Immunogenicity of a recombinant Borrelia burgdorferi outer surface protein A vaccine against Lyme disease in children

Evaluation of OspA vaccination-induced serological correlates of protection against Lyme borreliosis in a mouse model

BACKGROUND

For clinical development of a novel multivalent OspA vaccine against Lyme borreliosis, serological assays are required which can be used to establish immune correlates of protection against infection with Borrelia.

METHODS

Four assays (an OspA IgG ELISA, a competitive inhibition (CI) ELISA, a Borrelia surface-binding (SB) assay and a Borrelia killing assay) were used to evaluate the correlation between immune responses induced by rOspA 1/2 (a chimeric immunogen containing protective epitopes from OspA serotypes 1 and 2), and protective immunity against infection by B. burgdorferi s.s. (OspA-1) and B. afzelii (OspA-2). Mice were immunized with OspA 1/2 doses ranging from 0.3 ng to 100 ng, to induce a range of OspA antibody titers, and exposed to needle challenge with B. burgdorferi s.s. or tick challenge with B. afzelii. Receiver operator characteristics (ROC) curves were constructed for each assay, and the area under the curve (AUC), sensitivity, specificity and Youden Index were calculated. Potential cutoff antibody titers which could be used as correlates of vaccine-induced protection were derived from the maximum Youden Index.

RESULTS

Immunization with OspA-1/2 provided dose-dependent protection against infection with B. burgdorferi s.s. and B. afzelii. Antibody responses detected by all four assays were highly significantly correlated with protection from infection by either B. burgdorferi s.s. (p<0.0001 to 0.0062) or B. afzelii (p<0.0001). ROC analyses of the diagnostic effectiveness of each assay showed the AUC to range between 0.95 and 0.79, demonstrating that all assays distinguish well between infected and non-infected animals. Based on sensitivity, specificity and AUC, the OspA IgG ELISA and SB assays best discriminated between infected and non-infected animals.

CONCLUSIONS

All four assays differentiate well between Borrelia-infected and non-infected animals. The relatively simple, high throughput IgG ELISA would be suitable to establish immune correlates of protection for the novel OspA vaccine in clinical trials.

TLR-based immune adjuvants

This work describes the nature and strength of the immune response induced by various Toll-like receptor ligands and their ability to act as vaccine adjuvants. It reviews the various ligands capable of triggering individual TLRs, and then focuses on the efficacy and safety of those agents for which clinical results are available.

Correcting a public health fiasco: The need for a new vaccine against Lyme disease

A vaccine against Lyme disease was licensed in the United States in 1998 but was subsequently removed from the market because of lack of sales. I believe that the poor acceptance of the vaccine was based on tepid recommendations by the Centers for Disease Control and Prevention (CDC), undocumented and probably nonexistent safety issues, and insufficient education of physicians. A new vaccine is feasible but will not be developed unless there is a demand by infectious diseases specialists, epidemiologists, authorities in affected states and the public that is evident to manufacturers. The fact that there is no vaccine for an infection causing ∼20,000 annual cases is an egregious failure of public health.

An effective second-generation outer surface protein A-derived Lyme vaccine that eliminates a potentially autoreactive T cell epitope

The antigenic component of a common Lyme disease vaccine is recombinant outer surface protein A (rOspA) of Borrelia burgdorferi (Bb), the causative agent of Lyme disease. Coincidentally, patients with chronic, treatment-resistant Lyme arthritis develop an immune response against OspA, whereas those with acute Lyme disease usually do not. Treatment-resistant Lyme arthritis occurs in a subset of Lyme arthritis patients and is linked to HLA.DRB1*0401 (DR4) and related alleles. Recent work from our laboratory identified T cell crossreactivity between epitopes of OspA and lymphocyte function-associated antigen 1alpha(L) chain (LFA-1alpha(L)) in these patients. We generated a form of rOspA, FTK-OspA, in which the LFA-1alpha(L)/rOspA crossreactive T cell epitope was mutated to reduce the possible risk of autoimmunity in genetically susceptible individuals. FTK-OspA did not stimulate human or mouse DR4-restricted, WT-OspA-specific T cells, whereas it did stimulate antibody responses specific for WT-OspA that were similar to mice vaccinated WT-OspA. We show here that the protective efficacy of FTK-OspA is indistinguishable from that of WT-OspA in vaccination trials, as both C3H/HeJ and BALB/c FTK-OspA-vaccinated mice were protected from Bb infection. These data demonstrate that this rOspA-derived vaccine lacking the predicted cross-reactive T cell epitope, but retaining the capacity to elicit antibodies against infection, is effective in generating protective immunity.

An open-label, nonrandomized, single-center, prospective extension, clinical trial of booster dose schedules to assess the safety profile and immunogenicity of recombinant outer-surface protein A (OspA) Lyme disease vaccine

BACKGROUND

An efficacy trial of an outer-surface protein A (OspA) Lyme disease vaccine demonstrated tolerability and efficacy against laboratory-confirmed Lyme disease after a primary series of 3 doses at 0, 1, and 12 months.

OBJECTIVES

This extension of the efficacy study assessed the immunogenicity and tolerability of booster vaccinations administered at 24 and/or 36 months after the first vaccination.

METHODS

This open-label, nonrandomized, single-center, prospective extension, clinical trial was conducted in the general community in New Haven, Connecticut, where Lyme disease is endemic. Blood samples (to determine anti-OspA titer) were collected before administration of the booster doses at months 24 and 36, and at 1 and 12 months after each booster dose was administered. Immune response was assessed via total immunoglobulin G (IgG) anti-OspA antibody titers and the proportion of subjects with titers >or=1400 EL.U/mL. Adverse events (AEs) were recorded by the study volunteers on diary cards.

RESULTS

A total of 318 volunteers (173 women and 145 men) received at least 1 booster dose of Lyme disease vaccine, administered at 12 or 24 months after the third vaccination of the primary series (months 24 and 36, in relation to the primary series). Eighty-eight subjects of those who received a month-24 booster received a second booster dose at month 36 (12 months after the first booster). Overall, the mean age of the volunteers was 55 years (range, 19 to 73 years). The demographic characteristics of the groups were similar. Most AEs were limited induration and were rated by investigators and subjects as mild to moderate in severity. Administration of I or 2 booster doses did not elicit any patterns of AEs different from those reported in the efficacy trial. After the first booster dose, all volunteers had an anamnestic response and positive test results for total IgG antibody. Geometric mean titers increased at least 12-fold 1 month after the first booster dose at month 24 or 36. More than 96% of volunteers had titers>1400 EL.U/mL and 100% had titers >400 EL.U/mL (minimum seroprotective level) 1 month after the booster dose at month 24 or 36.

CONCLUSIONS

All booster doses were well tolerated, and the incidence of AEs did not increase after the second booster dose. The immune response generated after the 3-dose primary series waned; booster doses administered at 12 and/or 24 months after the primary series increased antibody levels above seroprotective levels.

[Lyme disease--new findings on its physiopathology, diagnosis, therapy and prevention]

INTRODUCTION

Lyme disease is a tick-borne disease caused by a spirochete Borrelia burgdorferi, which manifests as a multisystem disease of the skin, nervous system, heart and joints. Recently it is the most common vector-borne disease in Yugoslavia.

NEW EPIDEMIOLOGICAL STUDIES

New epidemiological studies revealed that ticks can occasionally be infected not only by Borrelia burgdorferi, but also by some other microbes that can cause diseases in humans. Recently discovered the variable major protein-like sequence, antigenic variation of B. burgdorferi B 31 partly explains the ability of this organism to evade an active immune response. A key role in development of clinical symptoms associated with lyme disease belongs to the connection with ability of B. burgdorferi to induce and activate metallopeptidases and fibrinolytic enzymes, leading to extracellular matrix destruction.

DIAGNOSIS AND TREATMENT

Diagnosis of Lyme borreliosis is made on the basis of clinical picture, exposure to ticks in endemic areas and serologic confirmation. It seems that polymerase chain reaction has little role in detection of B. burgdorferi in urine, blood, and spinal fluid samples, but it is most useful in evaluating the effectiveness of antibiotic therapy of Lyme arthritis. Infectious Diseases Society of America had prepared new guidelines for selective treatment of Lyme disease. Vaccination is still the best way of prevention for people living in high-risk areas.

Prevention of tick-borne diseases

Ticks are a part of the landscape where humans live, work, and play. Because ticks carry a wide range of organisms that potentially can cause disease in humans, many studies have focused on ways to reduce risk of these diseases. Ticks have biologically complex interactions with microorganisms and with their vertebrate hosts, on whom they depend for blood meals and survival. To consider ways to reduce the burden of tick-borne diseases in humans, it is necessary to understand the biology and ecology of ticks and their interface with humans. In many areas, changes in land use, reforestation, and patterns of human settlements have led to more abundant tick populations, increasing rates of infections in ticks, and increasing contact with human populations. Warmer winter temperatures in temperate regions may extend the transmission season for some ticks and pathogens. Although much of the discussion in this article has focused on I. scapularis and the Lyme disease spirochete (because they have been studied extensively), other tick-pathogen pairs may differ in risk factors for infection and transmission dynamics. Interventions studied to reduce the burden of tick-borne diseases include changing the environment, controlling vertebrate hosts, killing ticks, altering the behavior of humans, treating tick bites, and trying to protect humans through immunologic means (vaccine). All of these approaches have limitations and drawbacks. From a public health perspective, a plan that employs multiple strategies may be most effective. This article has reviewed what is known about preventive interventions, including the vaccine.

Future vaccines: recent advances and future prospects

The 20th century has witnessed the introduction of over 20 vaccines that prevent or even conquer diseases such as smallpox, polio, and measles. The continued threat of infectious diseases demands the creation of many more vaccines, especially against common respiratory and gastrointestinal pathogens. Thanks to recent advances in molecular biology, immunology, and adjuvant technology, the next decade likely will bring a vaccine for HIV/AIDS also. We enter the 21st century with a tempered optimism, proud of past achievements, but mindful of the challenges that lie ahead.

Lyme disease: an update

Lyme disease is a multisystem illness caused by the spirochete Borrelia burgdorferi, and it is the most common vector-borne illness in the United States. Lyme disease is also endemic in Europe and Asia. There have been major advances in the field since the disease was first described, including the sequencing of the B. burgdorferi genome; an increase in understanding of the interactions among the spirochete, the tick, and the mammalian host; new and improved laboratory tests; and a vaccine for prevention of the disease. Still, the diagnosis of Lyme disease remains based on history and clinical findings, supplemented by careful use of laboratory tests, and requires that the physician be familiar with the disease's clinical manifestations and the shortcomings of the available diagnostic tests.

Improved vectors for expression library immunization--application to Mycoplasma hyopneumoniae infection in pigs

Expression library immunization (ELI) has previously been used in a number of disease models in mice. Here, we describe the first example of the application of ELI to a large animal model with the immunization of pigs against enzootic pneumonia, a disease caused by Mycoplasma hyopneumoniae. The development of new plasmid vectors and library screening methods facilitated the application of ELI to this disease by allowing random libraries to be screened for clones expressing recombinant proteins. In this way the vast majority of clones in random libraries that are unproductive can be eliminated, meaning that libraries are more likely to give protection and are subsequently easier to further screen and analyze. By using this approach we have used one library screen and two animal trials to progress from an original library of 20,000 clones to a group of just 96 clones.

Lyme disease and current aspects of immunization

Lyme disease is a tick-borne multisystem disease that affects primarily the skin, nervous system, heart and joints. At least three species of Borrelia burgdorferi sensu lato, namely Borrelia burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii, can cause the disease. This review will focus mainly on the pathophysiology of Lyme arthritis, the long-term outcome of Lyme disease, and the recently licensed vaccine against Lyme disease.

Lyme disease in children

Lyme borreliosis is a multisystem disorder caused by Borrelia burgdorferi and transmitted by ticks in the northern hemisphere. The disease is common in children. In addition to frequently recognized manifestations such as erythema migrans, neuroborreliosis, and Lyme arthritis, rarer manifestations, including eye and ear disease, are increasingly understood. Clinical diagnosis is supported by serologic confirmation. Improvement of laboratory methodology, especially polymerase chain reaction-based tests, is continuing. Actual treatment recommendations based on controlled studies reflect expanding scientific knowledge. In the United States, license of a vaccine to prevent infection in children is awaited. Lyme borreliosis is an intriguing human example of bacterial persistence in the presence of the host immune system. Chronic Lyme arthritis is a model of chronic arthritis resembling forms of arthritis of unknown cause, such as rheumatoid arthritis and juvenile idiopathic arthritis.

Update on Lyme Disease Vaccine: Focus on Dosing and Adverse Events

With the rapid pace of immunologic research, it is more important than ever for readers to understand rational immunodiagnosis, immuno-prophylaxis, and immunotherapy. This column is intended to help you ensure proper immunologic drug use in your practice.

Prevention of Lyme disease: a review of the evidence

The Healthy People 2010 public health goals targeted a 44% decrease in the incidence of Lyme disease, the most commonly reported tick-borne illness in the United States. To review Lyme disease prevention, clinical trials, epidemiological and experimental studies, and predictive models were evaluated. Geographic distribution of ixodid vectors and local landscape predict Lyme disease risk. Density of infected ticks correlates with incidence and prevalence of Lyme disease, but risk quantitation is made uncertain by tick aggregation and inability to predict tick-human interactions. Outdoor activities are inconsistently or weakly associated with risk, and most infections likely occur in residential areas during routine activities. Tick control (burning or removing vegetation, acaricide use, and deer elimination) reduces Ixodes scapularis populations by up to 94%, and acaricide application to wildlife decreases nymphal I scapularis populations by up to 83%. The effect of these strategies on incidence of Lyme disease in humans is unknown. Studies show that only 40% to 50% of adults take precautions against tick bites even when they are aware of Lyme disease. Effective protection afforded by personal precautions (wearing protective clothing, avoiding ticks, and using insect repellant) has not been shown prospectively. Antimicrobial prophylaxis of tick bites is not warranted. Clinical trials showed vaccines containing recombinant OspA of Borrelia burgdorferi to be efficacious and well tolerated. Currently, vaccination is the only empirically demonstrated method to prevent Lyme disease. The best evidence supports prevention efforts focused on practices that encourage immunization, Lyme disease awareness, and possibly treatment of deer.

Safety and immunogenicity of a recombinant Borrelia burgdorferi outer surface protein A vaccine against lyme disease in healthy children and adolescents: a randomized controlled trial

OBJECTIVE

A recombinant lipoprotein outer surface protein A (OspA) Lyme disease (LD) vaccine (LYMErix) has been shown to be safe and effective in preventing LD in adults and in adolescents 15 years of age and older. Children are at risk for developing LD. This clinical study was conducted to address the safety and immunogenicity of LD vaccine in children 4 to 18 years of age.

METHODS

A randomized, placebo-controlled clinical trial was conducted at 17 investigational sites in Lyme-endemic areas in the United States. Immunogenicity data from this study also were compared with data obtained from the adult efficacy study. A total of 4090 healthy children and adolescents (age range: 4-18; mean age: 10.4 years) were randomized; 4087 were vaccinated, and a subset of 301 children participated in the immunogenicity analysis. Children were randomized to receive either 30 microgram of LD vaccine (N = 3063) or placebo (N = 1024) on a 0, 1, 12-month schedule. Safety assessments evaluated both solicited (local: redness, swelling, and pain; general: fever, headache, fatigue, arthralgia, and rash) and unsolicited adverse events. Serum specimens were collected at month 0 or month 2, and months 6, 12, and 13.

RESULTS

Solicited reactogenicity data revealed a higher incidence of local injection site reactions and general symptoms (fever, headache, fatigue, and arthralgia) in vaccine than placebo recipients. The majority of events were limited in duration (mean: 2-3 days) and were mild to moderate in severity. The total IgG anti-OspA geometric mean titer (GMT) in the pediatric vaccine recipients at month 13 was as good as and statistically higher than the GMT in the adult cohort at month 13 (27 485 enzyme-linked immunosorbent assay units [EL.U]/mL vs 8216 EL.U /mL). All of the pediatric vaccine recipients attained a level of antibody concentration >/=1400 EL.U/mL (proposed seroprotective level) compared with 90% of adults attaining levels >/=1400 EL.U/mL in the efficacy trial.

CONCLUSIONS

LD vaccine administered on a 0, 1, 12-month schedule generally is well tolerated and immunogenic in children 4 to 18 years of age. The safety profile consists of mild to moderate local injection site reactions and flu-like symptoms of limited duration and did not worsen with subsequent injections. IgG GMT at month 13 was threefold higher than the month 13 GMT obtained in the adult efficacy study. This higher immune response in children should provide protection against LD.

The prevention of Lyme disease with vaccine

Lyme disease is a potentially serious and debilitating infection caused by Borrelia burgdorferi that is endemic in North America, Europe, and Asia. Personal protective and environmental measures have not significantly impacted its increasing incidence. An adjuvanted recombinant vaccine (LYMErix) has been approved in the United States for the prevention of Lyme disease in adults, and has demonstrated both safety and efficacy. A clinical trial of over 10000 adults showed 76% efficacy following the third dose of a 0, 1, 12 schedule. Accelerated schedules demonstrate equivalent levels of protective antibody. Up to 100% of children 2-14 years of age achieve seroprotective levels of antibody. Booster doses induced protective levels of antibody in more than 96% of recipients when administered at months 12 and 24. Only mild or moderate, transient vaccine-associated adverse events have been reported after immunization. The vaccine is a safe and effective method of preventing Lyme disease.

Lyme vaccine: issues and controversies

The development of an effective vaccine for Lyme disease represents a major advance in the control of the most prevalent vector-borne disease in the United States. It has a definite place in the total approach to control of this disease. Its use should be restricted to individuals who are at moderate to high risk of exposure to infected vector ticks. Vaccinated individuals should not be complacent about other personal protection measures, because the vaccine is not uniformly effective and protective antibody levels decay rapidly. Booster doses will be necessary, but the intervals have not yet been determined. There is a theoretical concern about the possible induction of inflammatory arthritis through an autoimmune mechanism, but there is no evidence that this condition has clinical relevance. The impact of the current lawsuits on vaccine recommendations and use remains to be determined. Continued surveillance for rare long-term side effects should address the medical risk issue. Alternative primary vaccine administration schedules are currently under study, and could lead to regimens permitting achievement of protective immunity in 6 months or less. Vaccine is not approved for use in children under the age of 15 years.

Reactogenicity and immunogenicity of a Lyme disease vaccine in children 2-5 years old

Two doses of a recombinant Lyme disease vaccine (15 and 30 microg) were administered to children 2-5 years old (0-1-month schedule) and were well tolerated. Both doses were highly immunogenic with geometric mean titers 1 month after vaccination of 4366 and 9877 ELISA units (EU)/mL, respectively. Nearly all subjects had antibody levels of > or = 1400 EU/mL, suggesting protective tick titre for one tick season.

Lyme disease

Lyme disease (LD) is the most common tick-borne disease in the US. The overall trend has been an average annual increase in cases since surveillance was initiated by the Centers for Disease Control and Prevention in 1982. To date, 10 different Borrelia species have been described within the Borrelia burgdorferi sensu lato complex, although only Borrelia burgdorferi sensu strico, Borrelia garinii, and Borrelia afzelii have been associated with human disease. Ixodes ticks often carry more than one potential pathogen, and co-infection with B. burgdorferi and other organisms have been reported. Recent findings suggested that maintenance cycles of other tick-borne pathogens may be different than those for B. burgdorferi. A better understanding of the pathogenesis of Lyme arthritis has provided clues about the mechanisms responsible for variation in clinical expression of the disease. Results of therapeutic trials in Lyme neuroborreliosis are likely to have an impact upon treatment recommendations. A long term follow-up study of children treated for LD indicated that the prognosis is excellent in most cases. A safe vaccine for the prevention of LD has been approved in adults. Preliminary data suggested that the vaccine is safe and immunogenic in children.

Adjuvanted Lyme disease vaccine: a review of its use in the management of Lyme disease

Lyme disease is a potentially serious infection which is caused by the spirochaete Borrelia burgdorferi and is endemic in certain areas of North America, Europe and Asia. Lyme disease vaccine (LYMErix) is an adjuvanted formulation of the outer surface protein A (OspA) of the causative spirochaete. It acts by inducing high titres of anti-OspA antibodies (anti-OspA), which must be present in vaccinated individuals before exposure to B. burgdorferi to provide protection against Lyme disease. Lyme disease vaccine efficacy against Lyme disease was 80% for definite and asymptomatic cases and 76% for definite cases at year 2 using the recommended dosage regimen [30 microg at months 0, 1 and 12 (0, 1, 12 schedule)] in a randomised, double-blind, multicentre trial in 10,936 enrolled adult volunteers who resided in areas of the US endemic for Lyme disease. On the basis of an anti-OspA correlate of protection, Lyme disease vaccine 30 microg was equally effective when administered by a shorter schedule (0, 1, 6 schedule); > or = 90% of adult volunteers developed protective anti-OspA titres with this or the 0, 1, 12 schedule. Although published data are fewer, a 0, 1, 2 schedule has also shown promise in adults. In addition, virtually all children (aged 2 to 15 years) given Lyme disease vaccine 30 microg developed protective anti-OspA titres, but published data are also limited and results of a large paediatric trial are awaited with interest. Long term protection against Lyme disease appears to be possible with Lyme disease vaccine. Although anti-OspA titres decline rapidly after completion of the recommended schedule, booster doses of 30 microg of the vaccine induced protective anti-OspA titres in > or = 96% of adult volunteers when administered 12 and/or 24 months later. Lyme disease vaccine 30 microg is well tolerated: most vaccination-related adverse events were transient and mild or moderate in severity in clinical trials. The most common spontaneously reported adverse event was pain at the injection site in 24% of vaccine recipients (vs 7.6% of the placebo group). The incidence of spontaneously reported, early nonspecific systemic adverse events was <4% but was higher with the vaccine than with placebo for some events (e.g. myalgias, fever and chills but not arthralgia). There appeared to be no association between the vaccine and the incidence of arthritis or any late systemic adverse events. The tolerability profile of Lyme disease vaccine did not appear to vary with the schedule of administration, nor to differ between adults and children.

CONCLUSIONS

Lyme disease vaccine, an adjuvanted formulation of OspA, protects most adults against Lyme disease when administered by the recommended 0, 1, 12 schedule before disease exposure, and is well tolerated. The optimal schedule(s) of administration, duration of protection against Lyme disease, long term tolerability in adults and potential role in children are not fully defined for this vaccine. Lyme disease vaccine is indicated in North America for active immunisation of adults at moderate to high risk of contracting Lyme disease.