Induction of CTL responses and identification of a novel epitope of hepatitis B virus surface antigens in C57BL/6 mice immunized with recombinant vaccinia viruses

MHC class I-restricted cytotoxic T lymphocyte (CTL) response to hepatitis B virus (HBV) surface antigens (HBsAS) has been suggested to play essential roles in viral clearance and pathogenesis of HBV-induced hepatitis. In the present study, we analyzed CTL responses to endogenously synthesized or exo genously introduced HBsAg in C57BL/6 mice (H-2(b)). We show that the endoge nously synthesized surface antigens of adr-type HBV encoded by recombinant vaccinia virus efficiently elicit CTL responses in C57BL/6 mice previously defined as non-responders to vaccinia-HBV immunization. We also show that t wo peptides, S179-186 (FVQWFVGL) and S208-216 (ILSPFLPLL), serve as effecti ve motifs for CTL response in H-2(b) system after in vitro restimulation of the primed T cells with either of the two synthetic peptides. S208-215 has recently been identified as a CTL epitope which could be produced by exoge nous pathway only, in contrast to the current result, while S179-186 appear ed a novel epitope for CTL response. In addition, we show that soluble HBsA g also elicits CTL responses in H-2(b) mice upon in vitro restimulation wit h the two peptides, although less efficiently compared with the recombinant vaccinia viruses. These findings may provide an efficient experimental sys tem for studying H-2(b)-restricted immune responses against endogenously sy nthesized and exogenously introduced HBsAg. (C) 2001 Elsevier Science B.V. All rights reserved.