The full-length CsTegu20.6 gene sequence was isolated from an EST library of adult worms using polymerase chain reaction (PCR). C1000 TouchTM Thermal Cycler (Bio-Rad Laboratories Inc., Hercules, CA, USA) and TaKaRa LA Taq polymerase (TAKARA, RR042, Shiga, Japan) were used in the PCR reaction. The forward and reverse primers for CsTegu20.6 were 5′-GGG CAA GGT ACC ATG GAG CCA TTC TTA GAA G-3′ and 5′-CCC GTT AAG CTT TCA GCT TGG TGT CTT CCA C-3', incorporating Kpn I and Hind III restriction sites (underlined), respectively. Cycling conditions were as follows: 95 °C for 30 s, followed by 30 cycles of 94 °C for 30 s, 58 °C for 30 s, 72 °C for 60 s and, finally, 72 °C for 10 min. The amplified PCR products were purified, digested with Kpn I and Hind III endonucleases, run on a 1% agarose gel, excised from the gel and ligated into the bacterial expression vector pRSETb (Invitrogen, Carlsbad, CA, USA). After antibiotic selection, positive clones were confirmed by nucleotide sequencing (Macrogen, Seoul, Korea) and transformed into Escherichia coli BL21 (DE3) pLysS (Invitrogen).