Excretion of hepatitis B surface antigen particles from mouse cells transformed with cloned viral DNA.

Abstract

A plasmid containing 2 cloned hepatitis B virus genomes in a tandem head-to-tail arrangement was introduced into mouse fibroblasts by using cotransformation with the cloned herpes simplex virus thymidine kinase gene. Several copies of the plasmid were integrated into high MW cellular DNA. The original tandem structure of the hepatitis B virus DNA was conserved. Hepatitis B surface antigen was synthesized by all the 15 clones examined. The other viral antigens were not detected. The surface antigen was excreted into the cell culture medium as particles having the same characteristics as those found in human serum. It is estimated that 2-4 .times. 104 particles were produced/mouse cell per 24 h in 2 clones. This value corresponds to approximately 2-4 .times. 106 surface antigen polypeptides/cell per 24 h.