HIV-1, PFV, MLV and ASV
integration on naked and chromatinized p5S vectors. Concerted integration assay was performed with 10 ng of donor DNA and 100 ng of p5S naked plasmids (lanes 1), or polynucleosomal vectors assembled with increasing amounts of histones expressed as DNA/histones mass ratio (μg/μg) (1/1.1, lanes 2; 1/1.3, lanes 3) and either HIV-1, PFV, MLV (100nM) or ASV (600 nM) integrases. The reaction products were loaded onto 1% agarose gel and a representative set of experiments is shown in the figure (A). The position and structures of the donor substrate and different products obtained after half-site (HSI), full-site (FSI) and donor/donor integration (d/d) are shown. The circular FSI + HSI and linear FSI products were quantified on gel using the ImageJ software and are shown respectively in the left and right panels in (B). The circular FSI products were specifically quantified by cloning in bacteria and shown as the number of ampicillin-, kanamycin- and tetracycline-resistant selected clones as a percentage of integration reaction control performed with naked vectors (C). All the values are shown as the mean ± standard deviation (error bars) of at least three independent sets of experiments. The number of selected clones is also shown at the top of the histogram.