG and have provided unique insights into how it may possibly mediate disease progression. Further understanding these mechanisms may potentially reveal novel targets for the specific treatment of LD."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Lyme disease is fast becoming one of the most widespread vector-borne diseases in the United States, with an estimated 476,000 cases each year. Transmitted by the black legged tick, Borrelia burgdorferi causes a wide variety of different disease symptoms, including severe skin rashes, carditis, arthritis, and neurologic disorders. Despite advances in the field, we are still unable to reliably detect early-stage Lyme disease, which often leads to more severe symptoms associated with the later stages of the disease such as Lyme arthritis. This is perplexing in part due to the nature of the pathogen itself, as unlike most other bacteria, B. burgdorferi causes disease despite the complete absence of any typical toxins that may affect a host. Recent seminal work has furthered our understanding as to how this is the case. A component of the cell wall, peptidoglycan, has been identified as a major factor that causes inflammation, and has also been demonstrated to persist in Lyme arthritis patients. These same studies have also shown that B. burgdorferi peptidoglycan is unlike that of most other bacteria. We are thus interested in trying to tease apart the role of the structure of peptidoglycan in Lyme disease progression and investigating how we can exploit this unusual molecule to develop accurate and reliable diagnostics. To figure out if peptidoglycan structure plays a role in Lyme arthritis, we altered its structure in a strain of B. burgdorferi by disrupting one of the enzymes that maintains the normal structure of peptidoglycan. We studied its effects in a group of mice and found that they did not show any swelling of their ankles nor any other indication of arthritis. We concluded that peptidoglycan structure is indeed important, but this warranted further investigation into the exact mechanism behind this. We isolated the peptidoglycan from both normal and altered B. burgdorferi and found that the altered strain has much lower levels of a protein that has been shown to be necessary for the distribution of the pathogen. We also investigated differences in the peptidoglycan structure of different species of Borrelia pathogens, each of which is more strongly associated with a specific disease symptom. By measuring the abundance of peptidoglycan fragments and building blocks, we observed that these different species have are indeed quite different from each other. Taken together, this suggests that peptidoglycan chemistry may be a critical factor in disparate Lyme disease symptoms. In a promising first step, we also sought to make some progress in addressing the weaknesses of Lyme disease diagnostics by leveraging the unusual nature of B. burgdorferi peptidoglycan, which is released in prodigious amounts by the pathogen over the course of its life cycle, by obtaining antibodies specific to it. Overall, our findings present a novel avenue of research that may reveal key players in the progression of Lyme disease, which may very well lead to the discovery of novel therapeutics that may aid in the efforts to curb or alleviate this disease."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Leveraging <i>Borrelia burgdorferi</i> peptidoglycan chemistry to understand Lyme disease symptom progression"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Jutras, Brandon L."],"dc:contributor.committeemember":["Helm, Richard F.","Caswell, Clayton Christopher","Tu, Zhijian"],"dc:contributor.department":["Biochemistry"],"dc:creator":["Ahmad, Saadman Seraj"],"dc:date.accessioned":["2025-12-17T09:00:28Z"],"dc:date.available":["2025-12-17T09:00:28Z"],"dc:date.issued":["2025-12-16"],"dc:description.abstract":["With an estimated 476,000 cases each year, Lyme disease (LD) is fast becoming an epidemic in the Northeastern and Midwestern United States. Caused by the spirochete Borrelia burgdorferi, LD is characterized by a wide variety of disease manifestations such as the bull's eye rash or erythema migrans despite the lack of classical virulence factors like lipopolysaccharide, toxins, or secretion systems to transport them. More debilitating late-stage symptoms include Lyme arthritis (LA), acrodermatitis chronica atrophicans, and neuroborreliosis, each strongly associated with particular species of Borrelia. The bacterial peptidoglycan component of the cell wall has been recognized as an antigen in numerous other studies of human pathogens. Indeed, previous studies have shown that the peptidoglycan component of the cell wall alone is sufficient to induce severe LA in a murine model in a matter of days. Furthermore, it has been demonstrated that B. burgdorferi PG persists in host tissue and in the synovial fluid of LA patients, and the unique structure of B. burgdorferi PG may play a key role in that. As B. burgdorferi lacks the machinery to recycle shed PG fragments, the bacterium sheds nearly 50% of its cell wall every generation. All this taken as a whole, investigations into how PG mediates its diverse manifestations are warranted. In this dissertation, a D-Alanyl-D-Alanine carboxypeptidase in an infectious model of B. burgdorferi was characterized and disrupted, causing an alteration of PG chemistry. Using a murine model, we demonstrate that this subsequently results in the near total attenuation of LA, which we confirmed through visual tracking of LA progression and histopathology, and changes in tissue tropism. In addition, this change in PG chemistry causes a change in the binding of peptidoglycan associated proteins (PAPs), particularly P83/100. P83/100 was previously shown to drastically affect bacterial burden in a murine model, and using immunofluorescence, we established that our mutant strain exhibits low abundance of this protein. With this as impetus, we were interested as to whether different pathogenic Borrelia species have distinct PG structural motifs that may explain their different disease manifestations. We employed an -omics approach to analyzing liquid chromatography–mass spectrometry (LCMS) data and have observed that despite conserved amino acids, the PG varies significantly. With currently approved LD diagnostics leaving much to be desired, especially in the detection of early-stage Lyme disease, we sought to leverage the unique PG chemistry of B. burgdorferi and have screened a panel of high affinity and specific antibodies against it which may be the first step in the development of reliable LD diagnostics. We have made an endeavor to leverage Borrelia PG and have provided unique insights into how it may possibly mediate disease progression. Further understanding these mechanisms may potentially reveal novel targets for the specific treatment of LD."],"dc:description.abstractgeneral":["Lyme disease is fast becoming one of the most widespread vector-borne diseases in the United States, with an estimated 476,000 cases each year. Transmitted by the black legged tick, Borrelia burgdorferi causes a wide variety of different disease symptoms, including severe skin rashes, carditis, arthritis, and neurologic disorders. Despite advances in the field, we are still unable to reliably detect early-stage Lyme disease, which often leads to more severe symptoms associated with the later stages of the disease such as Lyme arthritis. This is perplexing in part due to the nature of the pathogen itself, as unlike most other bacteria, B. burgdorferi causes disease despite the complete absence of any typical toxins that may affect a host. Recent seminal work has furthered our understanding as to how this is the case. A component of the cell wall, peptidoglycan, has been identified as a major factor that causes inflammation, and has also been demonstrated to persist in Lyme arthritis patients. These same studies have also shown that B. burgdorferi peptidoglycan is unlike that of most other bacteria. We are thus interested in trying to tease apart the role of the structure of peptidoglycan in Lyme disease progression and investigating how we can exploit this unusual molecule to develop accurate and reliable diagnostics. To figure out if peptidoglycan structure plays a role in Lyme arthritis, we altered its structure in a strain of B. burgdorferi by disrupting one of the enzymes that maintains the normal structure of peptidoglycan. We studied its effects in a group of mice and found that they did not show any swelling of their ankles nor any other indication of arthritis. We concluded that peptidoglycan structure is indeed important, but this warranted further investigation into the exact mechanism behind this. We isolated the peptidoglycan from both normal and altered B. burgdorferi and found that the altered strain has much lower levels of a protein that has been shown to be necessary for the distribution of the pathogen. We also investigated differences in the peptidoglycan structure of different species of Borrelia pathogens, each of which is more strongly associated with a specific disease symptom. By measuring the abundance of peptidoglycan fragments and building blocks, we observed that these different species have are indeed quite different from each other. Taken together, this suggests that peptidoglycan chemistry may be a critical factor in disparate Lyme disease symptoms. In a promising first step, we also sought to make some progress in addressing the weaknesses of Lyme disease diagnostics by leveraging the unusual nature of B. burgdorferi peptidoglycan, which is released in prodigious amounts by the pathogen over the course of its life cycle, by obtaining antibodies specific to it. Overall, our findings present a novel avenue of research that may reveal key players in the progression of Lyme disease, which may very well lead to the discovery of novel therapeutics that may aid in the efforts to curb or alleviate this disease."],"dc:description.degree":["Doctor of Philosophy"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:45178"],"dc:identifier.uri":["https://hdl.handle.net/10919/139934"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Borrelia burgdorferi","Lyme disease","peptidoglycan","arthritis"],"dc:title":["Leveraging <i>Borrelia burgdorferi</i> peptidoglycan chemistry to understand Lyme disease symptom progression"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Biochemistry"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:29Z"}