Enhancement of gene expression by somatic hybridization with primary cells: high-level synthesis of the hepatitis B surface antigen in monkey Vero cells by fusion with primary hepatocytes.

Vero cells transfected with the S gene encoding the surface antigen (HBsAg) of the hepatitis B virus (HBV) synthesize HBsAg at low levels. We have obtained a large increase in S gene expression by somatic hybridization of Vero cells with primary hepatocytes, which are the natural target cells for HBV infection. Fusion with cells other than hepatocytes did not enhance expression of the S gene. The Vero/hepatocyte hybrid clones analyzed are stable and have maintained a high level of HBsAg synthesis over prolonged periods. Hybrid cell lines may be of general interest for the high-level synthesis of proteins using cloned genes.