Nucleic Acid, Antibody, and Virus Culture Methods to Detect XMRV

[Jemal]

Nucleic Acid, Antibody, and Virus Culture Methods to Detect Xenotropic MLV-Related Virus (XMRV) in Macaque and Human Blood Samples

Mary Kearney, Kyeongeun Lee, Rachel Bagni, Ann Wiegand, Jonathan Spindler, F. Maldarelli, Peter A. Pinto, W. Marston Linehan, Cathy D. Vocke, Krista Delvis-Frankenberry, Robert deVere White, Greg Del Prete, J. W. Mellors, Jeffrey D. Lifson, Vineet KewalRamani, Vinay Pathak, John Coffin, and S. F J Le Grice

Received 21 June 2011; Revised 8 August 2011; Accepted 27 August 2011

ABSTRACT
The MLV-related retrovirus, XMRV, was recently identified and reported to be associated with both prostate cancer and chronic fatigue syndrome. At the National Cancer Institute-Frederick, MD (NCI-Frederick), we developed highly sensitive methods to detect XMRV nucleic acids, antibodies, and replication competent virus. Analysis of XMRV spiked samples and/or specimens from two pigtail macaques experimentally inoculated with 22Rv1 cell derived XMRV confirmed the ability of the assays used to detect XMRV RNA and DNA, and culture isolatable virus when present, along with XMRV reactive antibody responses. Using these assays, we did not detect evidence of XMRV in blood samples (N=134) or prostate specimens (N=19) from two independent cohorts of patients with prostate cancer. Previous studies detected XMRV in prostate tissues. In the present study, we primarily investigated the levels of XMRV in blood plasma samples collected from patients with prostate cancer. These results demonstrate that while XMRV-related assays developed at the NCI-Frederick can readily measure XMRV nucleic acids, antibodies, and replication competent virus, no evidence of XMRV was found in the blood of patients with prostate cancer.

http://www.hindawi.com/journals/av/aip/272193/

 

[Jemal]

Looks like a macaque study is about to be published as well:

These pre- and post-inoculation specimens were used as reference control samples in evaluating X-SCA methods for detection of XMRV. Details of the macaque infection study will be reported elsewhere (Del Prete, et al. in preparation).

And I guess this is also significant:

We required that samples test positive for XMRV nucleic acid (RNA or DNA) and by at least one other detect method (immunoassay or culture assay) to be declared positive for XMRV infection.

If we had used less rigorous criteria basing an overall diagnosis on a single, non-confirmed test and not requiring all replicates to yield the same result, then our two cohorts would have given rise to an apparent, and in our view almost certainly incorrect, reported XMRV prevalence rate of approximately 12%. These considerations may explain conflicting prior reports for the prevalence of XMRV and are consistent with claims that XMRV detection is likely the result of laboratory contamination.