FIG. 3.

Northern blot analysis of vector-derived transcripts in transduced HeLa cells. Total RNA was extracted from HeLa cells transduced with an RRLPGK-GFP vector (lane 1) or with its SIN versions SIN-18 (lane 2), SIN-36 (lane 3), SIN-45 (lane 4), and SIN-78 (lane 5). In lane 1, three bands with the sizes expected for the LTR-derived transcripts (unspliced and spliced) and the PGK-derived transcripts are visible. As expected for HeLa cells, transcription was initiated much more frequently at the internal PGK promoter than at the 5′ HIV-1 LTR. In lanes 2 to 5, transcripts derived from SIN vectors are 340 to 400 nucleotides smaller than the corresponding transcripts in lane 1. RNA initiated at the HIV-1 LTR is detectable in lane 5 but not in lanes 2 to 4. Positions of molecular size markers (in kilobases) are indicated on the right. Ψ, encapsidation signal; SD, splice donor; SA, splice acceptor.