FIG. 4.

HAE cultures were treated with neuraminidase from Vibrio cholerae for 3 h at 37°C (A and B). Control cultures (C and D) were incubated with serum-free DMEM only. Cells were infected via the apical surface with human H3N2 influenza virus A/England/26/99 or PIV3-GFP and fixed at 24 h postinfection. Influenza virus-infected cultures were stained with mouse anti-influenza A nucleoprotein antibody, followed by goat anti-mouse IgG conjugated to Alexa Fluor 488. Representative photomicrographs of neuraminidase-treated HAE cultures infected with influenza virus (A) and PIV3-GFP (B) and control cultures infected with influenza virus (C) and PIV3-GFP (D) are shown.