Activation of human herpesviruses 6 and 7 in patients with chronic fatigue syndrome

J Clin Virol. 2006 Dec;37 Suppl 1:S47-51. doi: 10.1016/S1386-6532(06)70011-7.


Background: Human herpesvirus 6 (HHV-6) and 7 (HHV-7) have been suggested as possible triggering agents for chronic fatigue syndrome (CFS).

Objectives: To determine the possible association of HHV-6 and HHV-7 infections with CFS.

Study design: The prevalence of latent/persistent and active viral infections by nPCR, characteristic of HHV-6 variants using restriction endonuclease analysis and changes of lymphocyte subsets in peripheral blood by laser flow-cytometry in 17 CFS patients was examined. In addition, 12 patients with unexplained chronic fatigue and 20 blood donors (BD) were studied.

Results: No difference in prevalence of latent/persistent single viral infections between the patients and BD was found but dual infection rate was significantly higher in CFS patients. Active HHV-6 and dual (HHV-6 + HHV-7) infections were detected in CFS patients only and frequency of HHV-7 reactivation was also significantly higher in these patients. HHV-6 variant B was predominant in CFS patients (12/13). The changes of immunological parameters in CFS patients with active dual infection were characterized by significant decrease of CD3+ and CD4+ T cells, significant increase of CD95+ cells and decrease of CD4+/CD8+ ratio.

Conclusions: HHV-6 and HHV-7 may be involved in the pathogenesis of CFS and reactivation of both viruses may provoke changes in the phenotype of circulating lymphocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • CD3 Complex / analysis
  • CD4 Lymphocyte Count
  • CD4-CD8 Ratio
  • DNA, Viral / analysis
  • DNA, Viral / genetics
  • Fatigue Syndrome, Chronic / virology*
  • Female
  • Flow Cytometry
  • Herpesvirus 6, Human / classification
  • Herpesvirus 6, Human / immunology
  • Herpesvirus 6, Human / isolation & purification
  • Herpesvirus 6, Human / physiology*
  • Herpesvirus 7, Human / immunology
  • Herpesvirus 7, Human / isolation & purification
  • Herpesvirus 7, Human / physiology*
  • Humans
  • Lymphocyte Subsets
  • Male
  • Middle Aged
  • Polymerase Chain Reaction
  • Roseolovirus Infections / complications*
  • Roseolovirus Infections / immunology
  • Roseolovirus Infections / virology
  • Virus Activation*
  • fas Receptor / analysis


  • CD3 Complex
  • DNA, Viral
  • fas Receptor