Chronic hepatitis B virus (HBV)
infection, a serious public health problem leading to
cirrhosis and
hepatocellular carcinoma, is currently treated with either pegylated
alpha interferon (pegIFN-α) or one of the five nucleos(t)ide analogue
viral DNA polymerase inhibitors. However, neither pegIFN-α nor nucleos(t)ide analogues are capable of reliably curing the
viral infection. In order to develop novel
antiviral drugs against HBV, we established a cell-based screening assay by using an immortalized mouse hepatocyte-derived stable cell line supporting a high level of HBV replication in a
tetracycline-inducible manner. Screening of a library consisting of 26,900 small molecules led to the discovery of a series of sulfamoylbenzamide (SBA) derivatives that significantly reduced the amount of cytoplasmic HBV
DNA. Structure-activity relationship studies have thus far identified a group of
fluorine-substituted SBAs with submicromolar
antiviral activity against HBV in human
hepatoma cells. Mechanistic analyses reveal that the compounds dose dependently inhibit the formation of pregenomic
RNA (
pgRNA)-containing nucleocapsids of HBV but not other animal hepadnaviruses, such as woodchuck hepatitis virus (WHV) and duck hepatitis B virus (DHBV). Moreover, heterologous genetic complementation studies of
capsid protein,
DNA polymerase, and
pgRNA between HBV and WHV suggest that HBV
capsid protein confers sensitivity to the SBAs. In summary, SBAs represent a novel chemical entity with superior activity and a unique
antiviral mechanism and are thus warranted for further development as novel
antiviral therapeutics for the treatment of
chronic hepatitis B.