Objective To observe the synergic effect of the antibodies against surface membrance antigen of
Schistosoma japonicum
(Sj) adult worm and praziquantel(PZQ) in killing different developmental stage worms and to study the role of humoral immunity in the
schistosomicidal process of praziquantel. Methods Surface membrance antigen of Sj adult were extracted and characterized by SDS PAGE.Serum from rabbit immunized with surface membrance antigen of Sj adult was prepared. The cross reactions betwwen the immune serum and different developmental stage antigens of Sj were analyzed by Western blot. The groups of experimental mice were treated with PZQ plus immune serum injection at 2 d, 14 d and 35 d after infection, respectively. All mice were sacrificed 49 d after infection. Worm burden and liver eggs per gram (LEPG) were counted. Results Worm burden and egg burden of the experimental mice treated at 2 d, 14 d and 35 d by combining usage of immune serum and PZQ were dramatically reduced, compared with those only treated by praziquantel. The immune serum increased the schistosomicidal activity of PZQ against different developmental stage worms (2 d,14 d and 35 d) by 38.79%, 29.80% and 46.82%, respectively .Correspondingly, egg burden in liver decreased in each group by 62.04%, 42.78% and 29.81%. Conclusion Immune serum against surface membrance antigen of Sj adult combined with praziquantel can improve the schistosomicidal effect. That indicated that the humoral immunity play a key role in the schistosomicidal process of PZQ.