FIG. 1.

Schematic of the PCR strategy to detect and quantitate (−)ssDNA. Regions corresponding to R (+1 to +97) and U5 (+98 to +181) were detected by PCR using oligonucleotide probes as shown. Probes were used to detect and quantitate different regions of (−)ssDNA designated proximal (oligonucleotides P1 and P2, nt +132 to +181), intermediate (oligonucleotides S1 and P2, nt +96 to +181), and distal (oligonucleotides D1 and D2, nt +1 to +64) according to their positions relative to the site of reverse transcription initiation. The site of initiation and the direction of DNA synthesis by RT are indicated by the bent arrow.