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 affinity constant of $3.8×10^8$/M and the other group had the value of $6.0× 10^7$ /M.
5. The heterogeneity of PI values and peptide patterns of HBsAg particles were due to the difference of the affinity to pHSA. HBsAg having higher pHSA affinity ($HBsAg^H$) had a PI value of 3.82. Meanwhile, HBsAg having lower pHSA affinity ($HBsAg^L$) had a PI value of 3.32. GP85 and GP55 were the major peptides of HBsAgH meanwhile GP29 and P25 were the major peptides of $HBsAg^L$.
6. pHSA receptor on the surface of HBsAg was perfectly destroyed by trypsin or protease type X at $10^{-5}%$(W/V) at 37℃ for 1 h, but it was preserved about 80% when incubated with pepsin under the same condition.
7. Dansylated HBsAg showed much decrease in pHSA binding activity. Meanwhile, dithiothreitol did not affect the pHSA receptor on the surface of HBsAg. And antiHBs specific for determinant 'a' did not inhibit the pHSA-HBsAg interaction.
8. the presence of pHSA receptor on the plasma membrane of cultured human hepatocellular carcinoma cell (PLC/PRF/5; Alexander cell line) was investigated. Cell-pHSA binding was visualized by fluorescence microscopy. The interaction was not shown to be species-specific because pHSA also bound mouse $LMTK^-$ cell.
B형 간염 virus의 간세포내 침투 기전에 인혈장 알부민 중합체 (pHSA)가 관련한다는 가설이 제시되어 있다. 또한 B형간염 표면항원(HBsAg)의 pHSA 수용체 부위로 알려진 pre-S region이 B형간염 vaccine의 면역원성을 증진시킨다는 보고가 최근에 발표 되었다. 이에, 본 연구에서는 B형 간염 표면항원과 pHSA 간의 결합성질과 기타 성질을 고정상방사면역측정법(solid phase radioimmunoassay) 등의 방법으로 알아 보았다. pHSA은 glutaraldehyde 법으로 중합시켜 만들었으며 그 분자량은 약 2,000,000 dalton 이었다. HBsAg와 pHSA 간의 종합성질을 추정하기 위해서, 이온강도, pH, 온도가 결합에 미치는 영향을 알아 보았으며, 아울러 HBsAg 표면에 위치한 pHSA 수용체의 성질을 조사하기 위해서 pHSA affinity chromatography 등의 방법으로 HBsAg 입자들 중에서 pHSA과의 친화력이 높은 입자($HBsAg^H$)와 친화력이 낮은 입자($HBsAg^L$)를 각각 분리하여 등전점(PI value) 및 peptides 구성의 특징을 비교 분석하였으며 다수의 단백분해효소(proteases)와 단백변형제가 pHSA 수용체에 어떤 영향을 주는지도 알아 보았다.
HBsAg와 pHSA간의 결합은 이온강도가 증가함에 따라 감소 하였으며 $NaCl
