In-Depth Investigation of Archival and Prospectively Collected Samples Reveals No Evidence for XMRV Infection in Prostate Cancer
A probe hybridization mix containing XMRV-SO probe (full-length XMRV VP62) and CEP8-SA internal control probe (complementary to a centromeric region of human chromosome 8) was applied to each slide. (A) A representative image of XMRV-SO orange staining from a cell mixture of DU145 (uninfected; negative XMRV staining) and 22Rv1 (XMRV-infected; strong positive XMRV staining), showing two positively stained cells. (B) DAPI nuclear staining. (C) CEP8-SA aqua staining illustrating two and three CEP8 aqua signals per 22Rv1 and DU145 cell, respectively; (D–F) Representative images of FFPE prostate cancer tissue sections from patient VP62 (XMRV-SO, DAPI, and CEP8-SA, respectively). No XMRV-SO orange staining is observed. The white rectangle outlines the region magnified in panels G-I (G–I) A magnified image of FFPE prostate cancer tissue sections from patient VP62 (XMRV-SO, DAPI, and CEP8-SA, respectively). At this magnification, CEP8-SA aqua staining is clearly visible (panel I; white arrows highlight two representative CEP8 aqua signals). (J–L) Representative images showing no XMRV-SO orange staining in FFPE prostate cancer tissue sections from 3 representative patients (among the prospectively collected cohort of 39 patients).