[Effect of IgG3 antibody purified from sera of Microtus fortis against Schistosoma japonicum].

IgG3 antibody reaction to soluble antigens prepared from schistosomula (SSA), adult worms (SAWA) and eggs (SEA) in laboratory-bred Microtus fortis (Mf), BALB/c mice and Kunming (Km) mice challenged by cercariae of Schistosoma japonicum was detected by indirect ELISA. The effect of purified IgG3 antibody on in vitro killing schistosomula and protecting mice from infection of S. japonicum was evaluated. The IgG3 antibody level in Mf against SSA and SAWA increased significantly by 79.6 percent and 49.6 percent after the fourth week of challenge infection, but no significant increase in BALB/c mice. Purified IgG3 antibody from laboratory-bred Mf and wild Mf effectively killed schistosomula, and that of the wild Mf induced higher worm-reduction rate. The death rate of schistosomula due to IgG3 antibody purified from sera of laboratory-bred Mf and wild Mf was 2.35 and 5.88 times as high as that of Km mice respectively. The results suggest that IgG3 antibody from Microtus fortis may play an important role in immunity against S. japonicum.