EVALUATION OF B-CELL AND T-CELL RESPONSES IN CHIMPANZEES IMMUNIZED WITH HEPAGENE(R), A HEPATITIS-B VACCINE CONTAINING PRE-S1, PRE-S2 AND S-GENE-PRODUCTS

Approximately 5-10% of healthy young adults receiving the commercially available hepatitis B vaccine (either serum derived or recombinant) f ail to mount an adequate immune response. This nonresponder rate has p rompted tile demand for more immunogenic vaccines. An alternative to t he currently licensed hepatitis B vaccines is Hepagene(R), a novel rec ombinant hepatitis B vaccine containing S, pre-SI and pre-S2 antigenic components, produced in the mouse C127I clonal cell line after transf ection of the cells with genes encoding the three antigens, In this st udy, chimpanzees were immunized with Hepagene(R) to study the humoral and cellular immune responses to this vaccine, Two out of the three an imals immunized with this vaccine seroconverted 4 weeks after their fi rst injection and all of the animals elicited high anti-HBs levels tha t were maintained for at least 28-30 weeks after their third immunizat ion. The anti-HBs levels elicited in these animals protected them agai nst an experimental challenge with HBV. Peripheral blood mononuclear c ells (PBMCs) obtained front immunized animals could be stimulated in v itro by rHBsAg and peptides representing regions within all three of t ile vir-al envelope proteins, Additionally an anti-id that mimics the a determinant in the S-region of HBsAg could also stimulate in vitro p roliferation of PBMCs from these immune animals, These results indicat e that this new recombinant HBV vaccine encoding all three of the surf ace antigen proteins is highly immunogenic in that it can stimulate st rong cellular and humoral immune responses, (C) 1998 Elsevier Science Ltd, All rights reserved.