An Open-Label, Randomized Phase I Study in Healthy Adults of the Safety and Immunogenicity of Prime-Boost Intervals With Monovalent Influenza Subunit Virion (H5N1) Vaccine, A/Indonesia/05/2005 (Sanofi Pasteur, Inc.) Administered Alone or Following Re...

Background: \- New vaccines against avian influenza, also known as "bird flu," are being developed and require testing to determine if they are safe and effective and whether they have any side effects. Researchers are interested in testing two experimental avian influenza vaccines to see whether they are safe, if there are any side effects from the vaccines, and how the body's immune response differs in response to different vaccination schedules. One vaccine is an inactivated vaccine (made with killed or weakened influenza) and one is a DNA vaccine that allows the body to use vaccine to make an immune system response to a specific part of an avian influenza protein. Objectives: * To determine the safety and potential side effects of two experimental vaccines against avian influenza. * To evaluate whether the time between the two experimental vaccine injections affects the immune response to the vaccine. Eligibility: \- Healthy individuals between 18 and 60 years of age. Design: * Participants will be randomly divided (by chance) into six groups to receive two injections of vaccine at different intervals. One group will receive only the inactivated vaccine, while the other groups will receive the DNA vaccine followed by the inactivated vaccine at different intervals (e.g., 4 weeks, 8 weeks, 12 weeks, 16 weeks or 24 weeks later). * Participants will remain at the clinical center for at least 30 minutes after each vaccination. A few days after each injection, participants will contact staff by telephone or have a clinic visit. Participants will also be asked to complete a diary card at home for 5 days to keep track of temperature changes, injection site skin changes, and other effects. * Four weeks after the first injection, participants will return for a clinic visit and to provide blood samples for testing. * Two weeks after the second injection, participants will return for a clinic visit and provide blood samples (collected through apheresis) to provide in