title: Prevalence of TT virus infection in blood donors with elevated ALT in the absence of known hepatitis markers.
abstract: OBJECTIVE
  Recently a novel DNA virus (TT virus) has been identified in Japan and shown to be associated with elevated aminotransferase levels after blood transfusion. The exact role of TTV in the pathogenesis of liver disease is yet to be established. Our aim was to determine the prevalence and role of TTV in the pathogenesis of elevated transaminases in healthy blood donors in the absence of markers for viral hepatitis A-C.
  
  
  METHODS
  Stored sera were collected from 99 healthy blood donors with elevated alanine amino transferase (ALT) values that were discovered at the time of blood donation. A total of 146 samples were obtained from healthy donors with normal ALT values who were used as controls. None of the patients or controls had a history of blood transfusion or had clinical signs of acute or chronic hepatitis. Serological markers for hepatitis A, hepatitis B, and hepatitis C viruses were negative. TTV DNA was amplified and detected using polymerase chain reaction followed by gel electrophoresis.
  
  
  RESULTS
  Five of 99 (5%) samples obtained from donors with elevated ALT had TTV DNA detected by PCR, as compared to one of 146 (0.7%) of those with normal ALT (p = 0.006). Among those with elevated ALT, mean ALT values in patients with TTV (296 +/- 305 U/L) were higher than in patients without TTV (95 +/- 37 U/L), but the difference was not statistically significant (p = 0.08). The two samples with highest ALT values (both >450 U/L) were among the five samples with detectable TTV DNA in serum.
  
  
  CONCLUSIONS
  Although TTV is not likely to explain the majority of elevated ALT cases in otherwise healthy blood donors, TTV infection may potentially be associated with some cases. Based on these findings, we propose that the role of TTV in the pathogenesis of acute and chronic liver diseases merits further investigation.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Cleavinger
authors.forename: D H
authors.initials: DH
authors.lastname: Persing
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: S B
authors.initials: SB
authors.lastname: Moore
authors.forename: M R
authors.initials: MR
authors.lastname: Charlton
authors.forename: C
authors.initials: C
authors.lastname: Sievers
authors.forename: T M
authors.initials: TM
authors.lastname: Therneau
authors.forename: N N
authors.initials: NN
authors.lastname: Zein
mesh_terms: D000410:Alanine Transaminase / Q000097:blood*; D001483:Base Sequence / Q000235:genetics; D001782:Blood Donors / Q000706:statistics & numerical data*; D018173:Circoviridae Infections / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D017925:Circovirus / Q000235:genetics; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000235:genetics; D006525:Hepatitis, Viral, Human / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
chemical_list: D004279:DNA, Viral; D000410:Alanine Transaminase