[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.

[Development of immunoblot kit for the detection of anti-Toxoplasma antibodies].

OBJECTIVE: To develop a diagnostic kit for the detection of anti-Toxoplasma antibodies in human sera by immunoblot technique. METHODS: The cytoplasm proteins of Toxoplasma gondii were extracted from collected ascites in Kunming strain mice infected by tachyzoites of Toxoplasma gondii (RH strain). Toxoplasma gondii soluble antigens were separated by SDS-PAGE electrophoresis and transferred to pyroxylin membrane. Using nonpoisonous tetramethylbenzidine (TMB) as horseradish peroxidase substrate for immunoblot, the optimal experimental conditions were selected through comparison of antigen preparation, reagents for blocking or washing, dilution concentration, reaction time, and frequencies of reacting band. Sensitivity, specificity, Youden index and stability were evaluated as the standard for the kit. RESULTS: In 30 sera with anti-Toxoplasma [gM antibodies and 28 with IgG antibodies, the sensitivity for IgM and IgG antibody detection was 90.0% (27/30) and 85.7% (24/28) respectively, the specificity was all 100% in examining 40 healthy control sera, and the Youden index was 0.9 and 0.86 respectively. The kit was stable at 49 degrees C for 6 months. CONCLUSION: The immunoblot kit shows an easy operation, fast reaction and reliable result, and may be practical.

[A rapid procedure to purify serum IgG from Microtus fotis].

OBJECTIVE: To evaluate the procedure to purify IgG antibodies from Microtus fotis serum. METHODS: IgG antibodies from sera of three groups of Microtus fotis were purified by protein G or protein A affinity chromatography, their purity and binding capacity were compared. RESULTS: The protein G affinity chromatography was more efficient than protein A affinity chromatography. The antibodies isolated from protein G affinity chromatography showed a higher purity and better activity than that from protein A affinity chromatography monitored by SDS-PAGE and ELISA. The ability of the purified IgG to bind the second antibodies were 8.5 times and 3.1 times that of non-IgG proteins and unpurified sera, respectively. CONCLUSION: The protein G affinity chromatography is a rapid, convenient and reliable procedure for Microtus fotis serum IgG purification.