Enhancement Effect of CpG DNA on the Somatostatin DNA Vaccine in Mice

To study the immune effect of CpGDNA on somatostatin (SS) DNA vaccine, the 20-day-old experimental mice were immunized with 20 μg SS eukaryotic expression plasmid pES/2SS with different adjuvants in equal dose, such as the synthetic CpG-ODN, the pE-CpG plasmid, E. coli DNA and the crude liposome. A booster was given two weeks later. The results showed that the body weight gain of female mice in the SS immunized group was higher than that of the control (P < 0.05). The levels of antibodies against SS, IgG2a/IgG1, spleen lymphocyte proliferation activity and the concentrations of GH and IGF-1 in the DNA vaccine groups combined with CpGDNA were significantly increased compared to that of the group immunized with DNA vaccine alone. All these suggested the recombinant SS expression plasmid can stimulate animals to produce antibodies against SS, and CpGDNA adjuvant can enhance the immune effect of DNA vaccine against SS and influence the concentration of GH and IGF-I.