FIG. 1.

Alpharetroviral split-packaging design. Shown is a schematic depiction of wild-type RSV and the derived split-packaging system, consisting of the transfer vector pAlpha.SF.EGFP.wPRE (plasmid DNA) and required helper plasmids pcDNA3.alpha.gag/pol and pEnvelope. The long terminal repeats (LTRs) (U3, R, and U5), direct repeat element (DRE), packaging signal (ψ), splice donor and acceptor sites (SD and SA), spleen focus-forming virus promoter (SFFV), enhanced green fluorescent protein (EGFP), woodchuck hepatitis virus posttranscriptional regulatory element (wPRE), cytomegalovirus promoter (CMV), β-globin intron (βGI), and bovine growth hormone polyadenylation signal (bGH pA) are indicated.