A Phase 2 Safety and Immunogenicity Study for an Anthrax Vaccine Using 3 Schedules and Two Dose Levels

Inclusion Criteria: * Be 18-50 years old * Be in good health * Have access to a computer and the internet so you can complete a diary * Agree to abstain from sex the first 84 days of the study or practice birth control if you are a woman who is able to get pregnant * Have not donated blood for the previous 8 weeks Exclusion Criteria: * A known anaphylactic response, severe systemic response, or serious hypersensitivity reaction to a prior immunization. * A history of latex allergy. * Have received a shot (vaccine), including flu shots, in the past 6 weeks or plan to get a shot for 4 weeks after the last study shot is given. * Have previously served in the military any time after 1990 or plan to enlist in the military from Screening through Day 84. * Prior immunization with anthrax vaccine, recombinant protective antigen (rPA) vaccine, or known exposure to anthrax organisms. * Have participated in anthrax therapeutic or vaccine studies (monoclonal anti-PA or anthrax immune globulins or anthrax vaccines). * Participation in any investigational study involving use of a pharmacological intervention within 30 days before the Screening visit or planning to participate in a study requiring dosing through the 12-month safety follow-up telephone call. * Have a known diagnosis of any immunodeficiency disease including but not limited to: acquired immune deficiency syndrome (AIDS), common variable immunodeficiency disease, immunoglobulin A (IgA) deficiency, or hypogammaglobulinemia. * Past history of significant autoimmune disease such as rheumatoid arthritis, lupus erythematous, psoriasis in the area of vaccinations, or requires immunotherapy, glomerulonephritis, or autoimmune thyroiditis. * Have received immunosuppressive therapy with cytotoxic drugs or Rituximab within the past 2 years. * A history of cytotoxic chemotherapy or radiation therapy. * Chronic (\>10 days) daily oral or parenteral corticosteroid therapy in the past 12 months. * Any lung disease, including reactive airway disease, which requires the daily use of medications. * A female currently breastfeeding or with a positive pregnancy test. * A history of drug or alcohol abuse within 12 months prior to Screening, or a positive result on a urine drug screen for cocaine, marijuana, opiates, methamphetamines, benzodiazepines, or oxycodone. * Any tattoo or other skin condition in the deltoid region on either arm that may obscure the assessment of the injection sites. * A medical condition that, in the opinion of the PI or designee, could adversely impact the subject's participation or safety or the conduct of the study. * Any planned elective in-patient surgery during the study period.