FIG. 1.

Portion of the U3 region of the LTR of the MVV recombinant clones VA3 and VA4 comprising the duplications studied in this work. The repeated sequence is marked with vertical lines. The potential transcription factor binding sites where the sequence is identical to the consensus sequence are indicated by a solid line under the sequence; dotted lines below the sequence indicate sites that deviate from the consensus sequence by one nucleotide. Nucleotide deletions are indicated by dashes. The ability of each virus strain to replicate (+) or not (−) in SCP cells is indicated on the right.