title: Activation of human herpesviruses 6 and 7 in patients with chronic fatigue syndrome.
abstract: BACKGROUND
  Human herpesvirus 6 (HHV-6) and 7 (HHV-7) have been suggested as possible triggering agents for chronic fatigue syndrome (CFS).
  
  
  OBJECTIVE
  To determine the possible association of HHV-6 and HHV-7 infections with CFS.
  
  
  METHODS
  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.
authors.affiliation: August Kirchenstein Institute of Microbiology and Virology, Riga Stradins University, Ratsupites St.1, Riga, LV-1067, Latvia. modra@latnet.lv
authors.forename: S
authors.initials: S
authors.lastname: Chapenko
authors.forename: A
authors.initials: A
authors.lastname: Krumina
authors.forename: S
authors.initials: S
authors.lastname: Kozireva
authors.forename: Z
authors.initials: Z
authors.lastname: Nora
authors.forename: A
authors.initials: A
authors.lastname: Sultanova
authors.forename: L
authors.initials: L
authors.lastname: Viksna
authors.forename: M
authors.initials: M
authors.lastname: Murovska
mesh_terms: D000293:Adolescent; D000328:Adult; D017252:CD3 Complex / Q000032:analysis; D018791:CD4 Lymphocyte Count; D016516:CD4-CD8 Ratio; D004279:DNA, Viral / Q000032:analysis / Q000235:genetics; D015673:Fatigue Syndrome, Chronic / Q000821:virology*; D005260:Female; D005434:Flow Cytometry; D015654:Herpesvirus 6, Human / Q000145:classification / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D016199:Herpesvirus 7, Human / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D016131:Lymphocyte Subsets; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D019349:Roseolovirus Infections / Q000150:complications* / Q000276:immunology / Q000821:virology; D014775:Virus Activation; D019014:fas Receptor / Q000032:analysis
chemical_list: D017252:CD3 Complex; D004279:DNA, Viral; D019014:fas Receptor