FIG. 3.

A repressor element is present in the −67 to −55 region of the LRS. Mutations in the putative repressor site were introduced in the pgLRS(−106)CAT and pgLRS(−634)CAT plasmids, as indicated in Fig. 1 and in Materials and Methods. The reporter plasmids were transfected into the EBV-negative B-cell line DG75. The CAT activity is given as relative chloramphenicol acetylation expressed as a percentage of the activity obtained with the pgLRS(−54)CAT plasmid. The 100% value corresponded to acetylation of 19% of the substrate in the assay. The values are the means from three independent transfections with double samples. Error bars indicate standard errors of the means.