Muscle-specific expression of hepatitis B surface antigen: No effect on DNA-raised immune responses

The injection of plasmid DNA encoding hepatitis B virus (HBV) envelope prot eins in mouse muscle leads to the induction of specific humoral and cellula r immune responses. Most studies on DNA-based immunization have used viral promoters to drive antigen expression. In this study, we compared the effic iency of a muscle-specific promoter, the human desmin gene promoter, with t he commonly used cytomegalovirus (CMV) early gene promoter. We showed that increased in vitro expression of HBV envelope proteins from the human desmi n gene promoter has no effect on the in vivo immune response even after the injection of as little as 10 mu g of DNA. The injection of vectors encodin g HBV envelope proteins under the control of either the human desmin gene p romoter or the CMV promoter induced humoral and cytotoxic immune responses at comparable levels and of the same duration. The recruitment of antigen-p resenting cells to the DNA injection site by pretreatment of muscle with a necrotizing agent increases the precocity and the intensity of the response s, particularly when the nonspecific CMV vector was used. (C) 1999 Academic Press.