Primer extension analysis of HBV RNAs. HBV RNA isolated from Huh7 cells was analyzed by primer extension as described in Materials and Methods. (A) Primer extension analysis of the C gene transcripts. The locations of the precore RNA, core RNA, and hGH RNA are indicated. (B) Primer extension analysis of the S gene transcripts. The locations of the pre-S-2 RNA, major S RNA, and hGH RNA are indicated. Lanes 1, cells transfected with pWTD; lanes 2, cells transfected with pHBVΔSp1-1; lanes 3, cells transfected with pHBVΔSp1-2; lanes 4, cells transfected with pHBVΔSp1-1,2. Lanes M, DNA markers and their sizes (in kilodaltons).