[Innovation of vaccine adjuvants]

The enhancement of immune responses to vaccine antigen by adjuvants is critical for prevention of infectious disease. Here, we summarized the current status of adjuvant development and adjuvant categories like mineral salts, oil emulsion, and microorganism-derived adjuvants. Our resent study suggested that Ag85B of mycobacteria, which cross-reacts among mycobacteria species, elicits helper T-cell type 1 (Th1) immune responses as a novel adjuvant. These responses were enhanced in mice sensitized by BCG before vaccination. Since most humans have been sensitized by spontaneous infections or by vaccination with mycobacteria, these findings indicate that Ag85B is a promising adjuvant for enhancing Th1 immune responses of vaccine candidates. The study on the mechanisms of adjuvanticity will improve the development of novel vaccine adjuvants for human use.