Judy A. Mikovits

Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome

In October 2009, we reported the first direct isolation of infectious xenotropic murine leukemia virus-related virus (XMRV). In that study, we used a combination of biological amplification and molecular enhancement techniques to detect XMRV in more than 75% of 101 patients with chronic fatigue syndrome (CFS). Since our report, controversy arose after the publication of several studies that failed to detect XMRV infection in their CFS patient populations. In this addenda, we further detail the multiple detection methods we used in order to observe XMRV infection in our CFS cohort. Our results indicate that PCR from DNA of unstimulated peripheral blood mononuclear cells is the least sensitive method for detection of XMRV in subjects blood. We advocate the use of more than one type of assay in order to determine the frequency of XMRV infection in patient cohorts in future studies of the relevance of XMRV to human disease.

Immune correlates of XMRV infection

Methods This hypothesis was addressed by multiplex profiling of plasma cytokines and chemokines on a LuminexTM platform and phenotypic analysis of leukocyte subsets by multi-parameter flow cytometry in XMRV infected CFS patients versus uninfected controls. XMRV-infected subject and control samples were assayed blindly. Analysis was performed using the Gene Expression Pattern Analysis Suite and Random Forest tree classification algorithms. For immune profiling, 63 XMRV infected CFS patient samples were analyzed within 6 hours using an LSRII flow cytometer with BD FACSDiva software. Six normal donors and reference values based on a healthy population were used as normal baselines. Results