FIG 5.

Mutagenic nucleosides inhibit USUV replication in Vero cells. (A) Single-cycle replication kinetics of USUV treated with FU (dark-gray squares), RBV (light-gray triangles), or FAV (white inverted triangles) at 800 μM each, compared to that of untreated virus. Vero cells were inoculated at an MOI of 5 TCID₅₀ per cell. Cellular supernatants were collected at different time points after infection. Every value in the graph is the average of the results from at least three biological replicas (± SEM). (B and C) USUV titers obtained after multiple rounds of virus replication in Vero cells in the absence (0) or presence of increasing concentrations of each drug. To ensure that the virus titers are the result of several rounds of replication, we employed a low MOI to infect the cells (0.1 or 0.01). Statistically significant differences are represented (**, P < 0.01; ***, P < 0.001; 2-way ANOVA). Each value in the graph is calculated as the average virus titer obtained from at least three independent biological replicates (± SEM). Virus titers obtained in infected cells treated with DEC are represented as black bars, titers in FU-treated cells are in dark gray, RBV cells are in light gray, and FAV cells are in white. (B) Vero cell monolayers were infected at an MOI of 0.1 and supernatants collected for titration at 24 h postinfection. (C) Supernatants of infected cells were collected for virus titer analysis at 48 h postinfection. To ensure that virus titers were obtained during the exponential-growth phase, we used an MOI of 0.01 instead of 0.1.