FIG. 2.

v62i is a lethal conditional mutant. (A) Effect of IPTG on plaque formation. Vero C1008 cell monolayers were infected with the parental BA71V or v62i in the presence or absence of 0.5 mM IPTG. After 7 days, plaques were visualized using crystal violet. (B) One-step growth curves of v62i. COS cells were infected with 5 PFU per cell of BA71V or v62i. At the indicated times after infection, the total virus titer of each sample was determined by plaque assay. The recombinant virus was grown in the presence (+IPTG) or absence (−IPTG) of 0.5 mM IPTG or was grown under restrictive conditions for 12 (−/+12) or 18 (−/+18) hpi and then induced with 0.5 mM IPTG. The results are represented as the means from three independent experiments. Error bars indicate the standard errors of the means.