FIG. 1.
Preparation of prepackaging cell line for generating VSV-G-pseudotyped retroviruses. (A) MoMLV-based retroviral vector. The bicistronic retroviral vector, S2 (19), contains an internal ribosome entry site (IRES) derived from the swine vesicular disease virus, thereby allowing the Neor gene to be translated internally. The cDNA of GFP or HCV core antigen (C191) was cloned at the first cistron in front of the IRES, yielding GFP/S2 or C191/S2, respectively. (B) Expression of vector RNA in the prepackaging cell line. The GFP/S2 or C191/S2 viral vector was transduced into the PtG-S2 cell line via an amphotropic retroviral infection (see Materials and Methods). A single clone that expressed the highest levels of vector RNA was selected as indicated by Northern blot analysis. The data show the RNAs from the clones selected, which were hybridized with Neor and glyceraldehyde phosphate dehydrogenase (GAPDH) probes. The arrowhead indicates the vector RNA; the arrow indicates the GAPDH RNA.