FIG. 1.

BKV infection in RPTE cells requires a low-pH step. RPTE cells were either mock treated or treated with 6.25 mM NH₄Cl for 2 h at 37°C. The cells were infected with BKV at an MOI of 0.5 or 5 IU/cell for 1 h at 37°C with the drug present. The inoculum was removed after 1 h, and fresh medium with the drug was added to the cells. Cells were fixed 48 h postinfection, and infected cells were visualized by indirect immunofluorescence staining for TAg. (A) Fields of cells representing an MOI of 5 IU/cell. (B) The percentage of infected cells was normalized to that of the untreated samples. Each bar represents the mean of seven random fields from three independent experiments. The error bars are the standard deviation values.