Agent Of Lyme Disease Research Articles

An Overview of Lyme Disease in Europe

Vector-Borne and Zoonotic DiseasesVol. 23, No. 4 IntroductionFree AccessAn Overview of Lyme Disease in EuropeStephen Higgs and Catherine A. BrissetteStephen HiggsAddress correspondence to: Stephen Higgs, Editor-in-Chief, Vector-Borne and Zoonotic Diseases E-mail Address: shiggs@bri.ksu.eduEditor-in-Chief, Vector-Borne and Zoonotic Diseases.Biosecurity Research Institute, Kansas State University, Manhattan, Kansas, USA.Search for more papers by this author and Catherine A. BrissetteDepartment of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, USA.Search for more papers by this authorPublished Online:12 Apr 2023https://doi.org/10.1089/vbz.2023.29006.higAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Lyme disease is a high profile, and often controversial and emotive topic in the United States and as described hereunder, Vector-borne and Zoonotic Diseases (VBZ) has been at the forefront for dissemination of new information. However, many VBZ subscribers may not realize the significance of Lyme disease in Europe. This dedicated issue of VBZ, prepared by researchers from many different countries, presents data and resources to elevate awareness and inform our international readership on the importance of Lyme in Europe.For >20 years, VBZ has published articles on all aspects of Lyme disease, indeed the first editor Durland Fish was a highly respected and productive Lyme disease researcher, and the establishment of the journal in 2001 was in large part based on his passion to establish a resource for data related to Lyme disease. In a report published in 2018, it was estimated that between 2004 and 2016, the number of annually reported tick-borne diseases had doubled, and of the reported 491,671 cases, >80% were Lyme disease (Rosenberg et al., 2018).Cases of a previously unnamed diseases, initially thought to be juvenile rheumatoid arthritis, had been occurring since the mid 1970s in the Connecticut town of Lyme. What was initially called Lyme arthritis, was renamed to Lyme disease, due to the range and complexity of symptoms. Patients with symptoms consistent with Lyme disease, progressing to chronic arthritis, were subsequently identified in multiple states. Although a hard tick vector Ixodes dammini (now Ix. scapularis) was implicated, the etiologic agent remained elusive.In 1982, Burgdorfer et al. (1982) successfully identified the agent that caused Lyme disease. Spirochete bacteria isolated from ticks collected in New York and cultured in vitro were found to react with serum collected from Lyme disease patients, and with this essential clue, bacteria were subsequently isolated from patient tissues.As mentioned earlier, Lyme disease is, because of its name, regarded by many as a U.S. disease, but ironically, symptoms consistent with Lyme disease had been described in Europe in the 1880s (Buchwald, 1883). Cases of the disease presenting as chronic skin disorders (erythema migrans), sometimes associated with nervous system disorders, were subsequently described from multiple countries in Europe, and the first successful treatment using antibiotics was accomplished in 1949. Although an etiologic agent remained unknown, the treatment suggested that this must be bacterial. Although the possibility that the disease might be caused by pathogens transmitted by ticks was suggested in 1923 (Lipschutz, 1923), this was unconfirmed.With discoveries published in the late 1970s and early 1980s in the United States, isolates of the new species of Borrelia were soon obtained from both ticks and patients by European scientists. The new species was described in 1984 as Borrelia burgdorferi (Johnson et al., 1984). Various genotypes of the spirochete were later described as Borrelia afzelii and Borrelia garinii, which also cause Lyme disease symptoms.In this special issue of VBZ, 11 articles, by 38 coauthors with multiple affiliations in many different countries, provide much needed information to better understand the importance of Lyme disease in Europe, data for specific countries and implications for public health. All articles contained within this special issue have been peer reviewed by VBZ. This is not a sponsored supplement. Refer to each individual article for proper disclosures.ReferencesBuchwald A. A case of diffuse idiopathic skin atrophy [in German]. Arch Dermatol Syphilis 1883;10:553–556. Crossref, Google ScholarBurgdorfer W, Barbour AG, Hayes SF, et al. Lyme disease—A tick borne spirochetosis. Science 1982;216:1317–1319. Crossref, Medline, Google ScholarJohnson RC, Schmid GO, Hyde FW, et al. Borrelia burgdorferi sp.nov.: Etiologic agent of Lyme disease. Int J Syst Bacteriol 1984;34:496–497. Crossref, Google ScholarLipschutz B. Further contributions to the knowledge of “Erythema chronicum migrans” [in German]. Arch Dermatol Syphilis 1923;143:365–374. Google ScholarRosenberg R, Lindsey NP, Fischer M, et al. Vital signs: Trends in reported vectorborne disease cases—United States and territories, 2004–2016. MMWR 2018;67:496–501. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetails Volume 23Issue 4Apr 2023 InformationCopyright 2023, Mary Ann Liebert, Inc., publishersTo cite this article:Stephen Higgs and Catherine A. Brissette.An Overview of Lyme Disease in Europe.Vector-Borne and Zoonotic Diseases.Apr 2023.137-138.http://doi.org/10.1089/vbz.2023.29006.higPublished in Volume: 23 Issue 4: April 12, 2023PDF download

Structural Elucidation of a Protective B Cell Epitope on Outer Surface Protein C (OspC) of the Lyme Disease Spirochete, Borreliella burgdorferi.

Outer surface protein C (OspC) plays a pivotal role in mediating tick-to-host transmission and infectivity of the Lyme disease spirochete, Borreliella burgdorferi. OspC is a helical-rich homodimer that interacts with tick salivary proteins, as well as components of the mammalian immune system. Several decades ago, it was shown that the OspC-specific monoclonal antibody, B5, was able to passively protect mice from experimental tick-transmitted infection by B. burgdorferi strain B31. However, B5's epitope has never been elucidated, despite widespread interest in OspC as a possible Lyme disease vaccine antigen. Here, we report the crystal structure of B5 antigen-binding fragments (Fabs) in complex with recombinant OspC type A (OspCA). Each OspC monomer within the homodimer was bound by a single B5 Fab in a side-on orientation, with contact points along OspC's α-helix 1 and α-helix 6, as well as interactions with the loop between α-helices 5 and 6. In addition, B5's complementarity-determining region (CDR) H3 bridged the OspC-OspC' homodimer interface, revealing the quaternary nature of the protective epitope. To provide insight into the molecular basis of B5 serotype specificity, we solved the crystal structures of recombinant OspC types B and K and compared them to OspCA. This study represents the first structure of a protective B cell epitope on OspC and will aid in the rational design of OspC-based vaccines and therapeutics for Lyme disease. IMPORTANCE The spirochete Borreliella burgdorferi is a causative agent of Lyme disease, the most common tickborne disease in the United States. The spirochete is transmitted to humans during the course of a tick taking a bloodmeal. After B. burgdorferi is deposited into the skin of a human host, it replicates locally and spreads systemically, often resulting in clinical manifestations involving the central nervous system, joints, and/or heart. Antibodies directed against B. burgdorferi's outer surface protein C (OspC) are known to block tick-to-host transmission, as well as dissemination of the spirochete within a mammalian host. In this report, we reveal the first atomic structure of one such antibody in complex with OspC. Our results have implications for the design of a Lyme disease vaccine capable of interfering with multiple stages in B. burgdorferi infection.

Mechanistic movement models to predict geographic range expansions of ticks and tick-borne pathogens: Case studies with Ixodes scapularis and Amblyomma americanum in eastern North America

The geographic range of the blacklegged tick, Ixodes scapularis, is expanding northward from the United States into southern Canada, and studies suggest that the lone star tick, Amblyomma americanum, will follow suit. These tick species are vectors for many zoonotic pathogens, and their northward range expansion presents a serious threat to public health. Climate change (particularly increasing temperature) has been identified as an important driver permitting northward range expansion of blacklegged ticks, but the impacts of host movement, which is essential to tick dispersal into new climatically suitable regions, have received limited investigation. Here, a mechanistic movement model was applied to landscapes of eastern North America to explore 1) relationships between multiple ecological drivers and the speed of the northward invasion of blacklegged ticks infected with the causative agent of Lyme disease, Borrelia burgdorferi sensu stricto, and 2) its capacity to simulate the northward range expansion of infected blacklegged ticks and uninfected lone star ticks under theoretical scenarios of increasing temperature. Our results suggest that the attraction of migratory birds (long-distance tick dispersal hosts) to resource-rich areas during their spring migration and the mate-finding Allee effect in tick population dynamics are key drivers for the spread of infected blacklegged ticks. The modeled increases in temperature extended the climatically suitable areas of Canada for infected blacklegged ticks and uninfected lone star ticks towards higher latitudes by up to 31% and 1%, respectively, and with an average predicted speed of the range expansion reaching 61 km/year and 23 km/year, respectively. Differences in the projected spatial distribution patterns of these tick species were due to differences in climate envelopes of tick populations, as well as the availability and attractiveness of suitable habitats for migratory birds. Our results indicate that the northward invasion process of lone star ticks is primarily driven by local dispersal of resident terrestrial hosts, whereas that of blacklegged ticks is governed by long-distance migratory bird dispersal. The results also suggest that mechanistic movement models provide a powerful approach for predicting tick-borne disease risk patterns under complex scenarios of climate, socioeconomic and land use/land cover changes.

Diving into the complexity of the spirochetal endoflagellum.

Spirochaetes, a phylum that includes medically important pathogens such as the causative agents of Lyme disease, syphilis, and leptospirosis, are in many ways highly unique bacteria. Their cell morphology, subcellular organization, and metabolism reveal atypical features. Spirochetal motility is also singular, dependent on the presence of periplasmic flagella or endoflagella, inserted subterminally at cell poles and not penetrating the outer membrane and elongating outside the cell as in enterobacteria. In this review we present a comprehensive comparative genomics analysis of endoflagellar systems in spirochetes, highlighting recent findings on the flagellar basal body and filament. Continued progress in understanding the function and architecture of spirochetal flagella is uncovering paradigm-shifting mechanisms of bacterial motility.

Endogenous Linear Plasmids lp28-4 and lp25 Are Required for Infectivity and Restriction Protection in the Lyme Disease Spirochete Borrelia mayonii.

Borrelia mayonii is a newly recognized causative agent of Lyme disease in the Upper Midwestern United States, with distinct clinical presentations compared to classical Lyme disease caused by other Lyme Borrelia species. However, little is known about the B. mayonii genetic determinants required for establishing infection or perpetuating disease in mammals. Extrachromosomal plasmids in Borrelia species often encode proteins necessary for infection and pathogenesis, and spontaneous loss of these plasmids can lead to the identification of virulence determinant genes. Here, we describe infection of Lyme disease-susceptible C3H mice with B. mayonii, and show bacterial dissemination and persistence in peripheral tissues. Loss of endogenous plasmids, including lp28-4, lp25, and lp36 correlated with reduced infectivity in mice. The apparent requirement for lp28-4 during murine infection suggests the presence of a novel virulence determinant, as this plasmid does not encode homologs of any known virulence determinant. We also describe transformation and stable maintenance of a self-replicating shuttle vector in B. mayonii, and show that loss of either lp25 or lp28-4 correlated with increased transformation competency. Finally, we demonstrate that linear plasmids lp25 and lp28-4 each encode functional restriction modification systems with distinct but partially overlapping target modification sequences, which likely accounts for the observed decrease in transformation efficiency when those plasmids are present. Taken together, this study describes a role for endogenous plasmids in mammalian infection and restriction protection in the Lyme disease spirochete Borrelia mayonii.

Role of the Hypothetical Protein BB0563 during Borrelia burgdorferi Infection in Animals.

The alternative sigma factor RpoS in Borrelia burgdorferi, the etiological agent of Lyme disease, has long been postulated to regulate virulence-associated genes other than ospC and dbpA. Here, we demonstrate that bb0563, a gene encoding a hypothetical protein, is regulated by RpoS and contributes to the optimal infectivity of B. burgdorferi. When B. burgdorferi was exposed to environmental stimuli, bb0563 showed similar expression patterns as rpoS, ospC, and dbpA. Expression of bb0563 was significantly downregulated when rpoS was inactivated and was restored in the complemented strain. By using rapid amplification of cDNA ends (RACE) and luciferase reporter assays, a functional promoter was identified in the regulatory region upstream of bb0563. Gene expression from this promoter was drastically decreased in the rpoS mutant. We next investigated the role of bb0563 during animal infection. By using quantitative reverse transcription-PCR (RT-PCR), we found that bb0563 was highly expressed in mouse tissues during infection. We further created a bb0563-deficient mutant in a bioluminescent B. burgdorferi strain and examined infection dynamics using in vivo imaging. Relative to the parental and complemented strains, the mutant showed a delayed infection pattern and bacterial load was reduced. Another bb0563 deletion mutant was also created in the strain 297 background, and quantitative PCR (qPCR) analysis revealed a significantly lower spirochetal burden in tissue samples collected from animals infected with the mutant. In addition, localization studies indicate that BB0563 is not exposed on the cell surface but is associated with outer membrane. Taken together, these results suggest that bb0563 is required for optimal infectivity of B. burgdorferi during experimental infection.

Borrelia burgdorferi induces changes in the physical forces and immunity signaling pathways of endothelial cells early but not late during in vitro exposure

Borrelia burgdorferi (Bb) is the causative bacterial agent of Lyme disease which is on the rise in the USA and Europe. Once transmitted to the human host via an arthropod vector, Bb spreads through tissues by traveling along and through the vasculature, whose inner lumen is lined by a monolayer of endothelial cells (ECs). What are the precise mechanisms that Bb employs to achieve efficient dissemination through the vasculature is not well understood. Could extracellular Bb induce alterations in the EC force generation machinery, promoting its own spread by potentially weakening the EC barrier integrity? Using videomicroscopy coupled with traction force and monolayer stress microscopy, we monitored the response of ECs to Bb exposure and found a sharp, transient increase in EC traction and intercellular stresses, followed by a prolonged decrease in EC traction and monolayer stresses up to 15 hours post-exposure. After this point though all variables return to levels similar to those observed for never-exposed ECs. Using RNA-sequencing to better understand the underlying biochemical mechanisms involved, we discovered an upregulation of EC innate immune signaling pathways during early but not late exposure to Bb. In contrast to exposure of ECs to live Bb, when we exposed ECs to heat-inactivated Bb, we evidenced no sharp increase in traction forces at early exposure, neither reversal at late exposure, but found a sustained weakening of physical forces all throughout the exposure. Thus, we discovered a differential response of EC physical force generation and innate immune signaling to live versus heat-inactivated Bb. This indicates a tight interplay between the two and is suggestive of an active modulation of both processes that might be key in establishing infection.

Ecology and Epidemiology of Lyme Disease in Western North America

Lyme disease is the most common vector-borne disease in the United States and Canada. The causative agent of Lyme disease in North America is the spirochete Borrelia burgdorferi. In western North America, the primary vector of Borrelia burgdorferi is the western black-legged tick, Ixodes pacificus. Surveillance and modelling efforts indicate that I. pacificus is primarily found in coastal California, Oregon, Washington and the southern coastal regions of British Columbia However, infection rates with B. burgdorferi among I. pacificus ticks remain low, ranging from 0.6% to 9.9%. Lyme disease case numbers in western North America are also relatively low compared to eastern North America. Enzootic maintenance of B. burgdorferi by hosts in natural environments and climatic factors may influence Lyme disease risk. The borreliacidal western fence lizard, Sceloporus occidentalis, may contribute to the low infection rates observed in I. pacificus ticks, while the migratory nature of avian hosts can allow for long-distance tick dispersal. Moderately warm and moist environments and protection from sunlight define the suitable habitats of I. pacificus ticks. In this review, we discuss the ecology and epidemiology of Lyme disease in relation to I. pacificus, as well as the need for more studies in western North America.

A putative xanthine dehydrogenase is critical for Borrelia burgdorferi survival in ticks and mice.

Borrelia burgdorferi is a pathogenic bacterium and the causative agent of Lyme disease. It is exposed to reactive oxygen species (ROS) in both the vertebrate and tick hosts. While some mechanisms by which B. burgdorferi ameliorates the effects of ROS exposure have been studied, there are likely other unknown mechanisms of ROS neutralization that contribute to virulence. Here, we follow up on a three gene cluster of unknown function, bb_0554, bb_0555, and bb_0556, that our prior unbiased transposon insertional sequencing studies implicated in both ROS survival and survival in Ixodes scapularis. We confirmed these findings through genetic knockout and provide evidence that these genes are co-transcribed as an operon to produce a xanthine dehydrogenase. In agreement with these results, we found that B. burgdorferi exposure to either uric acid (a product of xanthine dehydrogenase) or allopurinol (an inhibitor of xanthine dehydrogenase) could modulate sensitivity to ROS in a bb_0554-bb_0556 dependent manner. Together, this study identifies a previously uncharacterized three gene operon in B. burgdorferi as encoding a putative xanthine dehydrogenase critical for virulence. We propose renaming this locus xdhACB.

Repeated Tick Infestations Impair Borrelia burgdorferi Transmission in a Non-Human Primate Model of Tick Feeding.

The blacklegged tick, Ixodes scapularis, is the predominant vector of Borrelia burgdorferi, the agent of Lyme disease in the USA. Natural hosts of I. scapularis such as Peromyscus leucopus are repeatedly infested by these ticks without acquiring tick resistance. However, upon repeated tick infestations, non-natural hosts such as guinea pigs, mount a robust immune response against critical tick salivary antigens and acquire tick resistance able to thwart tick feeding and Borrelia burgdorferi transmission. The salivary targets of acquired tick resistance could serve as vaccine targets to prevent tick feeding and the tick transmission of human pathogens. Currently, there is no animal model able to demonstrate both tick resistance and diverse clinical manifestations of Lyme disease. Non-human primates serve as robust models of human Lyme disease. By evaluating the responses to repeated tick infestation, this animal model could accelerate our ability to define the tick salivary targets of acquired resistance that may serve as vaccines to prevent the tick transmission of human pathogens. Towards this goal, we assessed the development of acquired tick resistance in non-human primates upon repeated tick infestations. We report that following repeated tick infestations, non-human primates do not develop the hallmarks of acquired tick resistance observed in guinea pigs. However, repeated tick infestations elicit immune responses able to impair the tick transmission of B. burgdorferi. A mechanistic understanding of the protective immune responses will provide insights into B. burgdorferi-tick-host interactions and additionally contribute to anti-tick vaccine discovery.

Borrelia burgdorferi DnaA and the Nucleoid-Associated Protein EbfC Coordinate Expression of the dnaX-ebfC Operon.

Borrelia burgdorferi, the spirochete agent of Lyme disease, has evolved within a consistent infectious cycle between tick and vertebrate hosts. The transmission of the pathogen from tick to vertebrate is characterized by rapid replication and a change in the outer surface protein profile. EbfC, a highly conserved nucleoid-associated protein, binds throughout the borrelial genome, affecting expression of many genes, including the Erp outer surface proteins. In B. burgdorferi, like many other bacterial species, ebfC is cotranscribed with dnaX, an essential component of the DNA polymerase III holoenzyme, which facilitates chromosomal replication. The expression of the dnaX-ebfC operon is tied to the spirochete's replication rate, but the underlying mechanism for this connection was unknown. In this work, we provide evidence that the expression of dnaX-ebfC is controlled by direct interactions of DnaA, the chromosomal replication initiator, and EbfC at the unusually long dnaX-ebfC 5' untranslated region (UTR). Both proteins bind to the 5' UTR DNA, with EbfC also binding to the RNA. The DNA binding of DnaA to this region was similarly impacted by ATP and ADP. In vitro studies characterized DnaA as an activator of dnaX-ebfC and EbfC as an antiactivator. We further found evidence that DnaA may regulate other genes essential for replication. IMPORTANCE The dual life cycle of Borrelia burgdorferi, the causative agent of Lyme disease, is characterized by periods of rapid and slowed replication. The expression patterns of many of the spirochete's virulence factors are impacted by these changes in replication rates. The connection between replication and virulence can be understood at the dnaX-ebfC operon. DnaX is an essential component of the DNA polymerase III holoenzyme, which replicates the chromosome. EbfC is a nucleoid-associated protein that regulates the infection-associated outer surface Erp proteins, as well as other transcripts. The expression of dnaX-ebfC is tied to replication rate, which we demonstrate is mediated by DnaA, the master chromosomal initiator protein and transcription factor, and EbfC.

402: FATAL TICK BITE

Introduction: As of 2022, there has been no fatality reported in NJ from severe Babesiosis. We present a case of Babesiosis with rapid clinical deterioration to shock and death in an immunocompetent patient despite early recognition and proper recommended treatment through multidisciplinary approach. Description: 48-year-old obese male with Diabetes Mellitus and Hypertension presented to emergency department two weeks after hiking, with epigastric, non-radiating pain associated with fevers, headache, worsening fatigue, poor intake, and watery diarrhea for a week. Patient was febrile, tachypneic, hypoxic, and jaundiced. Initial bloodwork reflected leukocytosis, anemia, elevated reticulocyte count, thrombocytopenia, elevated indirect bilirubinemia, acute kidney Injury and lactic acidosis. Chest radiograph with bilateral lower lobe infiltrates. Babesia microti IgG and IgM were detected with intra and extra cellular paracitemia of 9.9%. Patient was admitted to intensive care unit for Acute respiratory, renal and liver failure. Initially started on Intravenous Azithromycin, Atovaquone and later Doxycycline and Zosyn were added given continued deterioration. Patient required mechanical ventilation and hemodialysis, steroids, Intravenous immunoglobulin. Red blood exchange therapy was completed within 12 hours of admission given high parasitemia. Despite aggressive measures during ICU stay, patient declined and expired 72 hours into hospital course. Discussion: Babesia are intraerythrocytic protozoan parasites of animals and humans, a disease transmitted by infected tick, Ixodes scapularis, which also transmits other causative agents of Lyme Disease. Babesiosis can range from mild to severe disease and death. Severity depends on babesia species, age, host immune status, route of transmission, and parasitemia level. Incidence is highest in summer months, middle-aged patients. Fatality rate reported at 3-9% in hospitalized patients, 20% among immunosuppressed or disease acquisition via blood transfusion. Clinicians need to be aware of the risk of fulminant illness when practicing in known endemic regions. It is important to keep zoonotic infections as part of differential in patient presenting with multi organ failure.

Polyploidy, regular patterning of genome copies, and unusual control of DNA partitioning in the Lyme disease spirochete

Borrelia burgdorferi, the tick-transmitted spirochete agent of Lyme disease, has a highly segmented genome with a linear chromosome and various linear or circular plasmids. Here, by imaging several chromosomal loci and 16 distinct plasmids, we show that B. burgdorferi is polyploid during growth in culture and that the number of genome copies decreases during stationary phase. B. burgdorferi is also polyploid inside fed ticks and chromosome copies are regularly spaced along the spirochete’s length in both growing cultures and ticks. This patterning involves the conserved DNA partitioning protein ParA whose localization is controlled by a potentially phage-derived protein, ParZ, instead of its usual partner ParB. ParZ binds its own coding region and acts as a centromere-binding protein. While ParA works with ParZ, ParB controls the localization of the condensin, SMC. Together, the ParA/ParZ and ParB/SMC pairs ensure faithful chromosome inheritance. Our findings underscore the plasticity of cellular functions, even those as fundamental as chromosome segregation.

The environment, the tick, and the pathogen - It is an ensemble.

Ixodes scapularis is one of the predominant vectors of Borrelia burgdorferi, the agent of Lyme disease in the USA. The geographic distribution of I. scapularis, endemic to the northeastern and northcentral USA, is expanding as far south as Georgia and Texas, and northwards into Canada and poses an impending public health problem. The prevalence and spread of tick-borne diseases are influenced by the interplay of multiple factors including microbiological, ecological, and environmental. Molecular studies have focused on interactions between the tick-host and pathogen/s that determine the success of pathogen acquisition by the tick and transmission to the mammalian host. In this review we draw attention to additional critical environmental factors that impact tick biology and tick-pathogen interactions. With a focus on B. burgdorferi we highlight the interplay of abiotic factors such as temperature and humidity as well as biotic factors such as environmental microbiota that ticks are exposed to during their on- and off-host phases on tick, and infection prevalence. A molecular understanding of this ensemble of interactions will be essential to gain new insights into the biology of tick-pathogen interactions and to develop new approaches to control ticks and tick transmission of B. burgdorferi, the agent of Lyme disease.

A tick C1q protein alters infectivity of the Lyme disease agent by modulating interferon γ.

In North America, the Lyme disease agent, Borrelia burgdorferi, is commonly transmitted by the black-legged tick, Ixodes scapularis. Tick saliva facilitates blood feeding and enhances pathogen survival and transmission. Here, we demonstrate that I.scapularis complement C1q-like protein 3 (IsC1ql3), a tick salivary protein, directly interacts with B.burgdorferi and is important during the initial stage of spirochetal infection of mice. Mice fed upon by B.burgdorferi-infected IsC1ql3-silenced ticks, or IsC1ql3-immunized mice fed upon by B.burgdorferi-infected ticks, have a lower spirochete burden during the early phase of infection compared with control animals. Mechanically, IsC1ql3 interacts with the globular C1q receptor present on the surface of CD4+ and CD8+ Tcells, resulting in decreased production of interferon γ. IsC1ql3 is a C1q-domain-containing protein identified in arthropod vectors and has an important role in B.burgdorferi infectivity as the spirochete transitions from the tick to vertebrate host.

Limited detection of shared zoonotic pathogens in deer keds and blacklegged ticks co-parasitizing white-tailed deer in the eastern United States.

Deer keds, such as Lipoptena cervi Linnaeus (Diptera: Hippoboscidae), are blood-feeding flies from which several human and animal pathogens have been detected, including Borrelia burgdorferi sensu lato Johnson (Spirochaetales: Borreliaceae), the causative agent of Lyme disease. Cervids (Artiodactyla: Cervidae), which are the primary hosts of deer keds, are not natural reservoirs of B. burgdorferi sl, and it has been suggested that deer keds may acquire bacterial pathogens via co-feeding near infected ticks. We screened L. cervi (n=306) and Ixodes scapularis Say (Ixodida: Ixodidae) (n=315) collected from 38 white-tailed deer in Pennsylvania for the family Anaplasmataceae, Bartonella spp. (Hyphomicrobiales: Bartonellaceae), Borrelia spp., and Rickettsia spp. (Rickettsiales: Rickettsiaceae). Limited similarity in the bacterial DNA detected between these ectoparasites per host suggested that co-feeding may not be a mechanism by which deer keds acquire these bacteria. The feeding biology and life history of deer keds may impact the observed results, as could the season when specimens were collected. We separately screened L. cervi (n=410), L. mazamae Róndani (n=13), L. depressa Say (n=10), and Neolipoptena ferrisi Bequaert (n=14) collections from locations within the United States and Canada for the same pathogens. These results highlight the need to further study deer ked-host and deer ked-tick relationships.

An AP-3-dependent pathway directs phagosome fusion with Rab8 and Rab11 vesicles involved in TLR2 signaling.

Intracellular compartmentalization of ligands, receptors and signaling molecules has been recognized as an important regulator of inflammation. The toll-like receptor (TLR) 2 pathway utilizes the trafficking molecule adaptor protein 3 (AP-3) to activate interleukin (IL)-6 signaling from within phagosomal compartments. To better understand the vesicular pathways that may contribute to intracellular signaling and cooperate with AP-3, we performed a vesicular siRNA screen. We identified Rab8 and Rab11 GTPases as important in IL-6 induction upon stimulation with the TLR2 ligand Pam3 CSK4 or the pathogen, Borrelia burgdorferi (Bb), the causative agent of Lyme disease. These Rabs were recruited to late and lysosomal stage phagosomes and co-transported with TLR2 signaling adaptors and effectors, such as MyD88, TRAM and TAK1, in an AP-3-dependent manner. Our data support a model where AP-3 mediates the recruitment of recycling and secretory vesicles and the assembly of signaling complexes at the phagosome.

Tick transmission of Borrelia burgdorferi to the murine host is not influenced by environmentally acquired midgut microbiota

BackgroundIxodes scapularis is the predominant tick vector of Borrelia burgdorferi, the agent of Lyme disease, in the USA. Molecular interactions between the tick and B. burgdorferi orchestrate the migration of spirochetes from the midgut to the salivary glands—critical steps that precede transmission to the vertebrate host. Over the last decade, research efforts have invoked a potential role for the tick microbiome in modulating tick-pathogen interactions.ResultsUsing multiple strategies to perturb the microbiome composition of B. burgdorferi-infected nymphal ticks, we observe that changes in the microbiome composition do not significantly influence B. burgdorferi migration from the midgut, invasion of salivary glands, or transmission to the murine host. We also show that within 24 and 48 h of the onset of tick feeding, B. burgdorferi spirochetes are within the peritrophic matrix and epithelial cells of the midgut in preparation for exit from the midgut.ConclusionsThis study highlights two aspects of tick-spirochete interactions: (1) environmental bacteria associated with the tick do not influence spirochete transmission to the mammalian host and (2) the spirochete may utilize an intracellular exit route during migration from the midgut to the salivary glands, a strategy that may allow the spirochete to distance itself from microbiota in the midgut lumen effectively. This may explain in part, the inability of environment-acquired midgut microbiota to significantly influence spirochete transmission. Unraveling a molecular understanding of this exit strategy will be critical to gain new insights into the biology of the spirochete and the tick.7AdntFwsX5JjuXz-jKBq7oVideo

Direct Capture and Early Detection of Lyme Disease Spirochete in Skin with a Microneedle Patch.

Borrelia burgdorferi sensu lato family of spirochetes causes Lyme disease (LD) in animals and humans. As geographic territory of ticks expands across the globe, surveillance measures are needed to measure transmission rates and provide early risk testing of suspected bites. The current standard testing of LD uses an indirect two-step serological assay that detects host immune reactivity. Early detection remains a challenge because the host antibody response develops several weeks after infection. A microneedle (MN) device was developed to sample interstitial fluid (ISF) and capture spirochetes directly from skin. After sampling, the MN patch is easily dissolved in water or TE buffer, and the presence of spirochete DNA is detected by PCR. Performance was tested by spiking porcine ear skin with inactivated Borrelia burgdorferi, which had an approximate recovery of 80% of spirochetes. With further development, this simple direct PCR method could be a transformative approach for early detection of the causative agent of Lyme disease and enable rapid treatment to patients when infection is early, and numbers of systemic spirochetes are low.

Borrelia burgdorferi, the Lyme disease spirochete, possesses genetically-encoded responses to doxycycline, but not to amoxicillin.

Some species of bacteria respond to antibiotic stresses by altering their transcription profiles, in order to produce proteins that provide protection against the antibiotic. Understanding these compensatory mechanisms allows for informed treatment strategies, and could lead to the development of improved therapeutics. To this end, studies were performed to determine whether Borrelia burgdorferi, the spirochetal agent of Lyme disease, also exhibits genetically-encoded responses to the commonly prescribed antibiotics doxycycline and amoxicillin. After culturing for 24 h in a sublethal concentration of doxycycline, there were significant increases in a substantial number of transcripts for proteins that are involved with translation. In contrast, incubation with a sublethal concentration of amoxicillin did not lead to significant changes in levels of any bacterial transcript. We conclude that B. burgdorferi has a mechanism(s) that detects translational inhibition by doxycycline, and increases production of mRNAs for proteins involved with translation machinery in an attempt to compensate for that stress.