[In vitro expression of wild type and precore mutant woodchuck hepatitis virus]

Hepatitis B virus (HBV) precore 1896 and 1898 G-->A mutations are regarded as hot spots to study. Such mutants have been considered associating with molecular and biological changes of HBV and causing chronic hepatitis and severe forms of hepatitis, including fulminant hepatitis. Using oligonucleotide-directed mutagenesis, we have conducted the same point mutations in the precore gene of an infectious clone of woodchuck hepatitis virus (WHV-8). Transfection of mutant WHV DNA, 1896 mutant (WHV-M1) or both 1896 and 1898 mutants (WHV-M2) resulted in WHV replication. Southern blot and Northern blot tests showed that wild type and mutants both had similar DNA replication and transcription. It was concluded that the precore gene of the WHV genome is not essential for virus replication.