Polyomavirus JC in the Context of Immunosuppression: A Series of Adaptive, DNA Replication-Driven Recombination Events in the Development of Progressive Multifocal Leukoencephalopathy

Figure 3

Recombination between replicating plasmids or viral DNA bearing an SV40 ori sequence. Electron micrographs showing in vitro replication of plasmids pSVod (3.3 kb), pSV2-neo (5.6 kb), or SV40 (5.2 kb) are reprinted from Jenab and Johnson [74] with permission from Elsevier. (a) A theta form with replication forks indicated by arrows. (b) A theta form with a dsb creating a free DNA end. (c) Two pSVod circles connected by a DNA bridge. (d) A DNA bridge (arrows) indicating recombination between plasmid pSVod and SV40 viral DNA. (e) A DNA bridge indicating recombination between plasmids pSVod and pSV2-neo. No dual-circular forms or theta forms were seen in the absence of either an SV40 ori or large T-antigen. The drawing at bottom depicts potential dual circular recombination generated by dsb followed by strand invasion.