Figure 2.

Inhibitory effects on the virus lifecycle of Rg1 in Marc-145 cells. In the Pre-treatment assay, Marc-145 cells were pretreated with DMEM supplemented with 10 or 50 μM Rg1 for 2 h, then cells were washed twice with PBS before being infected with type 2 PRRSV XH-GD (0.1 MOI), and then samples were collected at 48 h.p.i. For the attachment and internalization assay, Marc-145 cells were pre-cultivated at 4 °C for 1 h and then infected with virus (0.1 MOI) at 4 °C for 2 h. During virus attachment upon PRRSV infection, cells were cultured with DMEM or DMEM containing 10 or 50 μM Rg1 to analyze PRRSV Nsp9 mRNA level. Marc-145 cells were infected with XH-GD at 4 °C for 2 h and then cultured with or without Rg1 for 3 h at 37 °C. To avoid interference of other steps of viral lifecycle on replication assay, Marc-145 cells were infected with XH-GD for 6 h and then incubated with DMEM with or without 10 or 50 μM Rg1 at 37 °C, and samples were collected at 4 h.p.i. In all of the trials, GAPDH was used as a housekeeping gene for normalization, and cells treated with 0.4% DMSO was used as a reference control. (A) The effect of Rg1 on viral attachment, internalization, replication, and Rg1 pretreatment was analyzed by evaluating Nsp9 mRNA expression levels. (B) The effect of Rg1 on PRRSV release was detected by the ratio of Nsp9 RNA copy numbers in the supernatant and the cell lysate detected by qPCR. The analysis above was performed in triplicate. Statistical significance is denoted by * p < 0.05, ** p < 0.01, and *** p < 0.001.