RECOMBINANT-DNA HEPATITIS-B VACCINE CONTAINING PRE-S COMPONENTS OF THE HBV COAT PROTEIN - A PRELIMINARY-STUDY ON IMMUNOGENICITY

A novel recombinant hepatitis B vaccine, trademarked Sci-B- Vac, was evaluated for safety, tolerability and immunogenicity in an open label trial performed in Singapore. The experimental vaccine, derived from Chinese hamster ovary (CHO) cells, consists of hepatitis B surface antigen (HBsAg) particles harbouring all three viral envelope polypeptides, the major S protein and the minor Pre-S2 and Pre-S1, in their glycosylated and non-glycosylated forms. The vaccine was administered intramuscularly at 0, 1 and 6 months. No unexpected adverse effects were observed. A high level anti-HBs response to Sci-B- Vac was indicative of its immunogenicity. Subsequent to the third injection, 100% and 92% of the 10-mu-g and 5-mu-g dose recipients, respectively, were seroprotected (anti-HBs titres greater-than-or-equal-to 10 mIU ml-1). Moreover, the geometric mean titres (GMT) of the anti-HBs response were very high.- 2687 and 1473 mIU ml-1, respectively. An immunogenic advantage of Sci-B- Vac was also suggested by the rapid onset of antibody response.- 96% of the 10-mu-g dose recipients were seroprotected with a GMT of 159 mIU ml-1, prior to the third injection.