FIG. 1.
EV70 binding to U-937 cells is sensitive to α2,3-specific sialidase. U-937 cells were pelleted, washed, resuspended (5 × 107 cells/ml) in OptiMEM, and incubated in the presence or absence of sialidase (10 to 100 mU/ml, as indicated) at 37°C for 30 min. After sialidase treatment, the cells were washed twice, counted, and used in virus binding assays. The results are presented as mean percentages of virus binding to cells incubated in the presence of sialidase compared to untreated cells ± standard deviation for at least two independent experiments, each performed with triplicate samples. (Inset) Radiolabeled EV70 was incubated at 32°C for 1 h with neutralizing monoclonal antibody ev-12 (76) at the indicated dilution and then used in virus binding assays. The concentration of undiluted antibody was 7.0 μg/ml. U, control samples in which virus was not treated with antibody.