RT Journal Article SR Electronic(1) A1 Caßens, Sven A1 Ulrich, Uwe A1 Beimling, Peter A1 Simon, DietrichYR 1994 T1 Inhibition of Human T Cell Leukaemia Virus Type I Long Terminal Repeat Expression by DNA Methylation: Implications for Latency JF Journal of General Virology, VO 75 IS 11 SP 3255 OP 3259 DO https://doi.org/10.1099/0022-1317-75-11-3255 PB Microbiology Society, SN 1465-2099, AB Human T cell leukaemia virus type I (HTLV-I) provirus DNA was found to be methylated in patients with adult T cell leukaemia. We have therefore examined the possibility that DNA methylation might contribute to HTLV-I latency. In vitro methylation of HTLV-I long terminal repeat (LTR)-chloramphenicol acetyltransfer- ase or LTR-Luciferase constructs at eight HpaII sites, a subset of the eukaryotic methylation site CpG, resulted in a three- to fourfold inhibition of transcription in transfected cells. Inhibition of transcription by methylation of all CpG methylation sites using Sxsl methylase was much more pronounced (50- to 80-fold). As partial methylation of the LTR showed, methylation of the promoter region was responsible for most of the effect. Whereas cellular stimulation by a combination of phorbol 12-myristate 13-acetate and Tax was able to reverse the HpaII methylation effect, the inhibition by SsjI methylation was not suppressible under these conditions. The results are in line with a possible function of DNA methylation in HTLV-I latency., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-75-11-3255