Antiviral effect of siRNA in vitro
Next, we investigated the antiviral effects of the four selected siRNAs (siN-3, siN-4, siR-7 and siR-11) in vitro . To evaluate their antiviral effect, we transfected Vero E6 cells with complexes of siRNA/Lipofectamine 3000 and four hours after transfection cells were infected with SARS-CoV-2 at MOI 0.0001. After 48 hours infection cells were lysed and viral RNA (vRNA) concentration was determined by qRT-PCR. We found a significant difference in vRNA concentration between cells treated with specific siR-7, compared to both unspecific siLuc-transfected and infected cells (P<0.05) (fig.2d). In addition, a significant reduction of vRNA in cells treated with siN-4 (P<0.05) compared to SARS-CoV-2 infected cells and a trend towards significance (P=0.0571) to reduce the amount of vRNA compared to unspecific siLuc-transfected cells were observed. According to these results the siR-7 targeting SARS-CoV-2 RdRp gene was chosen as best candidate for further analysis.