Objectives: To identify the properties of six monoclonal antibodies (McAbs) against recombinant signal protein 14-3-3 of Schistosoma japonicum, and investigate their value in the diagnosis of schistosomiasis.
Methods: The subclasses, titers, affinity-constants, detection limits and specificities of six McAbs were identified by ELISA and Western blotting. Dot Enzyme-linked Immunosorbent Assay (Dot-ELISA) for detecting the 14-3-3 protein in the sera of rabbits infected with Schistosoma japonicum was established, then it was used to observe the dynamics of 14-3-3 protein in sera of rabbits infected with Schistosoma japonicum before and after treatment. The diagnostic value of Dot-ELISA was investigated through detecting a group of sera samples of rabbits infected with Schistosoma japonicum.
Results: The types of six McAbs against recombinant signal protein 14-3-3 of Schistosoma japonicum of 3F1, 3F7, 5C6, 5D1, 5G9 and 1G6 were all IgG, their subclasses were IgG1, IgG2a, IgG2b, IgG1, IgG1 and IgG1, their antibody-titers in ascites were 1:6.4 x 10(5), 1:8.0 x 10(5) , 1:6.4 x 10(5), 1:3.2 x 10(5), 1:4.8 x 10(5) and 1:2.0 x 10(4), their affinity-constants were 8.82 x 10(8), 4.93 x 10(8), 1.56 x 10(8), 5.12 x 10(8), 1.41 x 10(8) moL/L and 2.30 x 10(7) mol/L, their detection limits in dot-ELISA were 1, 10, 100, 10, 10, 100 ng, respectively. All the six McAbs recognized the recombinant signal protein 14-3-3 of Schistosoma japonicum and the natural signal protein 14-3-3 in SEA, ESA and AWA, and did not react with the protein of E. coli and Clonorchis sinensis in Western blotting. 3F1 and 5D1 were selected to establish the Dot- ELISA for detecting the sera of rabbits infected with Schistosoma japonicum before and after treatment at different time points, it was found that the concentration of 14-3-3 protein in sera of rabbits was increased gradually with time and decreased gradually after the infected rabbits treated with praziquantel. Forty-two sera samples of rabbits infected with Schistosoma japonicum were detected by this Dot-ELISA, 41 samples were positive, the sensitivity was 97.6%, and all of the ten healthy rabbits' sera were negative, the specificity was 100%.
Conclusions: All the six McAbs could recognize natural signal protein 14-3-3. It has been proved preliminarily that the Dot-ELISA based on 3F1 and 5D1 is valuable for the diagnosis of active infection of Schistosoma japonicum and accessing the chemotherapeutic effect of schistosomiasis.