FIG 5 .

The CI-derived HN and Fs are less efficient at promoting cell-cell fusion than the proteins derived from HPIV3 virus adapted to growth in immortalized cells. (A) 293T cells coexpressing the indicated HN with the F derived from a laboratory reference strain, (B) 293T cells coexpressing the indicated F with the HN derived from a laboratory reference strain, or (C) 293T cells coexpressing the indicated HN/F pair were allowed to fuse with receptor-bearing cells at from 37°C on. Cell fusion was measured as relative light units (RLU [y axis, log scale]) in the presence of each HN/F pair (as indicated on the x axis). The bars represent means ± standard errors of the meant (SEM) from triplicate samples from a representative experiment.