Novel epitopes identified from Tembusu virus NS3 protein induce cytotoxic T lymphocyte response

Since 2010, Tembusu virus (TMUV) has spread widely in China, causing huge economic losses to the poultry industry. Due to the infectious and zoonotic nature of flaviviruses, their potential threat to public health is of great concern. Cellular immune responses usually play a critical role in combating viral infections. To study the molecular basis of cell immunity induced by TMUV, 14 cytotoxic T lymphocyte (CTL) epitope peptides of TMUV antigen E, NS1 and NS3 were predicted by bioinformatics tools. Their abilities to induce cellular immune responses were determined by IFN-γ ELISpot assay, and 4 peptides were found to exhibit highly significant responses upon stimulation. In addition, the cytotoxic activity induced by the epitope peptides was assessed by lactate dehydrogenase (LDH) release assay. Finally, among these peptides, we identified two murine TMUV NS3-derived H-2d-restricted CTL epitopes in BALB/c mice, which could be used to further study of epitope vaccines against TMUV infection.