The purpose of this study is to collect information on the safety, tolerability and immunogenicity of an investigational smallpox vaccine at different doses and using different routes of administration in vaccinia-naive and vaccinated healthy volunteers

Inclusion Criteria:

• Healthy male subjects, aged 20 - 55 years
• Signed informed consent

Exclusion Criteria:

• Prior vaccination against smallpox (study part I only)
• Abnormalities suspicious of any underlying disease, detected at routine tests prior to study inclusion.
• Any immune modifying therapy within 4 weeks prior to entry
• Participation in any other investigating drug trial
• Known allergy to a component which may be part of the vaccine
• Allergic reaction or any other severe adverse effects experienced after previous smallpox vaccination (study Part II only)