CpG ODN enhances immunization effects of hepatitis B vaccine in aged mice

Oligodeoxynucleotides (ODN) containing unmethylated CpG dinucleotides in contexts of unique sequence (CpG motifs) is active as adjuvant in induction of cellular and humoral immune responses in young mice. To date, there are only limited reports about effect of CpG ODN on immune responses against hepatitis B (HB) infection in aged mice. Our studies demonstrated there were significant increases in secreting of total anti-HB IgG, IgG1 and IgG2a, as well as of IL-12 and IFN-gamma, when CpG ODNs were injected together with hepatitis B antigen in aged mice. Moreover, CpG ODN could stimulate proliferation of spleen lymphocytes in a dose-dependent manner. Taken together, the results we obtained indicate that the adding of CpG ODN into the vaccine antigen might be useful in development of more effective vaccination for inducing anti-HB virus responses in the elderly.