Growth kinetics of WT and mutant recombinant viruses and characterization of V179F mutant viruses. (a) RD cells were inoculated with WT, V179F and double mutant viruses (moi of 5) for 1 h. Samples were harvested at the indicated times post-infection and the viral titres were determined by plaque-forming assays. (b and c) Interaction of recombinant viruses with PR66. Recombinant viruses were incubated with 30 μM PR66 or vehicle (DMSO) control for 1 h at 4°C. Unbound PR66 was then removed using Microsep centrifugal filters and the resultant viruses in the sample reservoir were harvested for plaque-forming assays: +, with PR66; −, without PR66; D, double mutant. (b) Titres of PR66-treated groups were normalized to those of the vehicle-treated controls, set arbitrarily to 1. Data are presented as the mean ± SD (n = 3). NS, not significant. (c) Original data of (b) are shown without normalization. (d and e) PaSTRy assays using 5 μg aliquots of purified WT (d) or V179 viruses (e) were incubated with SYTO9 dye to detect the accessibility of viral RNA; 500 nM PR66 or PR79 was used in these assays. This is a representative result from three independent and reproducible experiments. This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.