Studies on the interaction between polymerized human serum albumin and hepatitis B surface antigen

Abstract

Despite considerable progress in our knowledge of the nature of hepatitis B virus (HBV), the understanding concerning HBV and its target cell interaction remains incomplete. Some aspects of HBV-DNA replication, transcription, mRMA translation and processing of primary translation products could be studied by many investigators. However, a system allowing the detailed study of all aspects of HBV - target cell interaction from virus attachment to assembly and release of progeny virus is not available. For elucidation of the biological significance of the binding between HBV and altered albumin, it is indispensable to analyze the binding nature and the binding site of HBsAg. The results obtained are as follows; 1. The binding nature of HBsAg to glutar-aldehyde-polymerized human serum albumin (pHSA) has been studied. The binding was decreased by each addition of $NaCl$, $CaCl_2$ and $Al(OH)_3ㆍ $CaCl_2$ showed more inhibitory effect than $NaCl$. $Al(OH)_3$ displayed the most inhibitory effect. Meanwhile, the addition of $NH_4Cl$ ranging from 1.5 to 24 mM increased the adsorption proportionally but the interaction was rapidly decreased at concentration greater than 48 mM. The inhibitory effect of $Ca^{2+}$ was blocked by addition of EDTA. But EDTA itself had an adverse effect at 10 mM or higher concentration. KSCN promote the elution of HBsAg adsorbed to pHSA-Sepharose 4B. 2. The isoelectric points of HBsAg and pHSA, and their relationship with pH dependence were analyzed. The elution pH of $HBsAg^H$ and pHSA determined by DEAE-Sephacel and CM-Sephadex chromatography were 3.82 and 5.47, respectively. The optimum binding was shown at pH 6.0 - 6.5. 3. Kinetic studies were carried out between pHSA and HBsAg. Lineweaver-Burk plot and Hill plot showed that the interaction had a slight positive cooperative nature. 4. Results of Scatchard analyses indicated the presence of HBsAg particles with at least two classes of different affinities. One group had an apparent affin...