A, ~20 μg of protein extracted from uninduced (Uind) and induced (Ind) cultures of Escherichia coli containing SmTCTP expression construct were separated in a 12% SDS-PAGE. rSmTCTP was then purified from the cultures using a nickel-nitrilotriacetic acid chromatography column, and ~1 μg of the protein was separated in a 12% SDS-PAGE (rSmTCTP). B, affinity-purified rSmTCTP probed with sera collected from C57BL/6 mice on day 0 or week 2, 3, 8, or 9 after infection with S. mansoni. Purified rSmTCTP probed with a mouse anti-SmTCTP serum served as a positive control.