FIG 4.

CpG methylation status of the ERVWE1 enhancer (TSE) and promoter (U3) regions determined by pyrosequencing. Percent methylation of 7 CpG sites was measured in uninfected and influenza A/WSN/33 virus-infected SK-N-MC cells (MOI = 0.1 or 0.5) (A), A549 cells (MOI = 0.1, 0.5, or 1) (B), 293A cells (MOI = 0.1, 0.5, or 1) (C), and human fibroblast cultures (MOI = 0.5) (D) at 48 h after infection. Shown at the top is a schematic representation of the MaLR (LTR)-ERVWE1 (5′ LTR) region analyzed with the relative positions of the CpG sites analyzed (circles on vertical bars). Transcription starts at the U3/R (5′ LTR) boundary (arrow). CAAT and TATA boxes as well as putative and effective transcription factor binding sites (Sp-1, GATA, estrogen receptor [ER], and Oct-1) proximal to or containing CpG sites are indicated. The GCM1 binding site is underlined.