Dhanya K. Williams, Teresa A. Galvin, Hailun Ma, Arifa S. Khan:
Laboratory of Retroviruses, Division of Viral Products, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, 8800 Rockville Pike, HFM-454, Bethesda, MD 20892, USA
Received 1 June 2011; revised 17 August 2011; Accepted 18 August 2011. Available online 12 October 2011.
Xenotropic murine leukemia virus-related virus (XMRV) was discovered in human prostate tumors and later in some chronic fatigue syndrome (CFS) patients. However, subsequent studies have identified various sources of potential contamination with XMRV and other murine leukemia virus (MLV)-related sequences in test samples. Biological and nucleotide sequence analysis indicates that XMRV is distinct from known xenotropic MLVs and has a broad host range and cell tropism including human cells.
Therefore, it is prudent to minimize the risk of human exposure to infection by evaluating XMRV contamination in cell lines handled in laboratory research and particularly those used in the manufacture of biological products.
Nested DNA PCR assays were optimized for investigating XMRV gag and env sequences in various cell lines, which included MRC-5, Vero, HEK-293, MDCK, HeLa, and A549, that may be used in the development of some vaccines and other cell lines broadly used in research.
The sensitivity of the DNA PCR assays was <10 copies in approximately 1.8 x 105 cells equivalent of human DNA. The results indicated the absence of XMRV in the cell lines tested; although in some cases DNA fragments identified as cellular sequences were seen following the first round of PCR amplification with the env primer pair.