Schistosomiasis causes liver and intestinal damage and can be very debilitating.The pairing of a male worm with a female worm residing in the gynaecophoral canal of male plays a critical role in the development of female parasite.Because the male specific gynaecophoral canal protein of Schistosoma japonicum (SjGCP) is found in significant quantities in the adult female worm after pairing,it could play an important role in parasite pairing.In the present study,small interfering (si)RNA duplexes with and without 2-O-Methyal modification targeting the SjGCP gene were designed,synthesized and the silencing effects were evaluated in vitro as well as in mice infected with S.japonicum in vivo.In vitro studies using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time RT-PCR revealed the reduction of SjGCP at the transcript level.Similarly,western blotting and immunofluorescence studies showed its reduction at the protein level after treatment of parasites with siRNAs.