Figure 2.

Single-cycle direct repeat deletion assay to determine the percentage of template switching in vivo. Proviruses containing a direct repeat (horizontal arrows) of the green fluorescent protein gene (GFP) were mobilized and used to infect target cells. The frequency of a homologous template switch during reverse transcription in target cells, which reconstitutes a functional GFP gene, was measured by flow cytometry. IRES, internal ribosomal entry site; hygro, hygromycin gene; LTR, long terminal repeats.