Contribution of divergent positions 8, 12, and 13 at the 3′ end of SPII promoter on HBsAg production by the 1.3mer HBV DNA construct. Divergent positions 8, 13, or both were converted from two genotype A clones (5.4 and 6.5) to genotype D-specific sequences. Alternatively, divergent positions 8, 12/13, or 8/12/13 from two genotype D clones (1.2 and 20.11) were replaced with the genotype A sequences. The parental clones and the site-directed mutants as 1.3mer construct were transiently transfected to Huh7 cells, followed by Northern blot analysis of HBV RNAs (A), Western blot analysis of intracellular envelope proteins (B), and ELISA for intracellular HBsAg (1:600 dilution) (C) or extracellular HBsAg (1:200 dilution) (D).