Phosphorylated Codonopsis pilosula polysaccharide could inhibit the virulence of duck hepatitis A virus compared with Codonopsis pilosula polysaccharide

Abstract To screen effective anti-duck hepatitis A virus (DHAV) drugs, we applied STMP-STPP method to prepare phosphorylated Codonopsis pilosula polysaccharide (pCPPS), the phosphorylation-modified product of Codonopsis pilosula polysaccharide (CPPS). The IR spectrum and field emission scanning electron microscope (FE-SEM) were subsequently used to analyze the structure of pCPPS. Several tests were conducted to compare the anti-DHAV activities of CPPS and pCPPS. The MTT method was used to compare the effect of the drugs on DHAV-infected duck embryonic hepatocytes (DEHs), and the Reed-Muench assay was employed to observe changes in the virulence of DHAV. We also applied real-time PCR to examine the relationship between virus replication and the expression of IFN-β. The results indicated that CPPS could not inhibit the replication of DHAV. In contrast, pCPPS increased the virus TCID 50 , inhibited viral replication and, accordingly, increased the survival rate of DEHs infected with DHAV. Because DHAV induced the expression of IFN-β, and the IFN-β expression level was positively associated with the number of DHAV, the reduction of IFN-β expression levels after pCPPS treatment demonstrated a decrease in the number of virus particles. These results indicated that pCPPS, which reduces the number of DHAV, was more effective than CPPS in anti-DHAV activity.