CpG oligodeoxyribonucleotide with hepatitis B surface antigen (HBsAg) for vaccination in BALB/c and HBVª²transgenic mice

    Sun Yuª²Hong, Zhu Chaoª²Min, Yieª²Yao

    1Department of Infectious Diseases, General Hospital of Midª²China Oil Field,Puyang 457001, China, 2Department of Gastroenterology, Affiliated Children¬ðs Hospital, Chongqing University of Medical Sciences, Chongqing 400016, China, 3Department of Infectious Diseases, Beijingditan Hospital, Beijing 100010, China

    ¡¾Abstract¡¿AIM£º To study the effects of CpG oligodeoxyribonucleotide (ODN) as adjuvant on the immune responses in BALB/c and HBV-transgenic mice with hepatitis B surface antigen (HBsAg). METHODS: BALB/c and HBV transgenic mice were immunized by multipleª²site intramuscular injection with HBsAg and phosphorothioate oligodeoxynucleotides containing two CpG motifs. The HBsAg and antiª²HBs in serum from immunized mice were detected by ELISA and the number of IFNª²secreting T cells was examined by ELISPOT. RESULTS: In BALB/c mice, the mice immunized with CpG ODN plus HBsAg showed higher specific humoral immune responses to HBsAg than those immunized with HBsAg alone. Compared with the immunization with HBsAg or CpG ODN alone, the immunization with HBsAg plus CpG ODN activated respectively 3 or 9 times more HBs-specific IFNª²secreting T cells. In HBV transgenic mice, antiª²HBs in serum were detected in the mice immunized with HBsAg and CpG ODN while no antiª²HBs in serum in the mice immunized with HBsAg or CpG ODN alone. There was no significant difference in the level of HBsAg in serum between the three groups after vaccination (P>0.05) but the level declined in all three groups compared with those prevaccination (P<0.05). Compared with the immunization with HBsAg or CpG ODN alone, the immunization with HBsAg plus CpG ODN activated, respectively, 3 or 11 times more HBsª²specific IFNª²secreting T cells. CONCLUSION: CpG ODN can act as adjuvant to enhance the humoral and cell immune responses in BALB/c mice immunized with HBsAg. CpG ODN oligodeoxyribonucleotide combined with HBsAg can break the tolerance to this antigen in HBV transgenic mice and may become a potential prophylactic and therapeutic approach. ......