FIG 3.

Progeny production and spread of B141 and B388 in BSC-40 cells. (A) Comet tail formation by B141, B388, or VACV-WR 72 h postinfection. Representative images of 2 independent experiments are shown. (B) Multistep growth curve of clones B141 and B388. Cells were infected with B141, B388, or VACV-WR, and at the indicated time points, the monolayers (open symbols) and supernatants (closed symbols) were harvested for virus titration. (C) One-step growth curve of B141 and B388. Cells were infected with the indicated viruses and were harvested for virus titration at 0, 2, 4, 8, 16, and 24 h postinfection. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (one-way ANOVA followed by Tukey's posttest for time points in which 3 experiments were conducted).