Xenotropic Murine Leukemia Virus-Related Virus (XMRV) is a retrovirus originally identified in human prostate cancer tissues. Different studies show large differences in the detection of XMRV in prostate cancer patients (0 to 27%). While the explanation for this variability is unknown, genetics, geographical distribution, sequence diversity in viral strains, methodological variations and laboratory contamination are suspected.
Here we will describe our methods for detecting low copies of XMRV nucleic acids in urine. Urine specimens from cancer patients are sometimes used as a source of RNA for monitoring expression of genes of interest, such as genes implicated in oncogenesis and metastasis.
RNA was extracted from urine samples and real-time RT - PCR was used to measure low copies of XMRV RNA. Confirmation of the presence of XMRV nucleic acids was obtained by nested RT - PCR. These methods specifically amplify env sequences corresponding to variable regions A and C of the gp70 envelope protein. The amplicons were sequenced and matched to previously published XMRV sequences. The low levels of XMRV nucleic acids in patient samples highlight the challenges of performing PCR methods as an indicator of XMRV infections. However, in the future, high throughput automated PCR methods may lead to large-scale screening of prostate cancer patients. Such methods have the potential to be a convenient assay on a readily obtainable body fluid like urine.