Interaction Between Hepatitis B Surface Proteins and Monomeric Human Serum Albumin

Abstract

HBsAg is known to bind to human serum albumin polymerized by glutaraldehyde, human serum albumin has been found in preparations of HBsAg by several investigators. However, it is not yet known whether natural human serum albumin binds to hepatitis B virus under physiological conditions. We studied the binding between natural or recombinant HBsAg and monomeric human serum albumin by immunological, biochemical and biophysical methods. The binding capacity of 20-nm HBs spheres was variable but ranged up to six molecules HSA/sphere. A reversible binding site for human serum albumin was exclusively localized in the preS2 domain, whereas the S domain was inactive in vitro. Human serum albumin copurified with HBsAg of human origin during gel chromatography or sucrose-gradient centrifugation. This human serum albumin was monomeric in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preS2-bound part of the human serum albumin could be removed from HBsAg by high-salt, such as CsCl centrifugation, but another part could only be removed by treatment with a disulfide cleaving reagent. Most of this covalently bound human serum albumin was retained at the HBsAg particle after complete cleavage of medium-sized HBs protein with trypsin. This indicates a second way in which albumin binds irreversible to cysteine(s) of the small HBs protein (SHBs, P24 and GP27).

Role of glycosaminoglycans for binding and infection of hepatitis B virus

“…One possibility might be that the preS domains are covered in the blood by a serum protein partially protecting HBV from non-specific attachment to blood vessels. A number of serum proteins have been proposed for this function, including albumin (Krone et al, 1990) and apolipoprotein H (Mehdi et al, 1996;Stefas et al, 2001). In a recent publication, Deng et al (2007) propose lipoproteinlipase (LPL) as a binding factor for the preS1 domain.…”

A molecular analysis of viral persistence in surface antigen-negative chronic hepatitis B

“…26,27 This binding site has been 133, and 131 and 133, as found in cases 3 and 4, respectively, have not been described previously, so the signifthought to be located between amino acids 17 and 28 in the pre-S2 region. 28 Therefore, the finding that nu-icance of these observations are still unclear. However, it has been demonstrated that amino acid changes at cleotide deletions in the pre-S2 region partially overlap the binding site for glutaraldehyde cross-linked human codons 124, 129, 131, 137, 140, and 145 31 and at codons 126, 131, 132, and 145 34 were identified in liver transserum albumin in case 4 suggested that this mutant may have lower infectivity than wild-type particles.…”

Efficient and Specific Removal of Albumin from Human Serum Samples

“…HBsAg can be present at concentrations ranging from 1 g/ml to over 1000 g/ml in the serum of patients who are chronically infected with HBV (15). HBsAg has been shown to bind to some forms albumin (16), and therefore it could potentially be retained on the column through this interaction.…”