Section 1:

The purpose of the study is to obtain safety and immunogenicity data of different dose levels of a multivalent recombinant OspA Lyme Borreliosis (mv rOspA LB) Vaccine with and without adjuvant in seronegative healthy adults aged 18 to 70 years. The outcome shall provide the basis for dose/formulation selection for Section 2 of the study.

Section 2:

An additional purpose of the study is to evaluate the safety and immunogenicity of the optimal dose(s)/formulation of the mv rOspA LB Vaccine in a larger population of seronegative and seropositive healthy subjects aged 18 to 70 years.

Main Inclusion Criteria:

• Subject is 18 to 70 years old at the time of screening
• Subject has an understanding of the study, agrees to its provisions, and gives written informed consent prior to study entry
• Subject is generally healthy, as determined by the investigator's clinical judgment through collection of medical history and the performance of a physical examination
• If female of childbearing potential, presents with a negative urine pregnancy test, and agrees to employ adequate birth control measures for the duration of the study

Additional inclusion criterion for seropositive subjects in Section 2 only:

- Subject is seropositive for Borrelia burgdorferi sensu lato (s.l.) antibodies at study entry

Main Exclusion Criteria:

• Subject has a physician-diagnosed chronic illness related to Lyme borreliosis (LB) or active LB
• Subject has been treated for LB with antibiotics within 3 months of study entry
• Subject had a tick bite within 3 weeks prior to screening or first vaccination
• Subject has a history or active infection with Babesia microti (babesiosis) or Anaplasma phagocytophilum (ehrlichiosis)
• Subject currently has or has a history of significant cardiovascular, respiratory (including asthma), metabolic, neurological, hepatic, rheumatic, autoimmune, hematological, gastrointestinal or renal disorder
• Subject has clinically significant abnormal laboratory values at screening
• Subject currently has or has a history of immunodeficiency
• Subject tests positive for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV)
• Subject has a disease or is currently undergoing a form of treatment or was undergoing a form of treatment within 30 days prior to study entry that could be expected to influence immune response.
• Subject has a history of anaphylaxis or severe allergic reactions
• Subject has received any live vaccine within 4 weeks or inactivated vaccine within 2 weeks prior to vaccination in this study
• Subject is pregnant or lactating at the time of study enrollment

Additional exclusion criterion for subjects in Section 1 and seronegative subjects in Section 2:

- Subject is seropositive for Borrelia burgdorferi sensu lato (s.l.) antibodies at study entry