FIG. 1.

Schematic drawing of the expression vectors for 2LTRZFP-GFP, Aart-GFP, and RFP. (A) The transfer vectors used in this study were derived from the third-generation, self-inactivating vector pRRLSIN.cPPT.mPGK-GFP.WPRE. The XbaI and SalI sites were used as the cloning sites for all transgenes. (B) The packaging vector pMDLgag/polRRE expresses the gag and pol transcript, intervening sequences, and polyadenylation site, and it is driven by the CMV promoter. pRSV-Rev expresses rev cDNA. pMD.G encodes a heterologous envelope to pseudotype the virus coding for VSV-G. (C) The nonviral based vector pCEP4 was used to construct pCEP4-2LTRZFP-GFP and pCEP4-Aart-GFP for stable cell line production. NheI and NotI were used as cloning sites for both transgenes. The EBV origin of replication (oriP) and nuclear antigen (EBNA-1) signal result in high-copy episomal replication in primate and canine cell lines (Yates et al., 1985; Reisman and Sugden, 1986). cPPT, central polypurine tract; GA, fragment of the HIV-1 gag gene; RRE, Rev-responsive element; WPRE, woodchuck hepatitis virus posttranscriptional regulatory element.