[Note: The Centers for Disease Control & Prevention (CDC) has expedited the release of this research, reporting evidence of XMRV in the respiratory tract secretions of 2% to 10% of patients presenting with respiratory tract infections (and 3% of control subjects) in a German study. A full text PDF is available free at www.cdc.gov/eid/content/16/6/pdfs/10-0066.pdf ]
Xenotropic murine leukemia virus–related gammaretrovirus (XMRV) has been recently associated with prostate cancer and chronic fatigue syndrome. To identify nucleic acid sequences, we examined respiratory secretions by using PCR. XMRV-specific sequences were detected in 2% – 3% of samples from 168 immunocompetent carriers and about 10% of samples from 161 immunocompromised patients.
[Note: Specifically, of the 329 individuals tested for XMRV in this study:
• 62 were controls with no respiratory tract infection (RTI), of whom 2 (3.2%) were XMRV positive (all residents of North Germany).
• 75 had an RTI with no underlying condition, of whom 3 (2.3%) were XMRV positive (this group of people had traveled to Germany from Asia, permanent residency not recorded).
• 31 had an RTI with underlying chronic obstructive pulmonary disease (COPD), of whom 1 (2.3%) was XMRV positive (all residents of North Germany).
• 161 had RTI with immnosuppression owing to organ or bone marrow transplantation, of whom 16 (9.9%) were XMRV positive (all residents of North Germany).]
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Xenotropic murine leukemia virus-related gammaretrovirus (XMRV) was originally discovered in tissue from patients with familial prostate cancer homozygous for a missense mutation in the RNase L gene, R462Q. Detection of viral nucleic acid in tissue sections of cancerous prostate glands and cloning of the viral integration sites confirmed XMRV as a bona fide human infection with a murine leukemia virus-related retrovirus. Whether XMRV is actively involved in prostate cancer tumorigenesis or whether it is just a bystander virus remains unclear.
On the basis of its close homology (up to 94% nt identity) to endogenous and exogenous full-length sequences from Mus musculus mice, XMRV most likely originated in mice, although they are probably not the current reservoir of infection.
Recent findings of XMRV sequences in up to 67% of peripheral blood mononuclear cells (PBMCs) of patients with chronic fatigue syndrome and in 3.4% of PBMCs of healthy controls raise the question whether XMRV could be a blood-borne pathogen. However, the finding of XMRV in PBMCs from patients with chronic fatigue syndrome is controversial because multiple studies in Europe have failed to detect XMRV.
Similarly, frequency of XMRV in prostate cancer samples ranges from 0 to 23%, depending on geographic restriction of the virus or, more likely, diagnostic techniques used (PCR, quantitative PCR, immunohistochemistry). Indirect evidence has suggested sexual transmission.
Questions remain about worldwide distribution, host range, transmission routes, and organ tropism of the virus. To begin to answer some of them, we looked for XMRV in respiratory samples from 267 patients with respiratory tract infection (RTI) and 62 healthy persons….
Source: Emerging Infectious Diseases, Jun 2010, expedited release May 18, 2010. Fischer N, Schulz C, Stieler K, Hohn O, Lange C, Drosten C, Aepfelbacher M. University Medical Center Hamburg-Eppendorf, Hamburg; Robert Koch-Institute, Berlin; Leibniz-Center for Medicine and Biosciences, Borstel; University of Bonn Medical Centre, Bonn, Germany. [Email: firstname.lastname@example.org]