Antiviral activity of sulfated Chuanminshen violaceum polysaccharide against duck enteritis virus in vitro.

Duck enteritis virus (DEV) of the family Herpesviridae is one of the main diseases in waterfowl. Despite the wide use of vaccines to control the disease, infection with the virus cannot be completely prevented. Therefore, antiviral agents against DEV should be developed. This study presents a novel sulfated polysaccharide from Chuanminshen violaceum (sCVPS), which exhibits significant antiviral activity against DEV with 50% inhibitory concentrations (IC₅₀) ranging from 77.12 μg/mL to 104.81 μg/mL. sCVPS is more effective than heparan sulfate (HS, as a positive control) with IC₅₀=132.61 μg/mL. sCVPS and HS inhibit viral activity by preventing virus adsorption with IC₅₀ values ranging from 82.83 μg/mL to 109.28 μg/mL for sCVPS and 150.22 μg/mL for HS. Direct immunofluorescence assay and transmission electron microscopy demonstrated that the mechanism of action was the interference with virus adsorption. The amount of inhibited virus during adsorption was quantified using fluorescent quantitative polymerase chain reaction, which revealed that both sCVPS and HS can significantly reduce all viruses attached to cells. sCVPS also prevented the cell-to-cell spread of DEV. These results indicated that sCVPSs perform more effectively than does HS as antiviral agents against DEV and can be further examined for potential effects as an alternative control measure for DEV infection.