DNMT1 and HIV infectious disease: In regulatory T cells, the effect of X4-tropic HIV infection demonstrated no significant change in the expression of DNMT1 and DNMT3a, while there was a substantial increase in expression of DNMT3b (41); however, increased expression of DNMT1, DNMT3a and DNMT3b was observed in CEM*174 T cells with significantly higher expression of DNMT3b (44).