Expression of hepatitis B virus surface antigen gene in Escherichia coli.

Direct expression of hepatitis B virus (HBV) surface antigen (HBsAg) gene under the control of the Escherichia coli tryptophan operon (trp) promoter has been achieved. Synthesis of HBsAg (both complete and lacking its N-terminal segment) as a part of hybrid proteins with the N-terminal portion coded by genes cat, kan or bla is controlled by the appropriate promoters, as well as by the trp promoter. The highest levels of expression, including those for direct synthesis of HBsAg, provide the accumulation of about 10(5) polypeptide molecules per bacterial cell.