Fig. 3.

(A) Schematic of plasmids used to generate fully infectious viruses. Recombinant viruses were generated as described before (3, 4). The indicated combinations of plasmids were used to rescue the parental strains, viruses carrying G1 and G2 replacements, and viruses carrying single-amino-acid changes. (B) Virulence assays in the mouse model were performed as explained in the legend for Fig. 2.