ASN2 inhibits viral RNA synthesis.

<p>(A) Influenza A virus mini-genome activity in A549 cells transfected with the influenza virus firefly luciferase mini-genome reporter, pRL-TK control reporter, PB1, PB2, PA, and NP protein expressing plasmids. Treatment with DMSO or increasing concentrations of ASN2 (6.25–50 µM) was performed during transfection. Luciferase activity was assayed 24 hours post transfection. Firefly and Renilla luciferase values are represented as % activity from the mock (minigenome without NP expression) relative to the DMSO control. Error bars reflect the standard deviation of % activity. (B) Primer extension analysis of influenza virus mRNA and vRNA from A549 cells infected with influenza A/WSN/33 virus (MOI = 5) and treated with DMSO or decreasing concentrations of ASN2 (50–12.5 µM) for 6 hours. PB2, NA, and NS segments were analyzed. Ribavirin (100 µM) was used as a positive control and 5S rRNA was used as a loading control. Quantification of mRNA and vRNA expression, normalized to 5S rRNA, is shown on the right.