Fig. 1

Schematic of immune response to the vaccine. Antigens are delivered to and bind with naïve dendritic cells to form mature antigen-presenting cells. Then the processed antigens bind with T-cell receptors on naïve CD4⁺ cells or naïve CD8⁺ cells, respectively. The stimulated T cells secrete cytokines to drive Th1 or Th2 immune response, leading to humoral or cellular immunity. In addition, activated dendritic cells can act directly on CD8⁺ T cells to license them to become CTLs. Adjuvants, mainly immunostimulants, interact with PRRs that induce the production of cytokines and chemokines, facilitating the generation of T helper cell response. CTL, cytotoxic T-lymphocyte