FIG. 2.

Relative number of CFU on FUdR-containing plates expressed as the percentage of that on nucleoside analog-free plates. After PCR amplification, the TK ORF was digested with EcoRI and HindIII and was then inserted into pKK223-3 and subjected to the colony reduction assay as described in Materials and Methods. The number of colonies growing in the absence and in the presence of FUdR was recorded from at least three independent experiments. The relative number of CFU on FUdR-containing plates is expressed as the percentage of that on FUdR-free plates. The error bars correspond to the standard deviations. Sample names are indicated below each histogram. LY, LY-6625-resistant control; WT, a wild-type VZV TK control.