Comparison of AAV2 duplex genome replication supported by Ad pHelper to that supported by HBoV1 helper genes in HEK293 and HeLa cells. HEK293 and HeLa cells were cotransfected with SSV9 and the Ad pHelper or HBoV1 helper plasmid or were infected with Ad5. At 48 h posttransfection, the cells were collected and lysed for Hirt DNA extraction. Hirt DNA samples were subjected to Southern blotting with a 32P-labeled AAV2 probe. dRF, mRF, ssDNA, the 4.3-kb AAV2 marker, and DpnI-digested DNA are indicated.