Dear Sirs,

The findings in this report are quite valid and interesting. It is expected that an integrase-inhibitor, Rategravir, would inhibit the integration and replication of XMRV, a retrovirus.

However, the title and some text indicate that XMRV is implicated in Chronic Fatigue Syndrome and suggest that antiretroviral compounds may be useful in treating it. I believe this is a misleading and potentially dangerous assertion.

Recent reports in PLOS One indicate that XMRV is, in fact, NOT associated with Chronic Fatigue Syndrome.
1. Erlwein O, Robinson MJ, Kaye S, Wills G, Izui S, et al. (2011) Investigation into the Presence of and Serological Response to XMRV in CFS Patients. PLoS ONE 6(3): e17592.
2. Erlwein O, Kaye S, McClure MO, Weber J, Wills G, et al. (2010) Failure to Detect the Novel Retrovirus XMRV in Chronic Fatigue Syndrome. PLoS ONE 5(1): e8519.
3. Hohn O, Strohschein K, Brandt AU, Seeher S, Klein S, et al. (2010) No Evidence for XMRV in German CFS and MS Patients with Fatigue Despite the Ability of the Virus to Infect Human Blood Cells In Vitro. PLoS ONE 5(12): e15632.

Also, a report is being published in Journal of Virology that indicates the absence of XMRV in patients with Chronic Fatigue Syndrome.
Citation: Shin C, Bateman L, Schlaber R, Bunker A, Leonard C, Hughen R, Light A, Light K, Singh I. "Absence of XMRV and other MLV-related viruses in patients with Chronic Fatigue Syndrome." Journal of Virology. May 4 2011.

I will summarize with the following points:

1. Blood from Chronic Fatigue Syndrome and healthy volunteers was negative for XMRV DNA.
2. The sera from healthy volunteers and Chronic Fatigue Syndrome patients did not contain anti-XMRV antibodies.
3. There were no infectious XMRV viral particles in the plasma of either patients or healthy volunteers.
4. A subset of the patients from this study were used from a previous study.
5. Mouse DNA was present in a reagent used in previously published positive-finding study .... indicating a mechanism for the false-positive report (Lo, S. C., N. Pripuzova, B. Li, A. L. Komaroff, G. C. Hung, R. Wang, and H. J. Alter. 2010. Detection of MLV-related virus gene sequences in blood of patients with chronic fatigue syndrome and healthy blood donors. Proc Natl Acad Sci U S A.).

Secondly, XMRV is not linked to Prostate Cancer.
1. Furuta RA, Miyazawa T, Sugiyama T, Kuratsune H, Ikeda Y, Sato E, Misawa N,Nakatomi Y, Sakuma R, Yasui K, Yamaguti K, Hirayama F. No association of
xenotropic murine leukemia virus-related virus with prostate cancer or chronic fatigue syndrome in Japan. Retrovirology. 2011 Mar 17;8:20.
2. Garson JA, Kellam P, Towers GJ. Analysis of XMRV integration sites from human prostate cancer tissues suggests PCR contamination rather than genuine human infection. Retrovirology. 2011 Feb 25;8:13.

The prescription of expensive medication that may have harmful side effects, like antiretrovial compounds, should be made with precaution. There is a reason that these compounds are controlled substances and not available over the counter.

Many Thanks,
Erick Tatro