Screening And Characterization Of Peptides Specifically Binding To The Tegument Of Schistosoma Japonicum Hepato-portal Schistosomula

[Objectives] To screen peptides specifically binding to the tegument of Schistosoma japonicum (Sj) schistosomula for potential use as targeting vectors for Sj therapy.[Methods] A 12 phage-display peptide library was screened with the Sj schistosomula as the target cells for biopanning by degrees, positive clones picked randomly were deduced by DNA sequencing. The immunohistochemical staining and Western blot were performed to determine the specificity of the phages to the tegument in vitro. To test their targeting efficacy, the interested phage clones were infused back to the mice challenged with Sj, and assessed by titering the phage distribution in both the livers and the tegument of schistosomula, respectively.[Results] After 3 rounds of biopanning, the phage recovery rates increased from 0.77×10-8 to 0.75×10-5, indicating that the phage library was successfully enriched in the tegument of Sj schistosomula. Seventy-five percent (15/20) of the analyzed positive phages were identical with a sequence of QSFASLTNPRVL, named as ZW-15. The immunohistochemical stainings and Western blot showed this sequence specifically binding to the tegument. Phage enrichment was examined by in vivo phage titerring. Compared with the control phage, Phage ZW-15 enrichment was significant in the tegument of schistosomula (P1<0.01), but not significant in the liver(P2>0.05), indicating the selective binding to the tegument by the peptide sequence.[Conclusion] The peptide of QSFASLTNPRVL specifically binds to the tegument of Sj schistosomula, which may have some significance for the future use as potential vectors in targeting therapy of Schistosomiasis.