OspA Vaccine Research Articles

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

Background and Objective: A recombinant lipoprotein vaccine against Lyme disease, containing 30 μg of Borrelia burgdorferi outer surface protein A (OspA) with aluminum adjuvant, has been shown in a large US field trial of subjects ≥15 years of age to offer 76% efficacy against clinical Lyme disease after 3 injections given at 0, 1, and 12 months. Lyme disease is also an important problem in children; thus, OspA vaccine trials in children are needed. The purpose of this study was to investigate the safety and immunogenicity of 2 different doses of lipoprotein OspA with aluminum adjuvant vaccine in healthy children 5 to 15 years of age in a double-blind, randomized study. Study design: In a double-blind study, 250 children from the Czech Republic were randomly assigned to receive 15 μg or 30 μg of OspA vaccine at 0, 1, and 2 months. Serum samples, obtained before vaccination and 1 month after the second and third doses, were analyzed for antiOspA antibody. Solicited and unsolicited symptoms were collected from diary cards. Results: Local pain at the injection site was reported by approximately 76% of the 250 children. Headaches (after 5% to 18% of the injections) and malaise (after 2% to 16% of the injections) were the most frequently reported general symptoms. Local and generalized symptoms were not different between the 15 μg and 30 μg groups, and all symptoms resolved within 4 days. Both doses were highly immunogenic, with the 30 μg dose eliciting higher antibody levels. Seroconversion occurred in 99% of the 250 children. Conclusions: The OspA vaccine against Lyme disease was well tolerated and highly immunogenic in children. (J Pediatr 1999;135:575-9)

Lyme disease prevention and vaccine prophylaxis.

To provide a comprehensive review of the epidemiology, diagnosis, and prevention of Lyme disease with a focus on the Lyme disease vaccine. A computerized search of MEDLINE (January 1996-December 1998) was used to identify articles regarding Lyme disease, Borrelia burgdorferi, epidemiology, prevention, and vaccine. Lyme disease is a condition caused by infection with B. burgdorferi. The organism is carried by certain species of Ixodes ticks and is the most common tick-borne disease in the US. In patients with clinical manifestations of Lyme disease, various pharmacotherapeutic approaches have proven effective in treatment of the clinical features. Prevention strategies exist; however, their application is sometimes difficult. A vaccine for the prevention of Lyme disease is available, and another is being considered for approval. The recombinant outer surface protein A (OspA) vaccines to prevent Lyme disease are immunogenic and have an acceptable adverse effect profile. These vaccines are highly efficacious for the prevention of Lyme disease. Lyme disease is the most common tick-borne disease in the US. The infection, caused by B. burgdorferi, results in dermatologic, neurologic, cardiovascular, and musculoskeletal manifestations. Until recently, tick bite prevention strategies were the only means of decreasing the risk of acquiring the infection. The OspA vaccines are efficacious for the prevention of infection. Although universal immunization with these vaccines is unlikely, the availability of effective vaccines represents an important tool for the prevention of Lyme disease in endemic regions of the US.

VACCINATION AS A MODALITY TO PREVENT LYME DISEASE: A Status Report

Recombinant outer surface protein A (OspA) of Borrelia burgdorferi is a highly protective immunogen for prevention of Lyme disease in experimental animals. Humoral immunity is sufficient for protection. The principal mechanism of action is prevention of transmission of the spirochete from tick to host. A recombinant OspA vaccine has been licensed for use in dogs. The recent licensure of an OspA vaccine for humans resulted from a critical analysis of recently completed efficacy studies.

Safety and immunogenicity of recombinant Bacille Calmette-Guérin (rBCG) expressing Borrelia burgdorferi outer surface protein A (OspA) lipoprotein in adult volunteers: a candidate Lyme disease vaccine

This phase I clinical trial was designed to determine the feasibility of using rBCG as a live bacterial vaccine vector for the outer surface protein A (OspA) of Borrelia burgdorferi and as model for other vaccines based on a rBCG vector. To construct the vaccine, a signal peptide derived from a mycobacterial lipoprotein was used to direct the export, and membrane-associated surface expression, of OspA in a standard strain of BCG (Connaught). The rBCG–OspA vaccine was safe and immunogenic in several animal species, and protective in a mouse model of Lyme borreliosis. An intradermal injection (0.1 ml) of rBCG–OspA was administered to 24 healthy adult volunteers sequentially at one of four dose levels, ranging from 2.0×10 4 CFU to 2×10 7 CFU , using a dose-escalation design. All volunteers were initially PPD-skin test and OspA antibody negative, and they were monitored for 2 years after immunization. Three volunteers had mild flu-like reactions 1--2 days after vaccination. Local ulceration and drainage at the site of injection, which occurred in 50% and 83% of volunteers in the two highest dose groups, persisted for 1–70 days before the ulcers healed. Most of the drainage samples yielded rBCG colonies that contained the OspA plasmid. Thirteen of 24 vaccinees, principally in the two highest dose groups, converted their PPD skin tests from negative to positive. None of the 24 volunteers developed OspA antibody. In conclusion, the current rBCG vaccine construct, the first such construct tested in humans, had a safety profile comparable to that of licensed BCG, but it did not elicit primary humoral responses to the vectored antigen.

Killing of Borrelia burgdorferi by antibody elicited by OspA vaccine is inefficient in the absence of complement.

A Lyme disease vaccine, based on the Borrelia burgdorferi lipoprotein OspA, has recently undergone phase III trials in humans. The results of one of these trials indicate that vaccine efficacy positively correlates with anti-OspA antibody titer. Spirochete killing within the tick vector midgut, upon which vaccine efficacy appears to depend, may occur chiefly via a mechanism that involves antibody alone, as it has been reported that complement is degraded by tick saliva decomplementing factors. We compared the in vitro killing efficiencies of anti-OspA antibody elicited in rhesus monkeys by the OspA vaccine, in the presence and in the absence of monkey complement. Killing in the absence of complement was between 14 and 3,800 times less efficient than with complement present, depending on the spirochete strain. The relative inefficiency of the complement-independent killing mechanism by anti-OspA antibody may explain why OspA vaccine efficacy is critically dependent on antibody titer.

Canine viral vaccines at a turning point—A personal perspective

The most important canine viral infections are distemper and CPV-2. Problems of variable CD vaccine safety and efficacy persist, but CD vaccines have greatly reduced the prevalence of disease and cases in vaccinated dogs are now rare. Canine hepatitis (ICH, CAV-1 infection) also has been controlled well by vaccines for more than 35 years and it is now rare; the sporadic cases seen in the 1990s have usually occurred in unvaccinated dogs. CAV-2 vaccines should, therefore, continue to be given since they have proved to be safe and effective, and prevent hepatitis as well as adenoviral tracheobronchitis. Failure to vaccinate would likely result in increase in cases of ICH, a serious disease, but never as significant as distemper and CPV infection. "Are we vaccinating too often?" The question is complex, but the dominant opinion is "yes" (Smith, 1995). The question cannot be responded to unequivocally, however, since manufacturers employ different strains that vary in their immunizing capacity and, probably, duration of immunity. This question was frequent with distemper in the 1960s. At that time, many veterinarians tested batches of the vaccine they used by providing pre- and postvaccinal sera to competent diagnostic laboratories. That practice appeared to benefit veterinarians and dogs, as well as the quality of vaccines. Unfortunately, many owners and some veterinarians seem to hold the view that infectious diseases such as parvovirus infection can be controlled by frequent vaccination alone. The common practice of dog breeders of vaccinating their animals several times each year is senseless. Revaccination for distemper and parvovirus infection is suggested at 1 year of age, but recommendations regarding the frequency of most vaccinations given after that time are unclear. Since most distemper and CPV-2 vaccines probably provide immunity that endures several years, vaccination at 3- to 5-year intervals, after the first year, seems a reasonable practice until more data on duration of immunity become available. "Are too many kinds of vaccines being promoted for dogs?" Distemper and parvovirus vaccines are essential; canine adenovirus vaccines are recommended since the few cases brought to our attention in recent years have been in unvaccinated dogs. Vaccination against respiratory infections is recommended for most dogs, especially those in kennels, or if they are to be boarded. Need has not been clearly established for coronavirus vaccines; Lyme disease vaccines (see below) are useful in preventing illness in areas where the disease exists, but are unnecessary elsewhere since dogs respond rapidly to appropriate antibiotics; current Leptospira bacterins are without benefit since they contain serovars that fail to protect in most areas (noted below). Lyme disease (LD) was not considered here, but newer recombinant (OspA) vaccines are now available that appear to be safe and effective for at least 1 year and they have not caused vaccine-induced postvaccinal lameness, which has been documented with certain whole-cell Lyme disease bacterins. Lyme disease vaccines should be restricted to dogs in, or entering, endemic areas where infested ticks reside. More than 85% of LD cases occur in the mid-Atlantic and Northeastern States, about 10% in six Midwestern states (Michigan, Minnesota, and Wisconsin), and a smaller percentage in restricted areas of northern California and the Pacific Northwest. Leptospirosis also was not discussed here, but vaccines are commonly reported as a cause of anaphylaxis and current vaccines do not contain the serovars prevalent in most regions. The vast majority of cases diagnosed at the New York State Diagnostic Lab at Cornell are grippotyphosa and pomona serovars and there have been no recent cases caused by canicola or icterohemorrhagiae serovars. Because leptospirosis is an important disease of dogs, there is an urgent need for more research and the development of safer vaccines that contain the prevalent

Borrelia burgdorferi escape mutants that survive in the presence of antiserum to the OspA vaccine are killed when complement is also present.

As an initial attempt to investigate the possible role of outer surface protein A (OspA) escape mutants of Borrelia burgdorferi in decreasing the efficacy of the OspA vaccine, mutants of the HB19 strain of B. burgdorferi sensu stricto were selected in vitro from an uncloned, low-passage-number isolate. The antiserum used for selection was obtained from rhesus monkeys that had been given a vaccine of the same formulation and dose, and by the same route of administration, as that given to humans in several trials. All of the mutants selected in liquid medium and subsequently cloned twice in solid medium expressed a single abundant protein of 28 to 34 kDa instead of both OspA and OspB. Depending on the mutant, this protein reacted strongly, weakly, or not detectably with the anti-OspA antibody used for selection. Analysis of the ospAB locus of each of four representatives from these three groups of mutants by PCR with oligonucleotide primers that hybridize to flanking regions of the ospAB operon, and of the corresponding phenotype with monoclonal antibodies that bind to the amino or carboxyl terminus of the OspA or OspB polypeptide, indicated that in all cases a deletion within the operon had occurred. Spirochetes from the four mutant strains chosen for further analysis could be killed in antibody-dependent, complement-mediated killing assays with the selecting anti-OspA antibody, despite their resistance to killing with this antibody in the absence of complement. Complement-mediated killing occurred at an antibody concentration higher than that required to kill wild-type spirochetes. If anti-OspA antibody acts only within the tick, where complement is probably ineffective due to tick-derived decomplementing factors, then OspA escape mutants, if infectious, could seriously diminish the efficacy of OspA vaccines. On the other hand, if the killing of B. burgdorferi with anti-OspA antibody also takes place within the human host, then our results indicate that chimeric/deletion escape mutants will be killed as well.

The outer surface protein A (OspA) vaccine against Lyme disease: efficacy in the rhesus monkey

The efficacy of an outer surface protein A (OspA) vaccine in three different formulations was investigated in the rhesus monkey. The challenge infection was administered using Ixodes scapularis ticks that were infected with the B31 strain of Borrelia burgdorferi. Protection was assessed against both infection and disease, by a variety of procedures. Some of the animals were radically immune suppressed, as an attempt to reveal any putative low level infection in the vaccinated animals. The significant difference found between the spirochaetal infection rates of ticks that had fed on vaccinated vs. control monkeys, lack of seroconversion in the vaccinated animals, and the absence of spirochaetal DNA in the skin of vaccinated animals in the weeks following the challenge, indicate that vaccinated monkeys were protected against tick challenge. The post-mortem immunohistochemical and polymerase chain reaction analyses, however, suggest that these monkeys may have undergone a low-level infection that was transient.

Immunization with a polyvalent OspA vaccine protects mice against Ixodes ricinus tick bites infected by Borrelia burgdorferi ss, Borrelia garinii and Borrelia afzelii

Sequence variability of the outer surface protein (Osp) A among Borrelia burgdorferi sl species suggests that a monovalent OspA vaccine may not protect against the various Borrelia present in Eurasia. Here, we confirmed that a monovalent recombinant OspA (rOspA) vaccine does not protect mice against Ixodes ricinus mediated infection with B. burgdorferi ss, Borrelia garinii and Borrelia afzelii. However, when mice were vaccinated with a cocktail of various rOspA from these three species, they were protected, and all challenge ticks that fed on them were cleared of their spirochetes. These results showed that a multiple OspA antigens vaccine, compatible with human use, was very efficient at protecting mice against B. burgdorferi ss, B. garinii, and B. afzelii.

Activation of monocytes by three OspA vaccine candidates: lipoprotein OspA is a potent stimulator of monokines.

The outer surface protein (Osp) A of Borrelia burgdorferi is the first Lyme antigen to be tested in a vaccine for humans. Three forms of OspA vaccine candidates were investigated by the induction of the cytokines interleukin (IL)-1 beta, IL-6, tumor necrosis factor (TNF)-alpha, IL-10 and interferon (IFN)-gamma as markers of monocyte activation and immune stimulation: lipidated OspA (L-OspA), non-lipidated OspA (NL-OspA), and a fusion protein of 81 amino acids of the nonstructural protein 1 of influenza virus with OspA (NS1-OspA). All OspA preparations induced IL-1 beta, IL-6 and TNF-alpha in a concentration-dependent manner with peak levels at 12-24 h. These cytokines were entirely derived from the monocyte fraction. In peripheral blood mononuclear cells from 10 healthy donors, L-OspA at 10 micrograms ml-1 induced up to 4-fold more IL-1 beta, IL-6, and TNF-alpha than the other OspA preparations (P < or = 0.0068), followed by NS1-OspA, which was still superior to NL-OspA. L-OspA. L-OspA also induced high levels of IL-10 within 24 h but no significant amounts of IFN-gamma. This superior stimulating activity of L-OspA on unstimulated monocytes predominantly depended on N-terminal lipidation of OspA. Similarities to other lipoproteins and synthetic lipopeptides suggest that lipidation confers adjuvant properties on OspA. High induction of IL-10 by L-OspA further suggested a negative feedback on monocyte activation by the lipidated form. The in vitro results are in line with in vivo results in mice, monkeys and humans and indicates that lipoprotein OspA has the best potential for induction of a protective effect in humans, compared to non-lipidated antigens.

Activation of monocytes by three OspA vaccine candidates: lipoprotein OspA is a potent stimulator of monokines

The outer surface protein (Osp) A of Borrelia burgdorferi is the first Lyme antigen to be tested in a vaccine for humans. Three forms of OspA vaccine candidates were investigated by the induction of the cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, IL-10 and interferon (IFN)-γ as markers of monocyte activation and immune stimulation: lipidated OspA (L-OspA), non-lipidated OspA (NL-OspA), and a fusion protein of 81 amino acids of the nonstructural protein 1 of influenza virus with OspA (NS1-OspA). All OspA preparations induced IL-1β, IL-6 and TNF-α in a concentration-dependent manner with peak levels at 12–24 h. These cytokines were entirely derived from the monocyte fraction. In peripheral blood mononuclear cells from 10 healthy donors, L-OspA at 10 μg ml −1 induced up to 4-fold more IL-1β, IL-6, and TNF-α than the other OspA preparations ( P≤0.0068), followed by NS1-OspA, which was still superior to NL-OspA. L-OspA also induced high levels of IL-10 within 24 h but no significant amounts of IFN-γ. This superior stimulating activity of L-OspA on unstimulated monocytes predominantly depended on N-terminal lipidation of OspA. Similarities to other lipoproteins and synthetic lipopeptides suggest that lipidation confers adjuvant properties on OspA. High induction of IL-10 by L-OspA further suggested a negative feedback on monocyte activation by the lipidated form. The in vitro results are in line with in vivo results in mice, monkeys and humans and indicates that lipoprotein OspA has the best potential for induction of a protective effect in humans, compared to non-lipidated antigens.

Specific issues in the design and implementation of an efficacy trial for a Lyme disease vaccine.

Lyme disease is an emerging infection that has now become the most commonly reported vector-borne disease in the United States. In the 20 years since its initial description, scientific and technological advances have led to candidate vaccines for the prevention of Lyme disease. Recombinant outer surface protein A (OspA) vaccines have been successful in protecting mice in tick-challenge experiments. A candidate OspA vaccine has been found to be safe and immunogenic in phase I and II studies. This article describes some of the lessons that were learned and some of the unique obstacles encountered in the design and implementation of a large phase III efficacy field trial. Pivotal trials of vaccines for Lyme disease can be a major investment of time and resources for subjects, investigators, and sponsors. If properly conducted, they also present unique opportunities to expand our knowledge of the disease.

Treatment and prevention of Lyme disease, with emphasis on antimicrobial therapy for neuroborreliosis and vaccination.

Antibiotic therapy is recommended for all forms of neuroborreliosis. Although stage 2 neuroborreliosis will usually resolve without any treatment, antibiotic therapy has been associated with faster resolution of symptoms and may prevent additional non-neurologic disease manifestations. Ceftriaxone is the most convenient parenteral agent for stage 2 and 3 neuroborreliosis because of its once-daily dosage. Available data indicate that a 2-4-week treatment course is adequate for most patients. Patients with isolated seventh nerve palsy may be treated with an oral agent (for example, doxycycline). Recombinant outer surface protein A of Borrelia burgdorferi is a highly protective immunogen for prevention of Lyme disease in experimental animals. Humoral immunity is sufficient for protection. A recombinant OspA vaccine has been licensed for prevention of Lyme disease in dogs. Licensure of an OspA vaccine for humans will depend on a critical analysis of the results of recently completed efficacy studies.

Borrelia burgdorferi enzyme-linked immunosorbent assay for discrimination of OspA vaccination from spirochete infection.

Recombinant Lyme disease vaccines based on purified preparations of outer surface protein A (OspA) have been shown to be effective in preventing transmission of Borrelia burgdorferi in experimental animal models and are now being tested in humans. Since the most widely used screening tests for Lyme disease are based on a whole-cell sonicate of B. burgdorferi, serologic false positivity in vaccinated persons could result from reactivity to OspA within the antigen preparation. In order to avoid serologic false positivity in vaccinated subjects, we developed an immunoassay based on a low-passage-number, naturally occurring variant of B. burgdorferi which lacks the plasmid encoding OspA and OspB. The use of an antigen preparation derived from this organism provided sensitive and specific detection of B. burgdorferi seropositivity in experimental animals and in human Lyme disease cases. The OspA-B-negative enzyme-linked immunosorbent assay (ELISA) also appeared to be capable of discriminating the vaccinated state from vaccine failure and natural infection in experimental animals. Sera from human subjects participating in a vaccine trial gave false-positive results with an ELISA based on an OspA-containing strain, but no such reactivity was observed when the OspA-negative ELISA was used. We conclude that low-passage-number OspA-B-negative isolates in immunoassays may become useful for the immunologic discrimination of the vaccinated state, natural infection, and vaccine failure.

Lyme disease vaccine.

Subunit vaccines consisting of single recombinant outer surface proteins (Osp) of Borrelia burgdorferi have been highly successful in protecting mice against challenge by borrelial strains closely related to the strain from which the immunogen was derived. Humoral immunity is sufficient for protection. A dual mode of action for these vaccines has been suggested because serum factors ingested by the tick during the blood meal may begin to reduce the spirochete inoculum prior to transmission to the host. At present two different recombinant OspA vaccine preparations (monovalent) are being evaluated in humans in large-scale phase III efficacy trials in the United States. Local discomfort at the intramuscular injection site has been the principal adverse effect seen to date with these vaccines, but further data on safety are being collected. The greater heterogeneity of OspA among Lyme Borrelia in Europe implies that a vaccine preparation containing multiple antigens (multivalent) may be necessary there, although this is also a concern in the United States.

Prospects for a Vaccine to Prevent Lyme Disease in Humans

Vaccination with recombinant outer-surface protein A (OspA) preparations has been highly successful in protecting laboratory animals against challenge by strains of Borrelia burgdorferi closely related to the one from which the OspA was derived. Humoral immunity is sufficient for protection. Against natural infection introduced by ticks, the vaccine-induced immune response may begin to take effect in the tick itself--i.e., before the spirochete enters the host--and may extend to a broader spectrum of strains of B. burgdorferi than are represented in the vaccine. Single recombinant OspA vaccine preparations are currently being evaluated in two large-scale efficacy trials in adults in the United States. Greater heterogeneity among B. burgdorferi strains in Europe than among those in the United States will likely necessitate the development of a vaccine containing antigens from multiple strains; a multivalent vaccine may or may not be needed in the United States.

Characterization of Canine Humoral Immune Responses to Outer Surface Protein Subunit Vaccines and to Natural Infection by Lyme Disease Spirochetes

Canine antibody responses to Lyme disease subunit vaccines and to natural borrelial infection were investigated. Vaccines were formulated with QS21 and outer surface proteins A (OspA) and B (OspB) derived from Borrelia burgdorferi B31. Vaccines containing QS21 and the lipoproteins gave 4-fold higher IgG1 and 8-fold higher IgG2 antibody responses than without QS21. Antisera to lipidated OspA or OspB vaccines containing QS21 had high antiborrelial activity against isolates B31 and CA-2-87, similar to those with a vaccine containing both OspA and OspB. Only the combination vaccine induced antiborrelial activity against heterologous isolates 24008 Fr and Borrelia garinii G25. Nonlipidated OspA- and OspB-based vaccines with QS21 elicited lower antibody and antiborrelial activity than did lipidated OspA and OspB vaccines; 49% of naturally exposed dogs had low titers to OspA or OspB. Thus, vaccines using lipidated OspA, OspB, and QS21 could induce higher antiborrelial activity than did natural exposure.

The Lyme disease vaccine candidate outer surface protein A (OspA) in a formulation compatible with human use protects mice against natural tick transmission of B. burgdorferi

Development of a vaccine for the Lyme disease spirochete, Borrelia burgdorferi, has focused on the bacterial lipoprotein, major outer surface protein A (OspA). With few exceptions, testing of OspA vaccines in animal models has involved challenge with needle inoculation of cultured spirochetes. Recombinant OspA proteins from two OspA divergent strains of B. burgdorferi were tested for their vaccine potential in three different strains of mice challenged with laboratory reared ticks with a high rate of B. burgdorferi infection. All formulations of the B. burgdorferi sensu stricto derived OspA vaccine protected all strains of mice when challenged by ticks infected with an OspA homologous strain of the spirochete, whereas heterologous OspA from B. afzelii did not protect. Furthermore, ticks feeding on protected mice had reduced OspA levels compared to unvaccinated controls.

Vaccination against Lyme disease caused by diverse Borrelia burgdorferi.

Diversity and mutations in the genes for outer surface proteins (Osps) A and B of Borrelia burgdorferi sensu lato (B. burgdorferi), the spirochetal agent of Lyme disease, suggests that a monovalent OspA or OspB vaccine may not provide protection against antigenically variable naturally occurring B. burgdorferi. We now show that OspA or OspB immunizations protect mice from tick-borne infection with heterogeneous B. burgdorferi from different geographic regions. This result is in distinct contrast to in vitro killing analyses and in vivo protection studies using syringe injections of B. burgdorferi as the challenge inoculum. Evaluations of vaccine efficacy against Lyme disease and other vector-borne infections should use the natural mode of transmission and not be predicated on classification systems or assays that do not rely upon the vector to transmit infection.

OspA vaccination of mice with established Borrelia burgdorferi infection alters disease but not infection.

C3H mice were actively immunized with outer surface protein A (OspA) at different intervals after infection with Borrelia burgdorferi to determine the effect of postexposure vaccination on the course of murine Lyme borreliosis. Mice were vaccinated with an OspA-glutathione transferase fusion protein or glutathione transferase (control) in complete Freund's adjuvant; vaccination was followed by two weekly booster injections in incomplete adjuvant. Two weeks after the final booster injection, organs were cultured for B. burgdorferi (blood, spleen, skin, and bladder) and examined for histopathology (joints and hearts). When vaccination was commenced in the early stages (5 to 14 days) of infection, active immunization with OspA partially cleared spirochetes from the bloodstream but did not eliminate them from other tissues or alter the course of joint or heart disease. Commencement of vaccination at 60 days after infection (at which time joint or heart disease is resolving), however, reduced both the number of mice and individual joints with arthritis, a result suggesting an acceleration of the resolution phase of the disease. Postexposure immunization with OspA may partially alter the course of murine Lyme arthritis but does not eliminate infection.