Molecular insights into a tetraspanin in the hydatid tapeworm Echinococcus granulosus

Abstract

BACKGROUND: Cystic echinococcosis (hydatid disease), caused by the tapeworm Echinococcus granulosus (class Cestoda; family Taeniidae), is a neglected tropical disease that results in morbidity and mortality in millions of humans, as well as in huge economic losses in the livestock industry globally. Proteins from the tetraspanin family in parasites have recently become regarded as crucial molecules in interaction with hosts in parasitism and are therefore suitable for the development of vaccines and diagnostic agents. However, no information is available to date on E. granulosus tetraspanin. METHODS: In this study, a uroplakin-I-like tetraspanin (Eg-TSP1) of E. granulosus was cloned and expressed in E. coli. The immunolocalization of Eg-TSP1 in different life stages of E. granulosus was determined using specific polyclonal antibody. The antibody and cytokine profiles of mice that immunized with recombinant Eg-TSP1 (rEg-TSP1) were measured for the immunogenicity analysis of this protein. Additionally, we use RNA interference method to explore the biological function of Eg-TSP1 in larva of E. granulosus. RESULTS: Immunofluorescence analysis showed that endogenous Eg-TSP1 mainly localized in the tegument of larvae and adults. Significantly elevated levels of antibodies IgG1 and IgG2a and of cytokines IFN-γ and IL-12 were observed in the sera of mice after immunization with rEg-TSP1, suggesting a typical T helper (Th)1-mediated immune response elicited by rEg-TSP1. On further probing the role of Eg-TSP1 in E. granulosus by RNA interference, we found that a thinner tegmental distal cytoplasm was induced in protoscoleces treated with siRNA-132 compared to controls. CONCLUSIONS: This is the first report characterizing a tetraspanin from the tapeworm E. granulosus. Our results suggest that Eg-TSP1 is associated with biogenesis of the tegument and maintenance of structural integrity of E. granulosus and could therefore be a candidate intervention target for control of hydatid disease.