Identification of rGSTO2 protein of F. hepatica by SDS-PAGE and western blot. (A) Lane M, protein marker; lane 1, Sonicated supernatant of cultures after transformation of E. coli with the empty pET-28a plasmid; lane 2, lysate precipitation of rGSTO2 after induction for 6 h; lane 3-6, lysate supernatant of rGSTO2 at 2, 4, 6 and 8 hours induced by IPTG. (B) Lane M, protein marker; lane 1, purified rGSTO2 protein. (C) Lane M, protein marker; lane 1 and lane 2 were loaded with rGSTO2 protein and then incubated with sheep anti-F. hepatica sera or normal sheep serum, then incubated with HRP-conjugated rabbit anti-sheep IgG. (D) Lane M, protein marker; lane 1 and lane 2 were loaded with rGSTO2 protein and then incubated with mouse anti-rGSTO2 IgG or naïve mouse serum, respectively, and then incubated with HRP-conjugated goat anti-mouse IgG.