FIG. 6.

Heparin inhibits PRRSV attachment to PAM in a dose-dependent manner. Biotinylated PRRSV was incubated with different concentrations of heparin, and PAM were inoculated with the mixtures at 4°C for 1 h. After washing, bound virus particles were stained by direct immunofluorescence, and fluorescence intensity was analyzed by flow cytometry. The data represent the means ± standard deviations (error bars) of triplicate assays. The histogram shows the green fluorescence intensity frequency when no virus was added (shaded histogram), when virus was added (solid-line histogram), and when virus and heparin was added (dotted-line histogram).