[Immune response induced by combinant immunization of different HBsAg vaccines in mice]

To investigate the specific humoral and cellular immune response induced by prime-boost immunization of HBsAg protein vaccine (P), recombinant vaccinia virus vaccine (V) and DNA vaccine (D) in mice.

Groups of BALB/c mice were primed by one of the three vaccines P, V or D and boosted by another vaccine at 2, 5, 8 and 11 week later, thus 9 immune combinations were made: PP, PV, PD, VP, VV, VD, DP, DV and DD. Serum samples were collected at week 2, 5, 8 and 11 and levels of anti-HBsAg IgG antibodies and their sub-isotypes were determined. Seven days after every boost, spleen cells of vaccinated mice were separated and the specific CTL lysis ratio of P815S cells were determined.

Among the three HBsAg vaccines P, V and D, V could induce the quickest humoral immune response. The memory humoral immune response induced by P was the strongest. D induced the weakest antibody titer. The ratio of specific IgG1/IgG2a indicated that antibody induced by PP was more polarized to Th2. The other groups induced balanced Th1/Th2 immune response. Among all the groups, VD and DV induced the strongest CTL response, and the specific lysis ratio of P815S cells was 71% and 64%, respectively.

The experimental results suggested that among all the immune combinations, PV, PD, VP and VD can induce better humoral immune response while DV and VD can induce stronger CTL response in BALB/c mice.