The e antigen (eAg) of duck hepatitis B virus (DHBV) is a glycosylated secretory protein with a currently unknown function. We concentrated this antigen from the supernatants of persistently infected primary duck liver cell cultures by ammonium sulphate precipitation, adsorption chromatography over concanavalin A Sepharose, preparative isoelectric focusing and molecular sieve chromatography. The combined treatment of duck liver cells with DHBV eAg (DHBe) concentrate and alpha-methyl-d-mannopyranoside strongly inhibited DHBV replication at de novo infection. When DHBe was added to non-infected primary duck liver cells, it was found to be associated with liver sinusoidal endothelial cells. This binding could be inhibited by the addition of alpha-methyl-d-mannopyranoside and other sugar molecules. The inhibitory effect of DHBe on infection could play a role in maintaining viral persistence.
