Mechanism of apoptosis is mediated by AD55-Apoptin in Huh-7 cells. Huh-7 cells infected with ZD55-EGFP or ONYX-015 or AD55 or AD55-Apoptin at the MOI of 10, respectively. After 48 hours, the cells were trypsinized and washed once with complete medium. Aliquots of cells (5 × 105) were resuspended in 500 ml of binding buffer and stained with fluorescein isothiocyanate (FITC)-labeled annexin V kit, according to the manufacturer's instructions. A fluorescence-activated cell-sorting assay was performed immediately after staining. Mean ± SD;*.p < 0.01, compared with AD55 treated group.