FIG. 4.

Growth properties of viruses lacking the entire ORFS/L. (A) Plaque size measurements of vΔaa1-157 (clone 1 [c1] and c2), vP-Oka, and revertant vΔaa1-157-rev generated from clone 1. Recombinant viruses were reconstituted in MeWo cells, IIF was performed 7 days after transfection, and images were recorded. Twenty individual plaque areas were measured and are shown as averages (vP-Oka plaques were set at 100%) with standard deviations (error bars). *, Plaque areas induced by Δaa1-157 mutants were significantly reduced (P < 0.0001) compared to those of parental vP-Oka or the revertant virus by Student's t test. (B) Representative plaque images for vΔaa1-157 (clones 1 and 2), vP-Oka, and vΔaa1-157-rev. Scale bars correspond to 200 μm.