Characterization of Monoclonal Antibodies to the 26-kDa Glutathione S-transferase of Schistosoma japonicum

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Abstract
Six monoclonal antibodies (MAbs) were raised in mice against the 26-kDa glutathione S-transferase (GST) of the parasite Schistosoma japonicum. These MAbs were originally selected for their specific binding to the recombinant GST (r-GST) generated in E. coli by an enzyme-linked immunosorbent assay. A further study demonstrated that all these MAbs bound to plate-coated GST affinity-purified from the parasite Schistosoma japonicum. However, in Western blotting analysis only a single monoclonal antibody (MAb Y3D7) yielded positive binding. The binding of MAb Y3D7 on Western blotting was further characterized; specific binding was found on other GST fusion proteins and on the authentic 26-kDa GST but not the 28-kDa GST in the total soluble worm proteins from Schistosoma japonicum. Using protein—A-mediated immunoprecipitation, MAbs Y3D7 and Y5D5 precipitated r-GST while in parallel experiments the remaining MAbs did not generate r-GST precipitation. In an alternative co-precipitation experiment, r-GST was first bound to glutathione (GSH) Sepharose beads and subsequently tested for interaction with the MAbs. In this manner, all MAbs except MAb Y5D5 were co-precipitated with the complexes. Thus, these select MAbs readily reacted with GST although their binding characteristics were different. Because GST has been widely used in the generation of fusion proteins for various purposes and is a potential vaccine candidate in controlling schistosomiasis, these MAbs should prove valuable for their application to molecular biology and parasitology.