Cutting edge: DNA immunization with minigenes of carbohydrate mimotopes induce functional anti-carbohydrate antibody response.

To date, the generation of anti-carbohydrate Th1 immune responses, which would be useful for both tumor immunotherapy as well as in pathogen vaccine strategies, has been elusive. To augment Th1 immune responses to carbohydrate Ags, we describe results of DNA vaccination studies in mice using plasmids encoding designed peptide mimotopes (minigenes) of the neolactoseries Ag Lewis Y (LeY). In contrast to LeY immunization, immunization with mimotope-encoded plasmids induced LeY cross-reactive IgG2a Abs. Minigene immunization primed for a LeY-specific response that is rapidly activated upon encounter with nominal Ag upon subsequent boost. The resulting IgG2a response mediated complement-dependent cytotoxicity of a LeY-expressing human tumor cell line in the presence of human complement. These studies establish that peptide mimotopes of carbohydrate Ags encoded as DNA plasmids are novel immunogens providing a means to manipulate carbohydrate cross-reactive Th1 responses.