FIG. 5.

One-step growth curves of vE120Ri. Vero cells were infected with 10 PFU of BA71V or vE120Ri virus per cell in the presence or absence of 1 mM IPTG. Virus from the culture supernatants (A) and the infected cells (B) were collected at the indicated times of infection and titrated separately by plaque assay on fresh Vero cells in the presence of the inducer. (C) Curves of total virus yield were deduced from the intracellular and extracellular virus yields shown in panels A and B. (D) In the same experiment, recombinant virus vE120Ri was grown under nonpermissive conditions for the indicated times and then induced with IPTG. At different times postinfection, extracellular virus from the culture supernatant was titrated as described above in the presence of inducer. As a control, the extracellular virus yields of recombinant vE120Ri grown in the absence or presence of IPTG throughout the infection are shown.