Improved recombinant LC16m0 or LC16m8 vaccinia virus successfully expressing hepatitis B surface antigen

An attempt was made to develop a safe, efficacious live recombinant vaccine using low neurovirulent strains of vaccinia virus: LC16m0 (m0) or LC16m8 (m8). Recombinant vaccinia virus (RVV) was constructed by inserting the hepatitis B surface antigen (HBsAg) gene fused to a 7.5 kDa protein promoter (7.5 kDa promoter) within the vaccinia virus thymidine kinase (TK) gene using the m0 or m8 strain as vectors. These RVVs expressed significant amounts of HBsAg (1.1 microgram/2 X 10(5) cells) consisting of 24.5 and 28 kDa (glycosylated) proteins. HBsAg produced by RVV (vaccinia HBsAg) had physical properties very similar to plasma-derived HBsAg. Considering the safety of RVVs from m0 or m8 that have been constructed with HBsAg without the addition of a promoter and the high induction of anti-HBs antibody with RVV from m0 strain in rabbits, the RVVs constructed in the present study are likely to form the basis of a safe live RVV vaccine for hepatitis B virus (HBV).