A preliminary examination of the major integral membrane protein antigens of Schistosoma japonicum and Schistosoma mansoni adult worms for glycosyl-phosphatidylinositol membrane anchors.

Integral membrane protein (IMP) antigens isolated from S. japonicum and S. mansoni adult worms using Triton X-114 phase partitioning were treated with phosphatidylinositol-specific phospholipase C (piPLC). Following piPLC treatment, only one IMP antigen of 58 kDa from each species was released from the hydrophobic fraction and remained soluble in the absence of detergent. An additional 23 kDa antigen was identified following piPLC treatment of S. japonicum IMP's. This molecule has been previously characterized as an important species specific immunodiagnostic antigen. Alkaline phosphatase activity was observed in both the detergent and aqueous phases following treatment with piPLC but only in the hydrophobic fraction of the controls. These data suggest that only a small number of IMP antigens from both S. japonicum and S. mansoni adult worms possess glycosyl-phosphatidylinositol (GPI) lipid membrane anchors in a form which can be hydrolysed by a heterologous piPLC.