Sequential Administration of Nanoadjuvant and Nanoantigen Matters in Host Immunity

To explore the sequence of administrating particulate nanovaccines, we fabricate model antigen OVA and molecular adjuvant CpG into separate nanoparticles to generate nanoantigen (NP(OVA)) and nanoadjuvant (NP(CpG)). We found that administrating NP(CpG) ahead of NP(OVA) polarized immune response toward Th1. In normal mice, such administration stimulated higher frequency of antigen-specific CD8⁺ T cells and stronger memory T cells than both inverted sequence and coinjecting. In tumor-bearing mice, more effector T cells were observed in the NP(CpG) ahead group than that in other ways. This study demonstrates that the immunity could be modulated by the sequential inoculation.