Adriana Marques

Lyme borreliosis is the most common tick-borne disease in the northern hemisphere. It is a zoonosis caused by several species of Borrelia burgdorferi sensu lato and transmitted by the bite of infected ticks of the Ixodes ricinus complex. Lyme borreliosis in North America and Europe differs in certain respects, likely reflecting the different Borrelia species that cause human disease in these locations. The earliest manifestation of Lyme borreliosis is the skin lesion erythema migrans, which develops at the tick bite site, typically 7-14 days after the bite. Some untreated patients will then (within the first few weeks or months after onset of the infection) develop additional erythema migrans skin lesions or other clinical manifestations such as borrelial lymphocytoma, nervous system involvement or carditis. Several months or even years after infection onset, Lyme arthritis or acrodermatitis chronica atrophicans may develop. The diagnosis of typical erythema migrans is clinical, whereas for all other manifestations the diagnosis is supported via serological testing. Treatment with an appropriate antibiotic will result in resolution of clinical symptoms in most patients; however, some patients experience prolonged subjective symptoms, which usually improve over time. Repeated courses of antimicrobials are not beneficial except in rare cases when there is objective evidence of treatment failure.

Sam R Telford, III, Gary P Wormser, Kenneth Dardick, Luis A Marcos, Rafal Tokarz, Linden T Hu, Adriana R Marques; Vectors are not just culture vessels, Cli

Acquired tick resistance (ATR) is well characterized in tick‐exposed animals, compromising tick fitness through antibody‐mediated activation of basophils. Yet, anti‐tick vaccines inducing ATR have had limited success. Here, we describe a neuroimmune event preceding ATR that leads to rapid host‐mediated tick removal. Tick‐sensitized guinea pigs mechanically remove ticks within 3–6 h via an acquired neuroimmune‐induced itch response that correlates with increased dermal expression of itch‐associated genes and skin infiltration by CD3 ⁺ T cells and Iba‐1 ⁺ macrophages, independent of IgG and IgE antibodies. Inhibiting the development of acquired T cell memory by averting naive lymphocyte egress from lymph nodes with the sphingosine‐1‐phosphate receptor modulator FTY720, before tick sensitization, prevents Iba‐1 ⁺ macrophage and CD3 ⁺ T cell infiltration to the tick bite site and abrogates scratching and tick removal. This neuroimmune response is independent of Trpv1 as tick‐sensitized guinea pigs treated with the Trpv1 agonist, resiniferatoxin, remove ticks effectively. Strikingly, prior exposure to a single tick is sufficient to generate a fast and active itch‐induced tick removal (IITR) that is observed even in tick‐attached sites distant from the location of previous tick exposure. IITR represents a novel approach to tick‐borne disease prevention through early tick detection and fast removal.

Background: Some patients report nonspecific symptoms after antibiotic therapy for Lyme disease (LD), raising questions about ongoing infection, despite no compelling evidence. We investigated whether xenodiagnosis could detect Borrelia burgdorferi in such patients and if positive results correlated with symptoms. Methods: Participants were adults who completed antibiotic treatment for LD 3–12 months earlier (posttherapy, n = 40) or had persistent symptoms for ≥12 months after treatment, (posttreatment LD symptoms [PTLDS], n = 20). Controls included 1 patient with erythema migrans (EM), 1 patient with untreated Lyme arthritis (LA), and 9 healthy volunteers (HV). Participants had 25–30 larval Ixodes scapularis ticks placed; ticks were collected 3–6 days later and tested for B. burgdorferi. The primary analysis evaluated if B. burgdorferi detection by xenodiagnosis was associated with persistence of symptoms in patients during the first year after treatment. This trial is registered with ClinicalTrials.gov, NCT02446626. Results: Recovered ticks included 402 from posttherapy, 314 from PTLDS, 30 from the EM patient, 11 from the LA patient, and 80 from HV. All ticks tested negative for B. burgdorferi except for 1 tick from a recovered patient. An unplanned interim analysis led to the early termination of the study for futility. Conclusions: Xenodiagnosis with larval I. scapularis ticks showed no evidence of B. burgdorferi in most patients after treatment, irrespective of symptoms. This may be due to the absence of bacteria or to the low sensitivity of the technique in humans. This method is unlikely to detect persistent B. burgdorferi infection in humans, and further research on the use of xenodiagnosis is unwarranted.

Establishment of immunoglobulin diversity is contingent on recombination that occurs both at the Fab and at the Fc regions of the immunoglobulin, and this process is time dependent. Based on this principle, we questioned whether Lyme disease stage can be distinguished by quantification of immunoglobulin class and IgG isotype specific to VlsE in serum from clinically characterized patients. We used an enzyme immunoassay to categorize serologic antibodies to VlsE antigen as well as machine-learning techniques to train and integrate multiple predictors to identify likely disease stage. We found that IgM/IgG3/IgG1/IgA1 was enriched in serum obtained in the earliest stages, whereas IgG3/IgG1/IgG4 was enriched in Lyme arthritis. IgG2 detection was unremarkable across all disease stages. Post-Treatment Lyme Disease Syndrome (PTLDS) serum was enriched in IgG3/IgG1/IgA1 but lacked IgM. The multivariable models showed better predictive accuracy than any single immunoglobulin model, with more than half of panels perfectly identified by random forest under cross validation (56%) vs a maximum of 38% for a model using IgG1 alone. The findings suggest a characteristic succession of VlsE-specific antibody switching between immunoglobulin class and IgG isotype as Lyme disease progresses from early to late stages. The data also suggest that immunoglobulin class and IgG isotyping are likely more helpful to distinguish early Lyme disease cases. Comprehensive evaluation of immunoglobulin class (M, G, A) and IgG isotypes (1/2/3/4) provides time-dependent pathogen-induced host response information to current Lyme disease antibody detection and may be useful for differentiation of disease stage. IMPORTANCE: The order of switching between the immunoglobulin heavy chain (Fc) is time dependent, progressing from IgM/D to IgG3/IgG1/IgA1/IgG2/IgG4 and later to IgE/IgA2. In this study, we show that B. burgdorferi -VlsE-specific antibody switching proceeds in a predictable sequence between class (Ig M/G/A) and IgG isotype (IgG 1/2/3/4) as Lyme disease progresses from early to late stage and that antibody class and isotype may be more helpful to distinguish the early stages of Lyme disease. This study advances our understanding of the tempo and structure of the humoral immune response to B. burgdorferi and is applicable to the development of new diagnostic assays for Lyme disease.

Ixodes scapularis ticks are an important vector for at least seven tick-borne human pathogens, including a North American Lyme disease spirochete, Borrelia burgdorferi . The ability for these ticks to survive in nature is credited, in part, to their ability to feed on a variety of hosts without triggering an immune response capable of preventing tick feeding. While the ability of nymphal ticks to feed on a variety of hosts has been well documented, the host-parasite interactions between larval I. scapularis and different vertebrate hosts are relatively unexplored. Here we report on the changes in the vertebrate host transcriptome present at the larval tick bite site using the natural I. scapularis host Peromyscus leucopus , a non-natural rodent host, Mus musculus (BALB/c), and humans. We note substantially less evidence of activation of canonical proinflammatory pathways in P. leucopus compared to BALB/c mice and pronounced evidence of inflammation in humans. Pathway enrichment analyses revealed a particularly strong signature of interferon gamma, tumor necrosis factor, and interleukin 1 signaling at the BALB/c and human tick bite sites. We also note that bite sites on BALB/c mice and humans, but not deer mice, show activation of wound-healing pathways. These data provide molecular evidence of the coevolution between larval I. scapularis and P. leucopus and, in addition, expand our overall understanding of I. scapularis feeding.

Protracted fatigue and other symptoms can occur after Lyme disease and other infections, with numerous possible drivers. Studies on posttreatment Lyme disease have been inconclusive, with no confirmed biomarker emerging. Prolonged antibiotic therapy provides no benefit. Thus, a holistic approach toward understanding and treating this complex disease is necessary.

Borrelia burgdorferi, the agent of Lyme disease, is estimated to cause >400,000 annual infections in the United States. Serology is the primary laboratory method to support the diagnosis of Lyme disease, but current methods have intrinsic limitations that require alternative approaches or targets. We used a high-density peptide array that contains >90,000 short overlapping peptides to catalog immunoreactive linear epitopes from >60 primary antigens of B. burgdorferi . We then pursued a machine learning approach to identify immunoreactive peptide panels that provide optimal Lyme disease serodiagnosis and can differentiate antibody responses at various stages of disease. We examined 226 serum samples from the Lyme Biobank and the National Institutes of Health, which included sera from 110 individuals diagnosed with Lyme disease, 31 probable cases from symptomatic individuals, and 85 healthy controls. Cases were grouped based on disease stage and presentation and included individuals with early localized, early disseminated, and late Lyme disease. We identified a peptide panel originating from 14 different epitopes that differentiated cases versus controls, whereas another peptide panel built from 12 unique epitopes differentiated subjects with various disease manifestations. Our method demonstrated an improvement in B. burgdorferi antibody detection over the current two-tiered testing approach and confirmed the key diagnostic role of VlsE and FlaB antigens at all stages of Lyme disease. We also uncovered epitopes that triggered a temporal antibody response that was useful for differentiation of early and late disease. Our findings can be used to streamline serologic targets and improve antibody-based diagnosis of Lyme disease. IMPORTANCE: Serology is the primary method of Lyme disease diagnosis, but this approach has limitations, particularly early in disease. Currently employed antibody detection assays can be improved by the identification of alternative immunodominant epitopes and the selection of optimal diagnostic targets. We employed high-density peptide arrays that enabled precise epitope mapping for a wide range of B. burgdorferi antigens. In combination with machine learning, this approach facilitated the selection of serologic targets early in disease and the identification of serological indicators associated with different manifestations of Lyme disease. This study provides insights into differential antibody responses during infection and outlines a new approach for improved serologic diagnosis of Lyme disease.