FIG. 1.

Map of plasmids. Plasmid pHBV-WT contains a 1.2-mer overlength copy of the HBV genotype A genome (black bar). Numbering of the 3,221-bp-long genome starts with the deoxycytidine nucleotide of the unique EcoRI site. Some restriction enzyme sites and their positions are indicated for orientation. The transcription of the pregenome starts from the SV40 early promoter (striped box). Transcription start sites from the SV40 and HBV promoters are indicated by horizontal arrows. The HBV polyadenylation signal (pA) is shown as a black box. The four open reading frames C (core), E (envelope), P, and X are depicted as open boxes. Plasmid pHBV-E⁻ carries a point mutation that creates a stop codon in the E frame. This mutation is silent in P. Plasmid pHBV-RT⁻E⁻ carries an additional point mutation in P that destroys the reverse transcriptase activity of the P protein. Plasmid pHBV-C⁻ carries a 1.4-mer of the HBV genome. The pregenome is expressed from the authentic core promoter. The C gene carries a missense mutation. Plasmid pC expresses only the C protein. The point mutation C-I97L has been introduced into this plasmid. Plasmid pE directs the expression of all three HBV envelope proteins (L, M, and S). Plasmid pS expresses only the small envelope protein S.