Infectious mononucleosis, Epstein-Barr virus, and chronic fatigue syndrome: a prospective case series.

Epstein-Barr viral infection, specifically infectious mononucleosis, typically has a more protracted course than other acute viral illnesses. Some recent observers have additionally suggested the possibility that Epstein-Barr virus (EBV) is the etiologic infectious agent in chronic fatigue syndrome, based on the finding of higher proportions of elevated antibodies to the EBV early antigen in some patients complaining of chronic fatigue. Straus et al reported on 23 patients with chronic fatigue, 83% of whom exhibited persistently elevated antibodies in modest titer to the early antigen. Ten of these patients had never fully recovered from an episode of acute infectious mononucleosis. Other studies had noted similar associations between persistently elevated antibodies to EBV-specific antigens and chronic symptoms in patients who presented with chronic symptoms after mononucleosis. Three important antigen complexes, demonstrable by immunofluorescence procedures, are expressed in EBV-infected cells. The early antigen is thought to function perhaps in early replication of viral DNA. A late antigenic complex, the viral capsid antigen, may represent, in addition to structural capsid proteins, components of the viral enzymatic machinery for late phases of replication or transformation. The Epstein-Barr nuclear antigen is felt to function in viral transformation of host cells.