FIG. 5.

Gel electrophoresis of amplified linear 5′ viral DNA ends and LTR-LTR circle junctions. Mo-MuLV and Mo-MuLVΔ28 produced by chronically infected Rat2-2 cells were used to infect naive Rat2-2 cells. Low-molecular-weight DNA was extracted by the Hirt method 18 h postinfection, and aliquots were used to amplify the 5′ viral DNA ends by LM-PCR. Another aliquot of the same extracts was used to amplify LTR-LTR circle junctions. The PCR products were separated on a 2% agarose gel containing ethidium bromide. The expected sizes for the amplified 5′ linear viral DNA end and for the LTR-LTR circle junctions are 447 and 567 bp, respectively. Mock, no virus added; M, MspI-digested pBR322 plasmid DNA size markers.