FIG. 6.

Effect of ammonium chloride (NH₄Cl) on virus entry. (A) Vero cells were infected with virus RSΔsh,g,f/G^vsv for 1.5 h at 37°C in the presence of 0, 2, 5, or 20 mM NH₄Cl. Cells were then further incubated in the presence of the same NH₄Cl concentrations. At 20 h postinfection, cells were fixed with 4% paraformaldehyde and photographed with phase contrast (phase) or in the presence of UV light (GFP) (magnification, ×60). (B) Flow cytometry analysis. Vero cells were infected in the presence or absence of 20 mM NH₄Cl with viruses RSΔsh, RSΔsh,g/G^vsv, and RSΔsh,g,f/G^vsv. After infection, cells were washed and further incubated, maintaining the NH₄Cl concentrations used during infection. At 20 h postinfection, samples were trypsinized, fixed with paraformaldehyde, and analyzed by flow cytometry. Bars represent the number of GFP-expressing cells in the absence (−) or presence (+) of NH₄Cl, relative to the number of GFP-expressing cells in the absence of NH₄Cl × 100. Error bars are standard deviations from the mean of duplicate samples.