FIG. 2.

TAT-C⁻ blocks translocation of VP16 to the nucleus. Untreated virus (columns 1 to 3) and virus treated in solution with 300 μM TAT-C⁻ for 1 h at 37°C (column 4) were adsorbed to precooled cells for 80 min at 4°C. Cells were either fixed immediately (column 2) or after a 1-h entry period at 37°C (columns 1, 3, and 4). In experiment 3, 50 μM TAT-C⁻ was present from 20 min before shifting the cultures to 37°C through the end of the entry period. VP16 was detected by fluorescent microscopy following immunolabeling. As the result of peptide treatments (columns 3 and 4), nuclear VP16 labeling was significantly reduced compared to the positive control (column 1) and indistinguishable from background labeling (column 2) (two-tailed Student t test at 95% confidence level). The data points represent the means of triplicate determinations with standard errors of the means.