FIG. 5.

Analysis of the relationship between PAN and virus-cell fusion of R18-labeled PR8 virus as a function of antibody concentration (M). PAN and fusion are expressed as a percentage. All assays were carried out at the same time in the same batch of 3-cm-diameter monolayers. PAN was measured by ELISA, and fusion was measured by fluorescence dequenching of R18. (a and b) H36 IgG (a) and Fab (b); (c) H9 Fab. ▴, PAN; ■, fusion inhibition. Virus controls gave values of 1.2 to 1.4 OD units. All data are the mean of three experiments, and the bars represent the standard error of the mean. Curves were generated as in Fig. 2. R > 0.97 for all curves. P values were calculated using an unpaired t test, where P < 0.05 is considered significant.