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

Background: 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.

Methods: 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.

Results: 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.

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