FIG. 2.

DHBV virion-associated rcDNA deproteinization requires DNA polymerase activity. Approximately 10⁸ DHBV virion particles prepared from DHBV-positive duck serum were contained in each 100-μl EPR mixture as described in the legend of Fig. 1. The reaction mixtures were either without incubation (lanes 2 and 3) or incubated (lanes 4 to 10) at 37°C for the indicated periods of time. For the samples analyzed in lanes 8 to 10, dNTP was omitted (lane 8), or dCTP was replaced by ddCTP (lane 9), or 1 mM PFA was added into the EPR mixture (lane 10). Core and DP DNA were extracted from the reaction mixtures and analyzed by Southern blot hybridization assay. One hundred picograms of unit-length DHBV DNA served as the molecular weight marker (lane 1). The position of rcDNA (RC) is indicated.