Characterization of a recombinant outer surface protein A (OspA) vaccine against Lyme disease.

Lyme disease, the most prevalent tick-borne disease in the United States, results from infection with Borrelia burgdorferi sensu stricto. Early studies of Borrelia burgdorferi sensu stricto identified outer surface protein A (OspA), a lipoprotein on the surface of spirochetes that could be the target of protective antibodies to this agent. Pasteur Mérieux Connaught has developed a Lyme vaccine, ImuLyme, using recombinant OspA protein (rOspA). Methods were developed to routinely assess the identity, quantity, structure, purity, biological activity, heterogeneity, stability, and potency of rOspA. In addition, several methods were performed on a series of lots to support the routine testing methods and further our understanding of the physicochemical characteristics of rOspA. These tests were electrospray mass spectrometry, circular dichroism, two-dimensional gel electrophoresis, amino acid analysis, peptide mapping with peptide sequencing, and the application of proteomic methodology to identify trace contaminant host cell proteins. The results of these methods indicate that the rOspA lots are composed of highly purified and properly processed and folded rOspA with trace amounts of E. coli host cell proteins.

Safety and immunogenicity of a recombinant outer surface protein A Lyme vaccine.

OBJECTIVE: To evaluate the safety and immunogenicity of a recombinant outer surface lipoprotein A (OspA) Lyme vaccine in healthy adults. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Clinical research unit of a medical center. PARTICIPANTS: Thirty-six healthy adult volunteers aged 18 through 65 years. INTERVENTIONS: Volunteers were randomly assigned to receive two 10-micrograms doses of OspA Lyme vaccine, OspA Lyme vaccine adsorbed to alum, or a buffer placebo. Subjects in the OspA Lyme vaccine group received a third dose. Patients were assessed after each vaccination for a total follow-up period of 1 year. Serum samples for antibody determination were drawn at baseline, 2 and 3 weeks after dose 1, once per week for 4 weeks after dose 2, 20 weeks after dose 2, and 1 month after dose 3. MAIN OUTCOME MEASURES: Local and systemic adverse reactions and antibody levels specific for OspA. RESULTS: The most common reactions were local pain and tenderness at the injection site. Adverse events did not increase following the second or third dose. Two doses of both vaccine formulations elicited high-titer antibodies that inhibited replication of Borrelia burgdorferi in vitro. No differences were noted in antibody levels elicited by the adsorbed and nonadsorbed formulations. CONCLUSION: Two or three doses of OspA Lyme vaccine are safe and immunogenic in adults.

Role of attached lipid in immunogenicity of Borrelia burgdorferi OspA.

OspA is a protective antigen of the Lyme disease spirochete Borrelia burgdorferi. Expression of the full-length B. burgdorferi B31 OspA gene in Escherichia coli produces a protein that is processed posttranslationally by signal peptidase II and contains an attached lipid moiety. The recombinant OspA lipoprotein has been purified by detergent extraction and ion-exchange chromatography. Priming and boosting with OspA lipoprotein, either with no adjuvant or adsorbed to alum, elicited a strong, dose-dependent immunoglobulin G response. Serum from vaccinated mice inhibited spirochetal growth in vitro. Mice immunized twice with as little as 0.4 micrograms of OspA lipoprotein were protected against an intradermal challenge with 10(4) infectious spirochetes. The ability of the purified recombinant lipoprotein to induce a strong protective response in the absence of toxic adjuvants makes it an excellent candidate antigen for a human vaccine against Lyme disease. By contrast, no serum immunoglobulin G or growth inhibitory response to OspA nonlipoprotein was seen at any dose. The difference in immunogenicities of the lipoprotein and nonlipoprotein forms of OspA is not due to any difference in the antigenicities of the two proteins. These results suggest that posttranslational lipid attachment is a critical determinant of the immunogenicity of the OspA protein.