Fig. 2.

DIG could be packaged to generate defective interfering virus and competitively inhibit normal viral replication. a Antiviral activity of DIG-3 in A549-Dual KO-RIG-I cells. The A549-Dual KO-RIG-I cells were infected with A(H7N7) virus at 24 h post transfection of empty vector or DIG-3 (0.6 μg per well). Viral titers in cell supernatants of 40 h post infection were measured by plaque assay. b–d Full-length PA, full-length PB1, full-length PB2, DI-PA, DI-PB1, and DI-PB2 RNA levels in the supernatants of A(H7N7)-infected cells transfected with empty vector or DIG-3 before viral infection. e The percentage of DIG-3-treated virus compared with empty vector-treated virus in supernatants of 293T cells. Viral titers were measured by plaque assay and HA assay. f The passaged viral titers in supernatants of MDCK cells that were infected by the supernatant virus of A(H7N7)-infected 293T cells transfected with empty vector or DIG-3. g The virus titer ratio of DIG-3-treated virus compared with empty vector-treated virus in supernatants of MDCK cells. Viral titers were measured by plaque assay and HA assay. h The DI-PA RNA levels of passaged virus in the supernatants of MDCK cells. Dotted lines indicate the detection limit of RT-qPCR. Data were presented as mean ± SD of three independent experiments. ** Indicates P < 0.01. P values were calculated by the two-tailed Student’s t test