<qa>  What is the standard dose of Dryvax in healthy adults?1. Compare the safety and tolerability of three dose levels of ACAM1000 and a standard dose of Dryvax in healthy adults 18-29 years of age and naïve to smallpox vaccine. Safety and tolerability will be determined by examination of the local cutaneous reaction, adverse events, physical examinations, vital signs, structured interviews, and laboratory analysis. 