Prevention of Japanese encephalitis virus infections by low-degree-polymerisation sulfated saccharides from Gracilaria sp. and Monostroma nitidum

► Sulfated saccharides inhibit Japanese encephalitis virus (JEV) infection by blocking virus entry into cells. ► The direct binding of the low-DP sulfated saccharides with JEV was spotted by transmission electron microscopy. ► Low-DP sulfated saccharides can enhance survival rates of JEV-infected mice. ► Antiviral effects of sulfated saccharides correlate to the length of polysaccharide.