CpG DNA是含有非甲基化CpG基序的寡脱氧核苷酸，通过Toll样受体9（TLR9）激活树突状细胞（DC）和B细胞产生免疫应答。 CpG DNA可以促进专职抗原呈递细胞有效地呈递抗原，从而增强疫苗的特异性免疫应答。目前使用CpG DNA佐剂的疫苗免疫后能维持长期免疫，具有明显的全身和黏膜免疫效果。临床前和临床试验表明，CpG DNA佐剂安全有效，能够提高传染病和肿瘤疫苗的效能，增强疫苗的免疫原性。

CpG DNA containing unmethylated CpG motifs directly activates human plasmacytoid dendritic cells and B cells to induce immune response via TLR9. CpG DNA
can improve function of professional antigen-presenting cells and boost vaccine-specific immune responses. Immunization with vaccine and CpG DNA maintains persistent immunity, and has systemic and mucosal immune effects significantly. Preclinical and clinical trials demonstrate that CpG DNAs are safe and effective as vaccine adjuvants and can boost the efficacy and immunogenicity of vaccines targeting infectious diseases and cancer.