Interaction of fucoidan from Pelvetia fastigiata with surface antigens of hepatitis B and woodchuck hepatitis viruses.

A sulfated polysaccharide isolated from Pelvetia fastigiata, a marine algae, was found to inhibit in vitro the reaction of the surface antigen of hepatitis B virus (HBsAg) or of woodchuck hepatitis virus (WHsAg) with antibody to HBsAg (anti-HBs). The polysaccharide was composed mainly of 1----2 linked L-fucose-4-sulfate with some (less than 10%) 1----3 linkages. The inhibition of the reaction of HBsAg with anti-HBs or of WHsAg with anti-HBs was found to be directly proportional to the molecular size of the polysaccharide. Comparison of its inhibitory activity with that of carrageenans and dextran sulfates showed that, in addition to the size, the configuration of the component sugar and the presence of deoxy sugar may play a role in the inhibition of reaction of HBsAg or WHsAg with anti-HBs. The fucose sulfate polymer, fucoidan, however, had no effect in vivo on woodchuck hepatitis virus in woodchuck chronic carriers.