Sporadic mouse DNA contamination provided a satisfying explanation for the positive PCR results, but what was the source of XMRV itself? The key to this puzzle turned out to be the 22Rv1 cell line mentioned above (Figure 1). Around 1992, a tumor line named CWR22 was established from a prostate cancer by xenotransplantation into nude mice. The CWR22 tumor was maintained by serial nude mouse transplant for 7 years and spawned several sublines, one of which was 22Rv1. 22Rv1 has been grown continuously ever since, distributed to laboratories worldwide, and become popular as a prostate cancer model. Indeed, between its isolation in 1999 and the discovery that it was producing XMRV about 10 years later, there are no fewer than 134 papers reporting its use in many laboratories, none of which were aware that cultures contain about 1011 particles of virus per ml. Even in virology laboratories, there is occasional cross-contamination of cultures by viruses under study. It seems virtually certain that contamination of other cultures by infectious XMRV would have occurred when the cultures were handled by investigators who were unaware that their cultures were infected.
Not a surprise that it would be in a prostate cancer cell line, since a prostate cancer tumor would already have the virus present.
But it's the quantity of virus particles, and the presence in a variety of tumors (comfirmed 1st hand via my RNA seq virus pipeline) that demonstrates to me that it's not simply lab contamination, but actually present in a variety of cancer tumors.
I worked in a top notch clinical cancer sequencing lab, where the sample handling was very good. Cross contamination from cell lines would not account for the level of the virus present in samples
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Dougal_McHaggis ago
FULL STORY HERE https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(14)00071-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1931312814000717%3Fshowall%3Dtrue
Sporadic mouse DNA contamination provided a satisfying explanation for the positive PCR results, but what was the source of XMRV itself? The key to this puzzle turned out to be the 22Rv1 cell line mentioned above (Figure 1). Around 1992, a tumor line named CWR22 was established from a prostate cancer by xenotransplantation into nude mice. The CWR22 tumor was maintained by serial nude mouse transplant for 7 years and spawned several sublines, one of which was 22Rv1. 22Rv1 has been grown continuously ever since, distributed to laboratories worldwide, and become popular as a prostate cancer model. Indeed, between its isolation in 1999 and the discovery that it was producing XMRV about 10 years later, there are no fewer than 134 papers reporting its use in many laboratories, none of which were aware that cultures contain about 1011 particles of virus per ml. Even in virology laboratories, there is occasional cross-contamination of cultures by viruses under study. It seems virtually certain that contamination of other cultures by infectious XMRV would have occurred when the cultures were handled by investigators who were unaware that their cultures were infected.
meowski ago
Not a surprise that it would be in a prostate cancer cell line, since a prostate cancer tumor would already have the virus present.
But it's the quantity of virus particles, and the presence in a variety of tumors (comfirmed 1st hand via my RNA seq virus pipeline) that demonstrates to me that it's not simply lab contamination, but actually present in a variety of cancer tumors.
I worked in a top notch clinical cancer sequencing lab, where the sample handling was very good. Cross contamination from cell lines would not account for the level of the virus present in samples