Fig. 2.

DNA recombination is central to VSG switching. The active subtelomeric VSG locus is prone to spontaneous DNA breaks. Three classes of repair templates are shown with VSGs represented as coloured boxes; those sharing more (flanking) homology with the active site are used more frequently (grey arrows). The homologous sequences indicated are the 70-bp repeats (blue stripes), the telomeric repeats (black stripes), the VSG 3′-UTRs (thick black bars) and a portion of the VSG coding sequence (red). A break in or around the active VSG is followed by DNA resection extending towards the 70-bp repeats, often initiating recombination in this region.