Murine CD8+T cell cytotoxicity against schistosomula induced by inoculation of schistosomal 22.6/26GST coupled Sepharose 4B beads

Schistosomasis is a world-wide parasitic disease. Although chemotherapy is the main treatment method for schistosomasis currently, it cannot prevent schistosome reinfection. Up to now no effective vaccine is available to prevent schistosomiasis. Dendritic cells (DCs) are one of the key players in the cellular immune response and play an important role in antigen presentation as antigen-presenting cells. Here we reported a novel large particulate antigen, in which Sepharose 4B beads were coated with Sj22.6/26GST. Our results showed that this particulate antigen could be cross-presented by DCs to CD8+T cells. Furthermore, CD8+T cells stimulated by particulate antigen directly exerted cytotoxicity against Schistosoma japonicum schistosomula. We also demonstrated that S. japonicum schistosomula acquired the MHC class I molecules from host blood serum and presented the molecules at the larval surface. While it may help them escape from the host immune surveillance, these MHC I-antigen complexes presented on the surface render schistosomula the potential targets of the CD8+T cell cytotoxicity induced by particulate antigen-based vaccine. Finally we evaluated the protective immunity of this particulate vaccine in a mouse infection challenge model. Our data clearly showed that the particulate vaccine induced a partial reduction in both worm burdens and egg loads. Taken together, these results suggest that this large particulate vaccine could be a potential vaccine for the prevention of schistosome infection.

► DCs cross-present 22.6/26GST molecule-coupled Sepharose 4B beads to CD8+T cells.
► The cross-presentation is TAP-independent.
► CD8+T cells from particulate antigen-immunized mice kill schistosomula in vitro.
► Schistosomula acquired MHC I molecular from the host and became the cytotoxic targets.
► Worm burdens decreased in particulate antigen-immunized mice after infection.