Changes of DNA titer and sequence variance of TT virus in hepatic disorders

TT virus (TTV) has been reported to occur in association with elevated alan ine aminotransferase (ALT) levels in patients with posttransfusion hepatiti s of unknown etiology. We examined whether the presence, change of DNA tite r, or variation in sequence of this virus is associated with acute or chron ic liver dysfunction in Japanese. We detected TTV by polymerase chain react ion (PCR) using primers generated from the conserved region of the TTV geno me. Direct DNA sequencing of the original N22 region was used to characteri ze TTV isolates. We detected TTV DNA in 15 (25%) of 60 patients with liver dysfunction. Variants recovered from infected patients formed four genotype s/subtypes, corresponding to G1a, G1b, G2, and G4. Although TTV DNA titers in patients with G2 and G4 were lower than those with G1, TTV was consisten tly detected regardless of genotype/subtype. TTV infection continued for at least 1 year after normalization of ALT level in patients with acute liver dysfunction. Changes in DNA titer, substitutions of deduced amino acids, a nd variety of quasispecies of TTV were detected during the observation peri od, but no significant fluctuation in ALT level was found. We conclude that persistent infection, changes in DNA titer, and variation in sequence of t his novel virus are not significantly related to hepatic disorders. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.