Figure 6.

Heterologous and chimeric transfer vector RNAs cross-packaging. (A) Reciprocal cross-packaging of heterologous RNAs containing MMTV packaging signal. RT-PCR of cytoplasmic (upper panel) and viral (lower panel) cDNAs amplified using MMTV specific primers and probed with the PCR product amplified using the same set of primers and HYB MTV as a template. For this set of experiment, primers OTR567 and OTR560 were used and should amplify 149 bp fragment. (B) Reciprocal cross-packaging of heterologous RNAs containing MPMV packaging signals. RT-PCR of cytoplasmic (upper panel) and viral (lower panel) cDNAs amplified using MPMV specific primers and probed with the PCR product amplified using the same set of primers and pKAL011 as template. For this set of experiments, primers OTR112 and OTR197 were used and should amplify 154 bp fragment. (C) MMTV and MPMV chimeric transfer vectors RNA containing each other's packaging sequences can be packaged in a reciprocal fashion. Upper panel represents RT-PCR of cytoplasmic cDNAs using vector RNA specific primers to ensure their stable expression. Lower panel represents RT-PCR of viral cDNAs amplified using chimeric vector specific primers. For this set of experiment, primers OTR567 and OTR560 were used for pND011 and pND012 and should amplify 149 bp. For pND015 and pND016, primers OTR730 and OTR197 were used and should amplify 268 bp. However, for the sake of clarity and to follow cross-packaging, the PCR products are shown next to each others in this figure.