FIG 2.

6-TG and 6-TGo inhibit IAV replication. (A) A549 cells were mock infected or infected with IAV-PR8 at an MOI of 0.1. After 1 h, cell monolayers were washed and overlaid with medium containing drugs at the indicated concentrations or the vehicle control. At 24 hpi, cell supernatants were collected, and infectious virions were enumerated by a plaque assay. Data from 3 independent experiments are graphed (n = 3), and error bars denote standard deviations. One-way ANOVA and Tukey’s post hoc multiple-comparison tests were done to determine statistical significance (**, P value of <0.01). (B) A549 cells were treated with increasing doses of 6-TG, 6-TGo, 5-FU, or the vehicle control (DMSO) for 23 h, and cell viability was measured using an alamarBlue assay. Relative fluorescence units were normalized to the value for the vehicle control. Error bars represent standard deviations (n = 3). (C) Vero cells were infected with IAV-PR8 and treated with 6-TG (10 μM) or the vehicle (DMSO). After 72 hpi, cells were fixed with 5% formaldehyde and stained with 1% crystal violet. (D) Representative phase-contrast images of A549 cell monolayers treated with silvestrol (320 nM), 6-TG (10 μM), or the vehicle (DMSO) control for 23 h. Bars, 100 μm. (E) Lysates of A549 cells treated with silvestrol (320 nM), the indicated thiopurines (10 μM), or the vehicle control (DMSO) were analyzed by Western blotting for total PARP (full length and cleaved). Actin was used as a loading control.