FIG 3.

Drug resistance profiles of plaque-purified VACV-WR (A), CPXV-BR (B), and CML1 (C) KAY-2-41^r clones and of viruses with thymidine kinase deletions (D). (A to C) Three clones of each WT and drug-resistant virus were used for plaque reduction assays, and at least three to four independent experiments were performed for each compound tested. The data are presented as a dot plot of the EC₅₀s of the KAY-2-41^r clones (filled symbols) versus the EC₅₀s of the WT parent clones (empty symbols). On top of each graph are shown the fold changes in EC₅₀s, which were calculated as the ratio of the mean EC₅₀s of the KAY-2-41^r clones divided by the mean EC₅₀s of the WT clones. Results are presented as means ± standard deviations. The statistical significance of the differences in drug sensitivity of the resistant viruses compared to that of the WT is indicated as follows: *, P < 0.05; ***, P < 0.001; ****, P < 0.0001. (D) Plaque reduction assays were done with each of the three KAY-2-41^r strains, two VACV strains with TK deletions, and their corresponding WT viruses in three independent experiments. Results are plotted on a linear scale as the log₁₀ of the ratios of the EC₅₀s, and standard deviations are given. Resistance was observed with a ratio of >2 (log 0.3), and hypersensitivity was observed with a ratio of <0.5 (log −0.3).