Objective  To investigate the effects of the whole length of Duck Tambusu virus (DTMUV) E protein and its domains of I, II and III (DI, DII and DIII) on the cell cycle and apoptosis of duck embryo fibroblast (DEF) cells.

Method  The full-length of DTMUV E protein, DI, DII and DIII eukaryotic expression plasmids were designed and synthesized, and transfected into DEF. The changes of DEF apoptosis and cell cycle caused by different proteins were detected by flow cytometry.

Result  The results of apoptosis showed that after 24 h of plasmid transfection, the apoptosis rates of DEF induced by the full length, DI, DII and DIII were 16.4%, 15.1%, 14.0% and 17.2% respectively; after 36 h of plasmid transfection, the apoptosis rates of DEF induced by E protein full length, DI, DII and DIII were 23.4%, 18.5%, 26.7% and 29.4%. The results of cell cycle detection showed that the percentage of DNA synthesis phase (S-phase) cells transfected with E protein full length, DI, DII and DIII plasmid was obviously higher than those of cells transfected with pEGFP-N1 empty vector 24 h and 36 h later. After 24 h of plasmid transfection, the percentage of S-phase cells in E protein, DI, DII and DIII groups were 5.43%, 22.58%, 12.75% and 12.80%, respectively; After 36 h of plasmid transfection, the percentage of S-phase cells in E protein, DI, DII and DIII groups were 9.98%, 11.44%, 10.44% and 11.00%, respectively.

Conclusion  The full length of DTMUV E protein and its three domains can induce early cell apoptosis and arrest the S-phase cells, but the ability of each protein fragment to induce cell apoptosis and change the cell cycle is different.