EXPRESSION OF THE HEPATITIS-B VIRUS SURFACE-ANTIGEN IN MAMMALIAN-CELLS USING AN EPSTEIN-BARR-VIRUS-DERIVED VECTOR

The hepatitis B virus surface antigen (HBsAg) gene, under control of t he inducible mouse metallothionein I gene promoter, was inserted in an expression vector based on the Epstein-Barr virus (EBV). This vector was introduced into human cells by DNA transfection and clones were se lected for their resistance to hygromycin B. The recombinant EBV vecto r replicates efficiently as an episome in human cells and approximatel y six copies per cell were found in one clone of hygromycin-B-resistan t cells. These cells produce high levels of HBsAg in the presence of m etals. The protein is mainly found in the cell medium, suggesting that the HBsAg is secreted from the cells.