FIG. 6.

Plaque morphology and growth kinetics of the wild-type and K-D-K-E mutant viruses. (A) Plaque morphologies of wild-type and mutant viruses on Vero cells. A single- or double-nucleotide change was engineered into the genome-length RNA to introduce an Ala substitution within the K-D-K-E motif. Wild-type and K₆₁A (AAA to GCA; mutated nucleotide underlined), K₁₈₂A (AAG to GCG), and E₂₁₈A (GAG to GCG) mutant viruses were harvested on day 5 p.t. “Mutant” D₁₄₆A (GAC to GCC) virus was recovered starting on day 8 p.t. Plaques were developed at 96 h p.i. Sequences of the mutated regions, derived from the harvested viruses, are presented below the plaque assay plates. (B and C) Growth kinetics of the wild-type, K₆₁A, K₁₈₂A, and E₂₁₈A viruses were compared in Vero cells (B) and C6/36 cells (C) by infecting cells with an MOI of 0.1, followed by quantification of viral titers using plaque assay on Vero cells.