Phase 1 safety and immune response studies of a DNA vaccine encoding hepatitis B surface antigen delivered by a gene delivery device

This study was designed to determine the safety and immunogenicity in volun teers of a DNA vaccine consisting of a plasmid encoding hepatitis B surface antigen delivered by the PowderJect XR1 gene delivery system into human sk in. Seven healthy adult volunteers received two immunizations at one of thr ee forces of delivery on day 0 and 56. The vaccine was well tolerated. One of six seronegative volunteers developed high titers of persistent HBsAb af ter a single immunization. In retrospect, this volunteer may have had previ ous exposure to hepatitis B. Our study suggests that the hepatitis B DNA va ccine given by this gene delivery system may induce a booster response, but the vaccine at the extremely low DNA dose used (0.25 mu g) did not induce primary immune responses. (C) 1999 Elsevier Science Ltd. All rights reserve d.