Characterization of the humoral immune response in dogs after vaccination against the Lyme borreliosis agent A study with five commercial vaccines using two different vaccination schedules

Antibody-mediated immunological memory correlates with long-term Lyme veterinary vaccine protection in mice

Lyme disease, caused by the bacterium Borrelia burgdorferi, is the most common tick-borne illness in the United States. Despite the rise in Lyme disease incidence, there is no vaccine against B. burgdorferi approved for human use. Little is known about the immune correlates of protection needed to prevent Lyme disease. In this work, a mouse model was used to characterize the immune response and compare the protection provided by two USDA-approved vaccines for use in canines: Duramune (bacterin vaccine) and Vanguard crLyme (subunit vaccine composed of two outer surface proteins, OspA and OspC). C3H/HeNCrl mice were immunized with two doses of either Duramune or Vanguard, and immune responses and protection against B. burgdorferi were assessed in short (35 days) and long-term (120 days) studies. Flow cytometry, ELISPOT detection of antibody-producing cells, and antibody affinity studies were performed to identify correlates of vaccine-mediated protection. Both vaccines induced humoral responses, with high IgG titers against B. burgdorferi. However, the levels of anti-B. burgdorferi antibodies decayed over time in Vanguard-vaccinated mice. While both vaccines triggered the production of antibodies against both OspA and OspC, antibody levels against these proteins were also lower in Vanguard-vaccinated mice 120 days post-vaccination. Both vaccines only provided partial protection against B. burgdorferi at the dose used in this model. The protection provided by Duramune was superior to Vanguard 120 days post-vaccination, and was characterized by higher antibody titers, higher abundance of long-lived plasma cells, and higher avidity antibodies than Vanguard. Overall, these studies provide insights into the importance of the humoral memory response to veterinary vaccines against Lyme disease and will help inform the development of future human vaccines.

Lyme Borreliosis in Dogs: Background, Epidemiology, Diagnostics, Treatment and Prevention

Lyme borreliosis (LB) is a multisystemic tick-borne disease that can affect many organs and have various clinical manifestations in dogs. We attempted to summarise various aspects of Lyme disease: i. e., pathogenesis, epidemiology, benefits and risks of diagnostic approaches, treatment options, and prevention in dogs. Several diagnostic bottlenecks for LB in dogs and humans are compared. Because the occurrence of LB in both humans and dogs is closely related, monitoring its prevalence in dogs as sentinel animals is an excellent aid in assessing the risk of Lyme disease in a given geographic area. Although clinical symptoms in humans help clinicians diagnose LB, they are ineffective in dogs because canines rarely exhibit LB symptoms. Despite significant differences in sensitivity and specificity, sero-logical two-step detection of antibodies against Borrelia spp. (ELISA and Western blot) is the most commonly used method in humans and dogs. The limitations of the assay highlight the need for further research to develop new clinical markers and more accurate diagnostic tests. Due to the lack of a specific all-encompassing LB test, a definitive diagnosis of LB remains a difficult and time-consuming process in human and veterinary medicine. Understanding the disease prevalence and diagnostics, as well as preventing its spread with effective and timely treatment, are fundamental principles of good disease management.

Revealing the Tick Microbiome: Insights into Midgut and Salivary Gland Microbiota of Female Ixodes ricinus Ticks

The ectoparasite Ixodes ricinus is an important vector for many tick-borne diseases (TBD) in the northern hemisphere, such as Lyme borreliosis, rickettsiosis, human granulocytic anaplasmosis, or tick-borne encephalitis virus. As climate change will lead to rising temperatures in the next years, we expect an increase in tick activity, tick population, and thus in the spread of TBD. Consequently, it has never been more critical to understand relationships within the microbial communities in ticks that might contribute to the tick's fitness and the occurrence of TBD. Therefore, we analyzed the microbiota in different tick tissues such as midgut, salivary glands, and residual tick material, as well as the microbiota in complete Ixodes ricinus ticks using 16S rRNA gene amplicon sequencing. By using a newly developed DNA extraction protocol for tick tissue samples and a self-designed mock community, we were able to detect endosymbionts and pathogens that have been described in the literature previously. Further, this study displayed the usefulness of including a mock community during bioinformatic analysis to identify essential bacteria within the tick.

Vaccines for Lyme Borreliosis: Facts and Challenges

Lyme borreliosis (LB) is a multisystem infectious disease abundant in the northern countries of the world and is caused by Borrelia species. Vaccination against LB is an effective way to prevent and reduce the number of diseases in endemic areas. Several vaccines have been developed and tested in the past, but no human LB vaccine is currently available on the market. This review aims to uncover and delineate various strategies and diverse technological approaches related to vaccine production. Furthermore, we characterize already tested vaccines, possibilities for their future development, and reasons for their failure.

Human and Veterinary Vaccines for Lyme Disease

Lyme disease (LD) is an emerging zoonotic infection that is increasing in incidence in North America, Europe, and Asia. With the development of safe and efficacious vaccines, LD can potentially be prevented. Vaccination offers a cost-effective and safe approach for decreasing the risk of infection. While LD vaccines have been widely used in veterinary medicine, they are not available as a preventive tool for humans. Central to the development of effective vaccines is an understanding of the enzootic cycle of LD, differential gene expression of Borrelia burgdorferi in response to environmental variables, and the genetic and antigenic diversity of the unique bacteria that cause this debilitating disease. Here we review these areas as they pertain to past and present efforts to develop human, veterinary, and reservoir targeting LD vaccines. In addition, we offer a brief overview of additional preventative measures that should employed in conjunction with vaccination.

A study with a commercial vaccine against Lyme borreliosis in horses using two different vaccination schedules: Characterization of the humoral immune response

A total of 143 horses were included in a study to test a commercial vaccine against Lyme borreliosis. The vaccine contained three different antigens (outer surface protein A, OspA) to prevent the infection with spirochetes - B.burgdorferi sensu stricto, B. afzelii and B. garinii. Horses in Group A (49 animals) received two vaccinations on days 0 and 14 and a booster on day 365, whereas 50 horses in Group B received an additional booster vaccination on day 180. Group C (44 animals) was not immunized. Total antibody levels and specific OspA antibody responses were assessed quantitatively and qualitatively in two-month intervals over 13-month period. Vaccinees in Groups A and B developed high OspA antibodies levels, whereas horses in Group C did not show specific antibody responses. The additional vaccination applied in Group B enhanced the specific OspA antibody response significantly and prevented its rapid decline.

Borreliosis in Sport Horse Practice

Given the variable clinical signs attributed to Borrelia burgdorferi, including infectious arthritis, neurologic disease, and behavioral changes, B burgdorferi is an important differential for decreased performance in sport horses. The primary vectors (Ixodes tick species) are expanding their range and thus Borrelia species are located in a wider area, making exposure more likely. Due to regionally high seroprevalence and vague clinical signs, diagnosis of Lyme disease in the horse is believed overestimated. Antibiotics are first-line treatment of confirmed Lyme disease. A single positive serologic test, by itself, is not conformation of Lyme disease but is evidence of current or past infection.

Characterization of recombinant OspA in two different Borrelia vaccines with respect to immunological response and its relationship to functional parameters

Background

Prevention of Lyme disease in dogs in North America depends on effective vaccination against infection by the tick vector-born spirochete Borrelia burgdorferi. Most vaccines effectively prevent spirochete transmission to dogs during tick feeding based on immunization with the outer-surface lipoprotein A (OspA) of B. burgdorferi. More recently, vaccines containing additional OspC protein moieties have been introduced. These are designed to enhance protection by forming a second line of defense within the vertebrate host, where OspC expression replaces OspA as the dominant surface antigen. However, supportive data for demonstration of OspC mediated protection is still lacking. Since OspA immunogenicity is of paramount importance to protection against spirochete transmission; this study was designed to compare the immunogenicity of two commercially available vaccines against the Borrelia burgdorferi OspA. We further characterized OspA antigen fractions of these vaccines with respect to their biochemical and biophysical properties.

Results

Two groups of beagle dogs (n = 9) were administered either: (1) a nonadjuvanted/monovalent, recombinant OspA vaccine (Recombitek® Lyme) or (2) an adjuvanted, recombinant OspA /OspC chimeric fusion vaccine (Vanguard® crLyme). The onset of the anti-OspA antibody response elicited by the nonadjuvanted/monovalent OspA vaccine was significantly earlier than that for the bivalent OspA /OspC vaccine and serum borreliacidal activity was significantly greater at all post-vaccination time points. As expected, only dogs inoculated with the bivalent OspA/OspC vaccine mounted a humoral anti-OspC response. However, only three out of nine dogs in that group had a positive response. Comparison of the OspA vaccine structures revealed that the OspA in the nonadjuvanted/monovalent vaccine was primarily in the lipidated form, eluting (SEC-HPLC) at a high molecular weight, suggestive of micelle formation. Conversely, the OspA moiety of the OspA/OspC vaccine was found to be nonlipidated and eluted as the monomeric protein.

Conclusions

We hypothesize that these structural differences may account for the superior immunogenicity of the nonadjuvanted monovalent recombinant OspA vaccine in dogs over the adjuvanted OspA fraction of the OspA/OspC vaccine.

A scoping review of Lyme disease research relevant to public health

Lyme disease (LD) is an emerging infectious disease in Canada associated with expansion of the geographic range of the tick vector Ixodes scapularis in eastern and central Canada. A scoping review of published research was prioritized to identify and characterize the scientific evidence concerning key aspects of LD to support public health efforts. Prior to initiation of this review, an expert advisory group was surveyed to solicit insight on priority topics and scope. A pre-tested search strategy implemented in eight databases (updated September 2016) captured relevant research. Pre-tested screening and data characterization forms were completed by two independent reviewers and descriptive analysis was conducted to identify topic areas with solid evidence and knowledge gaps. Of 19,353 records screened, 2,258 relevant articles were included in the review under the following six public health focus areas: a) surveillance/monitoring in North America (n=809); b) evaluation of diagnostic tests (n=736); c) risk factors (n=545); d) public health interventions (n=205); e) public knowledge, attitudes and/or perceptions in North America (n=202); and f) the economic burden of LD or cost-benefit of interventions (n=32). The majority of research investigated Borrelia burgdorferi (n=1,664), humans (n=1,154) and Ixodes scapularis (n=459). Sufficient research was identified for potential systematic reviews in four topic areas: a) accuracy of diagnostic tests; b) risk factors for human illness; c) efficacy of LD intervention strategies; and d) prevalence and/or incidence of LD in humans or B. burgdorferi sensu stricto in vertebrate reservoirs or ticks in North America. Future primary research could focus on closing knowledge gaps, such as the role of less studied vertebrate reservoirs in the transmission cycle. Results of this scoping review can be used to quickly identify and summarize relevant research pertaining to specific questions about LD or B. burgdorferi sensu lato in humans, vertebrate hosts or vectors, providing evidence-informed information within timelines that are conducive for public health decision-making.

ACVIM consensus update on Lyme borreliosis in dogs and cats

An update of the 2006 American College of Veterinary Internal Medicine (ACVIM) Small Animal Consensus Statement on Lyme Disease in Dogs: Diagnosis, Treatment, and Prevention was presented at the 2016 ACVIM Forum in Denver, CO, followed by panel and audience discussion and a drafted consensus statement distributed online to diplomates for comment. The updated consensus statement is presented below. The consensus statement aims to provide guidance on the diagnosis, treatment, and prevention of Lyme borreliosis in dogs and cats.

[Heterogeneity of canine immune responses to Borrelia burgdorferi in a line immunoassay comprising recombinant VlsE and C6 peptide]

OBJECTIVE

The study aimed to investigate the distribution of specific immune responses (IgG) to Borrelia burgdorferi using a line immunoassay with recombinant VlsE (variable major protein-like sequence, expressed) protein and synthetic C peptide among other antigens. We compared the immune responses to VlsE protein and C₆ peptide, because both antigens have been considered specific for a Borrelia infection.

MATERIALS AND METHODS

A total of 1355 blood samples from dogs suspected of Borrelia infection were analysed. The line immunoassay employed nine antigens.

RESULTS

A total of 64.4% of all samples tested negative, 16.4% were positive for an infection and 17.4% were positive for vaccination. Band patterns specific for both infection and vaccination were observed in 1.2% of the dogs. The bands that most frequently tested positive were p100 (24.3%), p31/OspA (18.5%), C₆ (16.3%) and VlsE (13.9%). A total of 236 dogs (17.4% of the population) had antibodies to VlsE and/or C₆ peptide. In 73.3% of these dogs, results for VlsE and C₆ peptide were consistent, whereas this was not the case for 26.7% of these animals.

CONCLUSION AND CLINICAL RELEVANCE

Testing using a line immunoassay allows for qualitative analyses of different immune responses to various antigens used as probes. In our study, >  26% of the dogs displayed discrepant results with regard to VlsE and C₆, the two antigens considered specific for Borrelia burgdorferi infection. To confirm or rule out infection, the results of several band patterns, thought to be specific for infection, need to be taken into consideration.

Vaccination of horses with Lyme vaccines for dogs induces short-lasting antibody responses

Borrelia burgdorferi can induce Lyme disease. Approved Lyme vaccines for horses are currently not available. In an effort to protect horses, veterinarians are using Lyme vaccines licensed for dogs. However, data to assess the response of horses to, or determine the efficacy of this off-label vaccine use are missing. Here, antibodies against outer surface protein A (OspA), OspC, and OspF were quantified in diagnostic serum submissions from horses with a history of vaccination with canine Lyme vaccines. The results suggested that many horses respond with low and often short-lasting antibody responses. Subsequently, four experimental vaccination trials were performed. First, we investigated antibody responses to three canine vaccines in B. burgdorferi-naïve horses. One killed bacterin vaccine induced antibodies against OspC. OspA antibodies were low for all three vaccines and lasted less than 16weeks. The second trial tested the impact of the vaccine dose using the OspA/OspC inducing bacterin vaccine in horses. A 2mL dose produced higher OspA and OspC antibody values than a 1mL dose. However, the antibody response again quickly declined, independent of dose. Third, the horses were vaccinated with 2 doses of a recombinant OspA vaccine. Previous vaccination and/or environmental exposure enhanced the magnitude and longevity of the OspA antibody response to about 20weeks. Last, the influence of intramuscular versus subcutaneous vaccine administration was investigated for the recombinant OspA vaccine. OspA antibody responses were not influenced by injection route. The current work highlights that commercial Lyme vaccines for dogs induce only transient antibody responses in horses which can also be of low magnitude. Protection from infection with B. burgdorferi should not be automatically assumed after vaccinating horses with Lyme vaccines for dogs.

Searching for Lyme borreliosis in Australia: results of a canine sentinel study

BACKGROUND

Lyme borreliosis is a common tick-borne disease of the northern hemisphere that is caused by bacterial spirochaetes of the Borrelia burgdorferi (sensu lato) (Bbsl) complex. To date, there has been no convincing evidence for locally-acquired Lyme borreliosis on the Australian continent and there is currently a national debate concerning the nature and distributions of zoonotic tick-transmitted infectious disease in Australia. In studies conducted in Europe and the United States, dogs have been used as sentinels for tick-associated illness in people since they readily contact ticks that may harbour zoonotic pathogens. Applying this principle, we used a combination of serological assays to test dogs living in tick 'hot spots' and exposed to the Australian paralysis tick, Ixodes holocyclus, for evidence of exposure to B. burgdorferi (s.l.) antigens and other vector-borne pathogens.

RESULTS

Altogether, 555 dogs from four demographic groups were recruited into this study. One dog had evidence of exposure to Anaplasma spp. but no other dog was positive in screening tests. A total of 122 dogs (22.0%) had a kinetic ELISA (KELA) unit value > 100, and one dog with a high titre (399.9 KELA units) had been vaccinated against B. burgdorferi (sensu stricto) before travelling to Australia. Older dogs and those with a history of tick paralysis were significantly more likely to have a KELA unit value > 100. Line immunoassay analysis revealed moderate-to-weak (equivocal) bands in 27 (4.9%) dogs.

CONCLUSIONS

Except for a single dog presumed to have been exposed to Anaplasma platys, infection with Anaplasma spp. B. burgdorferi (s.l.), Ehrlichia spp., and Dirofilaria immitis, was not detected in the cohort of Australian dogs evaluated in this study. These results provide further evidence that Lyme borreliosis does not exist in Australia but that cross-reacting antibodies (false positive results) are common and may be caused by the transmission of other tick-associated organisms.

Lyme borreliosis

Lyme borreliosis is a tick-borne disease that predominantly occurs in temperate regions of the northern hemisphere and is primarily caused by the bacterium Borrelia burgdorferi in North America and Borrelia afzelii or Borrelia garinii in Europe and Asia. Infection usually begins with an expanding skin lesion, known as erythema migrans (referred to as stage 1), which, if untreated, can be followed by early disseminated infection, particularly neurological abnormalities (stage 2), and by late infection, especially arthritis in North America or acrodermatitis chronica atrophicans in Europe (stage 3). However, the disease can present with any of these manifestations. During infection, the bacteria migrate through the host tissues, adhere to certain cells and can evade immune clearance. Yet, these organisms are eventually killed by both innate and adaptive immune responses and most inflammatory manifestations of the infection resolve. Except for patients with erythema migrans, Lyme borreliosis is diagnosed based on a characteristic clinical constellation of signs and symptoms with serological confirmation of infection. All manifestations of the infection can usually be treated with appropriate antibiotic regimens, but the disease can be followed by post-infectious sequelae in some patients. Prevention of Lyme borreliosis primarily involves the avoidance of tick bites by personal protective measures.

Borrelia persica Infection in Immunocompetent Mice--A New Tool to Study the Infection Kinetics In Vivo

Borrelia persica, a bacterium transmitted by the soft tick Ornithodoros tholozani, causes tick-borne relapsing fever in humans in the Middle East, Central Asia and the Indian peninsula. Immunocompetent C3H/HeOuJ mice were infected intradermally with B. persica at varying doses: 1 x 10⁶, 1 x 10⁴, 1 x 10² and 4 x 10⁰ spirochetes/mouse. Subsequently, blood samples were collected and screened for the presence of B. persica DNA. Spirochetes were detected in all mice infected with 1 x 10⁶, 1 x 10⁴ and 1 x 10² borrelia by real-time PCR targeting the flaB gene of the bacterium. Spirochetemia developed with a one- to two-day delay when 1 x 10⁴ and 1 x 10² borrelia were inoculated. Mice injected with only four organisms were negative in all tests. No clinical signs were observed when infected mice were compared to negative control animals. Organs (heart, spleen, urinary bladder, tarsal joint, skin and brain) were tested for B. persica-specific DNA and cultured for the detection of viable spirochetes. Compiled data show that the target organs of B. persica infections are the brain and the skin. A newly developed serological two-tiered test system (ELISA and western blot) for the detection of murine IgM, IgG and IgA antibody titers against B. persica showed a vigorous antibody response of the mice during infection. In conclusion, the infection model described here for B. persica is a platform for in vivo studies to decipher the so far unexplored survival strategies of this Borrelia species.

The spirochete Borrelia persica is a tick-borne bacterium that is transmitted by the vector Ornithodoros tholozani to its vertebrate host in the Middle East, Central Asia and the Indian peninsula. Current migration of vast numbers of individuals from this area increases the likelihood that B. persica infections will be introduced into new geographic regions. After infection and distribution by the bloodstream, relapsing fever episodes occur in humans. Since no reliable in vivo tools have existed so far to study this organism, a murine model was established in this study to characterize the infection kinetics in immunocompetent mice. Aspects of the potential infectivity of the laboratory strain and of potential clinical signs, spirochetemia and antibody response as well as organ tropism and histopathological reactions were studied. With the successful infection model presented here, further studies are conceivable in order to gain advanced insights into the pathogenesis of B. persica infection and to characterize in detail the host immune response mounted against the bacterium. We propose that this model could also be used for the development of new rapid diagnostic approaches to initiate or monitor treatment regimes in order to clear or prevent the infection with B. persica.

Immunization with a recombinant subunit OspA vaccine markedly impacts the rate of newly acquired Borrelia burgdorferi infections in client-owned dogs living in a coastal community in Maine, USA

Background

In North America, Borrelia burgdorferi is the causative bacterial agent of canine Lyme borreliosis and is transmitted following prolonged attachment and feeding of vector ticks, Ixodes scapularis or Ixodes pacificus. Its prevention is predicated upon tick-avoidance, effective on-animal tick control and effective immunization strategies. The purpose of this study is to characterize dogs that are newly seropositive for Borrelia burgdorferi infection in relation to compliant use of a recombinant OspA canine Lyme borreliosis vaccine. Specifically, Preventive Fractions (PF) and Risk Ratios (RR) associated with the degree of vaccine compliancy (complete versus incomplete) are determined.

Methods

6,202 dogs were tested over a five year period in a single veterinary hospital utilizing a non-adjuvanted, recombinant OspA vaccine according to a 0, 1, 6 month (then yearly) protocol. Rates of newly acquired “Lyme-positive” antibody test results were compared between protocol compliant and poorly compliant (incompletely and/or non-vaccinated) dogs.

Results

Over the five-year span, one percent (range 0.39 - 1.3) of protocol compliant vaccinated, previously antibody negative dogs became seropositive for infection. Approximately twenty-one percent (range 16.8 – 33.3) of incompletely vaccinated dogs became positive for infection-specific antibodies. The Preventative Fraction for testing positive for antibodies specific for infection with Borrelia burgdorferi in any given year based on optimal vaccine compliance was, on average, 95.3% (range 93.29 - 98.08). The Risk Ratio for becoming infected with Borrelia burgdorferi antibodies in any given year if vaccine non-compliant was 21.41 (range 14.9 – 52.1). There was a high statistically significant relationship (p = <0.0001) in the observed data in terms of vaccination protocol compliance and the probability of Borrelia burgdorferi infection in each of the five years under study.

Conclusions

The recombinant outer surface protein A (rOspA) vaccine for dogs is highly effective in preventing new seropositive cases of Borrelia burgdoferi infection over a five-year period in dogs living in an endemic area. Dogs that were vaccine protocol-compliant were significantly less likely to become infected (as indirectly assessed by antibody) with the agent of canine Lyme borreliosis as measured by Preventive Fraction and Risk Ratio calculations.

Comparison of different diagnostic assays for the detection of Borrelia burgdorferi-specific antibodies in dogs

BACKGROUND

Antibody tests are frequently used in the diagnosis of canine Lyme borreliosis, including immunofluorescence assay (IFA) for immunoglobulin G (IgG) and M (IgM) antibodies, kinetic enzyme-linked immunosorbent assay (KELA), and Western blotting (WB). Recently, the SNAP4Dx, an in-house test using C6 technology has become available.

OBJECTIVES

The aim of this study was to compare IFA, KELA, and SNAP4Dx assay results, and to determine their sensitivity and specificity when compared with the WB, used as gold standard in this study.

METHODS

Two hundred canine sera were tested for the presence of specific antibodies against Borrelia spp. using the above-mentioned tests.

RESULTS

The sensitivity and specificity of IFA-IgG was 76.6% (95% confidence interval [CI] 46.87-86.72) and 87.1% (95% CI 80.06-91.90), and 26.3% (95% CI 11.81-48.79) and 81.0% (95% CI 73.64-86.71) for IFA-IgM, respectively. KELA was 100% (95% CI 83.18-100) sensitive and 75.4% (95% CI 67.02-82.09) specific, and the SNAP4Dx was 84.2% (95% CI 62.43-94.48) sensitive and 98.5% (95% CI 94.83-99.60) specific.

CONCLUSIONS

Both IFAs had very low sensitivity and specificity and cannot be recommended for screening purposes. In contrast, KELA showed excellent sensitivity, but positive results always need to be confirmed by WB to differentiate the source of antibody formation. The SNAP4Dx had a high sensitivity and specificity, and thus can potentially replace the more labor-intensive WB, at least in untreated dogs.

Functionalised Nanoliposomes for Construction of Recombinant Vaccines: Lyme Disease as an Example

Liposomes (phospholipid bilayer vesicles) represent an almost ideal carrier system for the preparation of synthetic vaccines due to their biodegradability and capacity to protect and transport molecules of different physicochemical properties (including size, hydrophilicity, hydrophobicity, and charge). Liposomal carriers can be applied by invasive (e.g. i.m., s.c., i.d.) as well as non-invasive (transdermal and mucosal) routes. In the last 15 years, liposome vaccine technology has matured and several vaccines containing liposome-based adjuvants have been approved for human and veterinary use or have reached late stages of clinical evaluation.

Given the intensifying interest in liposome-based vaccines, it is important to understand precisely how liposomes interact with the immune system and how they stimulate immunity. It has become clear that the physicochemical properties of liposomal vaccines – method of antigen attachment, lipid composition, bilayer fluidity, particle charge, and other properties – exert strong effects on the resulting immune response. In this chapter we will discuss some aspects of liposomal vaccines including the effect of novel and emerging immunomodulator incorporation. The application of metallochelating nanoliposomes for development of recombinant vaccine against Lyme disease will be presented as a suitable example.

Lyme nephritis

OBJECTIVE

To review what is known and highlight knowledge gaps regarding Lyme nephritis (LN).

DATA SOURCES

Publications identified via PubMed using the keywords "Borrelia burgdorferi," "Borreliosis," "glomerulonephritis," "protein-losing nephropathy," "autoimmunity," and "retriever," and as generated by investigators working in the fields of Borreliosis and immune-mediated glomerulonephritis.

HUMAN DATA SYNTHESIS

Postborrelial immune-mediated glomerulonephritis was described recently in 6 people; 3 responded to antimicrobials/steroids, 1 to antimicrobials/angiotensin-converting enzyme inhibitor/warfarin, 1 required hemodialysis but became hemodialysis independent after 5 months and treatment with antimicrobials, steroids, plasmapheresis, immunoglobulin, and 1 did not respond to steroids and angiotensin-converting enzyme inhibitor and still requires hemodialysis.

VETERINARY DATA SYNTHESIS

Lyme nephritis is seen in <1-2% of Lyme seropositive dogs, with an average onset at 5-6 years. Labrador and Golden Retrievers are predisposed to this condition. Prior or concurrent lameness is described in 9-28% cases. Historical presentations include acute progressive protein-losing nephropathy with membranoproliferative glomerulonephritis, tubular necrosis/regeneration, and interstitial nephritis, but possibly milder forms exist. Complications include thromboembolic events, hypertension, effusive disease, and oliguric/anuric renal failure. Diagnostic tests help stage disease and rule out other causes. Renal biopsy is advocated early, when intervention may help, and to prove if immune-complex disease exists. Treatment includes standard therapy for protein-losing nephropathy, long-term antimicrobials, and perhaps immunosuppressive therapy.

CONCLUSIONS

There is no experimental model of LN to study predisposing factors, pathogenesis, onset, progression, treatment, or prevention. There are no predictive tests to identify the few individuals at highest risk, therefore all seropositive dogs should be screened and monitored for proteinuria. Lyme nephritis mimics other forms of protein-losing nephropathy and sometimes Leptospirosis. Renal biopsy helps show if immune-complex disease exists, but may not prove LN specifically. More studies are warranted on dogs with Lyme-specific immune-complex deposition to evaluate risk factors, understand pathogenesis, variability of expression, and to validate treatment and prevention protocols.

Antibodies to Borrelia burgdorferi OspA, OspC, OspF, and C6 antigens as markers for early and late infection in dogs

Lyme disease in the United States is caused by Borrelia burgdorferi sensu stricto, which is transmitted to mammals by infected ticks. Borrelia spirochetes differentially express immunogenic outer surface proteins (Osp). Our aim was to evaluate antibody responses to Osp antigens to aid the diagnosis of early infection and the management of Lyme disease. We analyzed antibody responses during the first 3 months after the experimental infection of dogs using a novel multiplex assay. Results were compared to those obtained with two commercial assays detecting C6 antigen. Multiplex analysis identified antibodies to OspC and C6 as early as 3 weeks postinfection (p.i.) and those to OspF by 5 weeks p.i. Antibodies to C6 and OspF increased throughout the study, while antibodies to OspC peaked between 7 and 11 weeks p.i. and declined thereafter. A short-term antibody response to OspA was observed in 3/8 experimentally infected dogs on day 21 p.i. Quant C6 enzyme-linked immunosorbent assay (ELISA) results matched multiplex results during the first 7 weeks p.i.; however, antibody levels subsequently declined by up to 29%. Immune responses then were analyzed in sera from 125 client-owned dogs and revealed high agreement between antibodies to OspF and C6 as robust markers for infection. Results from canine patient sera supported that OspC is an early infection marker and antibodies to OspC decline over time. The onset and decline of antibody responses to B. burgdorferi Osp antigens and C6 reflect their differential expression during infection. They provide valuable tools to determine the stage of infection, treatment outcomes, and vaccination status in dogs.

Evaluation of the preventive capacities of a topically applied azithromycin formulation against Lyme borreliosis in a murine model

Objectives

Systemic antibiotic treatment of Lyme borreliosis is effective during the early stages of the infection, while chronic manifestations of the disease may remain refractory and difficult to treat. This study was carried out in order to evaluate the potential of topically applied azithromycin to eliminate the spirochaetal organisms in the skin of the freshly bitten host and thereby prevent Lyme borreliosis.

Methods

Laboratory mice were challenged with Borrelia burgdorferi sensu stricto by needle inoculation or via infected ticks as vectors. Then, an azithromycin-containing formulation was applied once daily to the sites of exposure for three consecutive days. In the case of needle inoculation, a 5% azithromycin formulation was applied starting 1 h, 3 days and 5 days after infection. In the case of tick exposure, 4%, 10% and 20% azithromycin formulations were applied, starting directly after the detachment of the engorged ticks. Subsequently, the infection status of the mice was determined.

Results

Concentrations of azithromycin in murine skin were >3800-fold higher than the published minimal inhibitory concentration for B. burgdorferi as soon as 3 h after the first application. After needle inoculation, spirochaetes were not detectable in all infected mice after treatment, if the first application started 1 h or even after 3 days post-infection. Furthermore, no borrelial organisms were detected after topical treatment when ticks were used for spirochaete inoculation.

Conclusions

Our data indicate that topical treatment with a formulation containing azithromycin is a promising approach to prevent Lyme borreliosis shortly after a tick bite.

Development of a multiplex assay for the detection of antibodies to Borrelia burgdorferi in horses and its validation using Bayesian and conventional statistical methods

Lyme disease is a zoonotic, vector-borne disease and occurs in mammals including horses. The disease is induced by infection with spirochetes of the Borrelia burgdorferi sensu lato group. Infection of mammalian hosts requires transmission of spirochetes by infected ticks during tick bites. Lyme disease diagnosis is based on clinical signs, possible exposure to infected ticks, and antibody testing which is traditionally performed by ELISA and Western blotting (WB). This report describes the development and validation of a new fluorescent bead-based multiplex assay for the detection of antibodies to B. burgdorferi outer surface protein A (OspA), OspC and OspF antigens in horse serum. Testing of 562 equine sera was performed blindly and in parallel by using WB and the new multiplex assay. Because a true gold standard is missing for Lyme antibody testing, we performed and compared different statistical approaches to validate the new Lyme multiplex assay. One approach was to use WB results as a 'relative gold standard' in ROC-curve and likelihood-ratio analyses of the new test. Cut-off values and interpretation ranges of the multiplex assay were established by the analysis. The second statistical approach used a Bayesian model for the calculation of diagnostic sensitivities and specificities of the multiplex assay. The Bayesian analysis takes into consideration that no true gold standard exists for detecting antibodies to B. burgdorferi and estimated sensitivities and specificities of both tests that were compared. Therefore, the Bayesian analysis also resulted in an evaluation of diagnostic sensitivity and specificity of WB. Overall, the new assay was characterized by low background values and a wide dynamic quantification range for the detection of antibodies to OspA, OspC and OspF antigens of B. burgdorferi. The diagnostic sensitivity and specificity for the OspA bead-based assay were calculated as 49% and 85%, respectively, and by a standard ROC curve analysis only because the Bayesian model could not be run on this parameter. The Bayesian-derived diagnostic sensitivities of the OspC and OspF assays were 80% and 86%, respectively. For comparison, the Bayesian-derived estimates for WB resulted in sensitivities of 72% for OspC and 80% for OspF. The Bayesian diagnostic specificities of the multiplex assay were 79% and 69% for OspC and OspF, respectively. WB analysis had specificities of 92% for OspC and 77% for OspF. Although the analysis of a new assay in the absence of a true gold standard remains challenging, the approach used here can help to address this problem when new technologies and traditionally used test standards differ significantly in their analytical sensitivities, which consequently causes problems in the calculation of diagnostic sensitivity and sensitivity values for the new assay. In summary, the new multiplex assay for the detection of antibodies to B. burgdorferi OspA, OspC and OspF antigens in horse serum has improved analytical and diagnostic sensitivities compared to WB analysis. Multiplex analysis is a valuable quantitative tool that simultaneously detects antibodies indicative for natural infection with and/or vaccination against the Lyme pathogen.

The immunopathology of canine vector-borne diseases

The canine vector-borne infectious diseases (CVBDs) are an emerging problem in veterinary medicine and the zoonotic potential of many of these agents is a significant consideration for human health. The successful diagnosis, treatment and prevention of these infections is dependent upon firm understanding of the underlying immunopathology of the diseases in which there are unique tripartite interactions between the microorganism, the vector and the host immune system. Although significant advances have been made in the areas of molecular speciation and the epidemiology of these infections and their vectors, basic knowledge of the pathology and immunology of the diseases has lagged behind. This review summarizes recent studies of the pathology and host immune response in the major CVBDs (leishmaniosis, babesiosis, ehrlichiosis, hepatozoonosis, anaplasmosis, bartonellosis and borreliosis). The ultimate application of such immunological investigation is the development of effective vaccines. The current commercially available vaccines for canine leishmaniosis, babesiosis and borreliosis are reviewed.

Lyme borreliosis in dogs and cats: background, diagnosis, treatment and prevention of infections with Borrelia burgdorferi sensu stricto

Lyme borreliosis (LB), synonymous with the often-used term Lyme disease, is an infectious disease caused by the spirochetal bacterium Borrelia burgdorferi. LB is the most frequent vector-borne disease in humans in the Northern Hemisphere. In animals, clinically apparent disease is found primarily in dogs. Severe polyarthritis, fever and lameness in dogs are reported from the main endemic areas of North America: the New England States, and eastern parts of the United States; several cases of LB are also seen in California and the Midwest. Because of the difficulties in finding sufficient indicative clinical signs, additional information (detailed case history, laboratory testing for antibodies) is especially important to make the clinical diagnosis of Lyme borreliosis. This article reviews the etiology, diagnosis, therapy, and prevention of LB.

Lyme borreliosis vaccination: the facts, the challenge, the future

Lyme disease, or Lyme borreliosis, the most prevalent arthropod-borne disease in the Western world, is caused by spirochetes belonging to the Borrelia burgdorferi sensu lato group and is predominantly transmitted through Ixodes ticks. There is currently no vaccine available to prevent Lyme borreliosis in humans. Borrelia outer membrane proteins are reviewed which have been investigated as vaccine candidates. In addition, several tick proteins are discussed, on which anti-tick vaccines have been based, or are interesting future candidates, to prevent transmission of the spirochete from the tick vector to the mammalian host. Finally, novel vaccination strategies to prevent Lyme borreliosis are proposed, based on multiple Borrelia antigens, tick antigens or a combination of both Borrelia as well as tick antigens.

Humoral immune response in dogs naturally infected with Borrelia burgdorferi sensu lato and in dogs after immunization with a Borrelia vaccine

Lyme arthritis in dogs can be induced under experimental and natural conditions. However, the veterinary relevance of canine borreliosis is still under extensive investigation. The prevalence of symptoms is clearly low, although the risk of tick exposure is high. Current research focuses on case definitions, methods for diagnosing clinical disease in dogs, and discrimination between an immune response to a natural infection and an immune response to vaccination. In this experimental study, 23 dogs raised under tick-free conditions were allocated to two groups. The 11 dogs in the first group were vaccinated with a commercial borrelia vaccine and subsequently developed detectable antibody titers. The 12 dogs in the second group were walked on two consecutive days in an area where ticks were endemic. On day 5 after exposure, engorged ticks were removed from the 12 dogs and were analyzed for Borrelia DNA by a real-time PCR assay. Blood samples were taken before exposure/vaccination and at defined time points thereafter. Antibody responses were evaluated using an immunofluorescence antibody test (IFAT) and Western blotting. Seven dogs from which Borrelia-positive ticks were removed seroconverted and developed individual immune responses. Blood and urine samples taken from the tick-exposed group at weeks 1 and 3 for real-time PCR analysis and culture were always negative for bacterial DNA. In conclusion, despite serological evidence of infection/immunization, no clinical signs of disease were observed. The antibody patterns in a single Western blot did not permit differentiation between the different antigen sources (vaccine versus natural infection). However, repeated Western blot analyses may be useful for the confirmation of infection or vaccination status, since the time courses of the levels of specific antibodies seem to be different.

Borrelia burgdorferi sensu lato species in Europe induce diverse immune responses against C6 peptides in infected mice

The diversity of Lyme-borreliosis-inducing Borrelia species in Europe set high standards for the use of serodiagnostic test systems in terms of specificity and sensitivity. In the United States, the one-step C6 antibody test system based on the invariable domain IR6 of the VlsE molecule has been established as a successful diagnostic tool for testing canine samples. However, only a limited set of data are available regarding the antigenicity of the C6 peptides in an experimental murine model and sensitivity of the test regarding European Borrelia species. In order to investigate antibody reactions induced by these spirochetes, a total of 142 C3H/HeN mice were inoculated with Borrelia burgdorferi sensu stricto N40, B. garinii PBi, two isolates of B. afzelii, B. spielmanii A14S, B. valaisiana Rio6, B. valaisiana VS116, or B. lusitaniae. Infection of the mice was documented utilizing tissue culture and PCR. The IR6 sequences of B. burgdorferi sensu stricto B31, B. garinii IP90, and two B. afzelii ACAI strains have been used to synthesize and test additional C6 peptides. Compared to the well-established two-tiered test system, the results indicate that single C6 peptides derived from B. burgdorferi sensu stricto and B. garinii can be used in an enzyme-linked immunosorbent assay-based technique to detect murine antibodies induced by either agent. Little is known about the prevalence or pathogenicity of the B. afzelii strains in mammalian hosts, but our experimental data indicate differences in the C6 peptide test sensitivity for the detection of antibodies induced by different strains or isolates of B. afzelii.