Figure 1.

Kinetics of replication in MDCK and SIAT cells. Cells were infected at a multiplicity of infection of 1.0 and samples were harvested from duplicate wells every 6–8 h. Yields for both cell-free virus in supernatants and cell-associated virus were titrated in MDCK cells. (a) MDCK cell free. (b) MDCK cell associated. (c) SIAT cell free. (d) SIAT cell associated. The Y155H NA mutation decreased replication in SIAT cells, but not in MDCK cells, whereas the combined HA D225G and NA Y155H mutations decreased replication in MDCK cells; D225G rescued the poorer growth of the Y155H NA mutant in SIAT cells.