FIG 2.

Mutation frequencies of each mutant and WT FMDV. Three independent stocks of virus were generated in ribavirin-free medium (A) and in medium containing 100 μM ribavirin (B). A mean of 70 partial P1 sequences (approximately 35,000 nucleotides per replicate) were obtained. The mean mutation frequencies (number of polymorphisms per 10,000 nt sequenced) ± standard deviations represent the averages of all replicates; the same pattern of reduced mutation frequency for each mutant compared to WT FMDV was observed for each replicate (n = 3) (*, P < 0.05; **, P < 0.01 [determined by a two-tailed Mann-Whitney U test]).