The Safety, Tolerability, and Immunogenicity of Three Dose Levels of ACAM3000 Modified Vaccinia Ankara (MVA) Smallpox Vaccine, in Adults Without Previous Smallpox Vaccination

Inclusion Criteria: Subjects must meet the following to be eligible for the study: * adult males or females who provided informed consent for the study. * adults 18 and 31 years (inclusive). * good general health, * female subjects must not be pregnant or lactating and be on appropriate contraception or be a female unable to bear children. * subjects be available for participation during the entire study. Exclusion Criteria: Any of the following exclusion criteria are met, the subject is NOT eligible. * military service prior to 1989 or after December 13th, 2002. * history of previous smallpox vaccination * known/suspected history of immunodeficiency, or with current radiation treatment or use of immunosuppressive or anti-neoplastic drugs. * subjects with a household member or intimate contact with the same conditions listed above. * known or suspected impairment of other immunologic function. * malignancy, including squamous cell or basal cell skin cancer at vaccination site * active autoimmune disease. * subjects with known eye diseases or other conditions that require the use of corticosteroid eye drops. * known/history of cardiac disease. * subjects who have been diagnosed with 3 or more of the following risk factors for ischemic coronary disease: a) high blood pressure b) elevated blood cholesterol levels c) diabetes or high blood sugar d) first degree relative (for example, mother, father, brother, or sister) who had a heart condition before the age of 50 e) smoke cigarettes * subjects with a history of palpitations or abnormalities of cardiac rhythm. * subjects with odd ECG patterns * subjects with a ten percent or greater risk of developing a myocardial infarction or coronary death within the next 10 years. * positive or elevated creatinine kinase, CK-MB, or Troponin I laboratory test levels. * abnormalities of clinical laboratory assessments. * past history or current diagnosis of chronic renal disease, adverse reactions to drugs characterized by renal impairment, a serum creatinine \> 1.5 mg/dL, or presence of 1+ protein in urinalysis at screening and a calculated creatinine clearance of not less than 80 mL/min. * current diagnosis or past history of eczema. * subjects with a household member or intimate contact with the same conditions listed above. * presence of acute, chronic, or exfoliative skin conditions, open wounds, or burns. * history of keloid formation. * known allergies to MVA or to any known components (Neomycin, Gentamycin) of the vaccine. * known allergy to eggs or egg products. * known allergies to any component of the Dryvax® vaccine. Antibiotics in Dryvax® include neomycin, streptomycin, chlortetracycline, and polymixin B. * known allergies to any known component of the Dryvax® diluent (i.e., glycerin and phenol). * known allergies to any known component of VIG, (i.e., thimerosal or previous allergic reaction to immunoglobulins). * known allergies to cidofovir or sulphur containing drugs, including probenecid, trimethoprim, and sulfonamide antibiotics. * transfusion of blood or treatment with any blood product, including intramuscular or intravenous serum globulin within 6 months of the screening visit. * positive serology result for HIV, hepatitis B surface antigen, or hepatitis C. * current diagnosis or history within six months of the screening visit of drug or alcohol abuse disorders. * significant acute or chronic psychiatric illness. * female subjects with a positive serum pregnancy test result * subjects with a household member or direct contact with someone who is pregnant or lactating. * temperature or acute illness within 3 days prior to vaccination * inoculation with an inactivated vaccine with 14 days of Day 0 or with a live attenuated vaccine within 30 days of Day 0. * subjects who have participated in another investigational drug or vaccine trial within 30 days of Day 0. * subjects who are planning on donating blood or organs within 30 days of vaccination.