Characterization of the T- and B-cell immune response to a new recombinantpre-S1, pre-S2 and SHBs antigen containing hepatitis B vaccine (Hepagene (TM)); evidence for superior anti-SHBs antibody induction in responder mice

Hepagene(TM) is a novel recombinant particle consisting of the pre-Si, pre- S2 and small surface (SHBs) antigens (Ag) of the hepatitis B virus (HBV) an d is adjuvanted with alhydrogel in the final formulation, It has been prima rily developed to enhance anti-SHBs antibody titres in inadequate responder s, to conventional SHBsAg vaccines, Since non-compliance is also a problem with existing HBV vaccine schedules, the ability to accelerate current immu nization regimens to provide more rapid protection has also been an importa nt objective. Here we describe the T- and B-cell responses to Hepagene(TM) in two strains of responder mouse (BALB/c and SWR/J). Hepagene(TM) induced high in vitro spleen T-cell proliferative responses in both strains (max. Stimulation Index = 43), following intraperitoneal immu nization, High concentrations of interferon-gamma (max. = 5000 pg/mL) were detected in the media of spleen cells cultured with non-adjuvanted Hepagene (TM) particles. SWR/J mice showed the highest serum antibody (Ab) titres to non-adjuvanted Hepagene(TM), The presence of alhydrogel adjuvant in the va ccine formulation significantly improved the titres, Anti-pre-Si Ab was det ected in both strains of mouse but anti-pre-S2 Ab was only detected in the SWR/J strain, In BALB/c mice, the anti-Hepagene(TM) (non-adjuvanted) IgG1 A b subclass was predominant but in SWR/J mice IgG1, IgG2a and IgG2b subclass es were of a similar magnitude. In BALB/c mice, Hepagene(TM) induced higher anti-SHBs Ab responses than Engerix-B(R) (11097 IU/mL and 1276 IU/mL, resp ectively), following two doses of vaccine (10 mu g/mouse), The vaccine ther efore, induces strong cellular and humoral immune responses and these data suggest that Hepagene(TM) is an improved hepatitis B vaccine.