Nested RT-PCR for sensitive and specific screening of patient tumor tissue RNA. (A) RT-PCR for all 589 RNA samples was carried out with In-For and In-Rev primers, followed by a quantitative real-time PCR using primers and probe as indicated. Using the Q445T forward primer spanning the XMRV typical deletion ensured specific detection of XMRV sequences. Primer sites are numbered according to the XMRV VP62 sequence. (B) Real-time PCR curves showing the mean of triplicates. The sensitivity shown in this example was 10 copies. (C) Example of the first 16 QQ patients RNA screen including GAPDH control reactions as the mean value of duplicates.