A 15mer peptide (2F10 peptide) is capable of mimicking the group specific "a" determinant of human hepatitis B surface antigen (HBsAg), both at the B and T cell level. This peptide represents a sequence on the heavy-chain hypervariable region of a monoclonal "internal image" anti-idiotype (anti-id) 2F10 that has partial sequence homology to the "a" determinant epitope of HBsAg. In order to potentiate the immunological properties of 2F10 peptide, a synthetic polymer of the 2F10 peptide was constructed (2F10 MAP). In this study we present the immunological evaluation of three generations of anti-idiotype vaccines, namely the 2F10 anti-id, 2F10 peptide and 2F10 MAP. Our results indicate that there is significant anti-HBs production in mice immunized with 2F10 anti-id or 2F10 MAP, in comparison to mice immunized with the linear monomeric 2F10 peptide. In priming experiments we found that only 2F10 antibody or 2F10 MAP (both at a suboptimal dose), could effectively prime B cells in vivo which could be efficiently recalled by challenge with a suboptimal dose of HBsAg. Collectively our findings indicate that 2F10 MAP retains all the immunological properties of the intact anti-id, and is qualitatively similar and quantitatively superior to the linear monomeric 15mer 2F10 peptide. The 2F10 MAP is the smallest MAP structure composed of a naturally occurring contiguous sequence having both a B and T cell epitope capable of eliciting a response to the native antigen.