FIG 7.

Adaptive mutations do not affect sensitivity to CD81 and SR-BI blocking. Anti-CD81 (A) or anti-SR-BI (B) was added to Huh7.5 cells at the indicated concentrations and incubated for 1 h. Following incubation, the indicated viruses were added to the Huh7.5 cells, as described in Materials and Methods, and incubated for 3 h. Antibody and virus were removed, and complete DMEM was added to all wells. Cells were fixed 48 h postinfection and stained, and the number of single HCV NS5A-positive cells per well was determined by automated counting as described in Materials and Methods. The percent blocking was calculated by relating counts of experimental wells to the mean count from eight replicate wells with untreated control virus. Data points are means from three replicates with SEM. Following logarithmic transformation of x values, variable-slope sigmoidal concentration-response curves were fitted {y = bottom + [top − bottom]/[1 + 10^{(log10EC50 − X) × HillSlope}]}. “Bottom” was constrained to 0. For CD81 blocking, a “top” constraint of 100 was introduced.