BK-Dunlop inserted into a pGEM vector (kindly provided by M. Imperiale) was digested using BamHI, then purified and re-ligated. The re-ligated genome was transfected into a T75 flask of RPTE cells in 5% FCS REGM. After three weeks, the cells were split into three T150 flasks and left for a further three weeks before harvesting. The cells were freeze thawed three times to release the virus and assayed using a fluorescent focus assay (protocols based on [57 (link)]).
The primary antibodies used were PAb597 against SV40 VP1 (kindly provided by W. Atwood), P5G6 against BKPyV VP1 (kindly provided by D. Galloway), ab53977 against SV40 VP1 (Abcam), ab53983 against SV40 VP2 and VP3 (Abcam), PAb416 against SV40 T-antigen (Abcam), H4A3 against LAMP-1 (Developmental Studies Hybridoma Bank) and ab6160 against tubulin [YL1/2] (Abcam). Secondary antibodies used were Alexa Fluor 568 donkey anti-mouse and Alexa Fluor 488 or 568 goat anti-rabbit (Invitrogen). LysoTracker red DND-99 was obtained from Life Technologies.