Identification of T cell epitopes on hepatitis B surface antigen

The antigenic sites for human T lymphocytes on hepatitis B surface antigen (HBsAg) have been studied using synthetic peptides. The results indicate that aminoacid residues 24-28 of HBsAg (located near the amino terminus of the HBsAg molecule) constitute an immunodominant "helper" determinant, whereas residues 17-18 and/or 34-36 represent a major "suppressor" epitope. However, non responsiveness to currently used hepatitis B virus (HBV) vaccines (employing the whole HBsAg molecule) does not depend, in the vast majority of cases, on suppressor T cells. In vivo experiments with synthetic peptide vaccines are needed to verify the possibility of enhancing the production of protective antibodies against the hepatitis B virus.