The polysaccharide κ/β-CRG and its oligosaccharide significantly inhibit the infection of cells with replication-defective viruses pseudotyped with envelope proteins GP160 and McERV, and exert a less pronounced antiviral effect on the virus pseudotyped with VSVG, which was intrinsic to both the cell lines used in this study. The gene discussed is ENPEP; the disease is infection.