Impact of TT virus infection in acute and chronic, viral- and non viral-related liver diseases

Background/Aims: The prevalence and pathogenicity of TT virus, recently identified in patients with non A-non G post-transfusional hepatitis, are questioned. Methods: We investigated the impact of this new viral infection in a large series of patients with non A-non G, cryptogenic, non-viral and viral-related, acute and chronic liver diseases (n=577) and blood donors (n=300). TTV DNA was detected in serum by heminested polymerase chain reaction. Phylogenetic analysis was performed in 13 isolates. Results: TTV DNA was detected in 6/25 and 15/127 patients with cryptogenic non A-non G acute and chronic liver disease, respectively. TTV DNA positive subjects with post-transfusional acute hepatitis scored negative before transfusion. TTV prevalence was increased in patients with cryptogenic non A-non G acute and chronic liver disease compared to blood donors (6/300; p<0;0.001) and non-viral-related chronic liver diseases (6/137; p<0;0.05). TTV/HBV coinfection was frequently identified (35/147), but this was not the case for HCV-infected subjects (4/77). Transaminase activity or liver histological score was not significantly increased among TTV positive, HBV infected or non A-non G patients. The HBV infection and Mediterranean origin were the risk factors associated with TTV infection. The majority of analysed sequences clustered in genotype 1 (8=1b; 3=1a). Two isolates showed homology to genotype 2. Conclusions: These results support the view that TTV is a widely spread infectious agent with a weak pathogenicity. It raises the possibility, however, that TTV might be implicated in a few cases of acute and chronic non A-non G hepatitis. TTV-DNA-analysed sequences are related to genotypes 1 and 2 described in Europe.