Generation of Replication-Competent Hepatitis B Virus Harboring Tagged Polymerase for Visualization and Quantification of the Infection.

Hepatitis B virus (HBV) infection is a serious global health problem causing acute and chronic hepatitis and related diseases. Approximately, 296 million patients have been chronically infected with the virus, leading to cirrhosis and hepatocellular carcinoma. Although HBV polymerase (HBVpol, pol) plays a pivotal role in HBV replication and must be a definite therapeutic target. The problems are that the detailed functions and intracellular dynamics of HBVpol remain unclear. Here, we constructed two kinds of tagged HBVpol, PA-tagged and HiBiT-tagged pol, and the HBV-producing vectors. Each PA tag and HiBiT tag were inserted into N-terminus of spacer region on HBVpol open reading frame. Transfection of the plasmids into HepG2 cells led to production of HBV. These tagged HBVpol were detectable in HBV replicating cells and pol-HiBiT enabled quantitative analysis. Furthermore, these recombinant HBV were infectious to primary human hepatocytes. Thus, we successfully designed infectious and replication-competent recombinant HBV harboring detectable tagged HBVpol. Such infectious recombinant HBV will provide a novel tool to study HBVpol dynamics and develop new therapeutics against HBV.