Biological impacts of core promoter mutations introduced to a genotype C clone. Clone 17.3 and its site-directed mutants as SphI dimers were transfected to Huh7 cells. Cells and culture supernatant were harvested 5 days later. (A) Intracellular replicative DNA; (B) extracellular virion DNA; (C) intracellular envelope proteins and GAPDH; (D and E) secreted HBsAg and HBeAg based on three transfection experiments. The value for the parental construct was set at 100%. Lanes: M, HBV size markers; 1, T1758C; 2, T1753C/T1758A; 3, A1762T/G1764A; 4, T1753C/A1762T/G1764A; 5, parental construct; 6, mock-transfected cells.