FIG. 3.

Heparin inhibits infection by cell-bound virus particles. Six 2-cm² tissue culture wells with SK6 cells were infected with about 1,200 PFU of CSFV strain Brescia clone C1.1.1 per well at 4°C. After 30 min of infection, the virus was removed and the cells were washed twice with medium. Subsequently, at 4°C, three wells were chased with 100 μl of EMEM (V) and three wells were chased with 100 μl of EMEM containing 100 μg of heparin per ml (H). After incubation for 30 min, chase media were collected and cells were washed twice with EMEM. Then, 200 μl of fresh EMEM was added, and the cells were incubated for 1 h at 37°C. The medium was removed, and the wells were supplied with overlay medium. After incubation for 24 h at 37°C, the wells were immunostained and plaques were counted. Open bars represent the average number of plaques of three wells. After 10-fold dilution in EMEM supplemented with 10% FBS, the collected chase media were used to infect 2-cm² tissue culture wells. After 90 min of infection, the virus was removed and overlay medium was added. After 24 h of growth, wells were stained and plaques were counted (shaded bars, average of three observations). The error bars represent the standard deviation (n − 1).