Trial to Evaluate the Safety and Immunogenicity of an Anthrax Recombinant Protective Antigen Vaccine

Inclusion Criteria: * Able to understand the study and give written informed consent. A signed informed consent must be in place before the initiation of any study interventions. * Healthy male or female aged 18 to 40 years old (inclusive) without significant physical or clinical laboratory abnormalities. * Two intact upper arms with sufficient intramuscular (IM) tissue in the deltoid region for vaccine administration. * For females, negative serum pregnancy test at screening and agreement to use adequate birth control during the first 3 months of the study. * Willingness and ability to return for all follow-up visits and blood draws for the duration of the study. * Willingness to complete the Volunteer Diary and to report concomitant medications and adverse events (AEs) to the study site monitors during the study period. Exclusion Criteria: * Prior history of, or known exposure to any form of B. anthracis or any anthrax immunization. * Member of the Armed Services (Active Duty or Reserve) since 1990, with history of previous anthrax vaccination. * Employment in an industry involved in contact with ruminant animals, veterinary sciences, or other exposure to B. anthracis. * Expected to be noncompliant with study visits or planning to move within 8 months. * Body mass index of \>35 or \<19. * Known allergy to aluminum hydroxide, formaldehyde, benzethonium chloride, latex, kanamycin, or any other aminoglycoside antibiotics (such as gentamycin). * Pregnancy (positive urine pregnancy test within 24 hours prior to vaccination), or lactation. * HIV positive (by history or screening ELISA). * Hepatitis B or C positive (by history or screening HBsAg/anti-HCV ELISA). * Active or past internal organ, hematologic malignancy, or metastatic cutaneous malignancy. * History of, or current autoimmune disease, including but not limited to systemic lupus erythematosus, scleroderma, and polyarteritis. * Immunodeficiency or unstable medical condition as determined by baseline medical history, physical exam, and laboratory assessment. * Received, or plans to receive, licensed live vaccines within 30 days of study vaccination. * Received, or plans to receive, licensed killed vaccines within 14 days of study vaccination. * Received, or plans to receive, immunoglobulin or other blood products within 60 days of study vaccination. * Received, or plans to receive, experimental drugs/vaccines within 30 days of study vaccination. * Received, or plans to receive, systemic immunosuppresive therapy, radiation therapy, or high-dose inhaled steroids within 30 days of study vaccination. * Use of systemic chemotherapy within 5 years prior to study. * History of Guillain-Barre Syndrome. * In addition to the conditions listed above, the following may qualify as a reason to exclude a volunteer from the study: fever along with moderate or serious illness within 3 days of vaccination or any condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the study evaluations. Pending resolution of these symptoms, a volunteer may be reconsidered for vaccination.