SjTat-TPI facilitates adaptive T-cell responses and reduces hepatic pathology during Schistosoma japonicum infection in BALB/c mice

Background: Schistosomiasis is a kind of parasitic zoonoses which causes serious damage to public health and social development. China is one of the countries most affected by Schistosoma japonicum and an effective vaccine is still needed. In this study, we adopted Tat-mediated protein transduction technology to investigate the impact of different antigen presented approaches on host's immune response and the potential protection against Schistosoma japonicum infection. Results: We successfully constructed the recombinant S. japonicum triosephosphate isomerase, Tat-TPI, as a vaccine candidate. Whether injected with Tat-TPI in foot pad or vaccinated with Tat-TPI in the back subcutaneously for three times, the draining popliteal lymph nodes and spleen both developed a stronger CD8T response (Tc1) in mice. Not only that, but it also helped CD4T cells to produce more IFN-γ than TPI immunisation. In addition, it could boost IgG production, especially IgG1 subclass. Most importantly, Tat-TPI immunisation led to the significant smaller area of a single egg granuloma in the livers as compared with TPI-vaccinated or control groups. However, the anti-infection efficiency induced by Tat-TPI was still restricted. Conclusion: This study indicated that immunisation with Tat-fused TPI could contribute to enhance CD4T-cell response and decrease hepatic egg granulomatous area after S. japonicum infection though it did not achieve our expected protection against Schistosoma japonicum infection. The optimal vaccine strategy warrants further research.