Figure 5

Biological characteristics of rescued wt and HN-mutated viruses.
(a) The relative expression of the NDV NP gene, HAd ability, NA activity and fusion index were assessed for virus-infected BHK-21F cells (MOI of 1). All values are expressed relative to that for rG7-wt, which was set at 100%. Each bar represents the mean ± SD of three independent experiments (n = 3) (*P < 0.05, ***P < 0.001). (b) Representative syncytium formation induced by viral infection of BHK-21F cells. Monolayers were fixed with 4% paraformaldehyde and stained with Giemsa. Syncytia are indicated by black arrows.