A Follow-On Study With an H5 Influenza Vaccine for Subjects Who Participated in Study FLU-001

DNA vaccines consist of small pieces of DNA also known as plasmids, and have several potential advantages over traditional vaccines. Thus far, DNA vaccines appear to be well tolerated in humans. The investigators have developed a DNA vaccine, INO-3401, which includes plasmids targeting the proteins of the H5N1 avian influenza virus. The vaccine will be delivered via electroporation (EP) which uses the CELLECTRA constant current device to deliver a small electric charge following injection, since animal studies have shown that this delivery method increases the immune response to vaccine. The vaccine will be given to up 30 healthy adult subjects who have participated in study FLU-001. It is hypothesized that a booster dose with INO-3401 + EP will be well tolerated and immunogenic.