FIG. 8.

HSV-1 does not inhibit endocytosis of Tf. HEC-1A cells were infected with wild-type HSV-1 for 4, 8, or 12 h or left uninfected. Specific binding of Tf was assessed by washing the cells in ice-cold uptake medium followed by a 1-h incubation with ice-cold uptake medium containing ¹²⁵I-labeled Tf in either the presence or absence of a 1,000-fold excess of unlabeled Tf. Cells were washed and lysed with detergent, and cell-associated radioactivity was counted. Uptake of Tf was assessed by washing the cells with serum-free medium at 37°C and incubating cells for 3, 6, 9, or 12 min with ¹²⁵I-Tf in either the presence or absence of excess unlabeled Tf at 37°C. Following these incubations, surface Tf was stripped from the cells by washing with 0.2 N acetic acid–0.5 M NaCl, the cells were washed, and internalized radioactivity was counted. Nonspecific binding or uptake (observed in the presence of excess unlabeled Tf) was subtracted from the total binding or uptake to give specific values. In all cases, nonspecific binding or uptake was less than 10% of the total binding. Percent Tf internalized was calculated by comparing the specific uptake at 37°C with the Tf that bound specifically at 4°C. Data points represent the mean of duplicate samples.