Protein-DNA interaction and CpG methylation at rep*/vIL-10p of latent Epstein-Barr virus genomes in lymphoid cell lines

The viral interleukin-10 promoter (vIL-10p), overlapping the rep* element i n the Epstein-Barr virus (EBV) genome, is a promoter element active mostly in the late phase of the lytic cycle and immediately upon infection of B ce lls. rep* was, through transfection experiments with small plasmids, charac terised as a cis element supporting oriP replicative function. In this stud y, in vivo protein binding and CpG methylation at rep*/vIL-10p were analyse d in five cell lines that harbour strictly latent EBV genomes. Contrary to the invariably unmethylated dyad symmetry element (DS) of oriP, rep*/vIL-10 p was highly methylated and showed only traces of protein binding in all ex amined cell lines. This result is in agreement with vIL-10p being an inacti ve promoter of EBV genomes, and makes it less likely that rep* functions as a replicative-element of latent EBV genomes.