Intranasal administration of synthetic recombinant peptide-based vaccine protects mice from infection by Schistosoma mansoni

Schistosomiasis is the cause of a chronic debilitating disease which accoun ts for significant mortality and morbidity every year, especially in tropic al and subtropical areas. An epitope derived from the protective surface pr otein 9B-Ag of Schistosoma mansoni, designated 9B peptide-1, was previously show ed to be protective in mice when conjugated to bovine serum albumin a nd administered subcutaneously in complete Freund's adjuvant. In this work, this protective peptide was expressed in the flagellin of a Salmonella vac cine strain, and the isolated recombinant flagella were used for immunizati on of mice. Since during the invasion of the parasite into the host the sch istosomula migrate first to the lungs, the intranasal route of administrati on was employed in order to halt the parasite at an early stage of the infe ction. Such intranasal immunization with this peptide expressed in flagelli n, without the addition of adjuvants, resulted in a significant humoral res ponse and also led to protection against challenge infection, manifested as a reduction of the worm burden by an average of 42%.