FIG. 2.

Selection and characterization of PPMO-resistant WNV. (A) Two schemes for the selection of PPMO-resistant viruses. (B) Plaque morphologies of wild-type and PPMO-resistant viruses. Plaque assays for the resistant and wild-type viruses were performed on Vero cells in the absence of PPMOs. The results of three independent selections for 5′-end-PPMO- and 3′ CSI PPMO-resistant viruses are presented. (C) Resistance phenotypes of the PPMO escape isolates. The left and right panels represent results for 5′-end-PPMO-resistant and 3′ CSI PPMO-resistant viruses, respectively. The results are expressed as the means and standard deviations derived from three independent experiments. See the experimental details in Materials and Methods. (D) Growth kinetics of the PPMO-resistant and wild-type (WT) viruses in the presence and absence of PPMO. Vero cells were infected (MOI of 0.1) for 1 h, washed with PBS, and incubated for the indicated times in medium with or without PPMO at 7.5 μM. The averages of results from three experiments are presented.