Fig. 4. ChIP assay reveals UBF preferentially precipitates sequences near the ends of the viral genome. Three different samples of target DNA were used to amplify different regions of the viral genome as indicated along the top. Either purified Ad2 DNA, or virally infected cells subjected to ChIP using anti UBF serum or virally infected cells subjected to ChIP using the matched pre-immune sera. In each case four different primer pairs were used to amplify, by PCR, four different regions of viral DNA, viz. sigma (250 bp from left hand end), E1 promoter (450 bp from left hand end), Major late promoter (6000 bp from left hand end), VA RNA I (12000 bp from left hand end), Fibre gene (4000 bp from right hand end) and E4 ORF3 (1500 bp from right hand end). The PCR products were separated on agarose gels and photographed as shown. The primer pair used in each sample is indicated at the top of the gel. On the right hand side the size of two markers are indicated, the intervening marker sizes are 400 bp, 350 bp and 300 bp.