Comparison of the characteristics of foci formed by expression of E1 and E2 proteins and naturally occurring replication foci in differentiated HPV containing cells.

<p>HFKs were transiently transfected with HPV16 E1 and E2 expression plasmids and the control plasmid pKS (left column), or with HPV16 E1 and E2 expression plasmids and the replication origin plasmid p16ori (middle column). HPV31 genome containing 9E cells (right column) were differentiated for five days as described in Methods. Cells were stained for E1, E2, Brd4, H3K4me1, H4K8ac and H3K56ac, Rad51, pATM and γH2AX, as indicated. The rabbit Brd4 mcb2 antiserum is used in most panels, except for H3K4me1, H4K8ac and H3K56ac staining in HPV31 9E cells (right column), where a mouse Brd4 antibody 8H2 was used. A goat anti-Rad51 antibody was also used in these panels. A mouse Rad51 antibody was used to stain HPV31 9E cells, along with Brd4 (rabbit mcb2) and γH2AX (mouse). Isotype specific secondary antibodies were used to distinguish between the mouse antibodies. Cellular DNA is counterstained with DAPI (blue in merged panels).