f-h) A padlock probe assay, as illustrated in Appendix Figure S4, was used to demonstrate persistence of proviral DNA either in a circular or integrated form. Representative images show DNA persistence in (f) LV-, (g) NILV- or (h) NILV-S/MAR-transduced cells. Each red dot (Cy3) represents a single DNA molecule and cell nuclei were stained with Hoechst 33342. 