A Short History of XMRV VP62 Plasmid

• XMRV was created by a chance contamination/recombination of two MLV-like retroviruses (preXMRV-1 and preXMRV-2). This happened in human cell lines that were cultured using mouse tissues, which expressed the MLVs as ERVs. This lead to the infection of the 22Rv1 cell line with XMRV (This created a virus capable of infecting human cell lines).
• 22Rv1, being a prostate cancer cell line, ended up in labs of people working on prostate cancer
• Somehow, the virus jumped from the 22Rv1 cell line to prostate cancer biopsy samples (Contamination of lab equipment?) in the Urisman et al. 2006 study
• Silverman's lab sequenced the viruses for Urisman et al. 2006. One sequence was VP62, which came from patient sample 62 (hence the name for "Virus from Patient sample 62").
• For research, Silverman's lab sequenced some of viruses (VP62, VP35, VP42) and turned VP62 into a plasmid, so people could work with it for research
• In March 2008 Silverman send XMRV VP62 plasmid to Dr. Mikovits at the WPI lab
• VP62 plasmid was used in Lombardi 2009 as a control
• Besides that, what else the XMRV VP62 plasmid was used for at the WPI remains unknown
• In the study Lombardi et al. 2009 (with Dr. Mikovits being the principal investigator of that study) XMRV was reported to have been found preferentially in patient samples
• For Lombardi et al. 2009 Dr. Silverman did test a few samples by PCR, while most of the PCR was done at WPI
• Only sequences closely related to VP62 were reported by the WPI both in Lombardi et al. 2009 and afterwards
• In September 2011 Silverman reported doing new tests and finding XMRV plasmid in the few samples he got from WPI for Lombardi et al. 2009

As a note: The sequence diversity reported by Urisman et al. 2006 (VP62, VP35, VP42) – for what is likely a lab contamination from cell lines – is far higher than the sequence diversity reported by Lombardi et al. 2009.