Cell-type dependent expression and secretion of hepatitis B virus pre-S1 surface antigen

The human hepatoma cell PLC/PRF/5 contains cloned genomes of hepatitis B virus, one of which was transfected to mouse cells (LTK-) or to human carcinoma cells (HeLa). Expression of the viral surface proteins was measured using monoclonal antibodies. The large protein with the pre-S1 domain was best expressed in HeLa cells and least in LTK- cells. In vivo growth of parental hepatoma cells or transfected HeLa cells increased expression of large, and decreased expression of small protein. Secretion of large protein required an excess of small protein. The secreted HBsAg from transfected HeLa cells contained filaments. Since the virus contains a defined proportion of all three proteins, a special regulatory situation is necessary for maturation of its envelope and its secretion in vivo.