FIG 12.
Replication of viruses with and without a 2nd SIA-binding site. MDCK-II cells were infected a multiplicity of infection of 0.001 with PR8 (7+1) viruses carrying wild-type (K432) or mutant (E432) HN NA proteins. Virus in the supernatant at the indicated time points postinfection was titrated. Means of three independent experiments are graphed. Standard deviations are indicated. Significant differences were analyzed using a Student t test, and the P values are shown. TCID50, 50% tissue culture infective dose.