High titers of anti-Epstein-Barr virus DNA polymerase are found in patients with severe fatiguing illness.
Natelson, B H, Ye, N, Moul, D E et al.·Journal of medical virology·1994
This study looked for specific antibodies (proteins the immune system makes) against Epstein-Barr virus (EBV) in people with ME/CFS compared to healthy people. Researchers found that abnormal levels of these antibodies were twice as common in ME/CFS patients, and the effect was even stronger in sicker patients. This suggests these antibodies might help doctors identify which ME/CFS patients have more severe illness.