Reactogenicity and immunogenicity of a new recombinant hepatitis B vaccine containing Pre S antigens: a preliminary report.

A new vaccine against hepatitis B virus (HBV) infection, produced in mammalian Chinese hamster ovary (CHO) cells, contains the small(s), middle (Pre S2) and large (Pre S1) surface proteins of HBV. Three injections of a 5-micrograms or 10-micrograms dose were administered intramuscularly (i.m.) at 0, 1 and 6 months to a group of 105 young adults, who were monitored for a period of 6 months after the third injection. Seroconversion rates were 100% after the second injection of the 5-micrograms or 10-micrograms dose. Geometric mean titres of HBsAb at 1 month after the third injection were 12,156 mIU ml-1 and 13,482 mIU ml-1 in those receiving the 5-micrograms and 10-micrograms dose respectively. The vaccine was well tolerated with no significant adverse events. These preliminary results suggest that the Pre S-s recombinant vaccine, produced in mammalian cells, is highly immunogenic, leading to 100% seroconversion in the population tested after injection of only two doses of 5 micrograms.