Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA).

Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.

Knowledge, protective behaviours, and perception of Lyme disease in an area of emerging risk: results from a cross-sectional survey of adults in Ottawa, Ontario.

BACKGROUND: The number of Lyme disease risk areas in Canada is growing. In regions with emerging tick populations, it is important to emphasize peridomestic risk and the importance of protective behaviours in local public health communication. This study aims to identify characteristics associated with high levels of Lyme disease knowledge and adoption of protective behaviours among residents in the Ottawa, Ontario region. METHODS: A geographically stratified web survey was conducted in November 2020 (n = 2018) to determine knowledge, attitudes, and practices regarding Lyme disease among adult residents. Responses were used to calculate: (i) composite scores for knowledge and adoption of protective practices; and (ii) an exposure risk index based on reported activity in woodlands during the spring-to-fall tick exposure risk period. RESULTS: 60% of respondents had a high knowledge of Lyme disease, yet only 14% indicated they often use five or more measures to protect themselves. Factors strongly associated with a high level of Lyme disease knowledge included being 55 or older (Odds Ratio (OR) = 2.04), living on a property with a yard (OR = 3.22), having a high exposure index (OR = 1.59), and knowing someone previously infected with Lyme disease (OR = 2.05). Strong associations with the adoption of a high number of protective behaviours were observed with membership in a non-Indigenous racialized group (OR = 1.70), living on a property with a yard (OR = 2.37), previous infection with Lyme disease (OR = 2.13), prior tick bite exposure (OR = 1.62), and primarily occupational activity in wooded areas (OR = 2.31). CONCLUSIONS: This study highlights the dynamics between Lyme disease knowledge, patterns of exposure risk awareness, and vigilance of personal protection in a Canadian region with emerging Lyme disease risk. Notably, this study identified gaps between perceived local risk and protective behaviours, presenting opportunities for targeted enhanced communication efforts in areas of Lyme disease emergence.

Lyme disease vaccine attitudes and intentions among parents of children aged 5-18 years in the United States.

BACKGROUND: Lyme disease (LD) is the most common vector-borne disease in the United States, with increasing incidence and geographic range. Case incidence peaks among school-aged children. New LD preventives are in clinical trials. METHODS: We conducted an online survey of parents of children aged 5-18 years in states with high or emerging incidence of LD. Our primary outcome was willingness ("definitely" or "probably") for their child to receive an LD vaccine. Our secondary outcome was preference for annual monoclonal antibody injections compared to a 3-dose vaccine series with boosters. Analyses were weighted to reflect parent gender, parent race/ethnicity, and child age by state. RESULTS: Among 1,351 parent respondents, most (68.0 %) would have their child vaccinated against LD, with significantly more being willing in high compared to emerging incidence states (70.4 % versus 63.6 %, p = 0.027). Of parents who were unsure or unwilling, 33.5 % and 16.5 %, respectively, would do so with a provider recommendation. Vaccine safety concerns were among the top reasons for LD vaccine hesitancy. More parents preferred a pre-formed antibody (42.3 %) compared to a 3-dose vaccine series (34.7 %). Significant predictors of willingness to have one's child vaccinated were higher parental education; higher perceived risk of child getting LD; child spending time outdoors daily or weekly; following a regular vaccine schedule; and positive attitude towards vaccines. Significant predictors of preference for monoclonal antibody over a 3-dose vaccine series included prior awareness of LD, living in a rural area, and less positive attitudes towards vaccines. CONCLUSIONS: Two-thirds of parents in high and emerging incidence states would vaccinate their children against Lyme disease. Addressing safety concerns will be important, and a health care provider recommendation could also encourage those who are unsure or unwilling. Given the slight preference for monoclonal antibody over vaccine, particularly in rural areas, access to both may increase LD prevention.

Intention to vaccinate for Lyme disease using the Health Belief Model.

AIMS: Lyme disease (LD) cases in the United States are estimated to be approaching 500,000 annually. Protective measures, such as repellent use and wearing protective clothing are recommended by public health officials. However, no protective measure has been proven to be consistently effective, partly because they require consistent and persistent behaviour change. While safe and effective vaccines are in development, it is unclear what factors influence the intention to vaccinate against LD. This study uses the Health Belief Model (HBM) framework to determine key drivers associated with vaccine intention. The HBM is widely applied in public health research and uses the following constructs: perceived susceptibility and severity of disease, perceived benefits and barriers to disease prevention, and cues to action for disease prevention to predict health behaviours. To date, the HBM framework has not been applied to vaccination intention for LD. METHODS AND RESULTS: Data were collected from 874 adults and 834 caregivers of children residing in US states endemic to LD. Sampling adults and caregivers allows us to explore how the intention to vaccinate differs among those at-risk. Estimates from structural equation modelling (SEM) show that the HBM constructs explain much of the variation in intention to vaccinate against LD. Both adult and caregiver intentions to vaccinate are positively influenced by cues to action, perceived susceptibility of LD, and perceived benefits to vaccination. However, there is variation in the influence of constructs across the samples. Caregiver's intention to vaccinate is positively influenced by the perceived severity of LD and negatively influenced by safety concerns about the vaccine, whereas adult intention is negatively influenced by perceived barriers to vaccination. CONCLUSION: A strong relationship of cues to action on vaccine intention in samples of adults and caregivers suggests the importance of a recommendation from a healthcare provider or the Centers for Disease Control and Prevention (CDC).

Biophysical and biochemical characterization of a recombinant Lyme disease vaccine antigen, CspZ-YA.

Lyme disease, caused by Lyme Borrelia spirochetes, is the most common vector-borne illness in the United States. Despite its global significance, with an estimated 14.5 % seroprevalence, there is currently no licensed vaccine. Previously, we demonstrated that CspZ-YA protein conferred protection against Lyme Borrelia infection, making it a promising vaccine candidate. However, such a protein was tagged with hexahistidine, and thus not preferred for vaccine development; furthermore, the formulation to stabilize the protein was understudied. In this work, we developed a two-step purification process for tag-free E. coli-expressed recombinant CspZ-YA. We further utilized various bioassays to analyze the protein and determine the suitable buffer system for long-term storage and formulation as a vaccine immunogen. The results indicated that a buffer with a pH between 6.5 and 8.5 stabilized CspZ-YA by reducing its surface hydrophobicity and colloidal interactions. Additionally, low pH values induced a change in local spatial conformation and resulted in a decrease in α-helix content. Lastly, an optimal salinity of 22-400 mM at pH 7.5 was found to be important for its stability. Collectively, this study provides a fundamental biochemical and biophysical understanding and insights into the ideal stabilizing conditions to produce CspZ-YA recombinant protein for use in vaccine formulation and development.

Operational Considerations for Using Deer-Targeted 4-Poster Tick Control Devices in a Tick-borne Disease Endemic Community.

CONTEXT: In the northeastern United States, recommendations to prevent diseases spread by black-legged ticks ( Ixodes scapularis ) and lone star ticks ( Amblyomma americanum ) often rely on individuals to use personal protection or yard-based strategies. The 4-Poster deer treatment stations (4-Posters) suppress tick populations by treating deer hosts with acaricide, potentially offering a community-wide approach for reducing tick-borne diseases in endemic areas. The 4-Poster deployment logistics in mainland community settings are not well documented but are needed for future public health tick control efforts. PROGRAM: As part of a public health research effort to design a population-based 4-Poster effectiveness study aimed at reducing tick-borne disease incidence, TickNET researchers partnered with the Town of Ridgefield (Connecticut) to understand the feasibility and operational logistics of deploying 4-Posters on public land within a residential community to inform future public health interventions by municipalities or vector control agencies. IMPLEMENTATION: We deployed three 4-Posters on a municipal property from July to December 2020 and used motion-activated cameras to record wildlife activity nearby. We documented per-device operational details, costs, materials consumed, and animal activity. EVALUATION: Operation of 4-Posters was feasible, and device challenges were easily remedied. Deer visitation and heavy nontarget animal use were documented at all devices. Unexpectedly, monthly corn consumption was not correlated with monthly deer-view days. The monthly cost per device was US $1279 or US $305 per hectare with an average 21 minutes of weekly service time. DISCUSSION: Use of 4-Posters by communities, public health agencies, or vector control programs may be a practicable addition to tick management programs in tick-borne disease endemic areas in the Northeast. Such programs should carefully consider local and state regulations, follow manufacturer and pesticide label guidelines, and include wildlife monitoring. High labor costs incurred in this project could be mitigated by training vector control agency or municipality staff to service 4-Posters.

Prospective incidence epidemiology study protocol: conducting active surveillance to assess the burden of Lyme disease (BOLD) in primary care practices in endemic areas of six European countries.

INTRODUCTION: Lyme disease (LD) is the most frequent tick-borne disease in the moderate climates of Europe. This study will inform the phase III efficacy study for Pfizer and Valneva's investigational Lyme disease vaccine, VLA15. VLA15 phase III will be conducted in the USA and Europe due to the vaccine's serotype coverage and public health burden of LD. In Europe, the existence and location of sites that have access to populations with high LD annual incidence is uncertain. This active, prospective surveillance study assesses annual LD incidence at general practice (GP)/primary care sites, allowing for phase III site vetting and better characterisation of LD burden in selected regions for study size calculations. METHODS AND ANALYSIS: This burden of Lyme disease (BOLD) study will assess LD incidence overall and by site at 15 GP/primary care practices in endemic areas of 6 European countries from Spring 2021 to December 2022 and will be summarised with counts (n), percentages (%) and associated 95% CIs. Suspected LD cases identified from site's practice panels are documented on screening logs, where clinical LD manifestations, diagnoses and standard of care diagnostic results are recorded. In the initial 12-month enrolment phase, suspected LD cases are offered enrolment. Participants undergo interview and clinical assessments to establish medical history, final clinical diagnosis, clinical manifestations and quality of life impact. Study-specific procedures include LD serology, skin punch biopsies and Lyme manifestation photographs. For every enrolled participant diagnosed with LD, 6-10 age-matched controls are randomly selected and offered enrolment for an embedded LD risk factor analysis. Persistent symptoms or post-treatment LD will be assessed at follow-up visits up to 2 years after initial diagnosis, while patients remain symptomatic. ETHICS AND DISSEMINATION: This study has been approved by all sites' local ethics committees. The results will be presented at conferences and published in peer-reviewed journals.

Knowledge, protection behaviours and seroprevalence of Lyme borreliosis in inhabitants of Lublin Province, eastern Poland - evaluation of a prophylaxis programme.

INTRODUCTION AND OBJECTIVE: Lyme borreliosis (LB) is the most frequent tick-borne disease with 17,338 cases reported in Poland in 2022. Since research on a LB vaccine is still ongoing, the promotion of individual behaviours and limiting of tick exposure is one of the most effective ways to prevent LB. The aim of the study was to evaluate the effectiveness of the LB prevention programme by assessing the knowledge, practice behaviours, seroprevalence of LB and satisfaction among the population of the Lublin Province in eastern Poland. MATERIAL AND METHODS: The prevention programme was carried out among 2,920 participants who were asked about their exposure to ticks, history of LB and prevention behaviours. Awareness of knowledge was evaluated before and after training. Seroprevalence of LB was rated by ELISA and immunoblot assays. RESULTS: Over 73% of participants reported tick bites in their lifetime, without significant differences between rural and urban area inhabitants. More than 80% of individuals declared that they use protective measures (PPM), such as proper clothes and body checking; repellents were the least frequently used by participants. The diagnosis of LB but not tick bites in a lifetime influenced the more frequent use of PPM. Increase in knowledge was observed in 86% of participants after education, and the highest knowledge was noted among respondents with higher education. The seroprevalence of anti-B. burgdorferi antibodies was 37% and was higher among men than women (40% vs. 36%). CONCLUSIONS: The population of Lublin Province is highly exposed to tick bites and infection with B. burgdorferi. The high seroprevalence and increase in knowledge confirmed the effectiveness and need for preventive programmes. These results can be useful for optimizing and enhancing the effects of future prevention campaigns.

Lyme Disease Knowledge, Practices, and Vaccine Acceptability Among Nurse Practitioners in Pediatric Practice.

INTRODUCTION: Lyme disease (LD) is a major public health problem in the United States. Given its incidence and geographic expansion, nurse practitioners (NPs) will likely encounter patients with this condition. METHOD: NPs were invited to participate in an electronic survey via email, newsletter, and social media posts. The 31-question survey collected information on provider characteristics, clinical scenario decisions, resources used, and vaccine sentiment for LD. RESULTS: Survey participants (n = 606) were primarily cisgender female (75%) and aged 30-49 years (62%). Responding to six hypothetical clinical scenarios, only 31% of participants answered most questions correctly. If an LD vaccine becomes available, 39% said they would incorporate it into practice; 48% would seek further information before deciding. DISCUSSION: Additional education on LD prevention, diagnosis, and treatment is needed for NPs. Increasing provider awareness of current guidelines and developing tailored resources for NPs may improve patient care.

Development of an mRNA-lipid nanoparticle vaccine against Lyme disease.

Lyme disease is the most common vector-borne infectious disease in the United States, in part because a vaccine against it is not currently available for humans. We propose utilizing the lipid nanoparticle-encapsulated nucleoside-modified mRNA (mRNA-LNP) platform to generate a Lyme disease vaccine like the successful clinical vaccines against SARS-CoV-2. Of the antigens expressed by Borrelia burgdorferi, the causative agent of Lyme disease, outer surface protein A (OspA) is the most promising candidate for vaccine development. We have designed and synthesized an OspA-encoding mRNA-LNP vaccine and compared its immunogenicity and protective efficacy to an alum-adjuvanted OspA protein subunit vaccine. OspA mRNA-LNP induced superior humoral and cell-mediated immune responses in mice after a single immunization. These potent immune responses resulted in protection against bacterial infection. Our study demonstrates that highly efficient mRNA vaccines can be developed against bacterial targets.

Acceptability of 4-poster deer treatment devices for community-wide tick control among residents of high Lyme disease incidence counties in Connecticut and New York, USA.

The 4-Poster Tick Control Deer Feeder (4-poster) device applies acaricide to white-tailed deer (Odocoileus virginianus) and can reduce populations of the blacklegged tick (Ixodes scapularis), which transmits the agents of Lyme disease, anaplasmosis, babesiosis, and Powassan virus disease in the Northeastern United States. While 4-poster devices have the potential to provide community-wide management of blacklegged ticks in Lyme disease endemic areas, no recent study has assessed their acceptability among residents. We conducted a survey of residents from 16 counties with high annual average Lyme disease incidence (≥ 10 cases per 100,000 persons between 2013 and 2017) in Connecticut and New York to understand perceptions and experiences related to tickborne diseases, support or concerns for placement of 4-poster devices in their community, and opinions on which entities should be responsible for tick control on private properties. Overall, 37% of 1652 respondents (5.5% response rate) would support placement of a 4-poster device on their own property, 71% would support placement on other private land in their community, and 90% would support placement on public land. Respondents who were male, rented their property, resided on larger properties, or were very or extremely concerned about encountering ticks on their property were each more likely to support placement of 4-poster devices on their own property. The primary reason for not supporting placement of a 4-poster device on one's own property was the need for weekly service visits from pest control professionals, whereas the top reason for not supporting placement on other land (private or public) was safety concerns. Most respondents (61%) felt property owners should be responsible for tick control on private properties. Communities considering 4-poster devices as part of a tick management strategy should consider targeting owners of larger properties and placing devices on public lands.

Citizen Science on Lyme Borreliosis in Spain Reveals Disease-Associated Risk Factors and Control Interventions.

Background: Lyme borreliosis (LB) caused by Borrelia burgdorferi sensu lato complex spirochetes is one of the tick-borne diseases with high prevalence and social/economic burden in the United States, Spain, and other European countries. The objective is to address limited information available about the incidence, prevalence, and symptoms of LB, current prevention, and treatment interventions that are not adequately focused and thus not very effective against this disease. Methods: To address these limitations, in this study, we used a citizen science approach to evaluate the LB-associated risks and implementation of control interventions in Spain. A total of 405 participants in the survey were included in the analysis. Responses to the questionnaire were received during January-July 2022. The questionnaire contained qualitative and quantitative questions. Homogeneity among binary variables was analyzed using a Fisher's exact test. Results: Despite limitations of the study associated with response to the questionnaire and information on tick species, the results evidenced the effect of factors such as age, gender, tick bites, disease clinical signs, comorbidities such as alpha-gal syndrome, health care services, and treatment effectiveness affecting LB. Conclusions: The main conclusions of the study highlight the need for better surveillance of tick infestations, pathogen infection, and diagnosis of LB and related comorbidities. To advance in disease prevention, diagnosis, and treatment, new interventions need to be developed and implemented in both public and private health care services. Providing access to these results to the society, health care system, and scientists is important to further advance in disease surveillance, diagnosis, control, and prevention.

Safety and immunogenicity of a novel multivalent OspA-based vaccine candidate against Lyme borreliosis: a randomised, phase 1 study in healthy adults.

BACKGROUND: Lyme borreliosis, potentially associated with serious long-term complications, is caused by the species complex Borrelia burgdorferi sensu lato. We investigated a novel Lyme borreliosis vaccine candidate (VLA15) targeting the six most common outer surface protein A (OspA) serotypes 1-6 to prevent infection with pathogenic Borrelia spp prevalent in Europe and North America. METHODS: This was a partially randomised, observer-masked, phase 1 study in healthy adults older than 18 years to younger than 40 years (n=179) done in trial sites in Belgium and the USA. Following a non-randomised run-in phase, a sealed envelope randomisation method was applied with a 1:1:1:1:1:1 ratio; three dose concentrations of VLA15 (12 µg, 48 µg, and 90 µg) were administered by intramuscular injection on days 1, 29, and 57. The primary outcome was safety (frequency of adverse events up to day 85) assessed in participants who received at least one vaccination. Immunogenicity was a secondary outcome. The trial is registered with ClinicalTrials.gov, NCT03010228, and is complete. FINDINGS: Between Jan 23, 2017 and Jan 16, 2019, of 254 participants screened for eligibility, 179 were randomly assigned into six groups: alum-adjuvanted 12 µg (n=29), 48 µg (n=31), or 90 µg (n=31) and non-adjuvanted 12 µg (n=29 participants), 48 µg (n=29), or 90 µg (n=30). VLA15 was safe and well tolerated and the majority of adverse events were mild or moderate. Overall, adverse events were more frequent in the 48 µg and 90 µg groups (range 28-30 participants [94-97%]) when compared with the 12 µg group (25 [86%] participants, 95% CI 69·4-94·5) for adjuvanted and non-adjuvanted groups. Common local reactions were tenderness (151 [84%] participants; 356 events, 95% CI 78·3-89·4) and injection site pain (120 [67%]; 224 events, 59·9-73·5); most frequent systemic reactions were headache (80 [45%]; 112 events, 37·6-52·0), excessive fatigue (45 [25%]; 56 events, 19·4-32·0), and myalgia (45 [25%]; 57 events, 19·4-32·0). A similar safety and tolerability profile was observed between adjuvanted and non-adjuvanted formulations. The majority of solicited adverse events were mild or moderate. VLA15 was immunogenic for all OspA serotypes with higher immune responses induced in the adjuvanted higher dose groups (geometric mean titre range 90 µg with alum 61·3 U/mL-321·7 U/mL vs 23·8 U/mL-111·5 U/mL at 90 µg without alum). INTERPRETATION: This novel multivalent vaccine candidate against Lyme borreliosis was safe and immunogenic and paves the way to further clinical development. FUNDING: Valneva Austria.

Can protection motivation theory predict protective behavior against ticks?

BACKGROUND: Cases of reported tick-borne diseases in humans have increased over the past decades. Strategies informing the public about ticks, their associated diseases, and preventive measures are often highlighted as important in limiting pathogen transfer and disease. However, knowledge about the motivation for people to apply preventative measures is sparse. METHODS: The aim was to examine if Protection Motivation Theory, a model of disease prevention and health promotion, can predict the use of protective measures against ticks. Ordinal logistic regression and Chi-square tests were used on data from a cross-sectional survey with respondents from Denmark, Norway, and Sweden (n = 2658). We examined the effect of (1) the perceived seriousness of tick bites, Lyme borreliosis (LB), and tick-borne encephalitis (TBE), and (2) the perceived probability of getting a tick bite, Lyme borreliosis, and tick-borne encephalitis on protection against ticks. Finally, we examined if there was an association between the use of a protective measure and the perceived efficacy of that measure. RESULTS: The perceived seriousness of a tick bite and LB significantly predict who is more likely to apply protective measures for all three countries combined. The perceived seriousness of TBE did not significantly predict the level of adoption of protective measures applied by respondents. The perceived likelihood of getting a tick bite within the next 12 months and the perceived likelihood of getting LB if bitten by a tick significantly predicted the application of protective measures. However, the increases in the likelihood of protection were very small. The application of a certain type of protection was always correlated with the perceived efficacy of the same protective measure. CONCLUSION: Some variables of PMT may be used to predict the level of adoption of protection applied against ticks and tick-borne diseases. We found that the perceived seriousness of a tick bite and LB significantly predict the level of adoption protection. The perceived likelihood of getting a tick bite or LB also significantly predicted the level of adoption of protection, although the change was very small. The results regarding TBE were less clear. Lastly, there was an association between applying a protective measure and the perceived efficacy of the same measure.

Deer management generally reduces densities of nymphal Ixodes scapularis, but not prevalence of infection with Borrelia burgdorferi sensu stricto.

Human Lyme disease-primarily caused by the bacterium Borrelia burgdorferi sensu stricto (s.s.) in North America-is the most common vector-borne disease in the United States. Research on risk mitigation strategies during the last three decades has emphasized methods to reduce densities of the primary vector in eastern North America, the blacklegged tick (Ixodes scapularis). Controlling white-tailed deer populations has been considered a potential method for reducing tick densities, as white-tailed deer are important hosts for blacklegged tick reproduction. However, the feasibility and efficacy of white-tailed deer management to impact acarological risk of encountering infected ticks (namely, density of host-seeking infected nymphs; DIN) is unclear. We investigated the effect of white-tailed deer density and management on the density of host-seeking nymphs and B. burgdorferi s.s. infection prevalence using surveillance data from eight national parks and park regions in the eastern United States from 2014-2022. We found that deer density was significantly positively correlated with the density of nymphs (nymph density increased by 49% with a 1 standard deviation increase in deer density) but was not strongly correlated with the prevalence of B. burgdorferi s.s. infection in nymphal ticks. Further, while white-tailed deer reduction efforts were followed by a decrease in the density of I. scapularis nymphs in parks, deer removal had variable effects on B. burgdorferi s.s. infection prevalence, with some parks experiencing slight declines and others slight increases in prevalence. Our findings suggest that managing white-tailed deer densities alone may not be effective in reducing DIN in all situations but may be a useful tool when implemented in integrated management regimes.

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.

The Ixodes ricinus salivary gland proteome during feeding and B. Afzelii infection: New avenues for an anti-tick vaccine.

INTRODUCTION: Borrelia burgdorferi sensu lato, the causative agents of Lyme borreliosis, are transmitted by Ixodes ticks. Tick saliva proteins are instrumental for survival of both the vector and spirochete and have been investigated as targets for vaccine targeting the vector. In Europe, the main vector for Lyme borreliosis is Ixodes ricinus, which predominantly transmits Borrelia afzelii. We here investigated the differential production of I. ricinus tick saliva proteins in response to feeding and B. afzelii infection. METHOD: Label-free Quantitative Proteomics and Progenesis QI software was used to identify, compare, and select tick salivary gland proteins differentially produced during tick feeding and in response to B. afzelii infection. Tick saliva proteins were selected for validation, recombinantly expressed and used in both mouse and guinea pig vaccination and tick-challenge studies. RESULTS: We identified 870 I. ricinus proteins from which 68 were overrepresented upon 24-hours of feeding and B. afzelii infection. Selected tick proteins were successfully validated by confirming their expression at the RNA and native protein level in independent tick pools. When used in a recombinant vaccine formulation, these tick proteins significantly reduced the post-engorgement weights of I. ricinus nymphs in two experimental animal models. Despite the reduced ability of ticks to feed on vaccinated animals, we observed efficient transmission of B. afzelii to the murine host. CONCLUSION: Using quantitative proteomics, we identified differential protein production in I. ricinus salivary glands in response to B. afzelii infection and different feeding conditions. These results provide novel insights into the process of I. ricinus feeding and B. afzelii transmission and revealed novel candidates for an anti-tick vaccine.

Impacts Over Time of Neighborhood-Scale Interventions to Control Ticks and Tick-Borne Disease Incidence.

Background: Controlling populations of ticks with biological or chemical acaricides is often advocated as a means of reducing human exposure to tick-borne diseases. Reducing tick abundance is expected to decrease immediate risk of tick encounters and disrupt pathogen transmission cycles, potentially reducing future exposure risk. Materials and Methods: We designed a placebo-controlled, randomized multiyear study to assess whether two methods of controlling ticks-tick control system (TCS) bait boxes and Met52 spray-reduced tick abundance, tick encounters with people and outdoor pets, and reported cases of tick-borne diseases. The study was conducted in 24 residential neighborhoods in a Lyme disease endemic zone in New York State. We tested the hypotheses that TCS bait boxes and Met52, alone or together, would be associated with increasing reductions in tick abundance, tick encounters, and cases of tick-borne disease over the 4-5 years of the study. Results: In neighborhoods with active TCS bait boxes, populations of blacklegged ticks (Ixodes scapularis) were not reduced over time in any of the three habitat types tested (forest, lawn, shrub/garden). There was no significant effect of Met52 on tick abundance overall, and there was no evidence for a compounding effect over time. Similarly, we observed no significant effect of either of the two tick control methods, used singly or together, on tick encounters or on reported cases of tick-borne diseases in humans overall, and there was no compounding effect over time. Thus, our hypothesis that effects of interventions would accumulate through time was not supported. Conclusions: The apparent inability of the selected tick control methods to reduce risk and incidence of tick-borne diseases after years of use requires further consideration.