Balada, Eva, Castro-Marrero, Jesús, Felip, Lledó et al. · Journal of clinical immunology · 2011 · DOI
Researchers tested whether a virus called XMRV—which had been found in some ME/CFS patients—might also be present in people with lupus (SLE), a different autoimmune disease that also causes severe fatigue. They checked blood samples from 95 lupus patients and 50 healthy people but found no sign of XMRV in any of them. This suggests that XMRV is probably not responsible for the fatigue seen in lupus patients.
This study is relevant to ME/CFS research because it tests a hypothesis about a potential viral cause of fatigue across different patient populations. The negative findings in SLE help narrow the search for XMRV's role in disease and suggest that fatigue in different conditions may have distinct biological origins, informing future pathophysiology research in ME/CFS.
This study does not prove that XMRV is absent in ME/CFS itself—it only examined SLE patients and controls. It cannot establish whether XMRV plays any role in ME/CFS pathology, nor can it rule out other viruses or environmental factors as contributors to fatigue. The cross-sectional design means no causality can be inferred for any associations.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Balada, Eva, Castro-Marrero, Jesús, Felip, Lledó, Vilardell-Tarrés, Miquel, & Ordi-Ros, Josep (2011). Xenotropic murine leukemia virus-related virus (XMRV) in patients with systemic lupus erythematosus.. Journal of clinical immunology. https://doi.org/10.1007/s10875-011-9535-5
BibTeX
@article{mecfsatlas-balada-2011-xenotropic-murine,
author = {Balada, Eva and Castro-Marrero, Jesús and Felip, Lledó and Vilardell-Tarrés, Miquel and Ordi-Ros, Josep},
title = {Xenotropic murine leukemia virus-related virus (XMRV) in patients with systemic lupus erythematosus.},
journal = {Journal of clinical immunology},
year = {2011},
doi = {10.1007/s10875-011-9535-5},
note = {PubMed: 21509625},
url = {https://www.mecfsatlas.com/evidence/balada-2011-xenotropic-murine},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/balada-2011-xenotropic-murine
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