not-yet-known not-yet-known not-yet-known unknown 2.2 Detection of MCPyV and HPV by Conventional PCR Genomic DNA was extracted using a QIAamp DNA Mini kit (Qiagen, Valencia, CA, USA) according to the manufacturer’s instructions and eluted in 70 µl. For MCPyV polymerase chain reaction (PCR) detection, we used four primer sets, namely, LT3 and LT1709.F-LT1846.R, VP1 and NCCR,12,26,29 targeting three different regions of the LT-ag, VP1 and NCCR. HPV-PCR using the GP5+/6+ primer was performed as described previously.30 The sequences of the primers used are shown in Supplementary Table S1 . The PCR mixtures contained a total volume of 50 μl, including 2 μl of genomic DNA , 1 μl each of the forward and reverse primers, 1 μl of a 10 mM dNTP mixture, 0.25 μl of 5 units of DiaStarTM Taq polymerase, and 5 μl of 10× Taq reaction buffer (SolGent, Daejeon, Republic of Korea). A PTC-200 Peltier Thermal Cycler (MJ Research, Reno, NV, USA) was used for the reaction. The PCR conditions for the 4 primer sets (LT1709-1846, LT3, VP1 and NCCR) were described previously.12,26,31 The PCR cycling for HPV included initial denaturation at 95 °C for 2 min, followed by 40 cycles of amplification at 95 °C for 20 sec, 45 °C for 30 sec, and 72 °C for 45 sec, with a final extension for 5 min at 72 °C. The experiments were repeated three times sequentially for accuracy. All PCRs were carried out using a negative control (PCR-grade water) in place of the template to assess cross-contamination. All PCR products were resolved by 2 % agarose gel electrophoresis and visualized under UV light with ethidium bromide (EtBr) staining.