Specific binding of the hepatitis B virus preS antigen to an EBV-transformed B-cell line

Specific attachment onto the target cell is one of the mechanisms that causes the restricted and specific host cell range of viral pathogens. In the case of hepatitis B virus (HBV), human hepatocytes are known to be the major host cells onto which HBV is believed to bind by the preS region of its surface antigen (HBsAg). To examine the host cell range of HBV, cells have to be analyzed primarily upon their ability to bind the preS antigen. To do this, in this study, the preS region of HBV was expressed as a maltose binding protein (MBP) fusion protein in prokaryotes and used for detection of putative HBV receptors on various cell lines. Among the cell lines investigated, we could identify one EBV-transformed B-cell line, Wa-cells, which showed specific binding to the MBP-preS fusion protein as revealed by FACS analysis. The expression level of the preS binding protein on Wa-cells was comparable to that of cells of hepatic origin such as HepG2 cells. With the identification of a non-hepatic cell line, that expresses putative HBV receptors, a novel way is opened for analysis of the host cell specificity of HBV as well as the possible pathogenicity of HBV in extra-hepatic tissues. Attempts for in vitro transfection of Wa-cells with HBV as well as the identification of preS binding proteins of these cells are under progress.ope