Activities of lamivudine, adefovir, and penciclovir against wild-type and lamivudine-resistant HBV in cell cultures. HepG2 cells were transfected with plasmids encoding wild-type, rtV173L, rtL180M and rtM204V, or rtV173L, rtL180M, and rtM204V HBV DNAs and then treated with the indicated concentrations of lamivudine, adefovir, or penciclovir. After 1 week of treatment, intracellular HBV replicative intermediates were isolated and analyzed by Southern blotting. Relaxed circular (RC), double-stranded (DS), and single-stranded (SS) forms of HBV DNA are indicated.