Wild-type levels of pregenomic RNA and replication but reduced pre-C RNA and e-antigen synthesis of hepatitis B virus with C(1653) --> T, A(1762) --> T and G(1764) --> A mutations in the core promoter.

Abstract

Hepatitis B virus (HBV) isolates with A-1762 to T and G-1764 to A mutations in the core promoter have been associated with active hepatitis, severe liver disease following liver transplantation, hepatocellular carcinoma and acute fulminant courses--in the latter case combined with a C-1653 to T mutation. In this study, a mutant core promoter region containing the T-1653, T-1762 and A-1764 mutations was placed into the context of a wild-type HBV genome and analysed by transfection. The mutations reduced the level of pre-C mRNA (by 55%) and e-antigen secretion. In contrast, no significant effects on the levels of pregenome/C and pre-S/S mRNAs, intracellular core, polymerase, and pre-S /S2 proteins and secreted S-antigen were observed. The amount of progeny virus DNA in the cells and in the culture medium was increased marginally, if at all.