Establishment of a Hepatitis B Virus Reporter System Harboring an HiBiT-Tag in the PreS2 Region

Approximately 296 million people have chronic hepatitis B (CHB) caused by hepatitis B virus (HBV). Current standard treatment, nucleos(t)ide analogs, are not efficient enough to eradicate HBV from the hepatocytes. Thus, developing new drugs for CHB is needed to achieve complete cure.

Here we established a novel HBV reporter system, HBV-HiBiT-PS2, to screen new drugs for CHB. HBV-HiBiT-PS2 was constructed by adding an HiBiT-tag at the 5' end of preS2 and introduced this into HepG2-NTCP cells. Culture supernatant containing HBV-HiBiT-PS2 virions was fractionated by sucrose density gradient ultracentrifugation to characterize their components. Replication kinetics and reporter function of HBV-HiBiT-PS2 were determined by analyzing the parameters for HBV replication in the presence or absence of HBV inhibitors.

HBV-HiBiT-PS2 could be used for monitoring most of the replication cycle of HBV. The effects of well-characterized HBV inhibitors could be evaluated by the HiBiT activity. HBV-HiBiT-PS2 could be specialized for screening secretion inhibitors for hepatitis B surface antigen (HBsAg) because most of the HiBiT activity was derived from subviral particles which are the multimers of HBsAg.

We demonstrated that HBV-HiBiT-PS2 would be a robust tool for screening novel drugs, especially HBsAg secretion inhibitors, targeted against CHB.