title: Human herpesvirus 6 and 7 reactivation and disease activity in multiple sclerosis.
abstract: Recent studies have focused on the associations between human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7), and multiple sclerosis (MS). The aim of this study was to investigate the associations between HHV-6 and HHV-7 reactivation and MS disease activity, and interleukin 12 (IL-12) and tumor necrosis factor α (TNF-α) production.
  
  
  METHODS
  The frequency of plasma viremia by nested polymerase chain reaction and transcription of viral mRNA in peripheral blood mononuclear cells by reverse transcriptase-polymerase chain reaction (RT-PCR) of 14 relapsing/remitting (RR) and 14 secondary progressive (SP) MS patients were studied in comparison with clinical manifestation of the disease. Serum concentrations of cytokines IL-12 and TNF-α were analyzed by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Plasma samples from 25 of the 28 MS patients with estimated latent/persistent HHV-6 and/or HHV-7 infection were examined during relapse and remission/relative remission. HHV-6 reactivation was found in 4 of the 7 RRMS and 4 of the 7 SPMS patients, and HHV-7 reactivation was identified in 3 of the 7 RRMS and 1 of the 7 SPMS patients (all in relapse). In 2 of the 3 RRMS patients without viremia in relapse, HHV-6 mRNA transcription was detected. In RRMS and SPMS patients with active HHV-6 and HHV-7 infection in relapse, the serum concentrations of IL-12 and TNF-α were significantly higher than in those with latent virus infection.
  
  
  CONCLUSIONS
  HHV-6 and HHV-7 reactivation could be implicated in the exacerbation of MS via activation of Th1 lymphocyte subsets.
authors.affiliation: August Kirchenstein Institute of Microbiology and Virology, Riga Stradins University, Latvia. zaiga.nora@gmail.com
authors.forename: Zaiga
authors.initials: Z
authors.lastname: Nora-Krukle
authors.forename: Svetlana
authors.initials: S
authors.lastname: Chapenko
authors.forename: Inara
authors.initials: I
authors.lastname: Logina
authors.forename: Andrejs
authors.initials: A
authors.lastname: Millers
authors.forename: Ardis
authors.initials: A
authors.lastname: Platkajis
authors.forename: Modra
authors.initials: M
authors.lastname: Murovska
mesh_terms: D000293:Adolescent; D000328:Adult; D018450:Disease Progression; D005260:Female; D015654:Herpesvirus 6, Human / Q000302:isolation & purification / Q000502:physiology*; D016199:Herpesvirus 7, Human / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D018664:Interleukin-12 / Q000097:blood; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000097:blood / Q000276:immunology* / Q000821:virology*; D019349:Roseolovirus Infections / Q000150:complications / Q000821:virology*; D018417:Th1 Cells / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014766:Viremia / Q000150:complications / Q000175:diagnosis / Q000821:virology; D014775:Virus Activation; D055815:Young Adult
chemical_list: D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12