Fig. 7

Plaque morphology of the wt and 3A mutant viruses in BHK-21 and FPK. Cells infected with with r/HN, r/HN/3A77–153, r/HN/3A80–153, r/HN/3A76I-153 and r/HN/3A76V-153 were incubated for 1 h at 37 °C, and after adsorption, 0.6% gum tragacanth overlay was added, and then monolayers were stained with crystal violet at 48 h post-infection