Identification and immunogenic evaluation of T cell epitopes based on tembusu virus envelope protein in ducks

Newly emerging tembusu virus (TMUV) is a severe threat to poultry industry and causes huge economic losses. Humoral and cell-mediated immunity are both play vital roles in TMUV infection. Up to now, there has been no report on identification of T cell epitopes of the TMUV. In this work, we identified T cell epitopes within TMUV envelope (E) protein using synthesized peptides predicted in silico. A total of ten peptides could stimulate TMUV-specific T cells in murine ELISPOT and duck lymphocyte proliferation assay. Subsequently, DNA vaccine containing these T cell epitopes was constructed (pVAX-T) and the expression of multiepitope protein was confirmed by transfection of BHK-21 cells in vitro. Ducks were administrated intramusclarly to evaluated the immunologic effect of pVAX-T. In ducks immunized with pVAX-T, antibody against TMUV was undetectable, but the expression level of cytokines (IL-2, IL-6, IFN-γ) was upregulated both in peripheral blood lymphocytes and spleen. Furthermore, TMUV challenge revealed that cell-mediated immune response sitmulated by pVAX-T contributed to protection against TMUV infection. The identification of these T cell epitopes will contribute to designing epitope vaccine for preventing infection of TMUV and possibly provide the basis for further studies on cell-mediate immune response activated by TMUV.