Figure 1.

RA inhibits EV-A71 infection. (A) Chemical structure of RA. (B–D) Anti-EV-A71 activities of RA at different time points of addition. (B) RD cells were infected with the indicated viruses at a multiplicity of infection (MOI) of 10 in the presence of RA (280 μM, converted from 100 μg/mL) treated at the various time points: prior to infection (−4 – −1 h p.i.), during virus infection (−1–0 h p.i.), and after virus entry (0–4 h p.i. and 4–8 h p.i.). DMSO (0.1%) was used as the vehicle control. Viruses and cell lysates under each condition were collected at 8 h p.i. for plaque assay analysis (C) and western blot analysis (D), respectively. The data shown are representative of two independent experiments. (D) The EV-A71 strains were BrCr, TW/50995/12, TW/2231/98, and TW/4643/98. * denotes the 3AB intermediate. (E) Attachment assay. The viruses were incubated with DMSO or RA (280 μM) at 4°C for 1 h, and then infected into RD cells at 4°C for another 1 h. The amount of attached virus was estimated by quantitative real-time RT-PCR. The data are expressed as the mean ± SD from three independent experiments and analysed by the Student’s t-tests (*P < 0.05 and **P < 0.01).