Enhanced core protein production by hepatitis B virus bearing a mutation in the precore region

An HBV DNA tandem dimer bearing GTG instead of the precore initiation codon (p2WPC-), that bearing an amber mutation at precore codon 28 (p2WPCTer) and that of a wild-type were introduced into HepG2 cells. p2WPC- produced no HBeAg, the same amount of HBsAg as the wild-type, and 2-4 times as much HBcAg and progeny virus DNA. p2WPCTer produced no HBeAg, the same amount of HBsAg, 2 times as much HBcAg and a slightly increased amount of progeny virus. The amounts of p21c peptide in both mutants determined by immunoblotting correlated well with the ELISA titers. These results suggest that these precore single point mutations are responsible for the enhanced core peptide production.