Polyalbumin receptors on hepatitis B virus and on 22 nm hepatitis B surface antigen (HBsAg)2 particles.

Receptors for polymerized human serum albumin ( pHSA ) were studied by solid-phase radioimmunoassay on different hepatitis B surface antigen (HBsAg) particles subpopulations prepared both from hepatitis B e antigen (HBeAg) and from anti-HBe-positive sera. HBsAg particles in HBeAg-positive serum showed higher expression of the receptor compared with HBsAg particles from anti-HBe-positive serum. Analysis of different morphological forms of virus particles was performed after separation by density-gradient ultracentrifugation. Maximum receptor expression was detected in HBV particles containing fractions while the 22-nm HBsAg particles had significantly lower receptor activity. These observations support the hypothesis of a pathogenetic role of the pHSA receptor in mediating virus access to hepatocytes. Indeed, the higher pHSA binding activity on HBV particles could allow selective attachment of the infectious virion to liver cells that bear similar albumin receptors on their surface.