RESUMO
Lyme disease is a zoonotic infection due to Ixodes tick-transmitted Borrelia burgdorferi sensu lato spirochetes and the most common vector-borne disease in the Northern Hemisphere. Despite nearly 50 years of investigation, the pathogenesis of this infection and its 2 main adverse outcomes-postinfectious Lyme arthritis and posttreatment Lyme disease syndrome-are incompletely understood. Advancement in sequencing and mass spectrometry have led to the rapid expansion of high-throughput omics technologies, including transcriptomics, metabolomics, and proteomics, which are now being applied to human diseases. This review summarizes findings of omics studies conducted on blood and tissue samples of people with acute Lyme disease and its postinfectious outcomes.
Assuntos
Doença de Lyme , Metabolômica , Proteômica , Humanos , Doença de Lyme/microbiologia , Animais , Borrelia burgdorferi/genética , Genômica , Ixodes/microbiologiaRESUMO
Lyme disease is a multisystem disorder caused by the spirochete Borrelia burgdorferi A common late-stage complication of this disease is oligoarticular arthritis, often involving the knee. In â¼10% of cases, arthritis persists after appropriate antibiotic treatment, leading to a proliferative synovitis typical of chronic inflammatory arthritides. Here, we provide evidence that peptidoglycan (PG), a major component of the B. burgdorferi cell envelope, may contribute to the development and persistence of Lyme arthritis (LA). We show that B. burgdorferi has a chemically atypical PG (PGBb) that is not recycled during cell-wall turnover. Instead, this pathogen sheds PGBb fragments into its environment during growth. Patients with LA mount a specific immunoglobulin G response against PGBb, which is significantly higher in the synovial fluid than in the serum of the same patient. We also detect PGBb in 94% of synovial fluid samples (32 of 34) from patients with LA, many of whom had undergone oral and intravenous antibiotic treatment. These same synovial fluid samples contain proinflammatory cytokines, similar to those produced by human peripheral blood mononuclear cells stimulated with PGBb In addition, systemic administration of PGBb in BALB/c mice elicits acute arthritis. Altogether, our study identifies PGBb as a likely contributor to inflammatory responses in LA. Persistence of this antigen in the joint may contribute to synovitis after antibiotics eradicate the pathogen. Furthermore, our finding that B. burgdorferi sheds immunogenic PGBb fragments during growth suggests a potential role for PGBb in the immunopathogenesis of other Lyme disease manifestations.
Assuntos
Antígenos de Bactérias/imunologia , Borrelia burgdorferi/imunologia , Doença de Lyme/imunologia , Peptidoglicano/imunologia , Imunidade Adaptativa/imunologia , Animais , Citocinas/metabolismo , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Peptidoglicano/análise , Peptidoglicano/química , Líquido Sinovial/química , Líquido Sinovial/imunologiaRESUMO
This evidence-based clinical practice guideline for the prevention, diagnosis, and treatment of Lyme disease was developed by a multidisciplinary panel representing the Infectious Diseases Society of America (IDSA), the American Academy of Neurology (AAN), and the American College of Rheumatology (ACR). The scope of this guideline includes prevention of Lyme disease, and the diagnosis and treatment of Lyme disease presenting as erythema migrans, Lyme disease complicated by neurologic, cardiac, and rheumatologic manifestations, Eurasian manifestations of Lyme disease, and Lyme disease complicated by coinfection with other tick-borne pathogens. This guideline does not include comprehensive recommendations for babesiosis and tick-borne rickettsial infections, which are published in separate guidelines. The target audience for this guideline includes primary care physicians and specialists caring for this condition such as infectious diseases specialists, emergency physicians, internists, pediatricians, family physicians, neurologists, rheumatologists, cardiologists and dermatologists in North America.
Assuntos
Doenças Transmissíveis , Doença de Lyme , Neurologia , Reumatologia , Animais , Humanos , Doença de Lyme/diagnóstico , Doença de Lyme/tratamento farmacológico , Doença de Lyme/prevenção & controle , América do Norte , Estados UnidosRESUMO
This evidence-based clinical practice guideline for the prevention, diagnosis, and treatment of Lyme disease was developed by a multidisciplinary panel representing the Infectious Diseases Society of America (IDSA), the American Academy of Neurology (AAN), and the American College of Rheumatology (ACR). The scope of this guideline includes prevention of Lyme disease, and the diagnosis and treatment of Lyme disease presenting as erythema migrans, Lyme disease complicated by neurologic, cardiac, and rheumatologic manifestations, Eurasian manifestations of Lyme disease, and Lyme disease complicated by coinfection with other tick-borne pathogens. This guideline does not include comprehensive recommendations for babesiosis and tick-borne rickettsial infections, which are published in separate guidelines. The target audience for this guideline includes primary care physicians and specialists caring for this condition such as infectious diseases specialists, emergency physicians, internists, pediatricians, family physicians, neurologists, rheumatologists, cardiologists and dermatologists in North America.
Assuntos
Doenças Transmissíveis , Doença de Lyme , Neurologia , Reumatologia , Animais , Humanos , Doença de Lyme/diagnóstico , Doença de Lyme/tratamento farmacológico , Doença de Lyme/prevenção & controle , América do Norte , Estados UnidosRESUMO
The mammalian host responds to infection with Borrelia spirochetes through a highly orchestrated immune defense involving innate and adaptive effector functions aimed toward limiting pathogen burdens, minimizing tissue injury, and preventing subsequent reinfection. The evolutionary adaptation of Borrelia spirochetes to their reservoir mammalian hosts may allow for its persistence despite this immune defense. This review summarizes our current understanding of the host immune response to B. burgdorferi sensu lato, the most widely studied Borrelia spp. and etiologic agent of Lyme borreliosis. Pertinent literature will be reviewed with emphasis on in vitro, ex vivo and animal studies that influenced our understanding of both the earliest responses to B. burgdorferi as it enters the mammalian host and those that evolve as spirochetes disseminate and establish infection in multiple tissues. Our focus is on the immune response of inbred mice, the most commonly studied animal model of B. burgdorferi infection and surrogate for one of this pathogen's principle natural reservoir hosts, the white-footed deer mouse. Comparison will be made to the immune responses of humans with Lyme borreliosis. Our goal is to provide an understanding of the dynamics of the mammalian immune response during infection with B. burgdorferi and its relation to the outcomes in reservoir (mouse) and non-reservoir (human) hosts.
Assuntos
Infecções por Borrelia/imunologia , Infecções por Borrelia/microbiologia , Borrelia/imunologia , Interações Hospedeiro-Patógeno/imunologia , Animais , Evolução Biológica , Infecções por Borrelia/transmissão , Reservatórios de Doenças , Humanos , Doença de Lyme/imunologia , Doença de Lyme/microbiologia , Doença de Lyme/transmissão , Especificidade de Órgãos/imunologiaRESUMO
Borrelia miyamotoi is a relapsing fever spirochete in Ixodes ticks that has been recently identified as a human pathogen causing hard tick-borne relapsing fever (HTBRF) across the Northern Hemisphere. No validated serologic test exists, and current serologic assays have low sensitivity in early HTBRF. To examine the humoral immune response against B. miyamotoi, we infected C3H/HeN mice with B. miyamotoi strain LB-2001 expressing variable small protein 1 (Vsp1) and demonstrated that spirochetemia was cleared after 3 d, coinciding with anti-Vsp1 IgM production. Clearance was also observed after passive transfer of immune sera to infected SCID mice. Next, we showed that anti-Vsp1 IgG eliminates Vsp1-expressing B. miyamotoi, selecting for spirochetes expressing a variable large protein (VlpC2) resistant to anti-Vsp1. The viability of Asian isolate B. miyamotoi HT31, expressing Vlp15/16 and Vlp18, was also unaffected by anti-Vsp1. Finally, in nine HTBRF patients, we demonstrated IgM reactivity to Vsp1 in two and against Vlp15/16 in four â¼1 wk after these patients tested positive for B. miyamotoi by PCR. Our data show that B. miyamotoi is able to express various variable major proteins (VMPs) to evade humoral immunity and that VMPs are antigenic in humans. We propose that serologic tests based on VMPs are of additional value in diagnosing HTBRF.
Assuntos
Anticorpos Antibacterianos/imunologia , Formação de Anticorpos , Proteínas da Membrana Bacteriana Externa/imunologia , Lipoproteínas/imunologia , Febre Recorrente/imunologia , Sequência de Aminoácidos , Animais , Anticorpos Antibacterianos/sangue , Sequência de Bases , Borrelia/imunologia , Feminino , Humanos , Imunização Passiva , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Camundongos , Camundongos Endogâmicos C3H , Camundongos SCID , Estrutura Terciária de ProteínaRESUMO
Borrelia burgdorferi, the spirochete that causes Lyme disease, is a tick-transmitted pathogen that requires motility to invade and colonize mammalian and tick hosts. These bacteria use a unique undulating flat-wave shape to penetrate and propel themselves through host tissues. Previous mathematical modeling has suggested that the morphology and motility of these spirochetes depends crucially on the flagellar/cell wall stiffness ratio. Here, we test this prediction using the antibiotic vancomycin to weaken the cell wall. We found that low to moderate doses of vancomycin (≤2.0 µg/mL for 24 h) produced small alterations in cell shape and that as the dose was increased, cell speed decreased. Vancomycin concentrations >1.0 µg/mL also inhibited cell growth and led to bleb formation on a fraction of the cells. To quantitatively assess how vancomycin affects cell stiffness, we used optical traps to bend unflagellated mutants of B. burgdorferi. We found that in the presence of vancomycin, cell wall stiffness gradually decreased over time, with a 40% reduction in the bending stiffness after 36 h. Under the same conditions, the swimming speed of wild-type B. burgdorferi slowed by â¼15%, with only marginal changes to cell morphology. Interestingly, our biophysical model for the swimming dynamics of B. burgdorferi suggested that cell speed should increase with decreasing cell stiffness. We show that this discrepancy can be resolved if the periplasmic volume decreases as the cell wall becomes softer. These results provide a testable hypothesis for how alterations of cell wall stiffness affect periplasmic volume regulation. Furthermore, since motility is crucial to the virulence of B. burgdorferi, the results suggest that sublethal doses of antibiotics could negatively impact spirochete survival by impeding their swim speed, thereby enabling their capture and elimination by phagocytes.
Assuntos
Antibacterianos/farmacologia , Borrelia burgdorferi/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Doença de Lyme/microbiologia , Fenômenos Mecânicos/efeitos dos fármacos , Movimento/efeitos dos fármacos , Vancomicina/farmacologia , Fenômenos Biomecânicos/efeitos dos fármacos , Borrelia burgdorferi/citologia , Borrelia burgdorferi/metabolismo , Borrelia burgdorferi/fisiologiaRESUMO
The Lyme disease spirochete Borrelia burgdorferi exists in nature in an enzootic cycle that involves the arthropod vector Ixodes scapularis and mammalian reservoirs. To disseminate within and between these hosts, spirochetes must migrate through complex, polymeric environments such as the basement membrane of the tick midgut and the dermis of the mammal. To date, most research on the motility of B. burgdorferi has been done in media that do not resemble the tissue milieus that B. burgdorferi encounter in vivo. Here we show that the motility of Borrelia in gelatin matrices in vitro resembles the pathogen's movements in the chronically infected mouse dermis imaged by intravital microscopy. More specifically, B. burgdorferi motility in mouse dermis and gelatin is heterogeneous, with the bacteria transitioning between at least three different motility states that depend on transient adhesions to the matrix. We also show that B. burgdorferi is able to penetrate matrices with pore sizes much smaller than the diameter of the bacterium. We find a complex relationship between the swimming behavior of B. burgdorferi and the rheological properties of the gelatin, which cannot be accounted for by recent theoretical predictions for microorganism swimming in gels. Our results also emphasize the importance of considering borrelial adhesion as a dynamic rather than a static process.
Assuntos
Borrelia burgdorferi/efeitos dos fármacos , Borrelia burgdorferi/fisiologia , Derme/efeitos dos fármacos , Derme/microbiologia , Gelatina/farmacologia , Doença de Lyme/microbiologia , Animais , Aderência Bacteriana/efeitos dos fármacos , Cinética , Metilcelulose/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Modelos Biológicos , Movimento/efeitos dos fármacos , Reologia/efeitos dos fármacos , Soluções , Imagem com Lapso de TempoRESUMO
Lyme disease, due to infection with the Ixodes-tick transmitted spirochete Borrelia burgdorferi, is the most common tick-transmitted disease in the northern hemisphere. Our understanding of the tick-pathogen-vertebrate host interactions that sustain an enzootic cycle for B. burgdorferi is incomplete. In this article, we describe a method for imaging the feeding of Ixodes scapularis nymphs in real-time using two-photon intravital microscopy and show how this technology can be applied to view the response of Lyme borrelia in the skin of an infected host to tick feeding.
Assuntos
Borrelia burgdorferi/fisiologia , Ixodes/fisiologia , Doença de Lyme/microbiologia , Pele/parasitologia , Infestações por Carrapato/parasitologia , Animais , Vetores Aracnídeos/microbiologia , Vetores Aracnídeos/fisiologia , Vetores Aracnídeos/ultraestrutura , Borrelia burgdorferi/genética , Borrelia burgdorferi/metabolismo , Comportamento Alimentar/fisiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Interações Hospedeiro-Parasita , Interações Hospedeiro-Patógeno , Ixodes/microbiologia , Ixodes/ultraestrutura , Doença de Lyme/transmissão , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência por Excitação Multifotônica , Ninfa/microbiologia , Ninfa/ultraestrutura , Fatores de TempoRESUMO
Infectious diseases are a significant burden in global healthcare. Pathogens engage with different host defense mechanisms. However, it is currently unknown if there are disease-specific immune signatures and/or if different pathogens elicit common immune-associated molecular entities to common therapeutic interventions. We studied patients enrolled through the Human Immunology Project Consortium (HIPC), which focuses on immune responses to various infections. Blood samples were collected and analyzed from patients during infection and follow-up time points at the convalescent stage. The study included samples from patients with Lyme disease (LD), tuberculosis (TB), malaria (MLA), dengue virus (DENV), and West Nile virus (WNV), as well as kidney transplant patients with cytomegalovirus (CMV) and polyomavirus (BKV) infections. Using an antibody-based assay, we quantified ~ 350 cell surface markers, cytokines, and chemokines involved in inflammation and immunity. Unique protein signatures were identified specific to the acute phase of infection irrespective of the pathogen type, with significant changes during convalescence. In addition, tumor necrosis factor receptor superfamily member 6 (TNR6), C-C Motif Chemokine Receptor 7 (CCR7), and C-C motif chemokine ligand-1 (CCL1) were increased in the acute and convalescent phases across all viral, bacterial, and protozoan compared to blood from healthy donors. Furthermore, despite the differences between pathogens, proteins were enriched in common biological pathways such as cell surface receptor signaling pathway and response to external stimulus. In conclusion, we demonstrated that irrespective of the pathogen type, there are common immunoregulatory and proinflammatory signals.
Assuntos
Proteoma , Vírus do Nilo Ocidental , Humanos , Inflamação , Citocinas , Transdução de Sinais/fisiologiaRESUMO
Advancement in proteomics methods for interrogating biological samples has helped identify disease biomarkers for early diagnostics and unravel underlying molecular mechanisms of disease. Herein, we examined the serum proteomes of 23 study participants presenting with one of two common arthropod-borne infections: Lyme disease (LD), an extracellular bacterial infection or West Nile virus infection (WNV), an intracellular viral infection. The LC/MS based serum proteomes of samples collected at the time of diagnosis and during convalescence were assessed using a depletion-based high-throughput shotgun proteomics (dHSP) pipeline as well as a non-depleting blotting-based low-throughput platform (MStern). The LC/MS integrated analyses identified host proteome responses in the acute and recovery phases shared by LD and WNV infections, as well as differentially abundant proteins that were unique to each infection. Notably, we also detected proteins that distinguished localized from disseminated LD and asymptomatic from symptomatic WNV infection. The proteins detected in both diseases with the dHSP pipeline identified unique and overlapping proteins detected with the non-depleting MStern platform, supporting the utility of both detection methods. Machine learning confirmed the use of the serum proteome to distinguish the infection from healthy control sera but could not develop discriminatory models between LD and WNV at current sample numbers. Our study is the first to compare the serum proteomes in two arthropod-borne infections and highlights the similarities in host responses even though the pathogens and the vectors themselves are different.
Assuntos
Doença de Lyme , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Humanos , Febre do Nilo Ocidental/diagnóstico , Vírus do Nilo Ocidental/fisiologia , Proteoma , Proteômica , Doença de Lyme/diagnósticoRESUMO
Hepcidin is the major regulator of systemic iron homeostasis in mammals. Hepcidin is produced mainly by the liver and is increased by inflammation, leading to hypoferremia. We measured serum levels of bioactive hepcidin and its effects on serum iron levels in mice infected with Borrelia burgdorferi. Bioactive hepcidin was elevated in the serum of mice resulting in hypoferremia. Infected mice produced hepcidin in both liver and spleen. Both intact and sonicated B burgdorferi induced hepcidin expression in cultured mouse bone marrrow macrophages. Hepcidin production by cultured macrophages represents a primary transcriptional response stimulated by B burgdorferi and not a secondary consequence of cytokine elaboration. Hepcidin expression induced by B burgdorferi was mediated primarily by activation of Toll-like receptor 2.
Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Borrelia burgdorferi/metabolismo , Receptor 2 Toll-Like/metabolismo , Receptores Toll-Like/metabolismo , Animais , Células da Medula Óssea/citologia , Citocinas/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Hepcidinas , Humanos , Inflamação , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos BiológicosRESUMO
The skin lesion erythema migrans (EM) is an initial sign of the Ixodes tick-transmitted Borreliella spirochetal infection known as Lyme disease. T cells and innate immune cells have previously been shown to predominate the EM lesion and promote the reaction. Despite the established importance of B cells and antibodies in preventing infection, the role of B cells in the skin immune response to Borreliella is unknown. Here, we used single-cell RNA-Seq in conjunction with B cell receptor (BCR) sequencing to immunophenotype EM lesions and their associated B cells and BCR repertoires. We found that B cells were more abundant in EM in comparison with autologous uninvolved skin; many were clonally expanded and had circulating relatives. EM-associated B cells upregulated the expression of MHC class II genes and exhibited preferential IgM isotype usage. A subset also exhibited low levels of somatic hypermutation despite a gene expression profile consistent with memory B cells. Our study demonstrates that single-cell gene expression with paired BCR sequencing can be used to interrogate the sparse B cell populations in human skin and reveals that B cells in the skin infection site in early Lyme disease expressed a phenotype consistent with local antigen presentation and antibody production.
Assuntos
Linfócitos B , Eritema Migrans Crônico , Imunofenotipagem/métodos , Análise de Célula Única/métodos , Adulto , Idoso , Linfócitos B/citologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Eritema Migrans Crônico/imunologia , Eritema Migrans Crônico/patologia , Feminino , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/imunologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Imunoglobulina M/genética , Imunoglobulina M/metabolismo , Doença de Lyme , Masculino , Pessoa de Meia-Idade , RNA-Seq , Pele/citologia , Transcriptoma/genética , Transcriptoma/imunologiaRESUMO
This evidence-based clinical practice guideline for the prevention, diagnosis, and treatment of Lyme disease was developed by a multidisciplinary panel representing the Infectious Diseases Society of America (IDSA), the American Academy of Neurology (AAN), and the American College of Rheumatology (ACR). The scope of this guideline includes prevention of Lyme disease, and the diagnosis and treatment of Lyme disease presenting as erythema migrans, Lyme disease complicated by neurologic, cardiac, and rheumatologic manifestations, Eurasian manifestations of Lyme disease, and Lyme disease complicated by coinfection with other tick-borne pathogens. This guideline does not include comprehensive recommendations for babesiosis and tick-borne rickettsial infections, which are published in separate guidelines. The target audience for this guideline includes primary care physicians and specialists caring for this condition such as infectious diseases specialists, emergency physicians, internists, pediatricians, family physicians, neurologists, rheumatologists, cardiologists and dermatologists in North America.
Assuntos
Doença de Lyme/diagnóstico , Doença de Lyme/terapia , Guias de Prática Clínica como Assunto/normas , Sociedades Médicas/normas , Humanos , Doença de Lyme/prevenção & controle , Estados UnidosRESUMO
Ixodes scapularis ticks transmit a number of human pathogens, including the Lyme disease spirochete Borrelia burgdorferi. I. scapularis suppresses host immunity in the skin to promote feeding and systemically skew T-helper (Th)-cell differentiation toward Th2 cells in secondary lymphoid organs. Although components of tick saliva are known to influence Th-cell polarization, the mechanism whereby tick feeding in the skin modulates regional and systemic Th-cell responses is unknown. In this study, the role of the epidermal Langerhans cell (LC) subset of skin dendritic cells in tick-mediated Th1/Th2-cell immunomodulation was assessed. Mice deficient in LCs (Langerin-DTA mice) exhibited enhanced lymph node (LN) concanavalin A (ConA)-induced Th1 responses after tick infestation in comparison to results for uninfested Langerin-DTA or wild-type (WT) mice, whereas effects on Th2-cell production of interleukin 4 were more variable. Nonetheless, the altered T-cell response did not impact tick feeding or refeeding. Gamma interferon production by ConA-stimulated LN cells of both WT and LC-deficient mice was enhanced by as much as fourfold after B. burgdorferi-infected-tick feeding, indicating that immunomodulatory effects of tick saliva were not able to attenuate the Th1 immune responses induced by this pathogen. Taken together, these findings show a requirement for LCs in the tick-mediated attenuation of Th1 responses in regional lymph nodes but not in the spleens of mice and show that the presence of a pathogen can overcome the Th1-inhibitory effects of tick feeding on the host.
Assuntos
Tolerância Imunológica , Ixodes/imunologia , Células de Langerhans/imunologia , Células Th1/imunologia , Animais , Comportamento Alimentar , Linfonodos/imunologia , Camundongos , Camundongos Knockout , Saliva/imunologia , Baço/imunologia , Células Th2/imunologiaRESUMO
The contribution of the inflammasome to the development of immune responses and disease during infection with the Lyme disease spirochete, Borrelia burgdorferi, is not well defined. Host defense against the spirochete is severely impaired in mice deficient in the adaptor molecule myeloid differentiation antigen 88 (MyD88), which is required not only for Toll-like receptor-mediated responses but also for the production of the proforms of interleukin 1beta (IL-1beta) and IL-18. These cytokines are released in active forms after cleavage by the inflammasome-associated enzyme caspase 1. To investigate the contribution of the inflammasome to host defense against B. burgdorferi, we examined Lyme borreliosis in mice deficient in either caspase 1 or apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), a molecule upstream of caspase 1 in the inflammasome signaling cascade. We found that caspase 1-deficient mice had a mild transient elevation in pathogen burden and a trend toward an increase in the prevalence of arthritis early in infection, but these differences resolved by day 14 postinfection. Caspase 1 deficiency had no effect on B. burgdorferi-induced humoral immunity, T-cell responses, or the abilities of macrophages to ingest and degrade spirochetes. The absence of the ASC protein had no effect on the control of the spirochete or the development of immune responses and disease. These findings reveal that the caspase 1 inflammasome is not critical to host defense against the extracellular pathogen Borrelia burgdorferi.
Assuntos
Borrelia burgdorferi/imunologia , Caspase 1/imunologia , Inflamação/patologia , Doença de Lyme/imunologia , Doença de Lyme/patologia , Animais , Anticorpos Antibacterianos/sangue , Proteínas Reguladoras de Apoptose , Proteínas Adaptadoras de Sinalização CARD , Caspase 1/deficiência , Proteínas do Citoesqueleto/deficiência , Proteínas do Citoesqueleto/imunologia , Feminino , Interleucina-12/metabolismo , Interleucina-1beta/metabolismo , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Linfócitos T/imunologiaAssuntos
Antibacterianos/uso terapêutico , Borrelia burgdorferi/crescimento & desenvolvimento , Doença de Lyme , Miocardite , Carrapatos/microbiologia , Animais , Doenças Endêmicas/prevenção & controle , Humanos , Doença de Lyme/diagnóstico , Doença de Lyme/tratamento farmacológico , Doença de Lyme/transmissão , Miocardite/diagnóstico , Miocardite/tratamento farmacológico , Miocardite/microbiologia , Roedores , Estados UnidosRESUMO
Borrelia miyamotoi is a relapsing fever spirochete transmitted by ticks in the Ixodes ricinus complex. In the eastern United States, B. miyamotoi is transmitted by I. scapularis, which also vectors several other pathogens including B. burgdorferi sensu stricto. In contrast to Lyme borreliae, B. miyamotoi can be transmitted vertically from infected female ticks to their progeny. Therefore, in addition to nymphs and adults, larvae can vector B. miyamotoi to wildlife and human hosts. Two widely varying filial infection prevalence (FIP) estimates - 6% and 73% - have been reported previously from two vertically infected larval clutches; to our knowledge, no other estimates of FIP or transovarial transmission (TOT) rates for B. miyamotoi have been described in the literature. Thus, we investigated TOT and FIP of larval clutches derived from engorged females collected from hunter-harvested white-tailed deer in 2015 (n = 664) and 2016 (n = 599) from Maine, New Hampshire, Tennessee, and Wisconsin. After engorged females oviposited in the lab, they (n = 492) were tested for B. miyamotoi infection by PCR. Subsequently, from each clutch produced by an infected female, larval pools, as well as 100 individual eggs or larvae, were tested. The TOT rate of the 11 infected females was 90.9% (95% CI; 57.1-99.5%) and the mean FIP of the resulting larval clutches was 84.4% (95% CI; 68.1-100%). Even though the overall observed vertical transmission rate (the product of TOT and FIP; 76.7%, 95% CI; 44.6-93.3%) was high, additional horizontal transmission may be required for enzootic maintenance of B. miyamotoi based on the results of a previously published deterministic model. Further investigation of TOT and FIP variability and the underlying mechanisms, both in nature and the laboratory, will be needed to resolve this question. Meanwhile, studies quantifying the acarological risk of Borrelia miyamotoi disease need to consider not only nymphs and adults, but larval I. scapularis as well.
Assuntos
Infecções por Borrelia/veterinária , Borrelia/isolamento & purificação , Cervos/parasitologia , Transmissão Vertical de Doenças Infecciosas , Ixodes/microbiologia , Animais , Animais Selvagens/parasitologia , Borrelia/genética , Infecções por Borrelia/epidemiologia , Infecções por Borrelia/transmissão , Feminino , Larva/microbiologia , Maine/epidemiologia , New Hampshire/epidemiologia , Ninfa/microbiologia , Reação em Cadeia da Polimerase , Tennessee/epidemiologiaRESUMO
Maintenance of Borrelia burgdorferi within its enzootic cycle requires a complex regulatory pathway involving the alternative σ factors RpoN and RpoS and two ancillary trans-acting factors, BosR and Rrp2. Activation of this pathway occurs within ticks during the nymphal blood meal when RpoS, the effector σ factor, transcribes genes required for tick transmission and mammalian infection. RpoS also exerts a 'gatekeeper' function by repressing σ70-dependent tick phase genes (e.g., ospA, lp6.6). Herein, we undertook a broad examination of RpoS functionality throughout the enzootic cycle, beginning with modeling to confirm that this alternative σ factor is a 'genuine' RpoS homolog. Using a novel dual color reporter system, we established at the single spirochete level that ospA is expressed in nymphal midguts throughout transmission and is not downregulated until spirochetes have been transmitted to a naïve host. Although it is well established that rpoS/RpoS is expressed throughout infection, its requirement for persistent infection has not been demonstrated. Plasmid retention studies using a trans-complemented ΔrpoS mutant demonstrated that (i) RpoS is required for maximal fitness throughout the mammalian phase and (ii) RpoS represses tick phase genes until spirochetes are acquired by a naïve vector. By transposon mutant screening, we established that bba34/oppA5, the only OppA oligopeptide-binding protein controlled by RpoS, is a bona fide persistence gene. Lastly, comparison of the strain 297 and B31 RpoS DMC regulons identified two cohorts of RpoS-regulated genes. The first consists of highly conserved syntenic genes that are similarly regulated by RpoS in both strains and likely required for maintenance of B. burgdorferi sensu stricto strains in the wild. The second includes RpoS-regulated plasmid-encoded variable surface lipoproteins ospC, dbpA and members of the ospE/ospF/elp, mlp, revA, and Pfam54 paralogous gene families, all of which have evolved via inter- and intra-strain recombination. Thus, while the RpoN/RpoS pathway regulates a 'core' group of orthologous genes, diversity within RpoS regulons of different strains could be an important determinant of reservoir host range as well as spirochete virulence.