Epstein-Barr virus load in the peripheral blood of patients with rheumatoid arthritis - Accurate quantification using real-time polymerase chain reaction

Objective. To determine whether patients with rheumatoid arthritis (RA) have elevated Epstein-Barr virus (EBV) load in their peripheral blood mononuclear cells (PBMCs) and whether it is correlated with the HLA-DR genes they express, we developed an accurate EBV DNA quantitative assay using real-time polymerase chain reaction (PCR) with fluorescent probes. Methods. We studied the EBV DNA load in the PBMCs of 84 patients with RA, 69 normal controls, and 22 patients with rheumatic conditions other than RA. A 214-bp segment from the long internal repeat of EBV was amplified from 500 ng of PBMC DNA (150,000 cells) and quantified by real-time PCR with fluorescent probes. Results. We demonstrated that in patients with RA, the EBV DNA load in PBMCs is increased almost 10-fold compared with that in normal controls. The EBV load is stable over time and is not obviously influenced by disease-modifying antirheumatic drugs or HLA-DR. Conclusion. Patients with RA have elevated EBV load in their peripheral blood.