FIG. 9.

Comparison of the effect of VCNA treatment of target cells on the promotion of fusion by wt F or L289A-F. Wt F and L289A-F were coexpressed with either wt HN or different NDV-hPIV3 HN chimeras. Target cells in the content-mixing assay for fusion were either untreated or treated for 1 h at 37°C with 50 mU of VCNA/ml. The extent of fusion induced by the two wt proteins was set at 100%, and fusion promotion by other combinations is expressed as a percentage of this amount. Error bars show the standard deviation from at least four independent determinations.