HIV-1 Rev/RRE and cis elements in the 5' UTR do not augment RNA encapsidation into MLV viral particles. A. Vector RNA packaged into MLV derived viral particles was isolated from equivalent amounts of RT units in the media of 293T producer cells. RNA levels were measured by qRT-PCR and are expressed as arbitrary units (AU). RNA levels are shown in the absence (white bars) and presence (black bars) of Rev. B. Cytoplasmic RNA was isolated from vector producer cells coincident with harvesting vector particles. Relative levels are expressed similar to vector RNA in part A. C. Efficiency of encapsidating RNA into MLV viral particles is expressed as a ratio of vector RNA in viral particles to cytoplasmic RNA available for encapsidation. D. Transduction of 293T cells with MLV/HIV RRE + RU5PS at 5 days post-transduction (no passaging of cells, P0), and after 5 passages of cells (P5). Percent GFP positive cells were assessed by FACscan analysis and compared to non-transduced (No Vector) 293T cells. Error for all bar graphs is expressed as ±S.D. All experiments were performed in triplicate.